Manual for Dental Technicians

MANT]AL FOR

DE NTA L TE CHNICIA N S rULCA] VI T E t]\'

J. A. SALZMANN, D.D.S. Chairnran, Conrmittee on Coursesfbr Dental Technicians and Head of Dental Service,New York City Vocational Schools: Editor, New York Journal of Dentistry : author of Principles and Praclice of Public Healtl Denristrl

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D E N T A L LABORATORY M E C H A N I C S

INTRODUCTION DEN-S~IL LAROR.ITORY MECHANICS is an art which deals with the construction of prosthetic (artificial) appliances for the replacement of teeth and gums lost through disease or accident. As an occupation it fills an important human need by corltributing to the health and happiness of mankind. I t has often been pointed out that the active demand for dental service includes only twenty to twenty-five per cent of the public, whercas the actual need for such service exists in between ninety to ninety-five per cent of the population. Whatever the reason for this condition, certainly the tendency at present is toward greater interest in Public Health, as shown by child health programs, the Social Security Act of the Federal Government and the public health programs of the various states and municipalities. Social legislatior1 now being considered and adopted by the different states also brings with it a greater interest in the physical welfare of the population. These activities indicate that the potential need for dental services will eventually be translated into an active demand. Aided by the services of the dental technician, the dentist is enabled to devote more of his time and attention to work which must actually be performed in the mouth of the patient. I t can be seen, therefore, that opportunities for employment of persons trained in dental laboratory work are bound to be increased. T h e field of the dentist and that of the technician, while closely related, are none the less very well defined. While the dental technician may be trained to assist the dentist in the construction of prosttl~eticappliances, his approach is, of necessity, from a technical htnndpoir~t. T h e dentist, on the other hand, because of his training i r l the basic biological and physical sciences is alone equipped to ;lhhunlc responsibility to the patient. I n order for the technician t o sh:lrc this responsibility directly he would have to be trained in I I I ( . :LCOI-cn~cntiollcd scicnccs, including graduation from a dental .
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M A N U A ~ , FOR DI?N'I'AI, T I ~ C INI I C I A N B

01<101N 01: DIIN'I'AL MJCCHANICY

xiii 1 I

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college and meeting state board requirements. Under those conditions the technician would indeed cease to be just a technician but would in fact become a dentist. The relationship of the dental technician to the dentist is not unlike that of the pharmacist to the physician, and more nearly that of the optician to the eye specialist or that of the maker of artificial limbs to the orthopedic surgeon. Specifically, the dental technician does not practice directly on the patient but fills the prescriptions furnished him by the dentist-in this instance, the prescriptions consist of impressions or "counters" obtained by the dentist from the mouth of the patient-plus written or oral instructions to be followed by the technician in constructing the required prosthetic appliances. Since no two persons have mouths of exactly the same dimensions, it can be readily seen that no two dental appliances can be exactly alike. Mass production as followed by certain industries is unknown to this occupation. Some commercial dental laboratories follow the principle of "division of labor." However, the processes involved, even under these conditions, require a high degree of skill, accuracy and supervision which can be mastered only after a comparatively long period of training. Dental laboratory mechanics is therefore an occupation which, while based on certain definite scientific principles, calls for the application of individual treatment to each case. As long as people will continue to differ physically, "technological unemployment" (replacement of workers by machines) is destined to remain unknown among dental laboratory workers. A successful dental laboratory technician or dental mechanic must be able to fashion with his hands the exact appliance indicated by the impression plus the written or oral instructions furnished him by the dentist. H e must have a high degree of digital dexterity, and his hands must otherwise be physically normal in every respect. The dental laboratory technician must possess a keen esthetic sense and be artistically inclined. The confining nature of the work makes it necessary for the technician to have good eyesight and to be free from respiratory defects. Since the finished product must fit accurately in the mouth of the patient, accuracy in the performance of dental laboratory work is of utmost importance. The technician must be endowed with innate ability to give infinite attention to details. T h e finished product of the dental laboratory technician must meet functional and esthetic requirements as interpreted by the dentist by whom the technician is employed. It is not only important that the completed dental appliance should give satisfaction when

the patient attempts to use it in chewing food, it must also improve and add to the appearance of the patient. After these first two requirements are satisfied, there is still a third which is of equal if not greater importance: an artificial dental appliance must not injure the natural tissues of the mouth with which it comes in contact. Thus, if a dental appliance functions well in chewing and looks well, but tends to loosen the remaining teeth or otherwise irritate or injure the gums, it is dangerous to the health of the-patient. T h e dental technician, in his relationship to the dentist, is an aid in preserving life. T h e ultimate aim, therefore, in the construction of artificial appliances, is to have them meet anatomic, functional and esthetic requirements.

ORIGIN OF DENTAL MECHANICS

I

'1 I

EXAMPLES OF artificial dental appliances have been found in the ruins of ancient Phoenicia in Asia Minor. The Phoenicians replaced lost human teeth by tying in their place with gold wire other teeth extracted from slaves. During the rise of the Roman Empire, artificial substitutes for lost teeth were well known. With the coming of the so-called Dark Ages of medieval times, the attempts to replace lost teeth by artificial substitutes declined, even as did medicine and other scientific pursuits. An interesting account is related of an Austrian jeweler who fashioned a gold cap (crown) and placed it over one of the molar teeth of his son. T h e news quickly spread that the boy wu born with a gold tooth. This event puzzled the various learned men throughout Europe, who wrote many books and articles on the subject in their attempts to explain the phenomenon of the boy with the gold tooth, until the crown finally wore out, showing the natural tooth under it. During the seventeenth century, and at the beginning of the eighteenth century, dental mechanics was more advanced in France than in any other country. It was in this country that the making of porcelain teeth originated. T h e development of dentistry in colonial times in America can be traced chiefly to France. While the Revolutionary War was in progress, the French fleet under Rochambeau, stationed off the coast of New England, brought with it a number of dentists who taught John Greenwood, an American from Boston, and one or two others in the Colonial Army. Greenwood finally became George

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xiv

MANUAL FOR DENTAL

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TECHNICIANS

Washington's dentist, and made several dentures for the Father of Our Country. One of these sets of dentures is at present preserved at the Baltimore College of Dental Surgery, School of Dentistry of the Universitj of Maryland. This dental college, established in r 840, was the first to be founded in the United States. Dental mechanics, and, in fact, dentistry of any kind during colonial times, was seldom practiced as a sole occupation, but was usually followed as a side-line. Among those who practiced dental mechanics were jewelers, silversmiths, blacksrniths and other artisans. Perhaps the most noted menlber of this group was I'aul Revere. During the eighteenth and early nineteenth centuries, dental technicians practiced dentistry in the United States, after obtaining their training b) apprenticeship to older practitioners. Although the first state law recluiring an examination before commencilig dental practice was passed hj Alabama in 1840, it was really not until the close of the nineteenth century that every state in the union required a dental diploma and an examination bv a state board of dental examiners before allowing persons to practice dentistry. Until comparatively recent years there were still some localities in the United States where technicians were allowed to practice dentistry. I n E,uropean countries, while the separation between the dental surgeon and dental technician has become very definitely defined since the beginning of the twentieth century, and especially since the World War, the field of operation of the dental technician was in the past, nevertheless, much wider than that of his colleague in America. I n some European countries, there are even todaji two dental groups engaged in the practice of dentistry. One group is composed of regularly qualified and registered dentists who are university and medical and dental school graduates. These are in effect physicians who specialize in the treatment of diseases affecting the mouth and the teeth. T h e second group consists of especially qualified technicians who obtained their early training by apprenticeships to other technicians or dentists. Within the past fifteen years, however, the practice of dentistry by technicians in European countries has been greatly curbed. While European dental technicians have formerly had a larger scope of operation in the field of dentistry, which included actual work on patients, it cannot be said that they have as a group made many outstanding contributions to the art of dental mechanics. F o r such advances we must turn our attention to America, and especiallv to the ITnited States. (Fig. 1.)

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VOCATIONAL DEVELOPMENT

No PROFESSION, trade or occupation can develop independently of Kenera1 technical advancement. This is true also of dental mec.h;tnics. When other trades and industries ~ r o f i t e dby the sudden sl'i11-t of general technical discoveries, such as the introduction of the 11c.wprocesses, the invention of new machinery and new materials in K c . ~ ~ c ~dental - a l , mechanics also benefited. As a result of earlier ex~,~-~.iliients in France by nuchateau, d e Chamant, Fonzi and others in tljc 1;ttter part of the eighteenth and early years of the nineteenth (.c.l~ti~~-ies, the manufacture of artificial teeth was begun in the United h:\tcr; i n 1875. These teeth were used in combination with metal I,:ISC.\ : t 1 1 ~ 1recluired a high degree of mechailical skill and accuracy. 1 1 1 I 839 Charles Goodyear discovered the process of curing or 1.11I( :I 1 1 ; / i l l g c : t o ~ ~ t ~ h ooru cIndia-rubber. Thomas Hancock of Eng1 . 1 1 1 ( 1 i s s;~icIto h:tve 111;t~le the same discovery at about the same time. I 1 1 , \ \ ( . \ . ( . I . , ( ;oocl1c;tl- is crcclitcd with prior discovery. O n January

xvi

MANUAL FOR DENTAL TECHNICIANS

30, 1844, Charles Goodyear was granted a patent for making soft or flexible rubber that would resist the action of solvents of caoutchouc and would not be affected by cold or heat, provided the temperature was not raised above the vulcanizing point. The process of making hard rubber was patented by Nelson Goodyear in 1851. A patent was granted to Charles Goodyear, Jr., March 4, I 855, "For improvement in plates for artificial teeth." (Fig. 2.) The foregoing account of the discovery of the vulcanizing process and its application in dentistry does not contain any inkling of the many trials and tribulations which the dental profession and dental technicians experienced, following Goodyear's discovery. I n the first place, many unqualified persons undertook to make artificial teeth set in vulcanized rubber. Furthermore, Charles Goodyear and his son patented the process and sold licenses allowing the holder to make dental plates with vulcanized rubber bases. T h e dental profession and dental technicians resented paying a tax to the Goodyear Company each time a dental plate was put through the vulcanizing process. I t was not until some time during the eighteen-eighties that the Goodyear process patent was voided by the United States Supreme Court. (Fig. 3.) T h e difficulties which involved the use of vulcanized rubber in dental operations also attended other processes and discoveries in the field of dental mechanics, including casting of gold for dentures and inlays. Not only did the discoverers patent the particular machines which were invented, but they also obtained process patents, which meant that a royalty had to be paid for following a particular technic. Since the definite separation in the respective fields of operation of dentists and dental technicians in the United States, the latter have found it difficult to obtain proper technical training. Many schools for dental mechanics were started. However, accredited educational authorities have only lately seen fit to establish courses for the training of dental technicians. In most instances even today (as was true in the last part of the nineteenth century) young men and women entering the dental l a b oratory industry receive their training through the "pick-up method," with the result that few technicians have a clear-cut picture of their field of operation and of the reasons why certain phases and sequences are necessary in the pursuit of their work. This condition has often led to misunderstanding between the dentist and the dental laboratory technician because the technician has been interested chiefly in only one phase of his chosen work: "How well does it look?" while the

VOCATIONAL

DEVELOPMENT

xvii

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C o u r t e s y Bonrd o f Edtrcation, New Yor-k, N . Y .

Courtesy Board o f Education, N e w Y o r k , N . Y .

xviii

MANUAL

FOR DENTAL

TECHNICIANS

VOCATIONAL ANALYSIS

xix

dentist is of necessity primarily interested in "How well does it fit?" The final test of a dental appliance is the accuracy with which it fits in the mouth, although esthetic requirements are highly important. The only method of coordinating these two viewpoints lies in the formal training of dental technicians so that the dentist and his technician may "speak the same language."

V O C A T I O N A L ANALYSIS Public Relation: Dental mechanics is the art of constructing prosthetic appliances to replace teeth and gums lost through disease or accident. T h e appliances produced by the dentist with the aid of the technician add to human happiness by assisting people in chewing their food and by improving their facial appearance. The dental technician renders service to the public through the dentist by whom he is employed directly or indirectly. - Dental laboratory work may be per2. Working Conditions: formed by the technician in the laboratory of the private dentist or it may be done in independently conducted laboratories which do work for a number of dentists and are owned by one or more persons who may be engaged in the work themselves or may employ other technicians. This trade is not influenced by seasonal factors to any great degree. The hours, wages and salaries compare favorably with those in other skilled trades. Hygienic conditions in the dental laboratory depend on the physical facilities provided and on the worker himself. Suction apparatus is now used in combination with polishing and grinding machines and other safety and hygienic measures have been introduced. The nature of the work itself makes it necessary to give - special attention to cleanliness. (Fig. 4.) 3. Opportunities for Advancement: A technician may perform all types of work or he may confine his activities to one phase of the work only. Workers usually have learned this trade through the slow "pick-up" method. Some technicians never learn more than a single phase of the work, although promotion for those showing special aptitude is quite common. There is a steady demand for qualified and trained dental technicians of high caliber. I.

4. Physical Qualifications of Workers: Men and women employed as dental technicians must be in good physical condition, free from respiratory defects. They must have good eyesight. Their hands must be normal in every respect. Digital dexterity, esthetic sense and artistic inclination are of paramount importance to the dental technician. Dental technicians must possess special ability to give exacting attention to details. (Fig. 5.) 5. Legal Restrictions of Workers: In the United States it is unlawful and punishable by fine and imprisonment for dental technicians to perform work for dental patients even when such work is not performed directly in the mouth of the patient. I t is a well recognized fact that the training of the technician is not intended to

VOCATIONAL ANALYSIS

metal arid vulcn~~itcfiles, scl.;ll)crs ;und chisels, contouring pliers, grinding stones and polishing whccls. All tools must be kept thoroughly clean. 8. Materials Commonly Used:

1'l:tstcr of Paris, waxes, investment material, compound, dental rubhcr and other denture base materials, gold, porcelain, silver alloy, 1io11-preciousmetals such as chrome alloys, artificial teeth, polishing stones and abrasives such as pumice, chalk and polishing rougc. (Fig. 7.)

9. Laboratory Office: The following are the main divisions of the dental laboratory office: a. Bookkeeping: filing, billing, accounting, collections and payroll. A knowledge of trade terms and practices is important to the dental laboratory office worker. b. Selling: soliciting by telephone or personal interviews; advertising by direct mail or professional magazines, construction of samples and display arrangements at gatherings of dentists; demonstrations at dental gatherings or in the laboratory. This phase of the work shows the close relationship of the laboratory to other distributive

xxiii

trades. T h e dental laboratory solicitor must be thoroughly acquainted with trade terms and practices. c. Buying: storekeeper and supervisor of maintenance of tools, materials, and equipment. A knowledge of trade terms and quality of materials, tools and equipment is necessary. d. Receiving and Shipping: inspection and checking of work received from dentists, mailing of finished work; management of messenger service. A knowledge of the requirements of completed work and of impressions and instructions to be followed is important. 10. Laboratory Workshop: T h e following are the main divisions of the laboratory workshop: a. Plaster department in charge of a plaster technician. T h e plaster worker prepares the impressions or counters supplied by the dentist. H e makes dental casts from the impressions and mounts on articulators the casts which have been related by the dentist with the aid

of biteplates. Investment of cases for casting and flasking for vulcanization is done by the plaster worker. Plaster work was formerly pcrfonned by junior mechanics; at present in the larger commercial Inboratories an expert dental plaster worker is frequently employed the more intricate phases of this work. to supcrvisc and to

XX~V

M A N U A L I:OR

DENTAL TECHNICIANS

b. The wlcanite or dentzcre depart me^ is under the supervision of a denture technician. Here the arranging of artificial teeth, waxing, vulcanization, trimming, grinding and polishing of vulcanite and other materials used as bases for dentures are accomplished. T h e denture technician may also fashion clasps and connecting bars out of gold or other precious and non-precious metals used in partial denture work, in combination with vulcanite or other denture bases. (Fig. 8.) c. I n the metal denture department, dentures are made of gold and other precious and non-precious metals. In this department the inlays and denture bases are cast or swaged, crowns and bridgework are constructed. Wrought and cast clasps are also made here. A

SAFETY INSTRUCTION FOR DENTAL TECHNICIANS

XXV

dental metal worker must possess a high degree of skill and accuracy. d. T h e ceramics department is usually separated from the rest of the laboratory by partitions. Cleanliness is of utmost importance. I n this department are made porcelain crowns, bridges and inlays. T h e staining of porcelain teeth to simulate the natural teeth of the patient is also performed here. T h e porcelain worker must possess a highly developed training which requires a long period of apprenticeship. (Fig. 9.) T h e various departments mentioned may be further subdivided in the larger commercial laboratories. Thus we may have technicians who do nothing but arrange artificial teeth, waxers, finishers of dentures, polishers of dentures, inlay workers, casting workers, crown and bridge workers and so forth. I t has been estimated that it takes from three to five years of constant practical work in a dental laboratory to produce a fully trained technician.

SAFETY INSTRUCTION FOR DENTAL TECHNICIANS

FIG. 9. A METALDENTURETECHNICIAN AT WORK Note glass safety screen and suction apparatus for grinding metal.

I. Personal Hygiene : T h e observance of proper personal hygiene is an important safety measure. Neglect of personal hygiene is harmful to health and leads to fatigue which frequently causes accidents. (a) Hair should be kept trimmed and combed to prevent disarranged, long hair from becoming entangled in machinery, or burned over an open flame. (b) Hands should be kept clean and nails trimmed. Dental technicians should avoid wearing finger rings or other jewelry on hands or wrists. Jewelry may act as a conductor of electricity. Untidy hands and untrimmed nails may be the cause of accidents, by making it difficult to handle small instruments properly. Chapped hands are more apt to become infected. Infection may ultimately be transmitted to the patient, for whom the work is intended, or may be received from the careless handling of old dentures. (c) Burns, cuts, bruises and other bodily injuries should be attended to promptly. 2. Required Dress: A laboratory coat or smock should be worn. ( a ) Coats should be of a length not exceeding 12 inches above the floor.

xXV~


(b) Coats must be kept buttoned to avoid catching in moving parts of machinery or burning over open flame. 3. Illuminating Gas : (a) All gas jets must be kept firmly closed when not in use.

(b) When flame is accidentally extinguished, close the gas feed (jet) at once. (c) Do not allow Bunsen burner flame or other open gas flame to come within 10inches of wood or other inflammable objects. Adjust burner guard before lighting burner. ( d ) Never leave anything over the Bunsen burner flame or gas stove without proper precaution and supervision. (e) Never allow blow-pipe flame to rest against the bench as flame may be extinguished accidentally or other equipment ignited. ( f ) See that rubber tubings are properly adjusted before opening gas outlets. 4. Bench Lathes: (a) All lathes should be turned off when not in use. (b) Chucks, wheels, brushes and other attachments should not be adjusted when lathe is in motion. (c) Be sure all chucks, lathes and brushes are securely attached before starting lathe. (d) Electric current to lathes should be disconnected before oiling or repairing is attempted. (e) Grinding'wheels should be kept true.

5. Grinding and Polishing Machines: (a) Electric current to all machines should be turned off when the machine is not in use. (b) Cleaning, oiling or repairing should not be attempted while electric current is on. (c) Be sure all chucks, wheels, brushes and other attachments are secure before starting lathe. 6. Machine Guards: (a) Use guards over moving parts of machines. (b) Guards over moving parts of machines should not be removed for cleaning, oiling or other reasons, while machine is in operation.

SPECIFIC SAFETY INSTRUCTIONS

XXVll

7. Vulcanizers : (a) Failure to follow the instructions for use of vulcanizers provided by the manufacturer may lead to serious injury or even loss of life. (b) Clean warm water should be used in the vulcanizer. (c) Water should not reach higher than one to two inches from the bottom of the vulcanizer pot. ( d ) Open blow-off valve before closing or opening vulcanizer. (e) Make sure gas regulator and time clock are properly adjusted before lighting gas burner under vulcanizer. ( f ) Do not release blow-off valve of the vulcanizer before a minimum of 15 minutes has elapsed after the gas has been shut off. Keep your head away from the top of the vulcanizer when opening blow-off valve or cross-bar. (g) Always use tongs in removing flasks from vulcanizers. ( h ) Vulcanizers in use should not be left without supervision. 8. Before closing laboratory :

(a) (b) (c) (d) (e) (f)

Shut off all gas jets. Disconnect current to all electrically operated appliances. Make sure all compressed air outlets are sechrely closed. Replace all instruments. Clean all work benches, machinery and laboratory floor. Make sure all acid containers are covered.

SPECIFIC SAFETY INSTRUCTIONS. Plaster spatula should not be used for cutting or any purpose except spatulation and shaping of soft plaster. 2 . Plaster knife should be kept clean and free from rust. Use the "thumb guard" in all operations involving use of plaster knife. Never use the plaster knife against the chest or in an outward direction without a guard. 3. Always use heated wax spatula with thumb or finger guard. In order to avoid burning fingers, wax spatula should not be grasped too close to the point to be heated. Do not allow heated point of spatula to come in contact with fingers. 4. Keep face as far as possible from gas feeds (jets) when lighting burners. 5. Runsen burner flame should not be directed against inflammable objects. I.

xxviii


6. Wax knife or carving knife should be used with finger or thumb guard. 7. Heated sticky or basewax should not be spilled on hands or fingers to avoid burns. D o not overheat basewax to avoid uncontrolled flow of wax. 8. Baseplate: Avoid touching heated baseplate without first moistening fingers. Smooth all sharp edges of baseplate to avoid cutting fingers and the patients' tissues when the dentist tries the denture in the mouth. 9. Plate-shears: Keep fingers from path of shears in cutting. 10.Carbon-tetrachloride, chloroform or other grease-solvents used in finishing waxed cases should be used sparingly. Avoid contact with fingers as much as possible and keep containers tightly closed. I I. Keep fingers from path of denture flask clamp wrenches. 12. Keep fingers from path of vulcanite files. 13. D o not touch or attempt to grasp revolving wheels, discs, chucks or burs. 14.Vulcanite chisels and scrapers must be used with thumb or finger guards only. I 5 . Express mercury from freshly mixed amalgam with chamois to avoid absorption through the skin of the hands. 16. D o not handle acids or open crucibles containing heated acids in other than designated places and according to directions. D o not inhale fumes of heated acids. D o not throw objects into acid container, use tweezers provided for purpose to avoid splashing. 17. Always pour melted metal away from the fingers, hands or clothing.

U N I T NO.

I

WAX TECHNIC I n learning dental mechanics, and this is true of any vocation, l' t is necessary for one to become acquainted first with the most commonly used tools and materials. I n dental laboratory work, wax is an all important material. Almost everyone at one time or another has kneaded a piece of beeswax or paraffin and molded it into little toy animals or other shapes. T h e use of wax for dental laboratory purposes is as old as the profession of dentistry itself. Fornlerly beeswax was used exclusively. Today, paraffin and other wax compounds are commonly employed. Wax enters into the construction of practically every type of dental laboratory work. By following the instruction provided in this unit, a knowledge may be obtained of the handling, melting, sealing and general manipulation of basewax which is used in making artificial dentures.

Process or Principle : No. I : Dental Waxing. a. Handling and c~btthgbasewax. b. Melting and sealing basewax. c. Manipzllation of carding-wax. d. Use of wax spat.ula. e. Use of Bunsen bzcrner. Project or Jobs: ( T o be performed by the learner.) TOB NO. I : a. Construct a 45 by 45 mm. basewax sealed box. (Fig. 10.) b. Construct a wax art-base tray to dimensions. (See Fig. I I.) NOTE: (Read the entire unit carefully before beginning work. Consult the glossary for definitions of new words.) Job Application: Wax is a commonly used material in dental laboratory work. Wax becomes a liquid when heat is applied to it. By passing a heated instrument over the edges of two or more pieces of wax which are held close to each other, they can be sealed together illto one piece. T h e joined pieces will remain united after the wax cools. Waxes of various types are employed in dental laboratory I

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3

WAX TECHNIC


work for joining broken parts of plaster impressions; boxing impressions; construction of baseplates; biteplates; bridgework; waxing for casting; inlay work and many other purposes. Vocational Information: Dental wax may be purchased in sheets, strips, blocks or stick-form. T h e essential ingredients of all waxes

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PLANOF WAXBOX

Exact dimensions for 45 X 45 mm, wax box, allowing of basewax.

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Exact dimensions for 75 X 90 mm. tray, allowing one millimeter for each thickness of wax.

millimeter for each thickness

are beeswax, paraffin, cottonseed oil, rosin, turpentine and coloring matter. T h e principal types of wax ai-e pink and red basewax; adhesive or "sticky" wax, inlay, carding (a black wax) and casting wax. T h e basewax required in this unit can be purchased in sheets 3 by 5% inches, in half-pound boxes, known as "Pink Baseplate Paraffin and Wax."

Tools and Equipment : Bunsen burner, with gas tubing (Fig. wax spatula, millimeter ruler and penknife (Fig. 13). Materials : Pink basewax, carding wax, absorbent cotton.

I2 ) ,

Procedure : (Follow operations in the order presented here.) CAUTIONS: a. T o avoid overheating the wax spatula, place a small piece of wax on the blade of the spatula and hold it over the Bunsen burner fEame until the wax begins to melt, m'thdraw th.e spatula and use. (Fig. 14.) b. T o avoid distortion, do not press fingers or spatula too hard on wax. c. Use the $at pointed end of the wax spatula to obtain uniform. sealing and sharp corners. d. Steady the hands when sealing with heated spatula. (Fig. 15.) c. Ilold the wax parts steadilv until the melted wax congeals (cools or hardens).

4

WAX TECHNIC


A. Construction of 45 by 45 mm. basewax box and sealed cover 1.

(Figs. 10 and 16). Using penknife and millimeter ruler, cut six pieces of basewax according to dimensions (Fig. 13).

5

3. Using the flat tapering surface of the warm spatula (heated over burner), smooth the edges of the box to form sharp lines. Finish edges with penknife.

I-Wax

spatula. 5-Penknife.

2-Millimeter ruler. 3 and 4-Basewax 6-Bunsen burner and tubing. 7-Black

marked for cutting. carding wax.

4. Cleanse the wax box with wet absorbent cotton wad while holding under running, cold water. Air is mixed with the illuminating gas before ignition. a-Pale blue or purple flame: this is the oxidizing flame. b-Pale blue or greenish flame: the reducing and gas mixture. Too much air will flame, the hottest part of flame. c-Air extinguish flame. d-Air hole. e-Gas supply. Note: Difficulty in keeping the Bunsen burner lighted may be due to a cold burner, too much or too little air or gas.

2.

Using heated wax spatula along adjoining wax edges, seal the pieces of wax to form a 45 by 45 mm. box with squared edges. Allow for thickness of wax by lapping 45 by 45 mm. pieces over 45 by 43 mm. pieces. 43 by 43 mm. pieces should be inserted.

H. Construction of Wax Art-base Tray (Figs. I I and I 6). I. Mark basewax to dimensions indicated (Figs. I I and I 6). 2. Cut wax using penknife and ruler. 3. Allow largest piece (bottom) to rest on the bench. Seal sides at right angles to bottom. Allow for wax thickness by placing narrower pieces on top of the bottom piece. 4. Using millimeter ruler, cut carding wax to enclose sides of wax art-base tray, obtaining measurements for carding wax on outer dimensions of wax art-base tray. 5 . Chill under gently running water, rub outer surfaces with wct ;il)sorl,cnt cotton wad to polish wax.

6

WAX TECHNIC

M A N U A L FOR DENTAL TECHNICIANS

I-Wax. 2-Outer cone (oxidation). 3-Middle cone (reduction). +-Inner cone (mixture of air and gas). 5-Bunsen burner. 6-Tubing. 7-Wax spatula.

7

Hold pieces of w a x lightly to avoid distortion. Learn to use the fingers and thumbs for holding the work, for guiding instruments and for protecting the hands from accidental injury by heated, pointed or revolving instruments.

Note: Hold base of spatula blade over apex of middle cone of flame. W a x will flow toward apex of spatula blade. If apex of spatula is heated first w a x will run toward base of spatula blade. By heating a piece of w a x on the spatula and withdrawing the spatula when the w a x begins to melt, the time needed for heating spatula for waxing purposes can be determined.

Supplementary Assignment: learner.) I.

2.

3. 4. 5. 6. 7. 8.

(Information to be obtained by

Composition of different basewaxes. Method of obtaining home-made basewaxes. Conservation of basewax. Effect of weather conditions on basewax. Care of Bunsen burner and wax spatula. Uses of five different types of wax. Definition of dental impressions; baseplates; biteplates; bridgework; casting; inlay work. Composition of carding wax; uses.

A-\\'ax

art-base tray.

B-Wax box and cover (sealed). C-Art-base sides reenforced with carding wax.

tray with

8


Questions : I. What are the principal ingredients of pink basewax; sticky wax; inlay wax? 2 . I n which part of the Bunsen burner flame should the spatula be heated? 3. What is the method of heating wax spatula? 4. What effect does rubbing with wet cotton have on the basewax? 5 . What effect does overheating have on the spatula? 6. What effect does overheating have on wax? 7. What care should be given to the tools, equipment and materials used? Job Appraisal : I. D o the finished box and wax art-base tray have sharp corners and sharp evenly-sealed edges, at right angles to each other, except where otherwise indicated? 2. Is the carding wax evenly sealed to the sides of the wax artbase tray? 3. Are all outer surfaces of the wax free from finger prints and other markings? 4. Were remakes necessary? How many? 5 . Did you waste any material? 6. Did you require longer than the 30 minutes (average) for making the wax box? 7. Did you require longer than one hour (average) for making the wax art-base tray? REFERENCES: (Books for Additional Information.) Hodgen, J. D.: Practical Dental Metallurgy. T h e C. V. Mosby Co., St. Louis, Mo., 1932. 2. Skinner, E. W.: T h e Science of Dental Materials. W. B. Saunders Co., Philadelphia, I 936. 3. Prinz, H.: Dental Formulary. Lea & Febiger, Philadelphia, 1936. I.

R E L A T E D INFORMATION: U N I T NO.

I

W A X TECHNIC Properties of Wax: When only slightly heated or warmed (about 80" to I 10" F.) wax becomes pliable and can be adapted to irregular surfaces, the shape of which the wax will retain when chilled. When wax is heated to a higher temperature (230" to 290" I?.) it assumes a liquid form and can be poured. A.t a still higher temperature wax begins to evaporate. Most waxes can be entirely eliminated by heating to high temperatures. Ingredients of Pink Wax: (Parts by weight.) White beeswax 50 parts Paraffin 2 5 parts Dyestuff (vermilion) I to 4 parts Ingredients of Black Carding Wax: Beeswax Black dye (coal black) REFERENCES: (Books for Additional Information.) I . Hodgen, J. D.: Practical Dental Metallurgy. T h e C. V. Mosby Co., St. Louis, Mo., 1932. Skinner, E. W.: T h e Science of Dental Materials. W. B. Saunders Co., , Philadelphia, Pa., 1936. 3. Prinz, H.: Dental Formulary. Lea & Febiger, Philadelphia, 1936. 2.

I IN11' N O .

2

PLASTER TECHNIC l ' l , c,j ~ I~J i i~, i j ~is ~I I ~~C ~~inI I?uilding ~ ~ ~ c r ~ t iin ~(..istin:; m s , plastcr .it.i~ua~-\ ;in,] for pl.lstcr b:~ndagcs.inJ other purposes too ~ L I I I I ~ ~ O to L I n S i e n t i o ~here. ~ I'l.~stcr is :11so tlscii in rlcnr.il 1nbor;ltory opci-.~tions. Next to w a s , i t 110t c q ~ ~ a l linlportant, y is the usc of pl~stcl-in ~ l c n t : ~l:~horntor!. l work. 1'1;lster o f I'aris is siiid lo h.l\-e bccn lirst llsed in dcntistl-y i l l I j j 0 by Phillip Pfaif \vho W.IS the dclltist O F 1"reciericL t l ~ c(;rent ol (;c.r~n;lily. 'l'hc heha\-ior of liiixed pl;~ster ~ v l ~ e!;I-st n uscct i l l the l,ll>orntor\ leucis tl-uth to t h e s.iying: "Plnstcr is y o u r master 11nti1 Y ~ L rn~stelI pl:istc.~.." .\nil it is rc;~llyso. T h e cnsc with wllicl~l>l;~stcr<.In be rnnnipul.itcii once the technic is 1e.1rned is nnlnzing. E ' ~ ~ r t l ~ c r mwit11 ~ ~ r cn, knoulcdgc o l t h e \vorkilli: o l w;lx 2nd plnster, t h c 1e;lrncr- Ilns I ~ i dthe. founci:ltion lor the building oi :I thorough t r ; ~ i n i ~3s~ :Ig dcllt:ll t e c I l ~ l i c i : l ~ ~ .

Process or Principle : No. 1 : l'laster Work. a. Navdling, mixinx, shapill~and ~ r i n l w ~ ip?/ n~ s~/ ~ rof Paris. b. Us(. o f plaster- spa/7rlaJ k n i f ~ hoad , ant) .
I3

M A N U A L FOR DENTAL TECIINICIANS

Vocational Information: Artificial stone, one of the many modified forms of dental plaster of Paris, is riow commonly used for making dental casts. Dental plaster may be mixed with a spatula or by shaking the plaster bowl after covering it with a glass slab or tin cover, or by usirig a mechanical spatulator. All plaster tools must be kept absolutely clean and the plaster itself should be kept in an airtight container as it absorbs moisture from the atmosphere. I t is well to follow the manufacturer's direction for the proportions of water to plaster. T h e setting time, hardness and expansion of mixed plaster can be controlled by means of "hasteners" or "retarders." T h e method of manufacture; the amount of spatulation; the ratio of plaster to water; the temperature of water and plaster; and the presence of impurities all influence the mix. T o o l s a n d E q u i p m e n t : Plaster saw (round barbed blade) ; 2 glass slabs; plaster knife; rubber plaster bowl; chanlois cloth; marking pcncil ; measuring cup; try-square. (Fig. I 9.)

I-Plaster saw. 2-'fry-square. 3-Glass slab. +-Pl;~btrr S I I ; I I I I ~ : I . 5- -I'I.I,I( I b~~ife.( i - K ~ ~ l ~ b e rbowl. 7-Chamois cloth. S - b l a ~ - k i ~ ~ j1x.11c.il. i o h l t , ; t i~~~~~i : cup. r e S a n d p a p c r No. o. r r - S a ~ ~ ( l p ; ~ p c ~No. . I. 1 2 :1';111..

Materials: I ; talc.

Dental plaster of I'aris;

water; sandpapci- Nos. o and

Procedure : (Follow operations in the order presented here.) a. W h i l e the steps in lii7ixing plaster must be followed care full^^, and completed before t h e they should be performed plaster besins to "set" or harden. h. As t h e plaster hardens it generates heat. This is called " s ~ t ting.)) W a i t until t h e plaster cools before proreedi~z~/o trim it. c. Llloisten tht, glass slab to prlivent the plaster fvo~rz adheriiz:< to it. d . c?lze,ays cut "full" dimensions to allow for 1-~(turtio71 w h , 11 using sandpapc,r. c . f'laster mixing tools, spatula and b o d , should be thorouRh7)l cleaned to prevent rusting of spatula and knife and faully mixes. f. Store plaster i n a dry place. Keep plaster container r l o s ~ d . 2 . If watr7r is accidentally spilled inlo dry plasler, rPmovr a77 -,tTptfllaferial at once.

I . Place the wax art-base tray on a moistened glass slab. 2 . Pour 3 fluid ounces of medium cold water into a clean plaster bowl. ,{. LJsing the plaster spatula as a ladle, sift 6 fluid ounces of powdered plaster into the bowl. Sift plaster along the sides as well as in the middle of the bowl. Allow each addition of Illaster to become submerged in the water before the next is added. Continue adding until all of the water is ah.- plaster . sorbed. 4. 'I'al' the plaster bowl gently on the bench so that air bubbles ;11-cIN-oughtto the surface and expelled. Wait until all b u b ~ l , l i l ~has ~ ceased. q . I Iolcl the lil:~stcr bowl in one hand and, using the plaster sl)ati~l:i,sl,:ttul;ite, or mix the plaster with a cutting motion t l ~ ~ r it i l ;tssu~~ics a CI-camyconsistency. O. I ) , . ~ U I G t l~~ cp1;tstc.t- 111ixinto the wax art-base tray by squecz~ I I,<. I~owlt o (01-m n spout :ind p i d i n g the plastcl- with I li(, ~ ~ K I I I I(l:i,y. ~ : I . ,:.om)

14

MANUAL FOR DEN'I'RI. TECHNICIANS

7. After filling the wax art-base tray with plaster, level the surface with a plaster spatula and cover evenly with a glass slab. Wait until plaster "sets" before proceeding. 8. While waiting for plaster to set construct a second wax artbase tray and fill with plaster. (Repeat procedures r to 7.)

I \ \ ' ; u art-h;tsr tl-;I!~. 0-\Vax a r t - b a r tl-a?. tilled with pla>ter. c-Plaster block I,.III,I\,C fl.om ~ ;~rt-llast:tray. d-I-pprlplaster art-base trimmed tu dimell. ~ O I I \ . e-Lo\\-rr plastel. art-haw trirnmed to dimerision\. t-upper piaster nrtI,;~sr\vith rrccs\rd top. g-\$'ax tlrpo\itt.ri i r ~ lo\\-cr plaster a r t - h a w

' 1 ilich fr-om the edges and 1/1 inch deep in both plaster art-bases. (1;ig. 19.) I 4. Using talc on chamois, polish bases. I 5 . T h e art-bases call be filled with basewax and stick!. wax respectivel! and used as wax containers. (Fig. 2 1 . ) I

,\. CJsirig k~liic,cut a recess

S11l)plementary Assignment:

hlethods of controlling setting time; warpage. hlcchanical spatulation. Closed bowl method of miuing plaster. Origin arid development of plaster of Paris for dental use. I'hh sical and chemical of plaster. Corrll)os~tio~~ of plaster compounds. I Iutics of 1)l;lster technician in laborator!. Collll)ositiotl of ;~rtificialstones.

a-Plaster l i r i ~ i gguideti \\-ith p l a t e l . \p;itirl;i from spoutetl luliher plaster bowl into \\.ax art-base tray or1 glass slah. h-\\'ax :irt-llaae tray filled with plaster.

9. About one hour after pouring each wax art-base tray, remove the carding and basewax from the set plaster blocks. Outline upper and lower art bases ~ I the I respective l)lastc~blocks according to the dinicnsio~is, using I-ulel- :111d try square. ( Figs. I 7 and I 8.) I . [Jsi~ig>anr a ~ i dl)lastc~k11ifc cut :I\v;I!.cxc~css11I:l~tc1., lr;~\,i~i,c "full" dinlensions to :~llow for s;l~idp:~l)cririg. rsit~gNos. I :111cl o s : ~ ~ i c l l ) : ~s~iioot ~)c~~ I1 -~, ~ I : I S I C ~ I II:IYS. 2.

10.

I

I

(Information to be obtained by

(,)~~c.stiolls: I .

L V l l ; ~ ti s ~ ) l : ~ s t01: c ~I'aris and what are its properties and uses

cic11t:ll l:ll)oratory.~ \\'11:1t is tlic COI-I-cct method of mixing plaster of Paris? \ . \\'ll;~t;II-cttic ;~clv;~rlt;igcs ; I I I ~disadvantages encountered in I l l ( . 115c. 0 1 . lll;l~lcli l l ttlc clc~1lt;lIl : ~ l ~ o l - ~ ~ t o r y ? i l l tI1c.

'.

I6

MANUAL FOR D E N T A L T E C H N l C l A N S

4. What happens when plaster is not mixed correctly? 5. What is the effect of too much water in the rnix? 6. H o w may the setting of plaster be hastened; how may it be retarded? 7. H o w do you deter~rlinewhen plaster has set? 8. What is the proper method of storing plaster of Paris? 9. What do we mean by the following: water of crystallization; gypsum; to spatulate; "setting" of plaster? I 0. Define : dental impression ; cast; articulator ; flasking.

Job Appraisal : I. H a s the plaster been evenly mixed? Is it free from soft spots, air bubbles, streaks and other faults? 2. Are all edges sharp, even and at right angles urlless otherwise indicated on the plans? 3. Are all surfaces smooth and evenly polished? 4. Is the finished work according to the dimensions indicated on the plans? 5. Were make-ovei-s necessary? Was economy of materials observed? 6. Was the time for completing each art-base tray longer than I hours (average) ? ~ZEFERENCES: (Books for Additional Information.) Skinner, E. W.: T h e Sciencc of Dcntnl M.~terinls. W. B. S:~unilersCo., Pllilndelphi~,I 936. 2. Nichols, 1. G.: Prosthe~icDcntistr!.. St. Louis, Mo.: C. V. Moshy Co., 1930. 3. Frallm, F. LV.: 'l'hc Principlvs nnci 'I'cchllics of Full D e n ~ n r eConstruction. Brooklyn: Dental Ttcnis O F Interest I'uhlishing Co., 1931.

I.

RELATED INFORMATION:

U N I T NO.

2

PLASTER TECHNIC Plaster of P a r i s : This is a mineral compound which is sold for dental laboratory use as a fine white powder. I t is obtained b) heatillg gypsum. 'l'he chemical equation when plaster is mixed nith \vatel- is as follows: 2CaS04?1H20 (gypsum) (heat) (solid)

+

+ =

(CaSO4)pH.O (Plaster of Paris) (powder)

+

+

3H.O (water) (steam)

When plaster of Paris is mixed with water it re-crystallizes. I t undergoes a hardening or setting process and becomes a solid. Heat is generated during the setting process. T h e setting process is divided into the iilitial s ~ and t the fii~al set. T h e time when the plaster may be molded into a desired shape is known as the initial setting period and lasts from 2 to 15 minutes, depending on the plaster used. Plaster used for the usual dental laboratory purposes sets in 8 to 15 minutes. 'The fiilal set which represents the length of time that must elapse before the plaster is hard enough for use is about % to I hour. T h e greatest hardness of plaster is reached about 24 hours after mixing. T h e plaster mix should be of a creamy consistency : ~ n dshould drop off, not pour off, the inverted plaster spatula.

I. Setting time may be influenced by the following: a. Mantifacturing process: Impurities may hasten or retard the S P ~ . T h e finer the plaster the faster the setting time. b. S p a t u l ~ t i o n : Within reasonable limits, the faster and the longer the spatulation, the quicker the setting time. Prolonged spatulation weakens the plaster mix by interfering with crystallization of the setting plaster. c. Ratio of water and plaster: If the ratio of water is increased the set is retarded. If the ratio of plaster is increased, the set is hastened. Too little plaster gives a wet mix and powdery casts when dry. Too much plaster gives a crumbly mix. tl. T e m p ~ u a t u r e :T h e higher the temperature of the water and plaster the fastel- the setting time. D r y plaster sets faster than wet plaster. At the time of using, water and plaster should be at room temperature. 17

e. Retarders a j ~ daccelerators: Substances which hasten setting time are known as accelerators. These include the following: table salt, potassium sulphate or alum. Substances which prolong the time of setting are known as retarders and include the following: lenlon juice, acetic acid in the form of vinegar, borax and powdered marshmallow root. 11. Expansion of Mixed P l a s t e r : a. Potassium sulphate and borax arc added to the plaster b ~ l the manufacturer in order to control expansion. b. Ry increasing the ratio of water to plaster in the mix, expan sion is reduced. c. Long spatulation increases expansion. d. Resistance to expansion can be offered 19 dental impressioti trays, flasks, and boxing of dental impressions before pouring plaster casts. 111. S t r e n g t h o r H a r d n e s s of P l a s t e r : a. Ratio of water to plaster: If the mixed plaster is allowed to dry it will withstand more pressure than when wet. T o o much water results in soft plaster. I.ess water gives a harder mix. b. Accelerators and retarders ma! weaken the mix. c. Temperature: T h e higher the temperature of the mix, the lower the strength will be. d. Spatulation: If spatulation is sufficient the mix will be harder than when it is not sufficiently spatulated. If spatulation is produced by "cutting not whipping" the plaster, the mix will be harder. SPATULATION O F PLASTER O p e n Bowl Spatulation: Rotate the bowl slowly in one hand while passing the plaster spatula through the plaster and water with a cutting motion until a creamy consistency is reached (about one minute.) Closed Bowl M e t h o d : Cover the plaster bowl col~taining the proper amounts of water and with a glass slab or a tin cover. H o l d the thumbs of both halids around the cover and the firigcrh oti the bottom of the bowl. Shake up :und down quickly for O I I C ~iiinutc. Mechanical Spatulation : 'l'hcrc :ire \,:isio~ts ~~icc.l~;~~~ic.:il ~ I I : L i11:1 ( tors 0 1 1 the principle of tlic egg 1)c;itcr. '!'fit ~i~cc~li:tr~ic:il S~I;L~LI~:L~OI-\ g i v t ~:I thoroi~gliniis i n ;I sliort(~~ti111ct l i : ~11:111(l ~ ~ \lx~tt~l;~tiot~.

U N I T NO. 3 PREPARATION O F PLASTER IMPRESSIONS F O R CASTS-I 'I'lic lirsl conk.ict ol t h e dei~t.iI tcctinici;ll~ \q.itli the work w l ~ i c h h e performs is when Ilc receives t h e dcllt.11 impression o h t , ~ i n c ~froin l the m o u t h b the dentist. A t this point the act~lalconstruction of ttic ~lcnturc,begins. 'l'hc impression must be cnrefully llandled. T h e dentist has spent a great deal of time ;illd effort in obtaining it frolll the pntient. I f the impression is carelessly hnndlcd it may be ncccss:iry to take nnother one. 1 h e patient lnay not like the idc.1 or tiillc m.1y not suflice for going through the p r o c c d ~ l r c:I second tinlc. Yurthermorc, the dentist Inay find :1 technician w h o is ~ l l o r ccnreful. linprcssions takcn in plaster usunlly come to the tcchnician in set-cr;ll pieces. ;\lthougl~ thc dentist should join the pieces together ivith stick! w:~x,so tli:lt he mil)- hc :tlilc to tell at n glance i f the impression is ~:~tisfnctor\,, this R.oI-~\is LISU;~~~!. t l . ~ ~ ~one ~toi the technician. So, b>- f o l l v \ ~ - i ~thc ~ g instructions in this nit, t h e technician will Icnrn IIOW to :~sscmblc tlic pnrts of hrokcn p1:lster imprcssions, in order that he m a y he able to iii.1kc :In ;IccLIr;ltc C ; I S ~ o n n-hich t h e npplinncc is to bc constructed. 7

.

Process o r Principle : No. 3 : Assembling Impressions. a. U s e of sticky wax. b. Handling of broken parts of dental impressions. c. A r r a n g i n ~broken parts in dental in~pressiontrays. d. Assembli~~g dental iynpr-~ssions,wi//7out using impression trays. Project o r Jobs: ( T o be performed b) the learner.) JOB No. 3. Assemble four sets of full (edentulous: all teeth have been lost) upper- and lower dental ilnpressions in impression trays. JOB No. 4. .Assemble four sets (four upper and four lower) of full (edentulous) upper and lower impressions without using impression trays. Jorl No. 5 . Assemble six partial impressions in impression trays (p:~rtiallyedentulous: not all teeth have been lost, some teeth still i l l the mouth)-three upper and three lower. J O I I No. 6. Assemble six partial (partially edentulous) impres\ I O I I S i11 i11i1)ressionti-ays-three uppel- ; ~ n dthree lower.

20

PREPARATION O F PLASTER IMPRESSIONS FOR CASTS-I


A-Palate

(roof of mouth).

B-Alveolar

21

ridge (gum).

ridge space (space occupied or covered by the tongue). B-Alveolar (gum ridge from which teeth have been extracted). hTote: Upper and lower casts of a mouth in which some of the teeth have been extracted. T h e casts shown here are known as partial casts, indicating that they require partial dentures (plates). A-Tongue

FIG.

22.

TEETH A N D GUMSIN RELATION TO FACE(CHEEK COVERING REMOVED)

LOCATION OF

THE

HUMAN

a-Upper lip. b-Upper gum (alveolar process). c-Upper remaining teeth. dLower remaining teeth. +Lower gum (alveolar process). f-Lower lip. Note: Some of the teeth have been lost (partially edentulous). Upper and lower partial dentures (plates) are needed to restore the lost teeth.

a-Upper

gum (alveolar process). b-Upper lip. c-Lower gum (alveolar process). d-lower lip. Note: A full upper and a full lower denture (plate) are needed to restore the lost teeth.

NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definition of new words.) Job Application: A dental impression is a counter of the dental arch (upper or lower) (Figs. 22, 23, 24, 25, 26a and b.) After the impression is assembled and properly prepared a cast is poured. If the impression is accurately assembled, the cast produced represents a true reproduction of the dental arch. T h e prosthetic appliance is then constructed on the cast to supply the lost teeth and gums. Sticky wax consists of beeswax and rosin. Vocational Information: Plaster of Paris produces an accurate impression of the dental tissues. As "set" plaster is not flexible, it is usually broken on being removed from the mouth. T h e dental technician must be able to assemble the broken parts of thc impres-

FULL UPPERCAST. a-Alveolar ridge (gum ridge from which teeth have been cxtracted). b--Palate (roof of mouth). c-Rugae (gum elevations in front part of palate. d-Base (art portion of the cast). b. FULL LOWER CAST. a-Alveolar ridge. b-Tongue space. c-Base. Note: Full upper and lower casts (edentulous casts). These casts are taken from : I I impression ~ ( a counter) of a mouth in which all the teeth have been lost. A full upper and a full lower denture (plate) are needed. :I.

24

MANUAL FOR

DENTAL

PREPARATION

TECHNICIANS

OF PLASTER IMPRESSIONS FOR CASTS-I

25

sions accurately, either in or out of the impression trays and to join the parts to each other or to the impression trays with "sticky" wax. Tools and Equipment: Camel's hair brush, wax spatula, Bunsen burner, paper towel, tweezers, upper and lower impression trays (Fig. 27). Materials: Sticky wax, basewax, plaster dental impressions. (Figs. 28a and b, 29 and 30.) NOTE: T h e impressions required for the Jobs described in this Unit may be obtained from dentists who must also furnish the learner with the necessary biteplates or wax "bites" to be used for relating the casts which will later be made from the impressions (Figs. IOO and 105). Plaster impressions made from metal dentoforms (Fig. 28a and b) as well as the dentoforms themselves and a dentoform "relator" (Figs. 29, 30, IOI and 102) or stone casts and a cast "relator" diagram may be purchased (Figs. 28a and b, 103 and 104). Procedure: (Follow operations in the order presented here.) CAUTIONS: a. Care should be exercised in handling impressions i n order not to lose parts and to avoid further breakage. Avoid rubbing the fracture edges together to preserve their accuracy. b. Be sure that the parts are thoroughly dry before beginning to assemble impressions. c. D o not pour wax over tissue surface of impressions. d. Be sure to remove all adhering particles of plaster from impression trays before beginning to assemble impressions i n them. e. Assemble parts consecutively, avoiding "undercuts." f. Brush fractured edges of impression carefully, using camel'.r ,hair brush to remove adhering particles of plaster. g. I n assembling zen'thout trays do not release pressure on parts until the wax has congealed. h. Freshen old md dried iwqression parts by immersing i n water until bubbling ceases; allow to dry and proceed. i. Keep freshly obtained impressions covered until assembled.

I. Operations for Assembling Impressions in Tray: D ~ ~ + r t o f o ~ ~\'u.s. r i ~ s 258, 011 t r c l i ~prcsrirt; > . j S ( r , 2jSh oird 2iSc. ~ r p / w rc , I . s / ~ . ( . , l / ~ / , l ~I ,I I I I I ~ ~ 10 ~ ~ ~ I casts frurir lop to butto~ir ill )right colrrnirr of / ~ l r o l u u r a p l r . ) L ) c r r I o j r ~ r . r ~ iN. ~u s . 259, it11 rcerli Pl'r.sclrt; sgpa, rgpb arzd 259c, lozuer casts. (To/> 10 bot10111,lcft ~ ~ 0 1 1 1 1 i r r i .()~ u f f r / ~ ~('o11,11111ia .vy Dcutofurwr Corporatioit, Ncw Yorl;, N . Y.

~ . ~

r . Arrange parts of broken impression on a paper towel in the I-clativeposition that they are to be placed in the impression tray (Fig. 28a and b).

26

PREPARATION O F PLASTER IMPRESSIONS FOR CASTS-I


27

Brush fractured edges of impression carefully with camel's hair brush and insert into impression tray in proper order (Fig. 31). 3. Fit all parts of broken impression into tray, using tweezers (Fig. 31). 4. After all parts of the impression are on the tray, fit them together closely (Figs. 32 and 33). 5. Apply sticky wax to join edges of impression to tray (Fig. 34). 2.

BROKEN I'ARTSO F UIJPERI~IPRESSION I N T O TRAY FIG.31. FITTING Note: Avoid creating undercuts by assembling the parts consecutively.

Note: Full upper and lower impressions assembled and closely fitted into impression trays.

A-Impression tray. B-Plaster impression (assembled). &Sticky wax applied to seal parts of the impression to each other and to the impression tray. Note: Do not run sticky wax too high on the alveolo-buccal fold or on the tissue surface of the impression. W a x the impression securely to the tray. See that the parts fit properly before beginning the application of sticky wax.

11. Operations for Assembling Impression Without Tray: NOTE: In old or dry impressions or where pieces do not seem to fit accurately, it is better to assemble without the tray. Sometimes the tray may have since been bent or the impression may have contracted on drying. I. Arrange the parts of the broken impression on a paper towel in the relative position that they are to be fitted. 2. Brush fractured edges carefully with camel's hair brush. 3. Fit two largest adjoining pieces, apply sticky wax on the tray surface of the impression (Fig. 35) and seal with heated wax spatula. Do not release the pressure on the parts until the wax has congealed (Figs. 36 and 37). 4. Hold the impression carefully and continue adding and joining parts with wax until the impression is fully assembled (Figs. 38 and 39).

28


PREPARATION

OF PLASTER

IMPRESSIONS FOR CASTS-I

29

Note: Plaster impressions assembled without trays, showing sticky w a x applied on "tray surface" of the impressions to hold parts together. T h e sticky w a x should be applied at different levels along the various lines of fracture on the tray surfaces of the impressions, as shown above, to aid in keeping the parts together.

A-Plaster

impression.

B-Wax spatula. C-Bunsen D-Bunsen burner.

burner flame.

Note: I t is sometimes necessary to join three pieces together a t the same time ( a s shown above) to avoid undercuts. Rest the convex under-surface of the w a x spatula against the tray surface of the impression, then tilt the spatula so that the sticky w a x is deposited on the tray surface. T h i s method warms the spot where the sticky w a x is to be deposited and helps the w a x to adhere to the impression.

Supplementary Assignment: (Information to be obtained by learner.) I. What other materials are used for taking dental impressions? 2. What are their disadvantages and advantages? 3. W h y should the dental technician not tamper with the im-pression ? 4. What should the technician do if part of the impression is missing? 5 . On assembling partial impressions what special PI-ecautions should be taken?

Note: Tissue surfaces of full upper and lower impressions assembled without using trays. (Note faint fracture lines.) T h e sticky w a x has been kept off the tissue ~ u r f a c e sand off the rim (periphery) of the impression. If the surfaces of the impression over which the plate is to be made are covered with sticky wax, the impression is marred and the plate (denture) will not fit properly.

3O


Questions : I . Why is it necessary to assemble impressions accurately? 2. Why should wet impressions not be assembled? 3. Why should wax not be used on tissue surfaces? 4. What are the relative merits of assembling in trays and without trays? 5. Why should parts of the impression be arranged in consecutive order before assembling? 6. Why should parts be held steady until the sticky wax congeals? 7. Define: dental impressions; edentulous; partial impression; dental arch; dental cast; fracture-edge; tray surface. Job Appraisal : I. Have all parts been assembled accurately? 2. Are the tissue surfaces free from wax? 3. Have the parts of the impression been closely approximated so that the fracture lines are almost invisible? 4. Have you observed economy of material? 5 . Were make-overs necessary? 6. Can you assemble an impression in not longer than 15 minutes (average) ?

REFERENCES: (Books for Additional Information.) Frahm, I?. W.: T h e Principles and Technics of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., 1934. 2. Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, Inc., 1932. 3. Kennedy, E.: Partial Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., 1928. I.

R E L A T E D INFORMATION: U N I T NO. 3 P R E P A R A T I O N O F I M P R E S S I O N S F O R CASTS-I Sticky W a x : Adhesive wax, commonly known as "sticky" wax, serves many purposes in the dental laboratory. I t is used in assembling plaster impressions and in waxing parts of bridgework before investing for soldering and for temporarily attaching teeth. Sticky wax usually consists of a compound containing rosin, beeswax, coloring matter, gum damar and mastic. The greater the proportion of rosin the more brittle and more adhesive the wax. Too much beeswax makes the sticky wax too yielding and too plastic. of Sticky W a x : Ingredients (1 1 Rosin 3 02. melt and mix Wax I 02. (2) Rosin I part by weight Beeswax 4 parts by weight Gum damar I part by weight

1

Impression Trays: Impression trays hold the impression material during the process of taking the impression by the dentist. The trays are also used as retainers in assembling the broken parts of the impression. Trays are manufactured from aluminum, brass, nickel, or Britannia metal. Trays may be cleansed by covering with petrolatum, soaking in hot water and wiping dry. REFERENCES: (Books for Additional Information.) I. 2.

Prinz, H.: Dental Formulary. Philadelphia: Lea & Febiger Co., 1936. Skinner, E. W.: T h e Science of Dental Materials. Philadelphia: W. B. Saunders Co., I 936.

PREPARATION O F DENTAL IMPRESSIONS FOR CASTS-I1

U N I T NO. 3 (Continued)

33

Materials: Pink wax, carding wax, sticky wax, shellac, Sandarac and denatured alcohol (Fig. 40). Procedure : (Follow operations in the order presented here.) CAUTIONS: a. Avoid covering the dentzlre beariltg area zen'th carding wax or any other wax. b. Do not box too shallow (Fig 41).

P R E P A R A T I O N O F I M P R E S S I O N S F O R CASTS-I1 T o y shops sell outfits that enable children to cast lead o r tin toys, such as tin soldiers, boats, animals and so forth. T h e melted metal is poured into a form and is allowed to cool and harden. Similarly, t h e dental impression is the form into which the casting is to be made. T h e impression is reenforced by a retaining wall, which confines the plaster and reduces the amount of trimming of the cast after it is poured.

Process o r Principle : No. 4. Boxing Dental Impressions. a. Use of carding wax. b. Technic of boxing impressions. c. Application of shellac and Sandarac varnish; zlse of other separating media. Project or Jobs: ( T o be performed by the learner.) JOB NO. 7: BOXassembled impressions. JOB NO. 8: Apply shellac and Sandarac to boxed impressions. NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definition of new words.) Job Application: T h e assembled impression is boxed, in order to give the cast a well proportioned form and to reenforce the impression so that the parts will not come apart during the process of pouring. Separating media are applied to prevent the impression from absorbing moisture from the plaster or artificial stone used in pouring casts, and to aid in separating the impression from the cast. Vocational Information: Among the separating media used are silicate of soda or silex, shellac and Sandarac. Solutions containing ether,.gum, alcohol, soap, collodion and coloring matter are also used in varlous commercial preparations employed to make the separation of the impression from the cast easier. Carding wax or a soft basewax may be used for boxing impressions. Tools and Equipment: Two camel's hair brushes, Bunsen burner, wax spatula, penknife. 32

c-Shellac (use thin). a-Camel's hair brush (use one brush for shellac and another for Sandarac). 3-Base-\~ax, showing wax cut for fitting into tongue space of lower impressions. 4-Sticky wax (use sparingly). 5-Sandarac varnish (use thin). 6-Carding wax strip cut from main body of carding wax. 7-Carding wax for boxing impression. Note: Use carding wax at least j/s in. thick. Do not heat carding wax too much; it melts quickly.

c. D o not place carding wax too high from top of impression. d. D o not allow pink wax in tongue space to cover the lingual edges of the lower impression. e. D o not apply separating media too thickly as the fine details of the impression &ll be lost and the denture &ll not fit. f. W a i t for the shellac to dry before applying Smdarac. g. D o not use the same brush for applying shellac and Sa~darac varnish.

PREPARATION O F DENTAL IMPRESSIONS FOR CASTS--I1


34

35

h. Dry impressions absorb separating media and make separation of t h e casts difficult. Dip dried-out impressions in water for a fm lruinutes. Remove excess water from t h e impression before applying separating media.

I.

N o t e : Have a carding wax wall (B1B2) parallel and deep enough around the impression ( C ) to allow for a sufficiently thick cast. If the walls of the carding wax are constricted, the edges of the cast will be too thin .and may break. If the carding wax is boxed too flaring, too much time will be lost in trimming the cast. If the carding wax strip ( A ) is too close to the edge of the impression (D), the latter will be marred and the seal of the denture will be imperfect. If the impression is boxed too shallow, the cast will be too thin.

With the penknife cut a 3/leN strip along the full length of the carding wax and seal it around the outer edges of the impression about %" away from the crest of the rim of the impression (Figs. 41, 42, 43 and 44). This is very important. 2. Shape the balance of the carding wax around the impression, boxing it in, then seal the wax to the outer border of the impression and along the adjoining edges of the carding wax itself (Figs. 41, 42, 43 and 44). 3. In lower impressions apply a piece of basewax in the space usually occupied by the tongue (the tongue-space) (Figs. 43 and 45). 4. Using the camel's hair brush with a dabbing or stippling motion, cover the tissue surface of the impression with a thin coating of shellac and wait until thoroughly dry before proceeding (Fig. 47). 5. Using a clean camel's hair brush with a dabbing motion, apply one coating of Sandarac on the tissue surface. Wait until thc Sandarac is dry before proceeding.

Carding wax strip applied. A-Rim of impression (periphery). B-Carding wax strip. 2. Carding wax wall applied. A-Carding wax wall.

Note: Although the carding wax wall does not flare outward, all parts of the impression can be seen by looking directly at it.

I.

r. Pink basewax in tongue space. A-Tongue space. B-Carding wax strip i~ppliedbelow rim of impression. C-Rim of impression (periphery). z. Carding wax wall applied.

N o t e : Carding wax wall should not be too close to rear part (condyles) of impression to avoid thin edges.

36

PREPARATION O F DENTAL IMPRESSIONS-I1

MANUAL FOR DENTAL T E C H N I C I A N S

37

Supplementary Assignment: (Information to be obtained by learner.) I . How may home-made separating media be prepared? (See Frahm, Prinz.) 2. Which types of separating media are harmful to impressions and dentures? 3. Which types of separating media are inflammable? 4. Why is basewax used in the tongue-space?

A-Impression. B-Carding w a x strip applied. C-Crest or rim of impression w a x wall. E-Section cut out of carding wax wall to (periphery). D-Carding show relationship of impression, carding w a x strip and carding w a x wall all sealed to each other.

Ouestions : . I. Why is it important to protect denture bearing areas in boxing impressions? 2 . What precautions should be taken in applying separating media? 3. How should separating media be kept in the laboratory? 4. What care should be given camel's hair brushes? 5. Why is shellac used? 6. Why is Sandarac used? 7. Why and how should carding wax be applied? 8. Define: Artificial stone, denture bearing areas, tongue-space.

A-Impression. B-Basewax in tongue A-Impression. B-Cast (cross section). space. C-Cast (cross section). C-Carding w a x retaining wall. Note: T h e cast takes its shape from the impression. T h e details of the rim of the callst taking shape over the carding w a x rim around the impression can be seen i n 111e above photographs. T h e shape of the gum and palate also can be seen as well as the retaining purpose of the w a x in the tongue space. T h e thickness of the cast is determined by the depth of the carding w a x wall. T h e above photographs show the effect of proper boxing on the shape of the casts.

Job Appraisal :

Is the carding wax strip attached below the crest of the rim of the impression? 2 . Is the impression boxed deep enough? 3. Are the walls of the boxed impression parallel and not too close to the rear (the condyles) of the lower impression? I.

N o t i , : T h e impression is held perpendicularly. T h e separating medium is applied I l ~ ~ nlot the tleepest parts (the ridge of the gum i n full impressions and the impress11111rc of

llic tcctli in partial impressions). collect in one place.

Do not allow the separating material to Apply i t sparingly.

38

M A N U A L FOR DENTAL TEC,HNrCIANS

4. W e r e the shellac and Sandarac varnish applied evenly and not too thickly?

5. Were make-overs necehhary.> 6. Can you box an impression in r5 minutes (average).? REFERENCES:(Books for Additional Information.) F r a h n ~ ,F. W.: 'l'l~c Princi1)lcs and Technics of Full Denture Construction. Brooklyn: DcntaI Itenls of Interest Publishing Co., 1934. 2. Prinz, H.: Dental Formulary. Philadelphia: Lcn & F'ehigcr, 1936. 3. Doxtater, L. W.: Full and Partial Denture Prosthesis. 131-ookl,111:Dental Items of Intcrcst Publishing Co., 1936. I.

R E L A T E D I N F O R M A T I O N : U N I T N O . 3 (Continued)

P R E P A R A T I O N O F IMPRESSIONS F O R CASTS-I1 Basewax, reenforced by a laster core, may be used for boxing, instead of carding was. h rim of art clay or plasticene, I-enforced by sheet lead, or a patented boxing apparatus may also be used instead of carding wax.

Boxing:

Separating Media:

T h e separating media should allow for the casy separation of the impression from the cast which has beell poured in it. Separating media must not have any harmful effect on the impression such as dissolving the surface of the plaster impression or otherwise marring the fine details of the impression. T h e separating media should not be harmful to the health of the technician. I t is well to use separating media which stain the impression to some depth. This will help the technician in separating the cast since he will have a guide when removing the impression from the cast.

Ingredients of Various Separating Media:

(Parts by weight.) Castile soap I oz. Water r pt. Eleat until soap is dissolved. "I Castor oil 7 parts illcohol I part Alcohol soluble dye :?.Beeswax 10 parts by weight Carboiltetrachloride (carbons) 00 parts b y weight 4. (;urn shellac I part by weight Denatured alcohol 3 parts by weight 5. Guln Sandarac 2 parts by weight Denatured alcohol 5 parts by weight I.

I( I,:I,.I;.R~,NCI<:S: (Rooks for Additional Information.) I'l-illx, 11.: Ilcntal Formulary. I'hilndclphia: Lea & Febiger, 1936. 'l'urncr, C. R., and Anthony, L. P.: American Textbook of Prosthetic i s I . l'i~ilnilclylri~~: Lea & Fcbiger, Inc., I 932. ;. I " I . . I ~ I I I I . I.'. \fr.: 'I'Irr l ' r i ~ r ~ i ~ ~ and l c sTechnics of Full Dcnture ConstrucI ~ ~ I I I:IIIIII,I! . 11: I ) L , I I ~ 1t~,11rs . I ~ of l~l[crcstI'uhlishing Co., 1934 1 . ,<\\,, I I S O I I . 11. (;.: 0 1 1 [ l i l l c01- 1'.1111D ( ~ l l ~ ~PI-osthesis. irc New York: Netv

I.

2.

)'
\'lli\..

I'l<,',S,

11);:.

io

DENTAL CAST TECHNIC-I

U N I T NO. 4

DENTAL CAST TECHNIC-I T h e cast to be made from the impression or counter is not like a piece of sculpture in which the artist can "express" himself and shape it according to "the way he sees it." T h e cast must be an exact duplicate of the mouth from which the impression is taken. We can readily see that if the impression or counter of the mouth is accurately assembled and prepared for casting and the cast is properly made, we shall have a base or foundation for the construction of a denture that will fit the mouth. O n the other hand, if the assembling of the impression is inaccurate or if the cast made from such an impression has faults such as air bubbles, soft spots, thin edges, etc., the cast will not be an exact duplicate of the patient's mouth and the denture made on such a cast will not fit. Dental mechanics involves basic principles which are related to each other. If one principle is mastered properly it serves as a foundation for the one following it.

Process or Principle: No. 5 : Pouring Dental Casts. a. Pozcring dental casts i n plaster of Paris, after boxing and application of separating media. b. Pouring dental casts in artificial stone, after boxhg and application of separating media. c. Use of mechanical vibrator. d. Reenforcing remaining teeth on partial casts. Project or Jobs: ( T o be performed by the learner.) JOB NO. 9: Pour in plaster, four sets (eight impressions) of full upper and lower boxed impressions, assembled in trays. JOB NO. 10: Pour in artificial stone, four sets (eight impressions) of full upper and lower boxed impressions, assembled in trays. JOB NO. I I : Pour in plaster, six boxed partial impressions, assembled without trays. JOB NO. 12: Pour in artificial stone, six boxed partial impressions, assembled in trays. NOTE: (Read the entire Unit carefully before beginning work.

Job Application: Plaster or artificial stone, when mixed with water and poured into a dental impression, if allowed to stand until "hard" 40

4I

or "set," assumes a shape which is a counter or mold of the impression into which it has been poured. A dental cast is in fact a counter or replica obtained by allowing plaster or artificial stone poured into a dental impression to set. The cast is obtained by carefully breaking away the impression from the set plaster or stone which had been poured into it. Artificial stone has now practically replaced plaster as a material for making dental casts.

Vocational Information: Accurate pouring of casts is important because the prosthetic appliance is constructed on the cast. If the cast is inaccurate the appliance constructed on it will not fit the mouth of the patient. Casting plaster sets slower than impression plaster. Artificial stone may contain "hydrocal" or Alpha gypsum; Portland cement, alum, sand, citric acid, pigment, Rochelle salt, etc. Artificial stone is better able to withstand usage in the construction of the dental prosthetic appliance. This is the main reason why it has practically displaced laster as a cast material. Mechanical vibrators consist of an off-center lathe chuck or wheel sometimes used in combination with a platform for holding the impression. Vibration helps to eliminate air bubbles from artificial stone casts. Tools and Equipment: Plaster bowl, plaster spatula, glass slab, mechanical vibrator, dental lathe (Fig. 48). Materials: Plaster of Paris, water, artificial stone, paper clips. Procedure : (Follow operations in the order presented here.) CAUTIONS : a. I n partial cases the tooth depressions in the impression shozlld be filled with plaster or artificial stone first, making sure that all air bubbles are exclzcded. b. W o r k carefully and expeditiously to prevent plaster from settiag before the cast is fully poured. c. Less Water is required for nrtifiial stone, roo grams stone to 30 cc. water. d. Hold impressions securely on mechanical vibrator. e. If the prepared impression is not soaked i~ water until all bubbling ceases, t h e inzpression well absorb moistzcre from the cast poured into it. This may make the cast too soft and otherm'se imperfect i n detail. f. Separating media must be thoroaghly dry before the cast is poured.

42

FIG. 49.

METHODOF JARRING FIRSTAPPLICATION OF PLASTER INTO PLACE I N THE INPRESSION

A-Plaster

I-Dental

43

DENTAL CAST TECHNIC-I MANUAL FOR DENTAL TECHNICIANS

Lathe. 2-Vibrating

platform.

3-Lathe

deposited a t rear of boxed impression. B-The

boxed impression.

chuck with off-center fibre disks.

Note: Attach chuck with off-center fibre disks to lathe spindle-end. Adjust platform between chuck release (A) and lathe bushing ( B ) . T h e vibrations are produced by the off-center fibre disks striking against the bottom of the vibrating platform.

I. Pouring Plaster: I. Immerse the prepared impression in cold water for 5 to 10 minutes. 2. Remove the impression from the water and drain all excess water adhering to tissue surfaces. 3. If plaster is to be used, make a plaster mix. 4. Place a small quantity of plaster in the rear of the impression which is held in the hand and jarred against the plaster bench, quickly covering the tissue surface of the impression (Figs. 49 and 50). 5. Holding the impression in one hand, add plaster, using plaster spatula. Tap the back of the hand holding the impression

I

d

PARTIAL IMPRESSIONS (CROSS SECTION VIEW) FIG.50. Mm.1-10~OF POURING I-First application of plaster or stone (x) into rear of boxed impression. 2-First r~ppIic:~~tion of plnstcr or stonc ( x ) j:~rrcd into place and second application added. 3-Air I)ul)l~lc( A ) rcnr~ltof ilnlrropcr iutrotluction of plaster or stonc (x) into boxed p11rli111itnl)rr!iui~>t~ (cross swtiol~).

44

M A N U A L ]'OR

I)I
gently against the plaster bench so that each addition of plaster settles in the impression before the next is deposited. Continue adding plaster and tapping the impression until plaster has filled the boxed impression. Wait until plaster has set thoroughly before procccding, NOTE: If artificial stone is to be used, the proportion of water is 2 5 per cent less than for plaster. 11. Pouring Stone: I. Follow the directions of the manufacturcr for mixing stone. T h e usual proportions are water I part and 3 parts of stone by weight. A small quantity of the mixed stone is placed at the rear of the impression. Using a jarring motion adapt the artificial stone to the impression. 2 . Add small quantities of the mixed stone, allowing each addition to settle or spread over the impression. Add stone until all of the boxed area is filled.

FIG. 5 1 . IMPRESSION POUREDI N STONEBEINGVIBRATED ON MECHANICAL VIBRATOR TO ELIMINATE AIR BUBBLES AND TO OBTAIN AN ACCURATE CAST (VIEWED FROM ABOVE) A-Dental

lathe. B-Vibrator

table. C-Poured

impression.

Noie: The amount of pressure of the hands holding the boxed impression on thc vibrating platform controls the amount of vibration. T h e boxed impression s l ~ o ~ ~ l t l be held carefully to avoid crushing or distorting the impression.


45

3. Vibrate the impression against the plaster bench while stone is being added until all air bubbles are brought to the surface and eliminated. 4. If a mechanical vibrator is used, hold the impression carefully while on vibrator platform. (Fig. 5 I.) 5 . Score the top of poured casts to facilitate attachment to plaster when mounting on articulator. (Fig. 5 2 . ) NOTE: TOreenforce isolated teeth in partial impressions bend a piece of a wire clip to extend from the rim of the impression to about 2 mm. from the occlusal surface of the tooth-impression and hold in place with sticky wax. (Fig. 5 3 . ) Supplementary Assignment: (Information to be obtained by the learner.) I. Difference between impression plaster and cast plaster. 2 . Types of artificial stone. 3. Warpage of casts; causes of warpage. 4. How does stone compare with plaster in respect to expansion and hardness. 5. Various types of mechanical vibrators. 6. Pouring of compound and other composition impressions. Questions : I. What may happen to the cast if plaster is not mixed properly? 2 . How is the first covering of plaster applied? 3. W h y is the impression jarred when being poured? 4. What is the correct procedure for pouring dental impressions in plaster; in artificial stone? 5 . What precautions should be taken in pouring partial impressions? 6. What precautions should be followed in using mechanical vibrators? 7. W h y are air bubbles in casts harmful? 8. Why are bases of casts scored? 9. W h y is artificial stone used for making casts? What happens when artificial stone is not properly mixed? 10.Define: mold, counter, prosthetic appliance, warpage? Job Appraisal : I. Are there any bubbles or other imperfections on the tissue surface of the cast? 2. Have the bubbles been vibrated to the base of the poured cast?

46

MANUAL FOR DHN'I'AL TECHNICIANS

DENTAL CAST TECHNIC-1

47

3. Was economy of material observed? Were the bases of the casts scored to facilitate mounting on articulators? 5. Were make-overs necessary? 6. Can you pour a cast in about 10 minutes (average)? . REFERENCES: (Books for Additional Information.) I . Frahm, I?. W.: T h e Principles and Technics of Full Denture ConstrucA.

-

tion. Brooklyn: Dental Items of Interest Publishing CO., 1934. z. Skinner, E. W.: T h e Science of Dental Materials. Philadelphia: W. B. Saunders Co., I 936. L. W.: Full and Partial Denture Prosthesis. Brooklyn: Dental - Doxtater. - Items of Interest Publishing CO., 1936. 4. P r i n r , H.: Dental Formulary. Philadelphia: Lea & Febiger, 1936. 2.

I-Carding Note: No.

wax retaining wall in place 2-Carding wax retaining wall removed. is roughened too much. I t should be smooth and grooved; otherwise the cast may be broken when i t is removed from the articulator.

2

No&: W a x the pieces of wire, cut from paper clips, opposite the tooth depressions (A, B, C) so that they are imbedded in the middle of the tooth impression and are not too near the tooth surface on the cast.


R E L A T E D INFORMATION:

U N I T NO. 4

DENTAL CAST TECHNIC-I Artificial Stone: A suitable material for dental casts must be sufficiently strong and hard to withstand usage during the construction of the denture. T h e material must withstand the pressure and temperature change during vulcanization. I t must not set too quickly so that enough time may be allowed for manipulation. When setting the material should not contract or expand. T h e mix should be of such consistency that it can be vibrated, poured or packed accurately into all parts of the impression. The cast material should set after a reasonably long interval: Artificial stone is usually mixed with one part of water to three parts of stone by weight. The initial set is 7 to 15 minutes. T h e final set is 12 to 25 minutes. Crushing strength in I hour is 2,400 pounds and in 24 hours it is 3,700 pounds per square inch. Ingredients of artificial stone vary and are usually kept as trade secrets by the manufacturers. Some a r t q a l stones consist of the following ingredients : ( I ) Calcium, I 9 parts by weight. Pure Silica, 20 parts by weight. Aluminum Oxide, 42 parts by weight. (2) Rochelle Salt, I to 5 per cent. Pigment, 0.5 per cent. Retarder, 0.1 per cent. Alpha ,Gypsum, balance (Skinner). Modeling Compound: This is a composition used for making impressions and biteblocks. I t may be white, brown, red or black in color. Modeling compound can be softened in hot water (12o0140° F.) and molded to any desired shape. On cooling, the compound hardens (9s0-105' F.) and retains its shape. For this reason it is possible to use it as an impression material. Impressions made of modeling compound are poured the same as plaster impressions excepting that separating media must not be used and artificial stone should be vibrated, but never packed in them. 48

49

Ingredients of Modeling Compound: ( I ) Stearin, 25 parts by weight. Gum Damar, 50 parts by weight. Powdered Soapstone, 85 parts by weight. Carmine to give color (Prinz). (2) Kouri, I part by weight. Stearin, 1.5 parts by weight. French Chalk, 1.75 parts by weight. Coloring material (Prinz) . Elastic Impression Materials: These are used occasionally, especially for partial impressions where undercuts are present. T h e materials contain rubber latex, cellulose, fiber, agar-agar, wax and water. Since most of these materials shrink when exposed to air, because of loss of water, they should be kept moist until poured. T h e Dentocoll impressions, as well as other elastic-material impressions, should never be packed with stone. T h e stone should be poured and vibrated into position, otherwise the impression will be distorted. I t is well to follow the formula of the manufacturer when working with elastic impression materials. Dentocoll: This is a commonly used impression compound and should be poured as soon as possible after it is taken from the mouth of the patient by the dentist. Dentocoll as well as other elastic compounds can easily be distorted when the attempt is made to box them. Patented boxing apparatus may be purchased for this purpose. Soft modeling clay can also be used for boxing. Cover the poured impression with a moist napkin during the setting period. Soluble Plaster: Plaster to which starch has been added is sometimes used as an impression material. One part of cornstarch to three parts of plaster is the usual composition of soluble plaster.


I

5'

the soluble elastic and other impression compounds are separated fro111 the casts by i n ~ i n e r s i iin ~ ~hot ol- boiling water. This is all advantage over plaster impressions, which must be carefully removed from casts. U N I T NO. 4 (Continued,) D E N T A L CAST TECHNIC-I1 W e spoke OF pourillg 01- castir~gmetnl toys into forms. After tllc pourcd lllctal hecoilles solid the mold or nwtris is removcd and thc cast toy is left. stonc or plaster cast which had I n pouring dental casts, 2ftc.r tlic .~rtifici.~l hecil pourcd in10 the illip1.cssiotl IS ~ e or t hardenetl, tllc in~prcssionis rc11iol-ed from thc ~ 1 s t . Sincc p1.1stcr :ind .~rtificinlstone ;Ire not as hard as ~netnland since the cast lnust he .ill ey.1c.t d ~ ~ p l i c : ~oft c tllc iilouth, wc can rcndily see that cxtreille cnrc should he t ; ~ t c ~inl scpni-;lting the impressiol~ from the cast. T h i s ~ l n i t prol-idcs mcthoils ~r-llicllm a t c tlic scparating PI-occsscornpnrati\-ely casy.

P r o c e s s o r Principle : No. 6: Separating Casts from In~prcssions. a. SeparalinR p l a s l ~ rcasts frorn iimprl,s.ri(~ns. b. S ~ p a r n t i n ~artificial p stonr casfs from i/lipurrsioiis. P r o j e c t o r Jobs: ('I'o be performed 1)y the 1 ~ ~ 1 r n e r . ) JOB NO. 13: Separate four sets of full u ~ p e rand lower plaster casts from impressions. JOB NO. 14: Separate four sets of f u l l upper a r ~ dIonct- artificial sto~iccasts ft-on1 inlpressions. J O B NO. I ;: Separate six p'lrtial plaster casts fiom irnl)t-cssiolis. JOB N O 16: Separate six partial artificial stone casts from ilnpressions. NOTE: (Read the entire ( i n i t carefullj before beginning work. Consult the glossar) for definitions of new words.) Job Application: After thc material (plastel- or artificial stone) which has been pourcd illto the houed inipression h:ls hardened 01.rt,t, the ir-npression is separated fl-on1 the cast. T h e cast is then read! to be trimmed to proper proportions. Vocational I n f o r m a t i o n : 111 addition to l~l;tstcr,other impressioti materials arc used which possess certain l~~-ol)e~-ties 11ot foi111~1 i 1 1 1)1:~% ter. Among the ni:~tc~-i:tls used 21-cdc~it:~l i1lll,1.cssio11 (.o111~,0~11(1, sol uble plaster, clastic co~nlloi~n(Is slid I~:II-d\\.;I\c.c;. 'I'l1c~sc. I I ~ : I ~ C , I . ~ : I I ~ vat-!. i n thc dcgrcc of :~ccu~-:tc!~ of tlic, inll,~-c-..;it,l)C; 1~.,~1utc.tl. R 1 o ~ ; ot f ,I

1

Tools and Equipment:

l'laster knife, penknife.

Materials : Alcohol, absorbent cotton. (Follow operations in the order preseilted here.) CAUTIONS: a. 110 n o t alltJnipt t o separate cast f r o m impressiom befort, t h e cast material has fully set. b, D o n u t allow poured impressions t o stand too l o n g befort, separating. c. L)u n u t cut i ~ z t ocast w h r n scorir~g tray surface of i ~ ~ ~ p r ~ , s s i o n or w h e n separating. d. Kt.11~oveinipressian f~iatrrzirlravefully fvoni nroullcl I / / ( -tt,t,t/~ of t/lc c a s ~b(2fore attempting to rrrfiovr 1/7e iiiipri~ssioilplri t s covt7ri?~gother tissues. e. B e sure t o sc urr until L O ~ O Y of srparoting media becomes visible t o assure t l ~ a t h e inapression has been suficiently weakened before a~tcnaptkagt o brtvk away parts t o srparate t h e cast. f. I n breaki~zgazeay prirts of t h e impressions, apply pressure azeay frowz ~ e e t hor t h i n edges of t h e cast. g. T r y t o b a l a ~ ~ corr c o ~ t r o lforce upplird in breaking away i m pression parts. h. D o not expose too / I I Z ~ (of / L t h e blade of .the k n i f e used i n separating parts of intprt,ssion f r o m cast. T h i s will aid t o avoid cutting into cast.

Procedure :

Remove carding wax and tongue-space wax used in boxing impressions. (Figs. 54, 55, j 6 and 57.) 2 . Score the impression until coloring material in separating media becomes visible. (Figs. 56 and 57.) 1. IJsi13g the point of the plaster knife, carefullj. remove the segregated parts of the impression, beginning at the heel or cond! Ic until all of the cast is exposed. (Fig. 58.) 4. 111 sep;~r:~ti~lg partial impressions first remove all parts of im1>1-e\\iol1 around teeth, being especiallq careful to do so around 1~)1,1tc(1 tectli. (1:ig. 59.) C. I
-9


A-Carding wax removed. B-Wax r e m o v e d from tongue space.


53

A-Carding wax removed. C-Impression scored to make separating easier. A-Knife

with impression parts removed. C-Scored impression parts not yet removed. Note: Pressure of the knife should be away from the cast. T h e thumb of the left hand can aid in guiding the piece to be separated and in checking the pressure of the knife blade. T h e sharp edge of the blade should never be directed toward the cast, to avoid cutting into the cast.

A-Carding

wax retaining walls. B-Scored impressions. C-Casts impression parts have been removed.

blade.

B-Cast

from which

Note: Upper and lower poured casts with carding wax boxing partially removed and impressions scored and partly removed from casts. T h e carding wax retaining walls and strips (A) have been removed. T h e impressions (B) have been scored and are partly removed from the casts (C). T h i s illustration is used to SIIOIY the various components of the poured casts. It is better to remove all the boxing material ant1 then to score the impressions until the color of the separating medium becomcs visible. T h e impression then can be removed easily frorn the cast.

Note: I t is best first to remove the impression material around the teeth of the cast. Clear the impression away especially from isolated teeth. Mark X opposite the tooth tlepressions on the tray surface of the impression to aid in locating the isolated teeth I)cfnre the cast is poured. Always direct the force of the knife blade away from the tcct11 on the cast. Score the cast well to weaken the impression plaster.



I

55

Supplementary Assignment: (Information to be obtained by the learner.) I . Various tools used for separating impressions from casts. 2 . P r o ~ r i e t a r vmaterials (compounds and soluble plasters) used for taking impressions. 3. Methods of separating dental compound from casts. 4. Methods of separating elastic impression materials from casts. 5. Composition of dental compound, elastic impression materials, soluble plaster. 6. Separating soluble plaster. Questions : I . W h y should the cast material be fully set before attempting to separate the impression from the cast? 2. What may happen if poured impressions are allowed to stand too long before separating? 3. W h y should the denture bearing area not be mutilated in separating impressions from casts? 4. W h y is it important not to break teeth from cast? 5. What may happen if the knife-blade is exposed too much in separating casts? 6. What are the advantages and disadvantages of plaster as an impression material (from the standpoint of the cast produced) ? 7. What are the advantages and disadvantages of compound, elastic materials and soluble plaster as dental impression materials (from the standpoint of separating impressions) ? 8. What are the advantages and disadvantages of plaster as a cast material? 9. What are the advantages and disadvantages of artificial stone as a dental cast material? A-Frenum (muscle attachment). BAlveolo-buccal fold (between cheek and alveolar process). C-Alveolar ridge (gum ridge). D-Palate (roof of mouth). E-Excess included by carding wax rim applied around impression. This should be trimmed away.

A-Alveolo-buccal fold. B-Alveolar ridge. C-Tongue space. D-Excess included by carding wax rim applied around impression. This should be trimmed away.

Note: Full upper and lower casts after the impressions have been removed, before trimming. T h e casts are already fairly well trimmed.

Job Appraisal : I. Are the casts free from cuts or other damage in separating? 2 . H a s all of the impression material been removed? 3 . Are air bubbles present? Are all details of the impression reproduced in the cast? 5. Have teeth been broken in partial casts? 6. Can you separate a full cast in 10minutes (average)? 7. Can you separate a partial cast in 15 minutes (average) ?

4.

56


REFERENCES: (Books for Additional Information.) I . Skiilner, E. W.: ?'he Sciencc of Dcntal Mxtcrials. phi lad el phi^: W. B. Saundcrs Co., 1936. 2. Ray, K. W.: Aletallurgy for Dental Students. Philadelphia: P. Blakiston's Son & Co., IIIC., I 9 j I . j. Frahni, F. W.: Principles 2nd 'l'cclinics of Full Denture Construction. Brooklyn: D c ~ l t a lItellls of Interest Publjsliinp Co., 1934. 4. Kennedy, E.: Partial Denture Const~uction. Brooklyn: Dental Items of Intercst Publislling Co., 1028. j. Prinz, H.: Dental Formulary. 1'1liln~icl~hi.r:Lea ik Fcbigcr, 1936.



D E N T A L C A S T TECHNIC-11 Separating Soluble Plaster: Immerse the impression with the poured cast in boiling water. T h e starch causes the impression to swell and disintegrate, allowing the impression to be easily removed from the cast. Separating Modeling Compound : Place the compound impression with the poured cast in hot water until the compound is sufficiently soft to be readily removed from the cast. If the compound is too hard the cast, especially teeth in partial casts, may be broken. If the compound is allowed to remain in boiling water too long it may adhere to the cast and become difficult to remove. Separating Elastic Impression Material: Follow directions for compound or the directions supplied by the manufacturer. Separating Dentocoll: Dentocoll can be p e l e d off by using a plaster knife. I n full impressions the dentocoll can be pulled off the cast by tugging on the impression tray handle. Care should be exercised in separating partial impressions.

D E N T A L CAST TECHNIC-111

U N I T NO. 4 ( C o t ~ t i ~ u e d ) D E N T A L C A S T TECHNIC-111 W h e n a metal toy is cast into n mold, it will be iound 011 sc~cirating W h e n n dcntal c.isl the mold that thci-c are rough edgcs on thc ~ ~ 1 toy. st is scpnrntcd fl,om the i ~ n ~ r c s s i ointo n which it hnd been poured n ccrt;lin amount of csccss, especially that covering the carding war rim, is included ~ ~l.illinlcdn\vny. A triinnlcd, ncnt cast is easier to in the cast 2nd I I ~ L I S be h;~ndle2nd is an iiiiiuccnlcnr to m-ork neatly. A11 cientnl casts should be trimmed.

Process o r Principle: No. 7: Trimming Dental Casts. a. Trimnaizg edentulous casts. b. T r i m i ~ i ~partial g casts. P r o j e c t o r Jobs : ( T o be performed by the Ieariler.) J O B No. 17: T r i m four sets of full upper and lower plaster casts. J O B No. 18: Trim four sets of full upper and lower artificial stone casts. J O B No. 19: Trim six partial plaster casts. J O B No. 20: T r i m six partial artificial stone casts. NOTE:(Read the entire Unit carefully before beginning work. Consult the glossary for definitions of new words.) Job Application: T h e casts are trimmed in order to make them symmetrical, to facilitate handling, mounting on articulator and in flasking. Vocational Information: If the casts are used for display purposes, "art portions" are constructed. There are many methods of trimming casts. T h e most practical is to have the base parallel to a straight edge placed across the crest of the alveolar ridges. T h e sidcb of the base should be about one-eighth to one-sixteenth higher that1 the alveolo-buccal fold or the periphery. A good method to follow is to cut along the ridge left by the carding wax strip. Tools and Equipment: and blade, rasp file. Material : Sn~ldlnpcl-.

Plaster knife, ruler, l)crlc.il, ljl:tqtc~-h:t\r

,

h

59

Procedure : (Follow operations in the order presented here.) CAUTIONS: a. Do n o t t r i m casts too close t o alv~olo-buccalfold. b. I l o n o t t r i m casts t o o thin o n palatal portion. c. D o n o t rut t o n g u e space t o o thin. d . 110 not ijiar tissue surfare of L / I P cast t o be covert7d b y t h e d ~ r a l u r e base. c. Rt, sure t h e base of t h e cast is parallel w i t h t h e alveolar ridgrs. f. I l o n o t use sandpaper o n i l e n t u r ~bearing area. I . LJsing pencil, mark the casts along the lines to be trimmed away. 2 . LJsing plaster knife in palm grip 01- plaster saw, cut around at right angles to the base along the part of the cast over the carding wax styip. D o not cut too close to alveolo-buccal fold. (17igs. 63 and 64.) .{. For artificial stone casts a rough or rasp file or plaster saw may be used. (Figs. 64 and 65.) 4. ];or partials the alveolo-buccal fold may be used as a guide to indicate the amount of gum and alveolar tissue lost hy the extraction. (Figs. 66 and 67.) 5. Finish with fine sandpaper. (Fig. 68.) Supplementary Assignment: (Information to he obtained by tll: learner.) 1 . Various tools used in dental laboratories to trim casts. 2 . Different methods of trimming casts. 3. Different apparatus used for marking at-t-bases. 4. Different types of trimming machines for plaster and stone casts. 5. Methods of duplicating casts. Questions : I . W h y are casts trimmed? 2. What is the most practical method of trilnllling casts? 3. Which tools may be used for trimming casts? 3. W h y should stone casts be trimmed immediately after separating? 5 . W h y is sandpaper used? 6. What rare should be evercised in trimming casts? 7. Whxt may hal)pen if casts are trimmed too thin? S. (live thc .tdvat~t:t~cs of a wcll trirnl-ned cast.



61

9. Define : gum ; alveolar tissue; extraction; alveolo-buccal fold ; palm grip; base of cast; condyle; heel; palatal portion; alveolar ridges; periphery; crest of ridge; articulators; flasking; denture bearing area.

FIG.63. METHOD OF TRIMMING DENTAL CASTS ALONG THE LINEESTABLISHED BY THE CARDING WAXSTRIP USEDIN BOXINGTHE IMPRESSION A-Line along inner margin of carding wax strip. B-Thumb guard and guide for controlling knife blade. C-Knife blade in palm grip. D-Lower cast. Note: If impressions are boxed properly there will be very little trimming of casts necessary. Palm grip and thumb guard are used in trimming casts.

FIG.64. METHOD OF SAWING EXCESSOF UPPERCAST Note: Saw to "full" dimensions to allow for sandpapering without making it neccssary to trim the cast beyond the beginning of the alveolo-buccal fold.

Job Appraisal : I. Is the crest of the alveolar ridge parallel to the base of the cast? 2 . Are the sides of the art-base at right angles to the base of the cast?

62


R E L A T E D INFORMATION:

U N I T NO. 4 (Continzced)

D E N T A L C A S T TECHNIC-111

A. Lower Cast.

I-Full

B. Upper cast. 5-Full

view.

2-Rear view. 3-Side view. .+-Front (inverted). view. 6-Front view. 7-Rear view (inverted). 8-Side

view view.

3. Are the sides of the art-base smooth? Has the base of the cast been scored? 4. Is the tissue surface, especially the denture bearing area, free from damage? 5. Did you spoil any casts? 6. Can you trim a cast in not longer than 10 minutes (average) ? REFERENCES:(Books for Additional Information.) I.

Nichols, I. G.: Prosthetic Dentistry.

\

St. Louis: The C. V. Mosby Co.,

1930Kennedy, E.: Partial Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., 1928. 3. Doxtater, L. W.: Full and Partial Prosthesis. Brooklyn: Dental I t c n ~ s of Interest Publishing Co., 1936.

2.

Patented Trimmers : There are several patented trimmers now on the market. They should be used with great care and by experienced workers. Duplicating-Casts : There are various duplicating compounds on the market. Dentocoll may be used. I t is best to follow the directions supplied by the manufacturer when using duplicating material. Ingredients of a Duplicating Compound (Prinz) : Fresh slaked lime, 10parts by weight. Sugar, 10parts by weight. Glycerine, 1 2 parts by weight. Dissolve the sugar in the glycerine by heating in water. T o Preserve Casts: Boil the dried cast in a solution of borax I part and water 50 parts by weight.

PREPARATION O F DENTURE BEARING AREA+I

a

exit of the main nerves and blood vessels through small bone openings. Vocational Information : Success or failure of a denture depends on proper relief of bony areas by the addition of tinfoil over these areas on the casts. There are many methods for outlining denture bearing areas and relief of hard and soft areas. This procedure is

UNIT NO. 5 P R E P A R A T I O N O F D E N T U R E B E A R I N G AREAS-I W i t h the completion of the casts, we have merely obtained the plot on which our s t r u c t u r e t h e denture--is to be built. Before building it is necessary to have a plan which shows the extent of the area to be covered by the building. Furthermore, the character of the ground on which the foundation is to be laid should be well known. Solid rock must be differentiated from soft boggy ground so that the foundation may be modified accordingly. T h e dentist is the surveyor and architect. However, the builder, in this instance the dental technician, must understand the reading of blue prints, and the meaning of the various terms used by the architect, the dentist, so that the plans may be followed accurately. T h e dental technician should know in a general way the location and the courses of certain blood vessels, nerves and hard and soft areas.

median line of palate

blood vessel

Process o r Principles: No. 8: Outlining Denture Bearing and Relief Areas on Casts. a. Locate anatomic landmarks. (Figs. 69 and 70.) b. Outline edentulous and partial denture bean'rag area-s. (Figs. 71, 72, 73 and 74.) Project o r Jobs: ( T o be performed by the learner.) JOB NO. 21: Locate anatomic landmarks and outline denture beafing areas on eight sets of edentulous casts (sixteen\casts). JOB NO. 22: Locate anatomic landmarks and outline denture bearing areas on twelve partial casts. (Figs. 75, 76, 77a and b.) NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definitions of new words.) Job Application: The dental arches consist of the palate and alveolar process in the upper jaw, and the alveolar process in the lower jaw. I n the construction of artificial dentures, a knowledge is necessary of the areas to be covered by the dentures, the various names and locations of the respective hard and soft areas and the points of 64

Note: In order to make accurate dentures it is necessary to have. some acquaintance with the names of the actual tissues of the mouth. Compare the landmarks indicated in the above diagram with those in the mouth of a person. While no two mouths or even two teeth are ever exactly alike, the general structural arrangement of the mouth is basically the same in all human beings.

known also as denture designing and should be done by the dentist who sees the patient and has the knowledge of and opportunity for examining the mouth. However, the technician should be familiar with the terms used and principles involved so that he may be able to understand the instructions of the dentist. Tools and Equipment: Marking pencil, notepaper. Materials : Dental casts.

66

67

PREPARATION O F DENTURE BEARING AREAS-I


Supplementary Assignment: (Information to be obtained by the learner.) I. Kennedy's method of partial denture classification and design. 2. Cummer's classification of partial denture design. 3. Various methods of outlining dentures.

A-Lingual (towards the tongue) surface of molar. B-Buccal (towards the cheek) surface (facing or closing with teeth in opposing surface of molar. C-Occlusal jaw). D-Incisal (cutting) edge of anterior teeth.

Note: Compare the above diagram with the upper jaw of a person. landmarks and note differences.

Locate the

Procedure : (Follow operations in the order presented here.) CAUTIONS: a. Do not scar casts in marking dentzlre bearing or relief areas. b. Relieve all hard or unduly soft areas. c. Avoid impinging on muscle attachments. NOTE: T r y to locate the various anatomic structures marked in Figs. 69 and 70 by looking into the mouth of a person. \ I. Using a pencil, outline the frenum on the casts. 2. Outline the muscle attachments on the casts. 3. Outline the denture bearing areas on the casts. 4. Outline the rugae on the upper casts. 5. Outline the median line. 6. Outline the condyles. 7. Outline the exits and courses of the main palatal and man dibular nerves and blood vessels. 8. Outline the division of the hard and soft palate. 9. Outline the dividing line of the alveolar ridges.

limit (in alveolo-buccal fold). A-Heel or tuberosity of upper jaw. B-Denture C-Muscle attachment (alveolo-buccal fold). D-Muscle attachment (frenum at cheek). E-Muscle attachment from upper lip to upper gum (labial frenum). F-Opening in bone at gum pad on the median line of the gum ridge. G--0pening in bone at molar region. A-Condyle (elevation at rear of lower alveolar ridge). B-Crest of ridge (highest muscle attachment between lower lip and part of alveolar process). C-Lower alveolar process (labial f renum) D-Muscle attachment (frenum) E--Denture area limit (in alveolo-buccal fold). F-Muscle attachment (alveolo-buccal fold). G--Tongue space. hrote: Bone openings exist for the passage of veins, arteries and nerves.

.

.

4. "Horseshoe" dentures, indications and contra-indications. 5. Palatal bar dentures, indications and contra-indications. 6. Lingual bar dentures, indications and contra-indications. 7. ccVacuum"chambers.

Questions : I. What are rugae? 2. What is the median line? 3. What are the condyles? .; What tlocs thc uppcr denture bearing area include?

68

PREPARATION O F DENTURE BEARING AREAS-I


69

5. What does the lower denture bearing area include? 6. Why is it important for dentures to avoid pressing on muscle attachments?

7. Where is the soft palate located? 8. What are the alveolar ridges?

+ . ? .

, '"

;.i t .

Note: Denture bearing areas on partial casts as outlined by the dentist. T h e denture follows the lingual aspect of the remaining teeth. T h e designing of dentures should be done by the dentist and not by the laboratory technician.

A-Blood-vessels.

B-Denture

bearing area limits. C-Relief opening for blood-vessels.

on ridge.

D-Bone

A-Blood-vessels. B-Denture bearing area limits. C-Relief over rugae. D-Bone opening under gum pad. &Relief over hard areas on palate. F-Median line. Note: T h e denture is made so that it does not extend over the frenums or the soft palate. If the denture covers too much area it will be displaced when the patient is eating or speaking. If the denture does not extend over a sufficiently large area it will not adhere properly to the tissues of the patient.

9. Where are the main exits of the nerves and blood vessels located? 10.What I I.

12.

are the dental arches? What is the alveolar process? What do we mean by denture bearing areas; anatomic landmarks; vacuum chambers; horseshoe dentures; palatal bar dentures; lingual bar dentures?

Note: Partial casts (top view) outlined for dentures.

7O


Job Appraisal : I. Can you outline the denture bearing areas on full and partial casts? 2. Can you outline hard and soft areas? 3. Can you answer the questions correctly? REFERENCES: (Books for Additional Information.) Doxtater, L. W: Full and Partial Denture Prosthesis. Brooklyn: Dental Items of Interest Publishing Co., 1928. 2. Kennedy, E.: Partial Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., I 928. 3. Nichols, I. G.: Prosthetic Dentistry. St. Louis: T h e C. V. Mosby Co., I.

= 930.

4. Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, 1932. 5. Swenson, M. G.: Outline of Full Denture Prosthesis, New York: New York Univ. Press, 1932.


PREPARATION OF DENTURE BEARING AREAS-I1 If a house is to be built on a hillside or on sloping, uneven ground, it is frequently necessary to modify the ground in order to obtain a solid, Ievel foundation. In building a denture it is necessary to relieve certain hard areas so that the gum overlying these areas will not be too compressed when the denture is worn in the mouth of the patient. It is also important to relieve pressure on blood vessels and nerves, especially where they come through the bone openings. T h e dental technician must know how to follow the instructions of the dentist in overcoming these difficulties and to take advantage of the favorable features presented by the landmarks found on the upper and lower denture bearing areas of the jaws.

Process or Principle : No. 9: Application of Relief Metal and Tinfoil to Casts. a. Application of relief metal t o edentulozls casts. b. Application of tinfoil t o edentulous and partial casts. Project or Jobs: (To be performed by the learner.) JOB NO. 23: Apply relief metal to four sets (eight casts) of edentulous casts. JOB NO. 24: Apply tinfoil to four sets of edentulous plaster casts (eight casts). JOB. NO. 25: Apply tinfoil to six partial plaster casts. NOTE: (Read the entire Unit carefully before beginning work. Consult glossary for definitions of new words.) Job Application: The relief metal establishes a form for the vulcanized denture to follow in relieving the hard or soft areas previously outlined on the cast. The tinfoil aids in keeping basewax intact when it is removed from the cast. Tinfoil produces a finer surface on vulcanite. Vocational Information: Britannia metal of 20, 22 or 2 4 gauge thickness (Brown & Sharpe) and .003 tinfoil is cut and adapted to relief areas. Tinfoil of .oar thickness is adapted over plaster models. Thicker relief metal was once used for "vacuum chamber" metal. 71

72


PREPARATION O F DENTURE BEARING AREAS-11

73

At one time, relief metal was applied for the purpose of creating a "vacuum chamber" between the tissues of the palate and the denture. T h e "vacuum chamber'' was intended to assist in keeping the denture against the tissues. T h e relief metal may be attached to the cast with rubber cement or with short pins. Tools and Equipment: Tinfoil, scissors or shears, rounded orangewood stick, two-row brush wheel, Bernard pliers. Materials: Tinfoil of .OOI and .003 thickness, Britannia metal of gauge, absorbent cotton, straight short pins. (Figs. 78 and 79.) Procedure : (Follow operations in the order presented here.) CAUTIONS: a. Do not waste relief material. b. Do not leave sharp edges on relief metal. c. Avoid folding, tearing or creasing tilzfoil. d. Do not mar cast or relief metal in application of reliefs and tinfoil. e. Do not use too much cement. f. Imbed pins securely. I . Cut tinfoil and relief metal with shears. 2. Using small scissors trim tinfoil and apply with rubber cement over relief areas. 3. Apply smallest piece of .003 tinfoil over median hard ridge of palate using rounded end of orangewood stick. (Figs. 80, 81 and 82.) 4. Apply second larger piece of .003 tinfoil following outline. (Fig. 80.) 5. Apply relief metal to cover hard median ridge 22 gauge. (Fig. 80.) 6. Apply kidney-shaped piece of .003 tinfoil. (Figs. 81 and 82.) 7. Apply 22-gauge relief metal on lower cast where indicated. (Figs. 80 and 82.) 8. Using Bernard pliers cut straight pin about inch from point. (Figs. 79 and 83.) 9. Holding with Bernard pliers push pin point through relief metal and cast and burnish relief metal and pin. (Fig. 83.) 1 0 . Using a soft bristle brush, adapt the center of the tinfoil sheet to the palate of the upper cast. (Fig. 84.) I I. Carefully burnish the tinfoil toward the alveolar ridges and extend to the limits of the denture bearing areas. Use absorbent cotton and orangewood stick for burnishing tinfoil. 22

USEDIN APPLYING RELIEFMETALAND TINFOIL FIG. 79. TOOLS I-Absorbent cotton. 2-Scissors. 3-Two-row brush wheel. 4-Cement for attaching relief metal. 5-Orangewood stick. 6-Bernard pliers for cutting pins.


74 12.

PREPARATION O F DENTURE BEARING AREAS--I1

75

Carefully remove the tinfoil from cast and, using scissors, trim to limits of denture bearing area, replace on cast and readapt with absorbent cotton and orangewood stick.

I-Initial piece of relief metal, No. 6 (.003 gauge), applied on upper cast. 2-Secpiece of relief ond piece of relief metal, No. 7 (.003 gauge), applied. 3-Third over bone openings in molar metal, No. 8 (22 gauge), applied. 4 and 5-Relief region (22 gauge). 6, 7 and 8-Outline of three layers of relief metal for median ridge of upper cast. q and 10-Outline of relief metal for alveolar ridge of lower cast.

13. I n adapting tinfoil over the lower cast, slit it halfway where it covers the lingual (tongue) space on the cast. Adapt the tinfoil over the ridge beginning at the anterior portion and work backward to the condyles. Trim the tinfoil to denture limits. (Fig. 84.) 14. I n partial cases carefully cut the tinfoil around the base of plaster teeth and around the outline of the denture bearing area. (Fig. 84.)

Supplementary Assignment: (Information to be obtained by the learner.) I. Patented reliefs. 2. Patented "suctions." 3. Soft vulcanized rubber reliefs.

A-Relief metal over hard area in median line is held in place by pins. B-The bone openings and courses of principal blood-vessels have been relieved by metal.

76

M A N I J A I . I:OR

DRN'I'AI. TECHNICIANS

PREPARATION O F DENTURE BEARING AREAS-I1

77

3. Has any of the tinfoil or relief metal been wasted? 4. Does the relief metal have smooth edges? 5. Can you apply relief metal in I o minutes (average) ? 6. Can you apply tinfoil to an edentulous cast in 15 minutes (average) ?

REFERENCES: (Books for Additional Information.) I.

Nichols, I. G.: Prosthetic Dentistry.

1930.

St. Louis: T h e C. V. Mosby CO.,

Brooklyn: Dental Items of Kennedy, ,- E.: Partial Denture Construction. Interest Publishing Co., 1928. q. Doxtater, L. W.: Full and Partial Denture Prosthesis. Brooklyn: Dental Items of Interest Publishing Co., 1936. 4. T u r n e r , C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, 1932.

2.

I-Upper partial ,cast with tinfoil partly adapted. 2-Lower partial cast with tinfoil partly adapted. 3-Full upper cast, tinfoil partly adapted. 4-Full lower cast, tinfoil partly adapted. 5-Tinfoil applied on full upper cast. &Tinfoil applied on full lower cast.

Gauges of tinfoil used for various purposes. Composition of Britannia metal. Composition of other relief metals. Tinfoil reliefs. 8. "Roofless plate" reliefs.

4. 5. 6. 7.

Questions : I. What is Britannia metal? 2. Why are reliefs used? 3. Why should relief metal be smooth? 4. Why should tinfoil be smoothly adapted? 5. Describe two different methods of applying relief metal. 6. What are the proper gauges of tinfoil and relief metals and where are they indicated? 7. What is the purpose of tinfoiling casts? 8. How is tinfoil adapted to the cast? 9. Define median ridge. Job Appraisal : I. Does the relief metal cover the hard and unduly soft areas? 2. ISthe tinfoil smooth and evcnly adapted?

U N I T NO. 6 RELATED INFORMATION:

U N I T NO. 5 (Coutrit/z/ed) T R I A L D E N T U R E B A S E TECHNIC-I

PREPARATION O F DENTURE BEARING AREAS-I1 Ingredients of Britannia Metal: Tin, 140 parts by weight. Copper, 2 parts by weight. Antimony, 5 parts by weight.

Used for relief purposes.

Scraping Impressions: T h e technician should never scrape the impression in order to relieve bony areas. All scraping of impressions 01-casts should be done by the dentist when he finds it necessary. B r o w n a n d S h a r p e G a u g e P l a t e : A metal plate with slits and holes of various graduated sizes used for measuring thicknesses of metals.

W c have already pointcd out that there arc no two peoplc whosc moutlls are exactly alike. I t would therelore be useless for dentists and technicians to construct stocks of denturcs and expect to fit them to people's jaws as we fit shoes, nlthough it might be argncd that there nrc no two pcoplc whose fect arc exactly alike. T h c sl~oe\r.llich is uscd as a foot co\.el.ing 2nd ior w3llting purposes does not have to fit with the same degree of rxnctness as a d e n t ~ r cwhich has to be worn in the mouth, which lnust bc used ior chewing iood and which must harmonize with the face of the person wearing it. T h c r e arc many other reasons known to dentists why the dcnture should lit the mouth with extreme accuracy and w h y it would bc impractical to manufacture them in advance. Since the denture must fit thc mouth accur2tcly, it is first made 011 n t r i d base such as wax or other ~n.iterial \vhich can bc casily molded and fitted to the mouth. T h i s matcrial mnst be strong cnough to hold its shape when the denture is tried in tllr lnouth so that the dcntist may scc if it fits accurately or whether any cl~.ii~ges are nccessary.

Process o r Principles: No. 10: Construction of Baseplates for Trial Dentures and for Biteplates. a. Const~uctionof baseplates witlz lnpped margins. b. Constrzlctiort of baseplates with trimmed margins. P r o j e c t o r Jobs: ( T o be performed by the learner.) JOB NO. 26: Construct baseplates with lapped margins on four sets of edentulous stone casts (eight casts). J O B No. 27: Construct baseplates with trimmed margins on six partial stone casts. NOTE: (Read the entire Urtit carefully before beginning work. Consult glossary for definitions of new words.) Job Application: Trial baseplates are constructed over the denture areas of the casts. Biteplates may be constructed or artificial tcrth mny he arranged for try-in on the baseplates.

11c;~ring

Vocational Information: There are different kinds of baseplate I I I . L ~ C . I - ~011 : L ~the S market. T h e baseplate may be softened by heating 7')

8o


8I

TRIAL DENTURE BASE TECHNIC-I

over the Bunsen flame or in boiling water. Baseplate is preferable to wax as a trial denture base material because it holds its shape better and is not easily softened by the temperature of the mouth while the denture is being fitted. Tools and Equipment : Bunsen burner, plate shears, wax spatula, penknife, rat-tail vulcanite file, half-round vulcanite file. Materials: Baseplate material, boiling water, cold water, absorbent cotton, wire paper clip, sandpaper. Procedure : (Follow operations in the order presented here.) a. D o not hold baseplate material too long over flame, to avoid melting or burning. b. D o not attempt to adapt trial baseplate material before softening it over the flame. c. Dip fingers in water to avoid burning t h e m when pressing the heated baseplate. d. Avoid buckling or creasing baseplate. e. W h e r e undercuts are present on the cast, adapt baseplate only so far over the undercuts as to permit t h e removal of the baseplate fro& the cast w'thout breaking or marring either the baseplate or the cast. f. Avoid having baseplate interfere with plaster teeth on cast by cutting the material about 1/32 of rn inch away from t h e g u m margin of plaster teeth. g. Smooth all edges weth sandpaper or files to avoid cutting fingers and tissues on sharp edges of the baseplate. h. Reenforcing wire on the upper partial cast should be placed midway around the center of the palate and the crest of the ridge. i. Adapting overheated reenforcing were w'll cut the baseplate. j. W h e n the baseplate begins to show signs of wilting, remove it from the flame. It is ready for use. k. Boiling water may be used instead of the Bunsen burner flame. 1. D o not immerse in boiling water longer than a few seconds. I.

Hold baseplate as shown (Fig. 85a) and pass the outer twothirds sideways in contact with the top of the flame for one second. Repeat this five times or until baseplate shows signs of wilting.

f

Courtesy Dentists Supply Co., New York

a-The baseplate is passed over the flame until it begins to wilt. b-The baseplate is placed over upper cast and softened part adapted. T h e cast with the partly adapted baseplate is then chilled in water. T h e partly adapted baseplate is now removed from the cast. T h e adapted side is held while the balance of the baseplate is passed through the flame and the adapting is completed. c-The adapted baseplate removed from the cast for trimming. T h e letters "C" indicate the line marked by the outer edge of the cast which is established by the carding wax strip used in boxing the original impression. T r i m the baseplate to this line. d-Shaped baseplate being passed through the side of the flame to soften edge for final adaptation. e-Method of lapping edges. f-Baseplate on cast with right side lapped.



2.

3.

4.

5.

6.

7.

8.

9.

TO. 11.

Place the baseplate over the upper cast as shown (Fig. 85b) and adapt the palatal portion of the softened baseplate closely to the cast by pressing with fingers lightly for half a second in one place, then raising the fingers and moving them forward, repeating the pressure until all of the softened area is adapted. Heat the baseplate compound when necessary and continue the adaptation over the alveolar border and the buccal and labial surfaces. Chill the adapted section with cold water on absorbent cotton. Using the adapted side as a handle, heat the other sides and adapt them over the cast beginning on the palate and working over the alveolar ridge and the buccal and labial surfaces (Fig. 85c). Re-heat any portion of the flange that may not be properly adapted and adapt same (Fig. 85d). Re-heat baseplate against side of the flame as shown (Fig. 85d) wherever folds are present and eliminate them by pressing against cast. Pass the partly adapted baseplate through the Bunsen flame and, using plate shears, trim away surplus baseplate extending beyond outer edge of the extension on the cast made by the carding wax rim used in boxing the impression before the cast was poured. This is illustrated by "C-CC" in Fig. 85c. Heat the baseplate which rests on the extension of the cast by passing through the flame and fold the buccal and labial portions at the limits of the denture area by pressure with fingers as shown (Figs. 85d and 85e). Fold also over the condyles and posterior portion of palate as shown (Fig. 85f). T o repair broken baseplate, place the broken pieces on the cast with the edges together. With very hot spatula fuse the edges together. Melt some of the surplus baseplate in the flame as sealing wax is melted and drop it on the break. Smooth the surface with a hot spatula. Chill the adapted baseplate with cold water and absorbent cotton before removing from cast. I n lower casts adapt the trial baseplate material over the highest portion of the alveolar ridge in the anterior region of the cast and work backward to the condyles. Treat the lingual and bucco-labial margins of lower baseplatc thc samc as the upper.

12.

83

I n partial casts after adapting the baseplate to the palate and alveolar ridges, heat the compound in the region of the plaster teeth of the cast and cut away the material with a hot spatula or with shears (Fig. 86). Use files to smooth the edges of the baseplate (Figs. 87 and 88).

I

A-Teeth

on partial cast. B-Heated

wax spatula.

Note: The baseplate is trimmed around the necks of the teeth with a hot spatula. It may also be cut with a curved scissors or a small abrasive wheel.

13. I n partial lowers adapt the lingual surface first. Soften the material on the lingual surface around the plaster teeth and cut away the portion interfering with the teeth. Continue the adaptation on the buccal and labial surface. 14. Adapt edging wire on lingual surface of lowers and on palatal surface of partial uppers. Melt baseplate material over the wire and smooth with a hot spatula (Fig. 89a, b, c, d, and e.) Supplementary Assignment: (Information to be obtained by the learner.) I. Method of using patented baseplate swager. 2. Method of constructing baseplates to be used as trays in taking impressions.

84



85

3. How gutta-percha is obtained. 4. Advantages and disadvantages of shellac baseplates over wax baseplates.

5 . Advantages and disadvantages of trimmed margins over lapped margins.

6. Methods of preventing baseplate from adhering to casts.

A-Baseplate.

B-Rat-tail

(round) file (6" cut No. 3).

a-Baseplate adapted to lower cast. "x" indicates shaped wire clip used to reenforce adapted to partial the baseplate. b-Baseplate adapted to upper cast. c-Baseplate and lower cast. "x" indicates wire clip used as reenforcement. d and -Upper baseplates before adapting.

Note: T h e original gloss of the baseplates can be seen on those adapted to the casts. If the baseplate is heated too much the gloss and strength of the baseplate are destroyed.

A-Half-round

vulcanite file (double end 8" cut No. 3). B-Baseplate cast. C-Bench block. Note: Rest left hand, holding baseplate, on I~enchblock.

for pi~rtial

Questions : I. W h y are trial baseplates used? 2 . What happens if the baseplate compound is not sufficiently heated before using? 3. What happens if the baseplate compound is held too long over the Bunsen flame? 4. How may folds or creases in the baseplate be removed? 5. H o w are undercuts in the cast overcome in adapting baseplate? 6. How are the margins of the trial baseplate treated? 7. Whcn may the baseplate be considered ready for using?

80

M A N I I I ~ L1;OR D E N T A L 'l'BCHNICIANS

S. IVI1:lt precautions should be taken before reinovitlg the base-

1)latc from the cast? 9. What procedure should be followed in adapting full upper

trial baseplates? 10. What procedure should be followed in adapting full lower trial baseplates? I I . What procedure should be followed ill adapting partial upper trial baseplates? 12. What procedure should be followed in adapting partial lower trial baseplates? 13. H o w is the reenforcing wire applied? 14. What is gutta-percha? I 5 . Define biteplate, try-in. Job Appraisal : I . Was the baseplate broken? 2 . Was the baseplate burned 01- is it snlooth and glossy? 3. Is the baseplate free from creases? 4. Is the reenforcing wire covered? 5 . Can you adapt a full upper or lower baseplate in 10 nlinutes (average) ? 6. Can you adapt a partial baseplate in 15 minutes (average)? REFERENCES: (Books for Additional Information.) I . Prinz, H.: Dcntal Formulary. Philadelphia: Lea & Febiger, 1936. 2.

Doxtnter, L. W.: Full and P ~ r t i a lDenture Prosthesis. Brooklyn: Dcntal lterns of Interest Publishing Co., 1936.


U N I T NO. 6

T R I A L D E N T U R E B A S E TECHNIC-I Baseplate Materials: T h e ingredients of baseplates are as follows: I . Gutta-percha I part Gum shellac I 8 parts 2. Gum shellac and modeling compound 3. Gutta-percha Zinc oxide Vermilion

Tin Baseplates: Castings of tin compounds or swaged soft metals are sometimes used for constructing trial baseplates. If a soft metal sheet is used, it is burnished to the cast. Vulcanite Baseplates : Baseplates constructed of vulcanized dental rubber are sometimes used. Shellac Baseplates: May be adapted by softening in hot (not boiling) water for onc or two minutes and pressing with a moist rubber sponge. Gutta-percha: A rubber-like nlaterial extracted from certain trees in the Malay Islands. I t is pinkish or grayish in color and may br obtained in sheets for use as trial baseplates. (Books for Additional Information.) REFERENCES: Prinz, H.: Dental Formulary. Philadelphix: Lea & Fehiger, 1930. Doxtatcr, L. W.: FulI and Partial Dcnturc Prosthesis. Brooklyn: Dent.11 Itcnls of Interest Publishing Co., I 936. 7. Skinncr, E. W.: T h e Science of Ilental Materials. Philadelpl>ia:W. K. S:~nndi~rs Co., Puhlishcrs, I 936.

I.

2.

go

TRIAL DENTURE BASE TECHNIC.--11


91

8. Place the cut copper sheet in position and, using fingers and orangewood stick with rounded end, shape copper to conform with palate (Fig. 91-21. 9. Replace upper wax base. Warm palatal surface of wax base over flame. Warm copper sheet and imbed in wax base. 10. Cover copper strengthener with a thin layer of melted wax (Fig. 92). 11. Run brush flame of Bunsen burner ( a soft flame) over base wax. Allow wax to congeal and chill under running cold water. While holding under cold water polish with wet absorbent cotton. 12. Seal the wax base to the cast to facilitate the work to follow and to prevent distortion.

FIG. 9oa. BASEWAX PARTLYADAPTED TO LOWER CAST A-Basewax

cut out in tongue space to aid in adapting. B-Basewax sheet not adapted. Note: Part of wax in. tongue space has been cut away to make adapting easier.

FIG.gob. BASEWAX PARTLYADAPTEDTO UPPERCAST A-Basewax adapted on palate and over alveolar ridge. B-Basewax not adapted. Note: T h e original gloss of the wax can still be seen. If the wax is heated too long or pressed too hard, the gloss is lost and the basewax is too thin. Do not leave fingerprints on the wax.

A-Cast.

B-Basewax.

A-Csst.

B-Basewax.

C C o p p e r strengthener in upper cast and wire strengthener in lower cast.

C-Wire

strengthener in lower cast, copper sheet in upper cast.

13. I n partial cases trim the wax

I-Copper sheet cut for reenforcement. 2-Copper adapted to cast. Note: Method of cutting the copper to make atlz~ptingeasier.

142 of an inch above the necks of the plaster teeth (Figs. 93a and b). 14.I n partial cases adapt edging wire on the upper as well as the lower casts (Figs. 93a and b).

Supplementary Assignment: (Information to be obtained by the learner.) I. Different types of wax used for bases.

92

93

TRIAL DENTURE BASE TECHNIC-I1


4. Were make-overs necessary? 5. Can you make a wax trial denture base in (average) ? REFERENCES: (Books for Additional Information.)

10

minutes

Skinner, E. W.: T h e Science of Dental Materials. Philadelphia: W. B. Saunders Co., 1936. 2. Prinz, H.: Dental Forn~ulary. Philadclphia: Lea & Febiger, 1936. 3. Frahm, F. W.: Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., I 936. 4. 'Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger Co., 1932. I.

a. Partial Lower

b. Partial Upper (horsesho: base)

FIG. 93. FULLVIEWOF PARTIAL UPPERA N D LOWERBASEWAX WITH WIRE REENFORCEMENTS ADAPTEDTO

CASTS

A-Wire used to reenforce wax bases covered with melted wax. Note: Basewax has been carefully cut around the bases of the plaster teeth.

2 . Different types of wax base reenforcements. 3. Methods of polishing wax base. 4. Method of refining used wax. 5. Marking wax sheets. 6. Advantages and disadvantages of wax bases. 7. Uses of wax as denture or biteplate bases. Questions : I. What is the purpose of wax in denture construction? 2. Why should wax be of uniform thickness? 3. Why should the wax base be properly sealed to the cast? 4. When and why is edging wire used? 5. How is edging wire applied? 6. What is the proper method of rendering wax pliable? 7. What care should be given to tools, materials and equipment used in waxing dentures? 8. What do we mean by the following: base wax; denture limits; denture area; lingual space; condyles? Job Appraisal : I. Is the wax evenly adapted? 2. IS the wax trial base smooth and free from pits or other marks? 3. Are the copper and wire recnforcemcnts imbcddcd in the wax properly?

RELATED INFORMATlON:

U N I T NO. 6 ( C o n t i n u e d )

T R I A L D E N T U R E BASE TECHNIC-I1

BITEPLATE TECHNIC

Refining Used W a x : Melt scrap wax in a pot, remove from gas stove and add a tablespoon of sulphuric acid. Allow to cool, cut away sediment. Remelt the wax. Fill a bottle with cold water and dip in wax several times. H o l d bottle over the pot containing the wax until the wax adhering to the surface of the bottle congeals. Cut the congealed wax away with a sharp knife. T h e bottle used should be clean and smooth on the outside. Wax may be melted and strained through cheesecloth to remove impurities. Ingredients of Basewax: There are many ingredients used fo1making different basewaxes. Basewax may be made from the following: Beeswax, 40 parts by weight. Gum turpentine, 10 parts by weight. Cottonseed oil, 3 parts by weight. Vermilion, 4 parts by weight. REFERENCES: (Books foi- Additional Information.) Prinz, H.: Dental F'or~nulary. Philadelphia: Lea 8i Febiger, 1936. Skinner, E. W . : T h e Science of Dental Materials. St. Louis: T h e Mosby Co., 1936.

U N I T NO. 7

C. V.

T l i e lower jaw (mandible), 1' s \\c nll know, is movdblc. I t has two illo\able joints, onc on either side which fit into depressions near the base ol the ski111 in ilont of the car holes. Wlicn the teeth are in position the jam inaj be opcncd but c'in dlwajs be r e t u ~ n e dto a rcat or centric position which is limited and dctcrnlined by the position , ~ n docclnsal surfaces of the upper teeth. W h e n the teeth are lost this re1.1tionship is also lost. T h e biteplates help the dentist in reestablishing this jaw relationship ior the individual who has lost his teeth. Since the technician is not prepared nor permitted to work directly on tlle patient, he can only approximate the rcquired shape and size of the bite~lates. T h e dentist must give the final shaping to the biteplates urhen he relates then1 to one another in the mouth of the patient. W i t h tlic rel'ltionship o i the biteplates and the jaws e s t ~ b lishcd, the dentist can return the biteplates to the technician who adjusts the casts on them and then mounts the casts with the biteplates on a nlechanical holder or relator known as an articulator. T l l c casts are now in the relationship obtained by the dentist, from tlle jaws in the patient's mouth, by means of the biteplatcs. Where only some of the teeth have been lost, in partial cases, the biteplates help to establish the relationship of the upper to the lower jaw so that the casts can be mounted in this relationship on the articulator. After the casts are mounted on the articulator the biteplates act as guides in arranging the artificial teeth.

B I T E P L A T E S AND CAST R E L A T I O N S H I P Process or Principle : No. I 2 : Construction of W a x Biteplates. a. Construction of w a x biteplates o n edentulous casts. b. Construction of biteplates o n partial casts. c. Construction of modeling compound biteplates. Project or Jobs: ( T o be performed by the learner.) JOB NO. 30: Construct wax biteplates on two sets of edentulous cxsts with bnscplate bases. Jon No. 3 1 : Construct modeling compound biteplates on two sets or c c l c . ~ ~ t ~ ~ casts l o i ~with s bnscplate hnscs. 05

9


f5

JOB NO. 32: Construct wax biteplates on four sets of edentulous casts with basewax bases. JOB NO. 33 : Construct six partial biteplates on baseplate bases. JOB NO. 34: Construct six ~ a r t i abiteplates l on wax bases. NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definitions of new words.) NOTE: Biteplates and Cast Relating. I n the ~racticaldental laboratory the biteplates are made by the technician to approximate size and returned to the dentist. T h e dentist in turn fits or relates the biteplates to each other in the mouth of the patient. T h e biteplates are than removed from the patient's mouth and the casts are substituted for the patient's jaws. T h e biteplates are sealed to the casts which are then mounted on an articulator. I n this manner the casts are related to one another in the same manner that the patient's jaws are related. (Fig. 94.) If the casts used by the learner have been obtained from impressions supplied by a dentist, the dentist should supply the relationship of the casts. Otherwise, this relationship would have to be guessed. If the casts have been made from the impressions of the dentoforms illustrated in Figs. 29 and 30, the cast relator (Figs. 95 and 96) or the cast relator diagram (Figs. 97a and b) can be used to obtain the relationship of the upper to the lower casts. T h e method of using this relationship is described directly under the illustrations (Figs. 95, 96, 97a and b).

Job Application: T h e biteplate is used as a guide by the dentist in obtaining the proper relationship between the upper and lower dental arches of the jaws. T h e dental technician employs the biteplates as a guide in mounting the casts on an articulator and in arranging artificial teeth. Vocational Information: Biteplates, also known as "bite blocks" or "bite rims," may be constructed from modeling compound or other compositions. Wax is commonly used because it can be trimmed easily. However, wax has a tendency to lose its rigidity at mouth temperature. Modeling compound biteplates are more suitable since they hold their shape better, but are somewhat more difficult t c manipulate. Tools a n d Equipment: Wax spatula, enk knife, template, Bunsen burner, glass slab, ruler, pencil, cast relator and cast relator diagram. Materials:

Basewax, modeling compound, cotton, alcohol.

BITEPLATES AND CAST RELATIONSHIP

I

FIG.94. CROSSSECTIONOF FACESHOWING POSITION OF BITEPLATES USEDFOR RELATINGLOWERJAW TO UPPER JAW A-The condyle at the joint between the lower jaw and the skull. B-Line denoting that the cheek has been removed to show the biteplates. C-Upper biteplate. Note: "x" is the imaginary line extended from the plane of occlusion to the head of the condyle of the lower jaw. T h e occlusal surfaces of the biteplates are trimmed by the dentist so that they remain in contact with each other when the lower jaw is moved in various positions. T h e dentist is said to be establishing the plane of occlusion when he shapes the occlusal surfaces of the biteplates in this manner. D-The upper lip. T h e upper biteplate is usually made by the dentist to extend about one or two millimeters below the edge of the upper lip. &The lower biteplate. This biteplate should be made so that a line bisecting the length of the alveolar ridge at the highest point (the crest of the ridge) will also bisect the biteplate. F-The lower lip. G--The mandible (the lower jawbone). Note: At best, the mechanic can only approximate the shape of the biteplates, which must receive their final shaping at the hands of the dentist who works in the mouth of the patient. By adding to or subtracting from the buccal and labial surfaces of the biteplates, the dentist can influence the appearance of the patient's face, making the face and lips appear fuller or thinner as desired. This is best accomplished with biteplates made of basewax.

98

BITEPLATES A N D CAST RELATIONSHIP


I

99

i

Courtesy Columbia Dentoform Corp., N e w York

'€1

I

Courtesy Columbia Dentoform Corp., New York

FIG.95. DENTOFORM RELATOR A-Upper platform (movable). B-Lower platform (stationary). C-Clamp with set-screw for holding dentoform in position. D-Backstop: Dentoform is placed line of dentoform over flush with backstop. E--Lower dentoform. F-Median median line of relator (lower). G--Median line of upper platform and backstop. Note: Metal dentoforms (Figs. 29 and 30) or their duplicate stone casts are so constructed that they can be related to one another by locking them in the above Dentoform Relator. T h e median line of the lower dentoform is placed over the median line on the lower platform of the relator flush against the backstop and clamped into position by means of the clamps. T h e movable upper platform of the relator is then brought down as f a r as it will go. This leaves a distance of 2%'' between the upper platform and the lower platform of the relator. T h e casts related in this manner are in the proper relationship to one another. A wax squash bite or a plasticene squash bite of the alveolar ridges in their proper relationship to one another can be obtained in this way.

A-Upper platform. B-Wax squash bite. C-Lower platform. Note: After the lower dentoform is adjusted on the lower platform and the upper dentoform is adjusted to the upper platform of the dentoform relator, a sheet of basewax or beeswax is made into a roll and adapted over the alveolar ridge of the lower dentoform. T h e upper dentoform is now approximated to the z T limit and the wax roll is adapted over the alveolar ridge. T h e wax roll is now chilled. T h e cast relator platforms are then opened and the wax squash bite removed. T h e stone or plaster casts to be related are now adapted to the squash bite and sealed with hot spatula. T h e related casts are mounted on the articulator as explained in Unit No. 8: Articulating Technic. T h e biteplates can now be made as explained in Unit No. 7.

Procedure : (Follow operations in the order presented here.) , For th; sake of convenience, if other casts than those indicated are used, the biteplates should be about 8 to 10millimeters in height from the anterior crest of the alveolar ridge and about one or two millimeters less in the region of the &st molar. The occlusal surface of the lower biteplate should bisect the alveolar ridge but should not be more than about 8 millimeters in width. : CAUTIONS a. W a r m the basewax before folding to avoid cracking. b. In sealing the wax roll do not cut through wax base.


101


100

c. Keep biteplates at a uniform h.eight.

d. I n partial cases, see that biteplate does not interfere with the remaining teeth on the cast. e. Occlusal surfaces of upper and lower biteplates for the same mouth shoz~ldapproximate each other evenly. f. Bite~latesshould be built to a height of between inch to inch above the lowest poilzt on the crest of the alveolar ridge. .r.D o not overheat modeling compound.

a-Lower cast with lines drawn to bisect the ridge. x and x' indicate the canine region. b-The wax roll placed on the trial base of the lower cast. c-Completed upper biteplate. d-Completed lower biteplate. T h e line x and x' in "a" has been transferred to the occlusal surface of the lower biteplate which it bisects, showing that the biteplate is properly constructed. e-The biteplates with the bases of the casts z and z' parallel to each other.

Duplicate casts made from dentoforms shown in Figs. 29 and 30, or the dentoforms themselves, can also be related by means of a diagram drawn on cardboard, consisting of two parallel lines 2%'' apart, bisected at right angles by a straight line. T h e wax roll is adapted over one of the casts which is placed on end over one of the parallel lines. T h e opposing cast is now approximated to the 2%" distance. T h e median lines of both casts must be exactly over the line which bisects the two parallel lines at right angles.

FIG.97b. CASTS RELATED ON DIAGRAM A-Upper cast. B-Plasticene (basewax or beeswax can be used). C-Lower cast. Note: After the squash bite is obtained in this manner the same procedure is followed as when the metal cast relator is used. I.

2.

Remove the baseplate and draw a line on the crest of each side of the alveolar ridge from the center of the condyle to the canine region. Draw a line from canine to canine, across the front part of the alveolar ridge (Fig. 98a). Soften a sheet of basewax, by passing it over the Bunscn bul-ncr flame, fold it along its lesser length into a tight roll (I'ig. 99).

OF APPLYING WAXROLLFOR MAKING A BITEPLATE FIG.99. METHOD

Lower cast with wax roll applied on the trial baseplate. A-Wax roll. B-Trial 2. Sheet of basewax showing method of making wax roll. I,;~sepli~te. C-Cast. I.

I02


BITEPLATES AND CAST R E L A T I O N S H I P

I

I03

3. Bend the wax roll to the approximate shape of the alveolar ridge of the lower cast (Fig. 99). 4. Replace the trial base on the cast and place the roll of wax on it (Figs. 98b and 99). 5. With heated wax spatula, seal the wax roll to the base (Fig. 100). 6. Using flat template or glass slab press the roll to the desired height (Figs. lor and 102).

I

FIG. 101.

FITTINGOF WAX ROLLOVER ALVEOLAR RIDGE

Note: A glass slab can be used to aid in adapting the roll to the alveolar ridge. T h e glass slab gives a clear view of the cast and enables the technician to see that the wax roll is placed so it bisects the length of the alveolar ridge of the lower cast.

1 1 I

Frc. loo.

METHOD OF SEALING WAXROLLTO TRIAL BASEWAX OR BASEPLATE IN MAKING A BITEPLATE A-Wax

roll. B-Spatula.

C-Cast.

7. Using wax knife, trim the excess of the wax roll over the condyle at a 45 degree angle about to 5 inch from edge of wax base over the condyles (Fig. 104). 8. Using the wax spatula, add melted wax to fill in recesses between wax roll and wax base on buccal, labial and lingual surfaces (Figs. 98c and 99). 9. Using wax spatula with glass slab or a template, square the occlusal surface with the sidcs of the wax roll, completing thc bitcplate (Fig. 98d).

A-A solid template. B-Side view showing curve. A- emplate. B-Side view showing curve. Note: T h e curved tem lates are intended to help in establishing the plane of occlusion of the teeth. Manufacturers of artificial teeth usually devise templates that make arranging of their own product easier. I.

2.

5

I04


Polish the biteplates with wet absorbent cotton, holding under running cold water. I I. In partial cases, cut the wax roll to fit on the alveolar ridge where teeth are missing and seal to wax base plate. Have the biteplate extended 1/16 inch above the teeth of the cast but do not cover the teeth (Figs. 103 and 104). 12. If modeling compound is used, place the compound in a clean cloth. Immerse the compound in heated water until soft. (Follow directions given by manufacturer for melting compound.) Make a compound roll and shape while soft. Allow compound to harden, trim with penknife. A biteplate former may be used (Figs. 105, 106 and 107). 13. After the lower biteplate is completed check to see if it is directly over the alveolar ridge. Lines drawn over the crest of the ridge should bisect the lower biteplate (Fig. 98d). 14. Make upper biteplate to conform to lower (Figs. 98e, 108 and 109).


10-5

10.

Supplementary Assignment: (Information to be obtained by the learner.) I. Different templates used. 2. Different matirials employed for making biteplates. 3. Aids in shaping biteplates. 4. Advantages and disadvantages of different aids and methods for making biteplates employed in dental laboratories. Questions : I. What is the proper method of shaping biteplates? 2. What is the method of trimming biteplates in partial cases? 3. How and why are the biteplates trimmed around the condyles? 4. How should the biteplates be shaped occlusally? 5 . What care should be taken in sealing the wax roll to the trial base? 6. What purposes do the biteplates serve? 7. What care should the tools, materials and equipment used in constructing biteplates receive? 8. How are the recesses between the wax roll and the wax base eliminated? 9. Advantages and disadvantages of modclirig conlpound.

Flc.

103.

FIG.1 0 3 FIG. 104 UPPERPARTIAL BITEPLATEox "HORSESHOE" SHAPEDBASE

FIG. 104. LOWERPARTIAL BITEPLATE "x" shows the method of shaping the posterior end of the biteplate.

FORMER FIG. 105. BITERIM O R BITEPLATE Used for making shaping of biteplate easier.

I 06

MANUAL FOR DENTAL

TECHNICIANS

Job Appraisal : I. Are the biteplates parallel? 2 . Are the biteplates smooth and even? 3. Are the approximating surfaces level? 4. Is the lower biteplate over the ridge? 5. Can you make biteplates for an edentulous cast in 30 minutes (average) ?

References : (Books for Additional Information.) I. 2.

Prinz, H.: 1)cntnl Formulary. Pliilndclphin: Lca & Fcbigcr, 1936. Doxt:~tcr,I,. W.: Full and Pnrti:~lDcnturc Prosthenis. Rrooklyn: Dcn1;11 I tcms of Intcrcst I'utlishing Co., I 936.

BITEPLATES AND CAST RELATIONSH lP

107

3. Frahm, F. W.: The Principles and Technics of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing CO., 1936. 4. Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, I 93 2. 5 . . Swenson, M. G.: Outline of Full Denture Prosthesis. New York: New York Univ. Press, 1932.

T

4

2. -

7 -. 2

C1

K, ?

m

5

or.

3 f:

T

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6

-$ 9

7

'2,

ARTICULATING TECHNIC-I

U N I T NO. 8 A R T I C U L A T I N G TECHNIC-I T h e upper and lower casts, with the biteplates constructed by the technician, are returned to the dentist who relates the biteplates to each other in the patient's mouth in accordance with the relationship of the lower jaw to the upper jaw of the patient. T h e dentist makes notches or other identifying marks on the biteblocks so that when the established relationship of the biteplates is disturbed, it can be reestablished easily. T h e mechanic seals the related biteplates to the casts on which they belong and mounts or fixes them with plaster on an instrument known as an articulator. T h e articulators used in this unit allow for an opening and closing motion or a limited lateral side motion of the casts and biteplates.

Process o r Principles: No. 13. Mounting casts on plain line and movable arm articulators. a. Mounting of edentulous casts. b. Mounting of partial casts. Project o r Jobs: (To be performed by the learner.) JOB NO. 35: Mount two sets of edentulous casts on plain line articulators. JOB NO. 36; Mount four sets of edentulous casts on movable arm articulator. JOB NO. 37: Mount six partial casts on straight line articulators. NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definitions of new terms.) Job Application: T h e casts with the biteplates in place are mounted on an appliance known as an articulator in order to maintain them in proper relationship during the process of arranging the teeth. A plain or straight line articulator is one that allows only for the opening and closing of the casts but not for lateral movement. This is an arbitrary type of articulator mounting without actually attempting to approximate conditions existing in the mouth of the individual patient. A movable arnl articulator allows for lateral movcment o f the upper extension arm. II0

I

1 1

III

Vocational Information: There are many different types of articulators; "anatomical" or adaptable as well as plain line. Articulators should not be too complicated or too heavy as the arranging of the teeth may be interfered with. T h e adjustments of the articulator should be carefully made, to avoid losing the jaw relationship established by the dentist. Tools and Equipment: Straight line articulators, movable arm articulator, plaster bowl, plaster spatula, plaster knife, glass slab, camel's hair brush, large hinges (Figs. I I I , I I 2, 1 I 3 and I 14).

I

Materials: Plaster, water, shellac, sticky wax, fine sandpaper. Procedure : (Follow operations in the order presented here.) CAUTIONS : a. Make sure that biteplates are sealed to the casts and lo each other before beginning work. b. Lubricate the glass slab before using. c. Immerse casts in water for three minutes before mozcncing. d. Be sure the bases of the casts are scored. e. Casts should be low enough to allow them to go be~weetzthe parallel arms of the articulator. (Fig. I I I .) f. Make sure the set-screw and the thumb screw of the articulator are tight and do not ope@ them again until after the casts are mounted and the biteplates are removed, to avoid losing the cast relationship. (Fig.IIZ.) g. Do not mar casts in removing biteplates from the articulator. I.

Seal the biteplates to the casts after they have been marked and related to each other and to the jaws of the patient by

I I2


113


the dentist. Place the sealed casts and biteplates into a pan of water until bubbling ceases. (Fig. I 10). 2 . Make a plaster mix. Deposit a portion of the plaster mix on the glass slab to a thickness of about % inch and large enough to enclose the lower extension of the articulator. 3. Set the lower extension arm of the articulator into the mass of plaster and set the lower cast on the lower extension arm of the articulator. Have the occlusal surface of the biteplates parallel with the extension arms.

A-Lower half of plain line articulator. B-Set-screw which opens or closes the extension arms of the articulator to allow for accommodation of the cast a s shown above. C-Thumb-screw for tightening upper extension arm of articulator. DBiteplates waxed to casts. E--One of the wire staples used to hold the biteplates together. ( T h e staples are placed by the dentist in practical cases.)

A-Upper extension arm. B-Screw for releasing upper half in separating the two halves of the articulator. C N u t for locking the set-screw after the desired amount of separation between the upper and lower extensions of the articulator is obtained. D-Lower extension a r m of articulator,

FIG. 1 13. M O V A I ~ LA ER M

AR.I.ICULI\.I.OR

A-J.~)\rcl. c.xtc11sio11nrm. 1%-MUV:IIBI~ joil~t. ('-Srt-?icl.c-w for o l , c ' ~ ~ori ~cloSilll: ~~ l l r l i c ~ ~ : ~Cl oXr ~ I I ~ I :I I r ~ ) - - I ~ I B I , cc.xtc.llyioll I. ; I ~ ~ I ~ .

4. Hold the articulator casts stationary and shape the plaster around the base of the lower cast and the lower extension arm of the articulator. Wait until the plaster has set before proceeding. (Fig. I I 5.) 5. Make a plaster mix and deposit a portion of it, sufficient to cover the base, on the upper cast to a thickness of 5 inch. 6. Press the upper extension arm of the articulator into the plaster and add more plaster to cover the upper extension arm, and trim with plaster spatula. (Fig. I IS.) 7. After the plaster has set remove the mounted casts from Using plaster knife trim all excess laster ' the glass sfab. around the articulator. (Fig. I I 6.)

I I4

M A N U A L FOR DENTAL T E C H N I C I A N S


115

8. Adjust the set screw to reach the upper extension and lock with thumb-nut. (Fig. I I 6.) 9. Sandpaper and varnish the plaster holding the casts on the articulator with shellac.

Left: Front view. A-Upper and lower lip lines (position when lips are opened as in smiling) marked by the dentist to aid in selecting teeth. B-Median line marked by the dentist to coincide with the median line of the patient's face. Right: Side view of the casts mounted on a plain line articulator. A-Set-screw resting against the under surface of the upper extension arm of the articulator.

A-Plaster attachment of lower articulator extension arm to cast. B-Upper articulator extension arm imbedded in plaster on upper cast. C-Plaster spatula used in shaping the plaster around upper articulator extension arm and upper cast.

10. Break

the seal between the biteplates and casts with heated spatula and carefully separate biteplates. I I. In partial cases it may be necessary to immerse the articulated casts in hot water when separating the biteplates to prevent breakage of plaster teeth which are sealed to each other and to the biteplates with sticky wax. (Fig. 118.) Supplementary Assignment: (Information to be obtained by the learner.) I. Types of line articulators. 2. Types of adaptable articulators. 3. Advantages and disadvantages of plain line, movable arm and "anatomical" articulators. 4. Various procedures followed in mounting casts. 5. Guards against disturbing jaw relationship indicated by biteplates.

A-Lower

cast. B-Upper

cast.

116


Job Appraisal : r. Are the extension arms of the articulator parallel? 2. Are the biteplates parallel to the extension arms of the articulator ? R E L A T E D I N F O R M A T I O N : U N I T NO. 8

ARTICULATING TECHNIC-I Hinges used as articulators: I n order to mount all of the casts at the same time it would be necessary to have a number of articulators. One movable arm and one plain line articulator or one of either type can be used. Hinges can be employed for mounting the casts while learning the process of mounting casts on articulators.

N o t e : T h e relating of the upper to the lower partial cast is done by the dentist i n practical cases.

NOTE: (This can be determined by placing a ruler over the occlusal surface of the upper biteplate after mounting is completed.) 3. Are the casts mounted securely? 4. Is the plaster smooth and shellacked properly? 5. Can you mount a case (upper and lower casts with biteplates in position) in 15 minutes (average)? REFERENCES: (Books for Additional Information.) I . Nichols, I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Co., I 930. Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, 1 9 3 2 . 3. Doxtater, L. W.: Full and Partial Denture Prosthesis. Brooklyn: Dcntal Items of Interest Poblishing Co., 1938. 4. Fmhm, F. W.: T h c Principles and Technics of T'L111 1)cnturc Con~trnction. Ilrooklyn: I>cntal I t c ~ n sof lntercst I'ublishing Co., 1c)31.. 2.

ARTICULATING TECHNIC-11

UNIT NO. 8 (Continued) A R T I C U L A T I N G TECHNIC-I1

I

119

to simulate the jaw movements ordinarily produced in chewing food by the individual patient. All measurements for adjusting should be provided by the dentist. The technician should know how to insert the casts and transfer the face bow relationship and measurements obtained by the dentist from the patient's jaws. (Fig. I 19.) The adjustable articulator makes it possible to maintain contact of the upper and lower teeth during various limited movements of the lower jaw as in chewing.

Adaptable or adjustable articulators, also known as anatomical articulators, have been devised so that the instrument may be able to imitate the movements of the jaws of the patient by moving the extension arms of t h e articulator. T h e adaptable articulators provide for the transference of certain measurements which are obtained .by the dentist from the patient's own jaws. I n the plain line or movable arm articulators there are no provisions for adjustment to conform to the sidewise and other jaw movements. T h e main reason for using an adjustable articulator is to provide a guide for the arrangement of the teeth in such a manner that the teeth may remain in contact when the lower jaw is moved about within certain limits as in chewing food. I n short, by means of an adaptable articulator we can achieve what is termed a balanced articulation or intermeshing of the teeth of the upper and lower dentures. Balanced articulation of dentures makes them more stable in the mouth (this helps in chewing), it eliminates undue changes in the gums and other tissues on which the dentures rest and adds to the comfort of the patient.

Process o r Principle : No. 14. Mounting on anatomical (adjustable) articulators. a. Face bow transfers. b. Mounting edentulous casts. Project o r Jobs: (To be performed by the learner.) JOB No. 38: Mount two sets of edentulous casts on Gysi or Hanau Articulator. NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definitions of new words.) Job Application: Anatomical or adjustable articulators are appliances that may be regulated to produce lateral and other movements similar to those of the human mandible. This instrument makes it possible to arrange the teeth so that they remain in contact during these movements, resulting in more stable dentures. Vocational Information: The theory underlying the usc of adjustable or anatomical articulators is that the articulator can bc made 118

Note: By adjusting the face bow over the condyles (in front of the ear holes) at the junction point between the lower jaw and the upper jaw and fixing the biteplates to the face bow, the dentist obtains the relationship of the jaws to the condyles (the junction point of the jaws). This relationship is transferred to the articulator by the technician and aids in obtaining a balanced occlusal relationship of the teeth which are later arranged on the denture bases.

Tools and Equipment: Adaptable articulator (Gysi or Hanau), plaster bowl, plaster spatula, plaster knife, face bow. (Fig. 120.) Materials : Plaster, water, vaseline. Procedure: (Follow operations in the order presented here.) CAUTIONS: a. Be szcre the articulator is in centric occlzwion before beginning to mmnt casts. b. Release the condyle bars evenly to meet the face bow adaptor tugs.

I20


c. Make sure that occlusal planes of the biteplates are parallel with lugs No. I r and point of pin No. 7 (Gysi Articulator.) d. T o prevent plaster sticking to articulatm and to facilitate removing the casts, vaseline should be applied where indicated. I . W h e n Using t h e Gysi Simplex Articulator (Fig. 120) proceed a s follows: A. T o Mount Casts Without the Use of the Face Bow: I. Place the straight incisor guide pin (Figs. 120 and 122) in the

ARTICULATING TECHNIC-I1

I21

4. Place an elastic band or a cord about the setscrew on the straight incisor guide point and in the notches on the outer sides of the vertical part of the frame (Fig. 122s). This will establish the correct occlusal plane. 5. Place a mass of soft wax on the lower extension arm and force the lower cast down over it until the occlunl place of the biteplate is level with the elastic band or cord and the median line of the biteplate touches the tip of the incisor guide. Adjust the casts so

Courtesy Dentists' Sufifily Co., New Yosk

FIG. I zo. G Y ~SIMPLEX I ARTICULATOR Note: This articulator reproduces average movements of the mandible. It is an improved movable arm articulator and is adaptable to various jaw movements within certain limits.

sleeve on the upper extension arm, keeping the top of the pin level with the top of the sleeve. 2. Place the incisal guide (Fig. 122C) on the pin, with setscrew, in the depression of the pin and the point directed backward to the median line. 3. Extend the median line mark on the front of the upper cast vertically upward to the top of the cast; make a similar mark vertically upward on the rear of the cast, starting from the median suture on the palatc. Draw a straight linc across the top of the cast, connecting these lines. This is the median line of the cast.

that the median line mark on the upper cast will be below the median line of the upper extension arm. Attach the upper cast to the upper extension arm, then invert the articulator and attach the lower cast to the lower extension arm. (Fig. 12I.) NOTE: T h e Snow Student's Articulator (Fig. 124) n ~ d yalso be used for this purpose. Directions for using are similar to the foregoing. B. T o Mount Casts with the Face Bow. (Figs. 1 2 2 and 123.) I . Place the curved incisor guide pin (Fig. 1221) in the sleeve on the upper extension arm of the Gysi Simplex Articulator, the top of

I22


ARTICULATING TECHNIC-11

123

the pin should be level with the top of the sleeve. T h e end of tl pin should touch the incisal incline on the lower extension arm. 2. Adjust and lock each condyle bar of the face-bow so that 01

T h e casts a r e related by means of the face bow and sealed to each other in the position indicated by the jaw relationship of the patient. B-Incisor guide pin set supporting block to support the front of in anterior supporting block. &Anterior stem connecting the horseshoe the face bow when mounting casts. F-Slip-joint plate, between the biteplates, with the face bow. E-Horseshoe plate connected to the slip-joint (F) holding the biteplates in proper relationship to the face bow. lock trays, guide pin incline. M-Bite I-Curved incisor guide pin. U-Incisor on vertical support of articulator. Dlocking the biteplates together. A-Notch of condyle b a r to fit Snow face bow. R-Lock nut for condyle bar. P-Slip-joint over face bow adapters. N-Face bow adapter of the articulator.

FIG. I 2 2 . GYSISIMPLEX ARTICULATOR Parts and Accessories I articulating frame, in two parts, I upper and I lower extension arm, I straight incisor guide pin ( B ) . A n incisor guide ( C ) for mounting casts on the articulator when the face bow is not used. A snow face bow ( D ) for mounting casts on the articulator in correct relation to the articulating joint (the condyles). Condyle bar ( P ) with slip joint for adjusting over the face bow adapters ( N ) of the articulator. ( R ) is the lock nut for the condyle bar. A horseshoe plate (E) and slip joint stem (F). T h e horseshoe plate is used with the incisor path marker to obtain correct bite relationship. T h e slip joint stem connects the horseshoe plate with the face bow. A mouth piece for the face bow ( H ) used only when squash bites a r e taken on partials. A curved incisor guide pin ( I ) used only when mounting casts with the face bow. A n incisor path marker (K) used with the horseshoe plate for determining correct bites. A n interior supporting block (L) to support the front of the face bow when mounting casts. T w o bite lock trays (M) for locking biteplates together. T h e two face bow adapters of the articulator ( N ) . A n incisor guide incline ( U ) .

A Gysi Simplex Articulator ( A ) composed of

and one-half divisions on the condyle bar arc exposed external to the locknut slccve on the face bow. 3. Set thc casts between the uppcr and lower extension arms of thc articulator and spring the condyle bars over the face bow adapters of thc at-ticuliltor (17ig. 123).

FIG.I 24. SNOW'SSTUDENTARTICULATOR Note: T h i s is a good articulator to use prior to undertaking the arrangement of teeth on the regular adaptable articulators.

I 26


ARTICULATING TECHNIC-I1

127

3. Principles underlying different adaptable articulators. 4. Advantages of adjustable articulators in partial cases. 5. Principles of "face bow transfer." Questions : I . W h y is the articulator adjusted to centric occlusion before mounting casts? 2 . Why should the condyle bars on the face bow be released evenly when adjusting them to the articulator? 3. Why should the occlusal plane of the biteplates be parallel with the lugs No. I I and the point of pin No. 72 (Fig. 125.)

Note: T h e upper cast has been attached to the upper extension arm. The face bow has been removed and the Qrticu~atorhas been turned upside down. The lower cast is now attached to the lower extension arm of the articulator.

pin No. 10. Invert the articulator and apply plaster as in the upper. Wait until the plaster has set before turning the instrument on its base. (Fig. 127.) 8. T h e articulator is now set according to the specifications which the dentist obtained from the patient. T h e sagittal condyle controls are set by releasing lock No. 2 and setting sagittal condyle path indicator No. 2 2 at the figure on the degree plate No. 3 as specified by the dentist. Lock nut No. 2 is then locked. This is done on the right and left sides. T h e arrangement of the teeth is the next step. (Fig. 128.) Supplementary Assignment: learner.)

(Information to be obtained by the

Other types of adjustable articulators on the market. (Figs. 129 and 130.) o. Advantages and disadvantages of: v;~riousstyles of: ndjustahle articulators. I.

Coi
4. Where and why is vaseline applied? 5. How is the articulator adjusted to obtain centric relations? 6. How is the upper cast mounted? 7. How is the lower cast mounted? 8. What is meant by the following: centric occlusion; occlusal plane of biteplates; incisal guide pin; sagittal condyle path; protrusion; retrusion; rotation center of lateral movement; what is the face bow?

U N I T NO. 9 MORPHOLOGY (STUDY OF FORM) OF ARTIFICIAL

TEETH

Vocational Information: 'l'liere are tualiy types, shades and nlolds o t artificial teeth un the market to supply the three primary facial types; i.e., square, tapering and ovoid. Artificial teeth are made of '1 combination of minerals, chiefly kaolin, which is a white opaque china claj ; feldsl)ar, a hard, white, translucent crystalline material; \ilica 01-sand and a flus such as calcium. T h e foregoing combination produces pure white porcelain. I n order to have teeth of different bhades coloring or tinting materials are added. Tools and E q u i p m e n t : Pencil, paper.

W e have mounted the casts on articulators and are now ready to begin the arranging of the artificial teeth. Until now you have probably given little thought to the shapes of the various teeth. We said in the introductory remarks to this manual that there are no two natural teeth alike in the human mouth. Artificial teeth are made lrom porcelain. T h e y are made in many hues and molds. I t can readily be seen, however, that it would be impractical to attenlpt to make artificial teeth to order for every case. I t is generally conceded that there are three basic forms of natural teeth: square, tapering and ovoid. Artificial teeth are now manufactured in various modifications of these three basic forms. T h e technician should acquaint himself with the terms used by dentists to denote the different teeth and parts of teeth so that he may be able to understand the instructions of the dentist for whom he works.

Process o r Principles: No. 15. T h e recognition and nomenclature of artificial teeth and tooth surfaces. Morphology of artificial teeth. a. Nomenclatzci.e. b. Topography. c. Identificatiorz of irzdividzcal teeth. Project o r Jobs: ( T o be performed by the learner.) Jo13 No. 39: Arrange a set of upper and lower teeth in proper bcquence. Joi3 No. 40: 1)raw a set of artificial teeth on paper and outline :~nntoniiclandmarks. J o ~ rNo. 41: Recognition of individual :~rtificialteeth. NOTF: (Rcad the cntirc IJiiil cnrcCullj, bcfol-c 1)eginning work. Cori\ult tlie glossal-y for dcfinitio~i\of new word\.) Jol) Application: A tliol-o11gli I;ric~wlctl~,rc of the sli:~l)c.s,r~urnhcr, t o ~ ~ o , ~ ~:LII
ill l ~ l l l , ! ~ ~ ~ l l 0 l 1 ~ ~ i ll l t

l(Y.tll. I

Materials : Full set of upper and lower artificial teeth; carding wax. Procedure : (Follow operations in the order presented here.) C I: ~ ~ ~ ~ ~ ~ Note: I n recognizing teeth you must tell whether it is an upper or lower, right or left, and the name of the tooth. Remove upper set of artificial teeth from carding wax. Keplace upper six anterior teeth on carding wax in proper sequence. 3. Arrange upper bicuspid teeth on carding wax in proper sequence. 4. Arrange upper molar teeth in proper sequence. 5. Remove the lower set of artificial teeth from the carding wax. 6. Replace the lower six anterior teeth in their proper sequence. 7. Replace the lower bicuspid teeth in their proper sequelice. 8. Replace the lower molar teeth in their proper sequence. 9. Remove all the teeth from the carding wax and replace them in their proper sequence. 10. Outline the various tooth surfaces on paper. I I . Outline the anatomic landmarks of the individual teeth. 12. Label all surfaces, landr~~arks and angles. I.

2.

Supplementary Assignment: (Information to be obtained by the learner.) I . Types of artificial teeth available. 3. modified forms of artificial teeth. 3. Shades of artificial teeth. 4. "Staining" of artificial teeth. 5. History and development of artificial teeth in dentistry. 6. Cornpal-ison of advantages and disadvnntages of different type\ of 21-tificialteeth.

132

M A N U A L I.(II< I ) I : N ' I ; \ I .

'I'I':L'LIN I C I L ~ N S

Questions : I . I\Jh:lt :~r-c.the. t1:ul)c.s :[I [d t i ~ l ~ i > l ~01' u t . thc I ~ L I I ~ ~ : teeth? III ,:. \\'h;~t:[I-c tlic n:ltncs : L I I ~ I~I L I I ~ ~ ~ > C ,uf I - ;it.titici;il teeth.; 3. \\'hat are the ~ ~ ; u l ~:111ci c s Ioc.:~tior~s ol' thc \.aric)us crown surfaces? 4. H o w rllny the tooth crow11 surf:lces bc divided? 5. Describe the physical appearance of the crowns of the individual teeth. 6. What questions must be answcred in rccogr~izingindividual teeth.; 7. Give divisioils of an artificial tooth. 8. W h a t are the main typal forms of artificial teeth? 0. W h a t d o we mean by the following: Cusp; tubercle; ridge; fossa; sulcus; groove; interproximate space; diatoric; mcsial ; distal; buccal; l i ~ l ~ u a pajatal; l; incisal; occlusal; gingival; axial; transverse ridge; cervical; point-angle; line-angle; crest; crown; collar of tooth; ridge-lap; shut; bite? Job Appraisal : I. Can you recognize each tooth, tell which tooth it is, which jaw, and the side of the jaw to which the tooth belongs? 2. DO you know the names and angles of the various tooth surfaces? Ii I ~ I ; ~ ; . R E N C E S(Books : for Additional Information.) 1 . R J ~ I<. , IV.: Metallurgy for Dental Students. P l ~ i l a d e l ~ l l i aY.: B1:tkis-

I

I

1IE:l ,AIT'b:Il I N I~'OKMA?'lON: T.JN I'T NO. 9

I

1

I

ton's Son & Co., IIIC., 193 1. z. Nichols, I. G.: Prostlletic Dentistry.

St. I,ouis: C. V. Mosby Co., 103o. 1'1-inz, H.: I)e11t.11 Fornll~lar).. 1'11 ilnclelpliia: T,ca S( Febigcr, I 936, . j . 'l'urncr, C. R. : ~ n dAlltllony, T,. I'.: Alncl.ic,ln Tcxthook o l 1'1.ostllc1ic I I . I'hil.~~lclpJli:~: Lca & Fcbigcl-, 193 2 . 5 . C l ~ ~ ~ r ~[ ~f . l I<.: ~ i lJ l~,L I I ~ I O : I ~~ ~ o r ~ o ~ o g:ili~l r , ~Hi>tolog?. ~~It~~ ~'ltil~~~~cl~~l~i~~. l,<.J& l:vl>isrl-, 5. 0. I ) i , t i n ~ ~ ~3'1.: i ~ l .l ) ~ ~ 1 1 1 , 1,1\ I I , I L O I I K I ~v .\ f York: & I , ~ c i ~ t iC'O., l l ~ ~I (~] ,~{ ; . 7. S<-ll!r..~lI~.. ,I. It.: I'r.icti(..il I)cllr.ll .\~l.iiOll~\ .11tt1 ' I ' O I I I ~ I C'.II!i ~ l f i , I:IOOI:I! 1 1 : l ) < , 1 1 1 . 1 1 I L V I I I S o r ~ I I I C I C S II ' L I I ~ I ~ ~ ICo., I ~ I ~I~~~~ j. 3.

1

M O R P H O L O G Y O F THE TEETH A N D DENTAL ARCHES Morphology: T h e study of the respective shapes and characteristic larldmarks of the teeth and dental arches, as usually found it1 humans. Definition a n d N u m b e r of H u m a n T e e t h : H u m a n teeth are the hard ivory-like bodies found in the mouth. They project through the mucous membrane or gums and are implanted or held in bone sockets or alveoli. They are arranged in two semi-circular ridges known as alveolar ridjies. T h e baby teeth are 20 in number. T h e complete set of teeth In the adult is 32 in number. There are 16 teeth in each jaw. (Fig. 131.) I n the normal mouth with all teeth present we find the following: 4 central i~icisors(two in each jaw) 4 lateral incisors (two in each jaw) q cuspids or canine teeth (two in each jaw) 8 bicuspid or prenlolar teeth (four in each jaw) 12 molar tceth (six in each jaw) I n artificial teeth the third molars are omitted, giving 28 teeth in an artificial set. (1:ig. I 32.) T h e Color of H u m a n T e e t h . Color is a visual sensation. Hum:ui teeth naturally vary in color according to form and structure. T h c color may be influenced by food, drugs, disease or environment. T h e C r o w n s of H u m a n T e e t h . T h e crown of a tooth is that portion which projects from the gum and is covered with en;lmel. T h e el-own has four surfaces ill incisor teeth or five surf:lces in bicuspids .[11c1 ii~olarteeth. 1'1 IY S I C A L C H A R A C T E R I S T I C S O F T O O T H C R O W N S

Ul)l)er C e n t r a l Incisors: (Fig. 132, Tooth No. I.) Two in numright nlid n left, separated by the median line of the face. I ' l r c , , . ;[re ncclgc~sll:il~cci tceth, co~lvcxlabially, concave lingually atid I ill. 'I'hc nlcsi:~l sidc is 1o11~c.1311d s t ~ . ; l i ~ h tth:111 ~r

11c.t-, :i

' .\.\

I34

I35

PHYSICAL CHARACTERISTICS O F TOOTH CROWNS


I

the distal side. T h e labial surface is more or less rectangular. The lingual surface is more or less triangular. The mesial and distal surfaces are triangular (Fig. 133). Upper Lateral Incisors: (Fig. 132, Tooth No. 2.) Two in number, a right and a left, each set distal to the central incisors. Right of patient or articulator

Left of patient or articulator

Upper

Labial and buccal view, surfaces facing lip and cheek.

7

6

5

4

3

2

Lower 1 1 2

3

4

5

6

7

FIG. 132. A FULL SET O F ARTIFICIAL TEETH-xAND x1 INDICATE THE MEDIANLINE I-Central incisor. 2-Lateral incisor. 3-Cuspid (canine). 4-First bicuspid (first premolar). 5-Second bicuspid (second premolar). 6-First molar. 7Second molar. Lingual (tongue) view.

FIG.131. NORMAL ARRANGEMENT OF THE HUMAN TEETH IN THE

JAWS

A. Upper jaw: I-Upper central incisor. 2-Upper lateral incisor. 3-Upper cuspid (canine). +-Upper first bicuspid (first premalar). s-Upper second bicuspid (second premolar). 6-Upper first molar. 7-Upper second molar. 8-Upper third molar. B. Lower jaw: I-Lower central incisor. 2-Lower lateral incisor. 3-Lower cuspid (canine). +-Lower first bicuspid (first premolar). 5-Lower second biscuspid (second premolar). 6-Lower first molar. 7-Lower second molar. 8-Lower third molar.

They are shorter and about one-third narrower than the upper central incisors, which they resemble. The distal surface is more rounded than in the upper central incisors. Upper Cuspids: (canines) (Fig. 132, Tooth No. 3.) Two in number, a right and a left set distal to each of the lateral incisors. They are shaped like an inverted miter. The cuspid is the largest of the anterior teeth, although its surface area is smaller than that of the upper central. The incisal edge has two slants, a mesial and a distal. T h e mesial slant is smaller than the distal slant. T h e cuspid has a lingual ridge running from the incisal edge towards the gingival border ending in a cingulum (a small cusp or elevation) or in a groove. Upper First Bicuspids: (Fig. 132, Tooth No. 4.) Two in number, a right and a left, each located distal to the cuspids. The buccal (cheek) and lingual (tongue) surfaces resemble the buccal surface of the upper cuspid. The vertical (axial) surfaces converge gingivally (toward the gum). Occlusally (surface toward the opposing tooth or teeth, the chewing surface), they have a central

1 3 ~



37

I

groove running mesiodistally. They have a buccal and a lingual cusp (elevation) on the occlusal surface. Upper Second Bicuspid: (Fig. 132, Tooth No. 5.) Two in number, a right and a left, are located distally to the fibt bicuspids which they resemble, but their crowns are more symmetrical (Fig. 134).

Labial surface (surface toward lip). A-This division is known as the gingival (toward gum) or cervical (toward neck). B-Middle third between gingival and incisal (toward cutting edge) thirds. C-Incisal (cutting edge) third. Note: Mesial denotes surface toward, or facing, median line of face. Distal denotes surface facing away from median line of the face. 2 . Lingual v i e w (surface facing tongue). A-Distal third (includes the surface facing in opposite direction from median line of face). B-Middle third, between distal and mesial thirds. C-Mesial third (including surface facing median line of face). D-Pin (which helps hold tooth on denture). 3. Cervical v i e w (surface toward gum of alveolar ridge). A-The shut (part of tooth which holds the pins). B-The ridge lap (part of tooth toward alveolar ridge). 4. Mesial v i e w (surface toward median line of face). A-The ridge lap (surface toward alveolar ridge). l3-The shut (surface containing metal pins). C-The bite (surface which glides over or faces toward lower incisor teeth). D-The collar (this surface is covered by the dental rubber and aids in attaching the tooth to the base of the denture). 5. lncisal v i e w (view of cutting edge of tooth). A-Mesial third. B-Middle third. C-Distal third. Note: Certain combinations of the terms can be used to denote various angles or divisions of the teeth. For example: I. Mesio-labial (surface or angle toward median line and lip). 2. Mtsio-inrisal (surface or angle towartl median line and c:l~tti~lg edge). 3. Mesio-gingival (surface or angle toward median line and gum). 4. Mesio-lingrtul (surface or n ~ ~ g lfacing e median line and tongue). 5. Mesioocclrtstrf (surface or anglr facing median line and occlusal). 6. Disto-labirr1 (sr~rfare or angle facing away from 1neciia11line n l ~ dtowarcl lip). 7. Dirlo-itrcisnl (s~~rf;~c.c. or angle facing away frorn median line and toward gllm). R. Disto-gi?i!/iwul (surfucc or nngle facing away frorn metlian line a~ltltoward RIIIII). 9. Dis~o-litry/rrnl ( s ~ ~ r f n cor c nnglc facing away from media11 linc aird toward ~ ~ I I ~ I I 10, C ) 1)isto. occlssrtl (serlacr or nl~glcfacing nwny from mcdin~lline nnd rownrd occl~~nnl). I.

Buccal (cheek) view. A-Gingival third. B-Middle third. C-Occlusal third (toward the opposing teeth). X-Collar (covered by denture base material). 2. Mesial view. A-Lingual third. B-Middle third. C-Buccal third. 3. Gingival view. (This surface faces toward the alveolar ridge.) A-Diatoric opening for attachment to denture base. 4. Labial view. A-Distal third. B-Middle third. B-Middle third. third. C-Mesial third. 5. Occlusal view. A-Mesial C-Distal third. A=-The bucco-lingual ridge characteristic of the upper bicuspids. 1 3 T h e marginal ridge; the ridge of the curvature which divides the horizontal from the vertical aspects of the tooth. I.

.

Upper First Molars: (Fig. 132, Tooth No. 6.) Two in number, a right and a left, they are located distally to the second bicuspids. Occlusally they show a rhomboid outline (Fig. 135).

1 3 ~



I39

toward the gum line. The mesio-incisal angles are sharper than the disto-incisal angles. The mesial surfaces are convex and the distal surfaces are straight or slightly concave. (Fig. 136.)

FIG. 1 3 5 .

UPPERLEFT FIRSTMOLAR

Buccal view. A-Gingival or cervical third. B-Middle third. C-Occlusal third. 2. Lingual view. A-Distal third. B-Middle third. C-Mesial third. 3. Ridge lap view (surface toward alveolar ridge). A-Diatoric opening. 4.. Mesial view. A-Lingual third. B-Middle third. C-Buccal third. 5. Occlusaf view. A-Mesial third. B-Middle third. C-Distal third. Outside letters: AMesio-buccal cusp. B-Linguo-distal groove. C-Transverse ridge. D-Distolingual cusp. Note: Details of tooth surfaces: Cusp-A pointed eminence on occlusal surface of tooth. Tubercle-A small nodular eminence on crown surface of anterior tooth. Ridge-An elongated eminence on occlusal surface of tooth. Fossa-A round or wedge-shaped depression on occlusal surface of tooth. Sulcus-An elongated fossa. Groove-A sharp linear depression on occlusal surface of tooth. 1.

Upper Second Molars: (Fig. 132, Tooth No. 7.) Two in number, a right and a left, located distally to the first molars. They are slightly smaller than the first molars. First and Second Lower Incisors: (Fig. 132, Teeth Nos. I and 2.) Two centrals and two laterals or four altogether, one of each tooth located on each side of the median line. The centrals are separated by the median line and the laterals are distal to the centrals. The lower incisors are wedge shaped, the laterals are somewhat larger than the centrals. The mesial and distal margins converge vertically

Labial view. A-Incisal third. B-Middle third. C-Gingival or cervical third. Lingual view. A-Distal third. B-Middle third. C-Mesial third. 3. lncisal v t m . A-Mesial third. B-Middle third. C-Distal third. 4. Mesial view. ABite. B-Shut. C-Ridge lap. D-Collar (this portion is covered by denture base material). 5. Gingival or cervical view. A-Shut. B-Ridge lap. I.

2..

I

a

I

,

Lower Cuspids : (Fig. 132, Tooth No. 3.) Two in number, a right and a left, located distal to the lower laterals. Resemble upper cuspids but are narrower and their vertical surfaces incline more distally. Lower First Bicuspids: (Fig. 132, Tooth No. 4.) Two in number, a right and a left, each located distal to the lower cuspids. The lingual cusps are much smaller and lower than the buccal cusps. The occlusal surface appears circular. The buccal surface is more convex than in the upper bicuspids. Lower Second Bicuspid: (Fig. 132, Tooth No. 5.) Two in number, a right and a left, each located distal to the first bicuspids. They resemble the first upper bicuspids. The buccal surface is more convex than the upper. (Fig. 137.)

I40


I . Buccal view. A-Occlusal third. B-Middle third. C-Gingival or cervical third. B-Middle third. C-Mesial third. third. z. Lingual view. A-Distal 3. Occlusal view. A-Mesial third. B-Middle third. C-Distal third. Ax-Occlusal pit and mesio-distal fissure, characteristic of a lower second bicuspid. B'-The marginal ridge. 4. Mesial view. A-Buccal third. BYMiddle third. C-Lingual third. 5. V i e w of ridge-lap (surface toward alveolar 'idge). A-Diatoric hole for attaching denture bare r n 4 1 1 .

First Lower Molar: (Fig. 132, Too . 6.) Two in number, a right and a left, each located distal second lower bicuspid. They usually have three buccal cusps ingual cusps. A long groove (central fossa) divides the oc ce into a buccal and lingual portion. T h e lingual surface than the buccal surface, mesio-distally (Fig. I 3 8). Lower Second Molar: (Fig. 132, Tooth No. 7.) Two in number, a right ;lnd L: left, each located distally to the first molar. T h e occlusal surface resembles a parallelogram. I t is smaller than the first molar. I t has a central groove running mesio-distally which divides thc occlusal surf;lcc into buccal and lingual cusps.

OCCLUSION O F INDIVIDUAL TEETH I N NORMAL RELATION

I41

1. Buccal view. A-Occlusal third. B-Middle third. C-Gingival third. 2. Lingual view. A-Distal third. B-Middle third. C-Mesial third. 3. Occlusal view. A-Mesial third. B-Middle third. C-Distal third. 4. Mesial view. A-Buccal third. B-Middle third. C-Lingual third. 5 . Ridge lap view. A-Diatoric opening.

OCCLUSION O F INDIVIDUAL TEETH IN NORMAL RELATION (Fig. 131) I.

Tooth Upper central incisor.

2.

Upper lateral incisor

3. Upper cuspid (canine)

.

4. Upper first bicuspid

OccZzlding teeth i~ opposite jaw Lower central incisor ( I ) and mesial third of lower lateral (2). Distal two-thirds of lower lateral incisor (2) and mesial third of lower cuspid (3). Distal two-thirds of lower cuspid (3) and mesial half of lower first bicuspid (4). Occludes between the lower first bicuspid (4) and second bicuspid (5).

142


5. Upper second bicuspid 6. Upper first molar

7. Upper second molar I.

Lower central incisor

2.

Lower lateral incisor

3. Lower cuspid 4. Lower first bicuspid

5 . Lower second bicuspid 6. Lower first molar

7. Lower second molar

Occludes between the second lower bicuspid (5) and first lower molar (6). Occlusion begins with the buccal groove of the first lower molar (6) and extends to the space between the lower first (6) and second (7) molars. Occlusion begins in the buccal groove of the second lower molar (7) and extends distally. Mesial two-thirds of upper central incisor ( I ) . Distal third of upper central incisor ( I ) and mesial two-thirds of upper lateral incisor ( 2 ) . Distal third of upper lateral incisor (2) and mesial half of upper cuspid (3). Occludes between the upper cuspid (3) and the upper first bicuspid (4). Occludes between the upper first bicuspid (4) and upper second bicuspid (5). Occlusion begins between the second upper bicuspid (5) and extends to the distal cusp of the first upper molar (6). Occlusion begins between the upper first molar (6) and upper second molar (7) and extends to the central fossa of the second upper molar (7).

COMPOSITION O F HIGH FUSING PORCELAIN BODY

I43

Philadelphia in 1820. I n 1825, he worked for Chas. W. Peale and S. W. Stockton, who began the manufacture of teeth. COMPOSITION O F H I G H FUSING PORCELAIN BODY 4% parts of Kaolin for plasticity

parts of flint or silica for framework 85% parts of feldspar for fusing Colors : Gold-red-yellow Platinum-gray Titanium oxide-yellow Cobalt-blue Iron oxide-gray Fluxing agents : Calcium carbonate Sodium carbonate Potassium carbonate

15

NOTE: T h e numbers following or preceding the teeth refer to the numbers on the teeth in Fig. 131.

O R I G I N O F A R T I F I C I A L TEETH Artificial T e e t h are made from porcelain. Duchateau of Paris, France (an apothecary), first conceived, in 1774, the idea of using porcelain for dentures and teeth. Another Frenchman, D e Chemant, in 1790, obtained a patent in France. H e moved to England and Formed n partnership with Claudius Ash for manufacturing porceInin teeth. Fonzi, I 808, Frcllch dentist, made individual tecth with platinum pins. A. A; Pl;~ntou,a PI-cnchmnn, practiced dctitist~yin

SECTION OF FIG. 139. CROSS

I.

ARTIFICIAL TOOTH WITH METALPINS Transverse section (horizontal). A-Lingual surface. B-Mesial surface. CAN

Labial surface. D-Distal surface. &Metal pins. z. Longitudinal section (vertical). A-Bite. B-Shut, including the metal pins. C-Ridge-lap. D-Collar.

P i n s of Artificial Teeth: (Fig. 139). T h e pins are made of nickel, gold, platinum or combinations of the foregoing metals. Shade Guides: Shade guides for matching teeth are supplied by the manufacturers of artificial teeth. (Figs. 140, 14s and 142.)

I4-4


AIDS IN SELECTING COLOR SHADES I N TEETH

I45

FIG. 140. TWENTIETH CENTURY SHADEGUIDE Twenty-five teeth exhibiting the 25 shades in which the tooth products of T h e Dentists' Supply Company are made. Each shade tooth may be drawn out of the guide for selecting and matching purposes. T h e teeth may be turned in any desired direction. Twentieth Century Shades in Order of Depth, Lightest First I. Lightest shade in use. No coloring. Basis of other shades. 2. Trace of purple. 3. Trace of blue, and a mere trace of yellow. Lightest blue. 12. Grayish blue. Follows No. 3 in the real blues. No. 3 and this are the only blues and they are not decided in character. 4. Trace of yellow. Lightest yellow. 5. Trifle of gray and trace of yellow. T i p same as No. 4. Neck darker. 7. Light yellow. Darker than No. 5, with color decidedly stronger in neck. 8. Light yellow. T i p darker than No. 5 or No. 7. Neck lighter than No. 7 and makes tooth look a straw color. More uniform than No. 7. Yellow is the only color present. 16. Yellow. Follows No. 8. 20. Brownish yellow. Follows No. 16. 21. Dark brown yellow. Follows No. 20, which it is like, only darker. 23. Darkest brown yellow. Follows No. 21. 25. Dark yellowish brown. Follows No. 23. 6. Same a s No. 4 with a little gray in the tip. Neck not so bright a yellow as No. 5. Lightest gray. 10. Gray. Lighter than No. 9 and slightly darker than No. 6. 11. Uniform gray throughout. Neck grayish yellow, slightly darker than 10, which it follows. 9 . A little yellow, a little gray, a little pink. Light brown yellow neck. T i p pink gray, follows No. 11. 13. Grayish blue. Follows No. 9. 14. Yellowish gray. Gray yellow neck. Follows No. 13. 15. Pinkish gray. Decidedly darker and shows more pink than No. 9 . The other grays are blue grays. This follows No. 14. 18. Dark yellowish gray. Follows No. 15. 22. Dark gray. Follows No. 18. 24. Dark grayish brown. Follows No. 22. 17. Greenish yellow. Green tip and yellow neck. 19. Dark greenish yellow. Follows No. 17. Light shades,

Lightest Shades Placed First 4-5-7-8-16-~0-~1-23-25. Greenish yellows, 17-19. Grays, 6-IWI1-9-13-14-15-18-22-24. Blues, 3-12.

1-2. Yellows,

* Shades for Principal Complexion Types Flaxen Blonde 36, 39, 42, 42, 44, 46, 51 Gray Blonde 32, 40, 4f, 42, 43, 44, 46 Auburn Blonde 36, - 3 2 for lighter types. For others 38, 391 41, 53 53 Medium Fair Type . 39, 4_f., 42, 43, 447 46 Medium Brown g, 4% 45, & 5% 53 Light Brunette 42, 43, 44, 461 48, 49, 53, 55 Medium Brunette . 42, 9, g,2,55, 57 Dark Brunette 41, 42, 43, 45, 46, 43, 5% 53 (The underlined numbers are those found most useful.)

.

. . .

. . .

. . . . . . - . . . . .

. . . . . . . .

e,

s,

e,

AIDS IN SELECTING COLOR SHADES IN T E E T H The selection of artificial teeth is done by the dentist who takes into consideration the color of the eyes, hair and skin of the patient or of the patient's natural teeth, the shape and size of the head, the teeth, the mouth, distance between the corners of the lips and the amount of gum tissue exposed when the patient is speaking or smiling. Coloration is the result of various influences, such as race, climate, diet, habit and condition of health. I t determines what

I

I

146


U N I T NO.

10

ARRANGING ARTIFICIAL TEETH Bluish White . . . . . BluishYellow. . . . . Blues . . . . . . Bluish Green . . . . . Yellow Green . . . . . Pinks . . . . . Light Yellow . . . . . Yellow to Red Yellow . . . Grayish to Brown Grayish Yellow

.

. . . . . . . . . . . . . . . . . .

I-

2

4-5 106-12-3 17-18-43 19-24 9-15 7- 8 16-20-21-25 11-14-22

we call the cccomplexion" of the individual. T h e terms "blonde" and "brunette" are entirely too general to be satisfactory, but because they have the weight of custom behind them they are usually used. I n the classification of patients for the purpose of tooth-shade selection it is necessary to select one element of the complexion as dominant. A tooth shade can then be selected to harmonize with this. T h e other elements are important but only contributory. I n matching artificial teeth where one or more are to be added to artificial teeth adjacent to them, it is important first to determine the modifying tint in the enamel. For instance, the basic color in tooth enamel is gray. I t may be modified by blue, yellow, red or brown. When the modifying tint is tentatively determined, the shade guide is held to the incisal edge of the tooth on the denture and turned to the group of shades containing the corresponding tint in the enamel. I n the new trubyte shade guide, shades 36 to 38, inclusive, have blue-gray enamel; shades 39 to 50, inclusive, have yellow-gray enamel; shades 51 to 57, inclusive, have red-gray enamel, and shades 58 and 59 are designated as cctobacco." No attempt should be made to match the tooth as a whole until the enamel at the incisal edge has been matched. T h e shade-guide teeth may be turned on their handles to permit holding them in any relation to the teeth to be matched.

Artificial teeth are constructed so that they may be arranged easily on the denture base, over the alveolar ridges. T h e arrangement must be such as to maintain the stability of the bases of the dentures when eating or speaking and, at the same time, the teeth should be in accord with the esthetic requirements of the individual patient. T h e saying "It is an art to conceal art" is important in this respect. T h e dentures should not be too conspicuous or too false-looking. In this unit the beginner is provided with methods for the ideal arrangement of artificial teeth. I t is well to learn the ideal before undertaking to arrange artificial teeth so that they meet the requirements of the individual patient.

Process o r Principle : No. Teeth.

I6

Arranging (setting-up) Artificial

a. Arranging full zlpper and lower dentares on a plain line articulator or Gysi Syrnplex Articalator. b. Arranging teeth of six upper and lower partial dentzlres.

,

Project or Jobs : (To be performed by the learner.) JOB NO. 42: Make an additional set of upper and lower biteplates on baseplate trial-bases. Arrange upper teeth on upper edentulous cast against lower biteplate by cutting the upper biteplate and inserting the teeth. JOB NO. 43: Place two new biteplates in position on the articulated casts and arrange lower teeth on lower edentulous cast against zlpper biteplate by cutting the lower biteplate, set on a baseplate trial base, and insert teeth. JOBNO 44: Using the second set of upper and lower casts with biteplates set on baseplate trial bases, arrange upper teeth agknst lower biteplate by cutting the upper biteplate. Set lower teeth against upper teeth by cutting the lower biteplate. JOB NO. 45: Using the casts with biteplates set on wax bases, make a new upper wax trial base and arrange the upper teeth againsr the lower biteplate. '47

I

48

M A N U A L F01<

UliNTAI.

l ' l i C l I NICIANS

J013 No. 46: Make a new lower trial wax base and set lower tcet h a~di.w.ctfLpper bitrplnte. . l o 1 3 No. 4;: 4rr;uigc upper tccth, 11i;tkirrg I I ~ Ww,tu trial 1)asc ( ~ ; ~ i i i I~ol sx/ ~ ibi/c,pl(zt~.. . ~lrfiulgclo\vcr teeth agaiu~tupp~ji-t c ~ / l l , u\irlg a new trial wax base. J O B No. 48: Arrange six partial dentures. Make two of the partial cases "horseshoe" tvpe. NOTE:(Read the entire' Unit carefully before beginning work. Consult the glossary for definitions of new words.)

J o b Application: Artificial teeth must be so arranged 011 the denture base as to afford a pleasing facial appearance and a maximum of stability under functional stress: during speech or chewing. T h e :u-tificial dentures must allow for the proper chewing of food and not interfere with speech. T h e denturcs must not have ally harmrul effect on the oral tissues or organs. Vocational I n f o r m a t i o n : T h e ideal and basic principles of tooth xrrangement are presented here. T h e arrangement of teeth should I)c i l l keeping with the esthetic and functional requirements of the i t~clividualpatient. Teeth set too evenly present an artificial appear I . Tceth are often ground, stained, rotated or otherwise modified I roni the ideal to lend individual it^ to the denture. T o o l s a n d E q u i p m e n t : W a x spatula, Bunsen burner, straight c ~ l ~ tooth c, grinding carborundum wheel, lathe chuck and dental I;ttlic, articulating paper. Materials:

,%rtificial teeth; basewax; baseplates; 30-gauge copper

I'oI- I-ceiiforcing upper dentures set on wax bases; reenforceme~it ~vir-cfor lowcr deiiturcs and partials. N I YII, . Srlrction of Artificial T p ~ t / z : /\I-~if;cial teeth must be selected to fit each case. If casts made 01 the ~lentoforrnsshown in Figs. 29 and 30 arc used it is ;tdvisablc to uw the followi~lgtooth selections:

d. Universal N u f orrn Teeth: 1Jppel-s mould 84; loivers mould 81; posteriors mould 50. c. U~iiv~rsril I : . S. 1'. ' i r r > c ~ / / l :I I I ~ ~ ~iioulti ~ I - s 17; Io\\u.s nio~llci 3 1 ; I'ustei-iors mould 03. f. Ideal 'I'ilcr-J'OYPYL Y'l'c~eth:l"1111 lTpper and 1,ower Anteriors mould 48; Posteriors, True-Kusp mould 62 or Anatomical Posteriors mould M4. g. iVyersons True-BIt~ldi??ltrriors: mould 48. h. Ideal New-Bite: Upper Anteriors mould 7'12. 1,ower Anteriors mould 38; Posteriors 39. Dentoform No. 255 (Fig. 29, No. 2). a. T i z ~ b y t eTeeth: Mould ;N with mould 3 o L I'osteriors. b. New Trubyte: blould 263 with mould 301. Posteriors, mould 291, 20" I'osteriors. c. Solila: Anterior Mould 90; Posteriors mould 99; lowel-\ mould 39. d. U ~ ~ i v e r s aNlbfor?)z l Tepth: Anteriors mould 86; Posteriors mould 54. e. Universal U . S. P. Trr7th: Mould I 8-133 upper and rnould 14-26 lower; mould 90 I'osterior. f. Ideal True-F'orm ' I ' e ~ t h :LTppcr hilteriors mould 64; lower Anteriors mould 7 j ; True-Kusp Posteriors mould 53 or True-Form Posteriors mould Mg. g. Alyerson's 'I'rue-Blend ,4nteriors: 'CJpper mould 64; lower mould 73. h. Ideal New-Bite: Upper Anteric~rs rnould S o luwcr Anteriors mould 34; Posteriors mould 37. 1)entoform No. 256 (Fig. 29, No. 3). a. Il'rzrbytlq Tppth: Mould 4 M with mould 28L Posteriors. b. N e w Il'rubyte: lllould 243 with mould 30111 Posteriors: mould 291, 20" Posteriors. c. Solila: Anterior nlould 19: Posteriol-s mould 99; lowers mould 67. ~ 1 .lIfiivc7rsaL Nuforru Tr7eth: Lrpper anteriors mould 83; lower :~iitc~-iors rnould 50; Posteriol-s mould 50. c. il~lis~~i~.\cil I T . S. I]. T r e / / l : Mould No. 284.3 upper; mould 0.7 lowel-. 1. ' / ' I - / / ( ' 1*'ot.?11 'l'c~i'//i:1 Jpper and lower Anteriors mould . ~ 8 ' ;I ~ I - ~ I CI i t 1 ~ 1 )I'osteriors 11ioi11~i 6 2 or r13~-ue-170rtn 1'0steri01-s 1 l 1 0 I l 1 ~ l MA. /,/(.(I/

1 5 0

M A N 1 1.41. I'OR

DENTAI.

TECHNICIANS

g. h/ly~~i-su,Js l'rue-Bbei~rlAlzteriovs: ~nould48. 11. IIZcnl New-Bile; IJpper Anteriors mould Anteriors mould 38; Posteriors mould 39.

ARRANGING ARTlI'lCIAL

TI2 ; I O U I C ~

1)entoform No. 257 (Fig. 29, No. 4) : :t. Il'rubyre Teeth: Mould r Y with mould 321, Posteriors. 11, N m Trubyte: Mould 315 with ~nould32L Posteriors and mould ~ I 20" L Posteriors. c. Solila: Anterior mould 49; Posteriors mould 50; lowers mould I I . d. Universal N u f o r m Teeth: Anteriors mould 72; Posteriors mould 54. e. Universal U . S. P. Teeth: Mould 18 Anteriors; mould go Posteriors. f. Ideal Trzde-Form Teeth: Upper iinteriors mould I 8; lower Anteriors mould 28; True-Kusp Posteriors mould 76 or True-Form Posteriors mould Mq. g. Myerson's ?'rut.-Blend Anteviors: IJpper nlould 18; lower mould 28, h. Ideal New-Bite Teeth: Upper Anteriors n~ouldTI?j J O W ~ C ~ Anteriors lnould 38; I'osteriors mould 39. I I Partials: Dentoform No. 258A (Fig. 30, No. 2). a. Trubyte Teeth: Upper posterivrs mould 34M. b. N e w Trzcbylz: Upper posteriors nlould 34M. c. Solila: Upper posteriors. Kight first bicuspid ~nould48 or 69. Kight first molar 11lould 69. ],eft first bicuspid mould 6:). I x f t first molar rnould 69. d. lInivlv-scrl N~bfofikz7'c:eth: I.Jpper left first bicuspid and sec-oncl 1no1:u- nlould 5;; upper right first bicuspid and first n1ol:lr mould 5 I . c.. lIiti~<.rsill C:. S . 1'. 'l'~et/r:T Jppcr lcft first bicuspid and scc ontl rnolztl- n~ouldc10; upper right first bicuspid 2nd seconc~ mol:tr mould q - 3 0 . I-. /~/i,a/7'~z(i,Por/-lzTertll: I'trstr.~.ior.s~ ~ ~ o Mq u l d01- T~-~rc-Kusl, I'ostcriors mould 76. g. N1'7~Hi/(,:l'ostcriors nioul~l;I(). l)c.r1tofo1-1i1 No. 258H ();is. 30, No. i ) . :I. 'I'I./I/JI!/(, '/'(*(,//): I I / ) J ) C . I - ; I I I I ~ I . ~ I I I I. I\I O I I I , I . / I I ; i l ~ ) , ) ~ , l I I I ~ ) L I I ( I :{4hl.

l j ~ ~ \ ~ < , ~ . i , , ~ ~ ,

TEETH

I jl

b. N e w Tritbyte: Upper anteriors mould 146; upper ~osteriors mould 34M. c, Solila: Upper anteriors mould 48 or 69. Upper posteriors: Right secorld bicuspid mould 48. Right first molar mould 48. Left second bicuspid mould 69. Left sccond il~olarinould 48. d. U,~ivrrsuLN Z I ~ O T~ PI ICZI / IUpper : antcriors mould 73 ; upper lcft second bicuspid mould j I ; uppcr right second bicuspid and first molar mould 54; upper left first molar mould 54. e. Urtiz~ersal I / . S. I ) . Il'eerh: T_Tpper anteriors mould 204; upper left bicuspid mould 5 - 3 9 ; uppw right second bicuspid and first molar mould go; upper left first nlolar mould 90. f. Ideal True-Foiw~l'ecth: A~ltcriors(short bite) mould 70; True-Kusp Postcriors mvuld 62. g. Myerson's True-HIe~zil,I~~teriors: mould 70. h. Ideal New-Bite Teeth: Aatcriors (short bite) mould 011; Postcriors mould 38. Dentoform No. 258C (Fig. 30, No. 4). a. T p u b y ~ eTeeth: IJppcr Posteriors nlould 345. b. N e w Trztdytr:: Upper I'osteriors mould 34s. c. Solila: Upper Posteriors. Right first bicuspid mould 84. Right first and second n~olarmould 84. Left first bicuspid mould 84. Left first and second molars nlould 84. d. Universal Nufornz Teeth: IJpper right bicuspid mould 54; upper right first and second molars mould 57; upper left second bicuspid ~nould57; upper left first and secorld molars mould 5 I . c. Universal T I . S. P. Teeth: Upper right bicuspid mould 90; upper right first and second molars mould go; upper left second bicuspid inould 90; upper left first and second molars mould 4. I . lrli .(/I 'I1rz/.cl / ' o , . / ~'I1c.(-t/, , : l'ostel-iol-s mould 3.2 or True-Kusp l l l ~ l ~ 1~, : l. ~ i

c. 1 ~ 1 ~ ~\', 0 1..c I<;/,, '/',,( I /

:

I ' o ~ t ( ~ ~ ~~i on r
I ) ( . I I ( I , I . I , I 111 {OC' ( I;:. ;{o, N o . .+). . I . 'ITit1/,\~/,~ 'I5,', I / , : 1 . I ~ \ v ( . I .I ' o , ~ c . I - ~ o I - ~ 1110111(1 34s. 11. N ; '1'1tt/1\'/,, ' / ' , , , , I / ,I:, O \ V C , I . lpo,tr~.io~.s I I ~ O U I ~34s. I ,'.I

152

ARRANGING A R T I F I C I A L TEETH

MANUAL FOR D E N T A L TECHNICIANS

c. SOl;l(f: 1,ower Posteriors Right first bicuspid inould 5; Right first and second molars mould roo; 1,ctt first bicuspid mould I 2; I,eft first molar mould roo. d. U7civcrsal Nziform Jl'ezth: Lower right second bicuspid mould 51 ; lower right first and second molar mould 51 ; lower right first bicuspid mould g r ; lower left first molar mould 5 I . e. U ~ ~ i v e r s aUl . S. 1'. Il'eeth: Lower right second bicuspid mould 4, lower right first and second molar mould 4; lvwcr right first bicuspid mould 4; lower left first molar mould 4. i. 7dcal Trut, F ' o r ~ iTi>eth: ~ I'osteriors mould 32 or True-Kusl) I'osteriors mould 62. g. Ideal N m - B i t e 7'eelli: I-'osteriors mould 39. 1)entofonn 259B (Fig. 30, No. 3). a. Trubyte 7 ' e ~ t h :Lower posteriors mould 34M. b. h'ew Jl'rubytr 7 ' e ~ t h :L,ower Posteriors mould 34M. c. Solila: 1,ower l'ostcriors, right second bicuspid mould 5; right first molar nloulci 100; left first and second bicuspid nlould 5; left fir5t molar moulci 100. d . Univrrsn! hrltfur~ii 7'cetlz: 1,ower right second bicuspids mould 51; lower right first molar mould 51; lower left second bicuspid and first molar nlould 54. e. Ufiiversal I;. S. P. Teeth: Idowel- right second bicuspids mould 4; lower right first molar mould 4 ; lower left second bicuspid and first molar mould yo. f. Ideal T r v r FUYWLIl',~r/ll:rnould 70. g. Idrsal A'ca-Riii, Il'rzth: mould 38. Ikntofol-m 25cjA (Fig. 30, No. 2 ) . :I. 7 ' r u h y l ~'l'(:c~lh:Lower anteriors mould 4H; lower postcrio~-s nlould 34s. 1). Ni,.i~ 7'1.~/.byir:Lower Anteriors mould 45 or if butted : ~ g : ~ i rthe ~ s t gun1 use mould 35; lower posteriors rnoultl 34s. ( ~ .So/dr~:Idourc~d ~ ~ ~ t c ~ll~ol~lcj - i o ~ - 5s ; ~ , C ) W ~ I -1'0steri01-s t-ight I;t-st Kic.uspitl moultl 65; Sccor~d Ki(.trxl)id 111o111(1 < ; l
e.

f.

g. h.

I53

lcft fii-st bicuspid mould 54; lowel- lcft first 1ilol:u- rnoultl 5 I ; lowel- a ~ ~ t e r i o r(:s ccl~tt-:i!s:~ncilcft l:lter~il\) n~oultl7 0 . Unic;,rsal Li. S. P. 'flri./li:1 .ourel-right first mo1;ir n ~ o u l d4 ; lower right first and seco~ld1)icuspids ~ n o u l d90; lourel- left first bicuspid nlould go; lower left first molar mould 4; lower anteriors ( 2 centrals and left laterals) mould 2 I I. Ideal T r u e - F o r m T e e t h : Anteriors mould 7 3 ; Posteriors mould M 4 or True-Kusp Posteriors mould 76. Myersoqz's 7'iue-Blend Teeth: n ~ o u l d7.3. Ideal New-Bite T e e t h : L\nteriors mould 35; Posteriors mould 39.

Procedure : (Follow operations in order preseritcd here.) CLzu.r.ro~s: a. iwake sure t h e trial base is serurely sealed to t h e casts b ~ f o r e arrangir~gteeth. b. I t is necessary to not& t h e Lower bit,, r i m slightly in t l i ~ region of ~ I I Pcuspid t o allow t h e incisal ?(lye t o c x t s ~ l d slightly below the plane of occlusion. c. T h e inciral edges of t h e zrpper anterior tcrtlz shouliZ br, set against he outer border of tlze l o i i t ~ rbiteplate and slloulll follow t l ~ ccurvature of t h r lower biteplat?. d. T h e occlusal surfaces of t h e upper posterior teeth should bisect t h e line o n t h e lower bitepiare wliich folloau t h e lifizc drawn on tlze lowLzr ~ a s tf r o ~ n t h r wrst of condyle to tilt' cuspid area. e. D o not sel tile necks of t h e Irppdr anlerior teetli too far under t h e upper alveolar ridge. Set t h r uppei teeth against t l z ~ r i d ~ i-atlier r tiran 072, or under it. f. 7'hr~upper i~rcisorsi n a nor?iiril set oj natural t r i ~ l hare u ~ u a / / ~ about -. 2 ti1il1irrrr~c.r.ianterior to t h e lower incisors. (7'12i.i is tlie oil/ rjei.) g . ' / ' / i f , z>rrrpi~r;< of d ~ . t ~ / u r eass wrll as t h e possibility of t c e ~ h . r i / c t v ; l r ~ oul of aliynmcnt during vulcanizing d u r to tiit' rliri~rka,qc,of vulcanite (dental rubber) will be mach reduced I ] ri .\/ulrc' of about 5/4 of a rwillin~eteris left between tlle iippr,r r l~spidand /lie upper first bicuspid on earh side and rilro l / r ' ~ i ~ ' r t/ie ~ > ~ upper second bicuspids a r ~ d first rr~olars. Slii/i/rrr rp[i( I ' F rI~ouldbe lefi b e l w e ~ nt h e lower first molars (iilrl /hc*/owe;- .r, rot~tlbiruspiils anrl, if possibl~,brtzrlfvw tl~c, / o ? ~ v , ]it ) \ / /)/I//.rpjrLs rit/(/ i / i ( ~ ~u.\ph/s.

>

I54

ARRANGING ARTIFICIAL T E E T H


lower biteplate when viewed from the front. T h e teeth should incline downward and forward when viewed from the side. T h e incisal edges should be in contact with, and follow, the contour of the outer edge of the occlusal surface of the lower biteplate. T h e distal angle of the centrals should incline slightly inward and begin the curvature of the dental arch. Attach the centrals with wax on heated wax spatula. (Fig. 143.1

h. T h e compensating curve to which the occlusal surfaces of the lower molars and the second bicuspids are set should be governed by the curvature of the posterior portion of the lower ridge. If the occlusal surfaces of the lower molars are set parallel to the uptwned posterior section of the ridge, the force applied to the ridge through the teeth i n the act of chewing will be at right angles to the surface of the ridge alzd will hold the lower delzture rigidly in place. i. A lower ridge that has a great curve m.11 call for a correspondingly great curvature in the arrangement of the molars and bicuspids. j. I n many cases a compensating curvature great enough to stabilize the lower denture may have a tendency to create a forward, dislodging pressure on the upper denture, if the upper has no curvature of the alveolar ridge. For such cases the compensating curve must be modified so that it will take an inclination which is halfway between the fiat character of the upper alveolar ridge and the steep slope of the lower alveolar ridge. k. T h e lower cuspids should glide against the upper cuspids when the extension arms of the articulator are moved sidewise. T h e lower cuspids should not touch the upper laterals when the extension arms of the articulator are moved sidewise. 1. W h e n the dentures are in centric occlusion ( t h e articulator extension arms are at rest), the lower incisors should not be in contact with the opposing upper incisors. m. T h e danger of breaking the incisors in using the denture zen'll be eliminated if the foregoing instructions are observed in arranging the teeth. Errors that may become evident in the filzished dentures are corrected by the dentist who grinds the teeth w'th a stone when the dentures are examined and fitted in the mouth of the patient.

I. Arranging Upper T e e t h : NOTE: Arrange upper teeth in edentulous cases as follows: (The same method should be followed for all uppers.) r . Seal the biteplates to the casts, using sticky wax on hot spatula. Cut out sufKcient wax on the upper biteplate and attach the upper central incisor teeth against the alveolar ridge of the upper baseplate, to.the right and left of the median line. The incisal edge, should be parallel with the outer edge of the

I55

FIG. 143. B-Labial

2.

,-

UPPERRITEPLA.I.E CUT 0 ~ 1 1.0 . ALLOWF O R PLACING O F LEFT UPPERCEN.I-RA+( INCISOR view. Note: T h e incisal edge is parallel with the edge of the upper biteplate. C-Distal view. Note: Inward inclination of tooth.

Cut out the biteplate and set the upper laterals distal to the centrals. T h e incisal edges of the laterals should be threefourths of a millimeter above the level of the incisal edges of the centrals. T h e long axis should incline distally when viewed from the front and downward and forward incisally when viewed from the side. (Fig. 144.) T h e necks of the upper laterals should be less prominent (they should be set inward) and closer to the alveolar ridge than those of the upper centrals. The incisal edges of the laterals should continue the curvature of the dental arch along the outer cdgc of the occlusal surface of the lower biteplate. Attach the laterals with wax on heated wax spatula.

1 5 ~


ARRANGING ARTIFICIAL TEETH

I57

3. Cut out the biteplate and set the upper cuspids distal to the upper laterals. T h e incisal tips should extend just slightly below the outer edge of the lower biteplate. T h e labio-axial ridge of the cuspid is the dividing line between the labial and buccal aspects (anterior and lateral views) of the denture.

B-Labial view. Note: T h e tooth is raised upward from the edge of the biteplate, while the long axis of the tooth inclines somewhat distally, the rnesio-incisal angle is nevertheless longer than the disto-incisal angle. C-Distal view of the upper lateral incisor. Note: T h e inward inclination at the neck of the tooth is greater in the lateral than in the central.

T h e mesial half of the labial surface of the cuspid should be set to face the lips while the disto-labial half faces buccally. T h e long axis of the cuspid should incline slightly distally from the incisal tip. T h e incisal edge should follow the curvature of the outer edge of the lower biteplate. Attach the

FIG. 145. METHODOF SETTINGCUSPID B-Labial view. Note: T h e cuspid is inclined slightly distally from the incisal on its long axis. C-Distal view. Note: T h e cuspid has less inward inclination at the neck than the lateral. D-Incisal view. Note: T h e teeth are set so that they carry out the occlusal atch. T h e incisal tip of the canine is slightly lower than the central.

cuspid with melted wax on heated wax spatula. T h e necks of the cuspids should be more prominent than those of the laterals. (Figs. 145, 146 and 147.) 4. Set the upper bicuspid teeth to follow the general outline (shown in Fig. 148). Cut out sufficient wax on the biteplatc to allow the insertion of each of the teeth to follow.

158


ARRANGING ARTIFICIAL

TEJTI"I'

I59

6. T h e upper second bicuspid is set similarly to the upper first bicuspid excepting that both the lingual and buccal cusps touch the occlusal surface of the lower biteplate. (Figs. 148 and 150.) 7. Using a straight edge, test the position of the buccal surfaces of the bicuspids in relation to the cuspids. T h e straight edge should touch the buccal ridges of the cuspid and the first and First Second First Bicuspid Bicuspid BIolar

Second Molar

I n arranging Trubyte Posteriors, look for the small raised dots on the mesial side of the diatoric surface. One dot on a bicuspid designates the first bicuspid; two dots, the second bicuspid. One dot on a molar designates the first molar; two dots, the second molar. As these dots are always on the mesial side of the tooth they also show at a glance whether the tooth is right or left.

Courtesy Dentists' Sut.ply Co., dVcw York

After

Clafip

Nofe: T h e compensating curve can be made to follow the template. Where the template is not used, follow the instructions provided in Unit No. 10.

5. T h e upper first bicuspid should be set so that the buccal cusp touches the occlusal surface of the lower biteplate while the lingual cusp does not quite touch it. T h e tooth viewed laterally should bisect the line on the lower biteplate that folridge. (Figs. 148, 14') lows the crest of the l o w ~;~lvcolnr ~and 150.)

A-First bicuspid, buccal and distal views. B-Second bicuspid, buccal and distal views. C-Buccal relationship of the cuspids and bicuspids. Note: T h e white lines show the relationship of the bucco-lingual aspect of the teeth to the straight edge. T h e white lines are parallel and bisect the alveolar ridge.

second bicuspids. Rotate the bicuspids on their long axis so that lines through their linguo-buccal dimensions follow the line c in Fig. 150, with relation to the straight edge. 8. Attach the upper first molars so that the long axis when viewed from the buccal aspect appears as shown in Figs. 148 and 151. T h e disto-buccal cusp of the first molar should be raised slightly off the lower biteplate.

I 62


13. T h e lower second molar is set distally to the first molar in a manner similar to that employed in setting the first lower molar. T h e second lower molar should occlude with the distal cusp of the first molar and most of the occlusal surface of the upper second molar. 14. With wax and heated spatula attach the lower second bicuspid to the lower baseplate. T h e lower second bicuspid should


163

16. Apply a triangular piece of pink wax to the crest of the anterior portion of the lower ridge from canine to canine. Set the lower anterior teeth in the following order: the lower cen- . trals on both sides of the median line corresponding to the median line formed by the upper centrals; place the lower

Note: T h e long axes of the incisors and laterals are parallel but the cuspids incline distally at the gingival margin.

FIG. 1 5 3 . RELATIONSHIP OF UPPERA N D LOWER BICUSPIDSA N D CUSPIDS A-Detail

of articulation of upper cuspid and first bicuspid and lower first bicuspid. B-The lower bicuspids and cuspid have been set in position.

Note: T h e relationship to the alveolar ridge and inclination of each tooth varies although the incisal edges are all on the same line.

occlude with the distal incisal incline of the upper first bicuspid and the mesial incisal incline of the upper second bicuspid. (Fig. I 53.) 15. Set the lower first bicuspid mesial to, and in the same manner, as the lower second bicuspid. T h e lower first bicuspid should occlude with the distal incisal incline of the upper cuspid and the mesial occlusal incline of the upper first bicuspid. (Fig. 154.1

Note: T h e lower anterior teeth are set inward at the occlusal edge and are out of I1ontnct with the lingual surfaces of the upper anterior teeth. T h i s is known as the swcr-jet. T h e lower anteriors should be slightly higher than the incisal edge of the \lppcr anteriors. This is known as the over-bite and is equal to the depth of the cusps of the molar teeth. See Fig. 150.

lateral incisors distally to the lower laterals. Set the necks of the lower incisor teeth directly over the lower ridge. Set the necks of the lower cuspids anterior to the ridge. (Figs. 154, 155 and 1-56.) I 7. T h e upper and lower teeth at the bicuspids and molars should be in full contact when the articulator is closed in centric occlusion.

164



18. A sheet of softened basewax when closed between the upper and lower dentures should show bitemarks. (Figs. r 57, I 58 and 159.)

I-Cross

section showing cuspal relationship. H-Shows the distance of the cuspal height. G-Occlusal view of bicuspids and molars in Trubyte Teeth.

A-Plaster attaching lower cast to articulator extension arm. B-Lower cast. CLower basewax. D-Upper basewax. E--Upper cast. F-Plaster attaching upper cast to extension arm of articulator.

Note: T h e white markings show the occlusal contacts between the upper and lower teeth as seen in a piece of modeling compound which had been softened and pressed between an upper and lower set-up o f Trtthyte Teeth.

111. Arranging Teeth on Partial Dentures: NOTE: T h e clasps used to retain partial dentures are not included in this Unit since making clasps involves advanced procedures not described here. Arrange the necessary teeth in a manner similar to that followed in arranging full dentures. Teeth

in partial dentures are often set directly to the cast without any labial wax on the denture base. I t rn-dy be necessary to grind the ridge-lap portion or mesial and distal surfaces of certain teeth in order to fit them closer to the gum or the natural teeth. When grinding porcelain teeth proceed as follows: I. Mount carborundum wheel on lathe chuck. 2. Cut a small strip of articulating paper. (Paper coated with coloring which comes off on an object when pressed against it.) Place the articulating paper on the gum over the place where the tooth is to be fitted (Fig. 160). 3. Press the tooth against the paper and rub the tooth slightly against the paper. This will indicate on the tooth, by means of the coloring rubbed off the articulating paper, where the

I 68



169

tooth is to be ground in order to fit it closer to the gum (Fig. 160). 4. Holding the tooth between the index finger and thumb of the right hand and using the fingers of the left hand to steady the right hand, bring the marked portion of the tooth to be ground against the revolving carborundum wheel (Fig. I 61) . 5. Expose the part of the tooth to be ground so that the fingers holding the tooth do not come into contact with the revolving wheel. 6. Repeat marking the tooth on the articulating paper and grinding until the tooth fits closely against the gum. Do not keep the tooth too long against the revolving carborundum wheel. Doing so overheats the tooth and may cause it to crack. NOTE:There are many types of modified teeth on the market. (Figs. 162, 163, 164, 165, and 166.

Courtesy Universal Dental Co., Philadelphia, Pa.

FIG. 164. DR. FRENCH'S MODIFIED POSTERIOR TEETH

Questions : I. Why are specific principles followed in arranging teeth? 2. What principle is followed in setting up upper anterior teeth? 3. What principle is followed in setting up upper posterior teeth? 4. Why is it advantageous to set up the lower first molars first in setting up lower teeth? 5. Why should the teeth be firmly attached to the base? 6. How far is the basewax extended? 7. What principles are followed in setting up the following teeth as regards their relationship to each other? a. The upper central, lateral and cuspid?

I70



,

171

*-.,

Courtesy Idcnl T o o t h Mfg.Co., Cambridge, Mass.

FIG.166. TRUE CUSPPOSTERIORS Note: Modified posterior teeth.

Manufactured for purposes of increasing stability of dentures during mastication.

FIG.165. UJ-'PER AND

DENTURES \\'ITH DR. FRENCH'S MODIFIED POSTERIORS ~A~~~~

Note: T h e inclined planes have been eliminated in order to prevent throwing the teeth "or~tof gear" when the dentures settle. At the same time, a sharp edge ant1 food escapes were added to increase masticating efficiency.

b. The upper cuspid, first bicuspid and second bicuspid? c. The upper first and second molars? d. What principle governs the relationship of the upper bicuspids to the upper molars? 8. Why is a plain line articulator inefficient as an instrument for setting up artificial teeth? Job Appraisal : I. Are the uppers set according to the lower biteplate? 2 . Are the lowers set according to the upper biteplate? 3. Do the teeth interdigitate (occlude) properly? 4. Can you arrange the upper and lower teeth in 60 minutes (average) ? Supplementary Assignment: (Information to be obtained by the learner.) I. Makes of teeth available on market. 2 . Modified posteriors, types. 3. Pinless teeth. 4. Anatomical arrangement of teeth. 5. Staining processes.

172


6. Modifications of tooth arrangement. 7. Grinding and polishing of teeth. 8. Advantages, disadvantages, indications and contra-indications of different types of teeth. REFERENCES: (Books for Additional Information.) I . Trubyte Compend (Fifth edition). XT

2.

3. 4.

5. 6.


U N I T NO. 10


Dentists Supply Co., New York,

V

Principles of Selection and Articulation. Dentists Supply Co., New York, N. Y. Nichols, I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Co., 193I . Frahm, F. W.: T h e Principles and Technics of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., 1934. Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, I 93 2. Swenson, M. G.: Outline of Full Denture Prosthesis, New York: New York University Press, I 93 2.

CHART OF NORMAL INDIVIDUAL TOOTH POSITIONS

Labio-lingual

MesiO-distal

Rotational

w "u,E ($ni, position)

CENTRAL

Labial face is Perpendicular parallel to profile line of face which is USUally perpendicular I

2

Parallel with On the cuwe of arch plane

3

4

To the lingual To the distal Distal half to- Above the a t the neck a t the neck tated to the plane lingual o r UPPER LATERAL mesial to the labial 8 6 5 7

UPPER

From perpendic- Very slightly Distal half of Tip on plane ular to out at to the distal l a b i a1 f a c e and not bethe neck, ac- at the neck pointing in di- low it rection of poscording to the terior arch gender of the face 9

10

To the lingual Perpendicular LOWER at the neck CENTRAL 14 13 Perpendicular LOWER ~ATERAL

18

Labio-lingual and me$?-distal PoS1'On

II

12

Parallel to the On the plane curve of the arch 16 IS

According to the t y p e of t h e a r c h ; in t h e square, the centrals are very little forward of the cuspids; in the tapering, they are considerably forward of the cuspids; and In the ovoid arch, the centrals are more forward than in the s uare arch and less than in the tapering.

Slightly to the Distal to the On the plane distal lingual slightly I7 21 20 I9

Out at the neck To the distal Distal half of Tip on the a t the neck labia! face plane and I.OWER polntlng i n ?ot above CUSPID directipn of ~ t . posterlors 22

23

24

C o ~ ~ r l a sofy Dr. Merrill G. Swenson, Professor of Prosthetic Dentistry,

~lntry.

173

25

New York University, College of Den-

I74

MANUAL FOR

DEN'rAL

TECIINICIANS

Curve of Spee: This is an imaginary curve which begins at the incisal tip of the lower front teeth (incisors) and passes through the top of the cusps (occlusal elevations) of the posterior teeth. Compensating Plane: T h e compensating plane is a mechailical I t is that arrangement of the teeth whereby the contact is maintained between the upper and lower artificial dentures when the teeth are moved, as in chewing. T h e plane must be in harmony with the excursions of the condyle. Efficiency of Artificial Dentures: Sound human teeth in healthy gums can exert a biting power of about roo pounds and a crushing strength of about 200 pounds. T h e human teeth are held individually in the bony sockets of the jaws. Artificial teeth mounted on artificial dentures are easily displaced. They can exert only about I 5 to I 8 pounds pressure under favorable conditions. Modified Teeth: Bicuspids and molars have been designed especially to increase stability of dentures. During the past few years, bicuspids and molars have been modified as the result of various theories so that they bear little resemblance to human teeth. (Figs. 162, 163, 164, 165 and 166.)

U N I T NO.

11

DENTURE WAXING TECHNIC After the technician arranges the tectli 01; the trial base, he proceeds to triin, ~ilould:tnd carve the wax so th;tt he has n matrix or pattern of the base of tlle finished denturc. T'lle wax p;lttcrn, u~llich togctl~crwith the teeth is known as the waxed case or trial denture, is tried in tllc patient's ~ n o u t hby tile dentist. Since tlie pattern or t r i d denture is madc o l w a x i t can bc changed easily, wllcn necessary to change the arrangement o l the teeth or tlie wnxing to any degree. T h e dentist obscrves at this time tllc effect of the denture on the appeamnce of the patient. If the patient's face looks too full, the dentist riiay reduce the thickness of tllc wax on tllc bucc,tI and labial surfaces of the denture. Contrnrily, i f tllc denture docs not fill out the p~cticnt's face the dentist 1113) add \vax to the buccal and 1:lbinl surf & ~ . 'I'hcrc are many re.lsons wily the waxing of tllc denture bnsc rnust be accur;ltely perforincd. 7'hcse reasons will bc discussed in the following pilges.

Process or Principle : No. I 7: Waxing Vulcanite Ilentures. a. IVaxinx ftdl uppcrs and Lo;r.el-s. b. ?4'axinX partial rases. Project or Jobs: ( T o be performed by the lear~ler.) J O B NO. 49: Wax an edentulous upper and lower ( a wax denture base without artificial teeth). Jon No. 50: \Tax two full upper and lower dentures on baseplate bases. J O B No. 51: Wax two full upper and lower dentures on basewax bases. Jon No. 52: U7ax six partial dentures. NOTE: (Read the entire Unit carefully before beginning work. Col~sultthe glossary for definitions of new words.) Job Application: After the teeth are arranged wax is applied over thc dcntul-e base, making a matrix which is later replaced by vul( ; i l ~ i t r .01- sonic other pcrmanent denture base material. When the w:ising is completed, the dcriture is rcady for- trial in the patient's I I I O L I I 11 I)y thc dcrltist. '

I

,

1 7 ~


Vocational Information : Waxing should be done carefullv and u neatly as the permanent denture base duplicates the wax matrix. Faults in waxing' are, therefore, repeated in the permanent denture. Waxing on the buccal and labial surfaces should be modified by the dentist to suit the facial appearance of the patient. Pits in the wax should be eliminated and all teeth should be waxed securely. Tools and Equipment: Bunsen burner, wax spatula, roach carver or pen knife. Materials: Basewax; blue casting wax (26-gauge); absorbent cotton. Procedure: (Follow operations in the order presented here.) CAUTIONS: a. D o not press too hard on wax as the arranged teeth may be displaced. b. To prevent burninx and distortion do not flame wax too lonx. c. ~ ~ wax p evenly ? ~i n d not too thickly on palate. . d. Teeth should not be covered with wax too far over the buccal and labial surfaces. e. W a x should not be too thin over t h e pins of the anterior teeth. f. D o not allow pits to remain in the wax. g. T r i m borders bf wax dentures to prevent cuttilzg or scra~ching the patient's mouth durilzg t r y i n . h. W i p e waxed denture with alcohol for hygienic reasons, before returning to dentist. I. Make wax bases on an upper and lower set of casts which have had reliefs and tinfoil applied. (Follow procedure in Unit No. 6 (11) ; Process or Principle No. I I ; Job. No. 28) There will be no teeth arranged on this set of casts. NOTE: These casts will be used later for technic purposes in the instruction UnitJ to follow. 2 . I n the full cases, after the teeth have been arranged, add melted wax to reenforce teeth, extending ridge-like elevations half way toward the rim of the denture on the buccal and labial surfaces, opposite each of the teeth. (Fig. 167.) 3. Adapt a piece of wax, folded to double thickness, over the buccal and labial surfaces, allowing the ridge-like elevations to remain on the buccal aspect, especially at the cuspids, less at laterals, gradually less about the molars and least at the lower incisors. (Fig. I 68.)

DENTURE WAXING TECHNIC

I77

Note: D o not make the elevations too pronounced. T h e elevation over the cuspid should be most prominent, that over the lateral incisor least prominent. T h e elevations should be smooth and should not extend too far toward the rim of the denture. In the lower denture the elevations below the anterior teeth should be practically eliminated.

.

'

Note: Fold a sheet of basewax to double thickness. Allow the wax to extend over the cervical thirds of the teeth and past the rim of the denture.

178



I79

4. Holding the penknife with a pen-grasp, festoon all teeth at the junction of tHe buccal, labial and lingual surfaces at the "collar" of the artificial teeth, and in the approximating spaces between the teeth. All festoons should be at right angles to the long axes of the teeth. (Figs. 169, 170 and

Note: Festooning should follow the cervical line a t the beginning of the "collar." T h e wax at the interproximate surfaces between the teeth should not be d u g out too deeply. In this illustration the wax has been trimmed around the rim of the denture to follow the denture limit. T h e rim should be smooth to avoid injuring the patient's mouth when the dentist tries the dentures in the mouth.

Note: Another method of carving buccal and labial surfaces of waxed denture is to wax denture completely and then use a Roach carver to form buccal and lingual elevations. T h e method shown in Figs. 167 and 168 is easier for the beginner. A-Plaster holding lower cast to articulator. B-Lower cast. C-Denture base. cast. F-Plaster holding upper cast to D-Upper denture base. &Upper articulator. G--Wax before carving.

5. 6.

7. 8. Note: T h e w a x should be festooned a t right angles to the long axes of the teeth. the anterior teeth having pins, the wax should cover the pins well.

111

171.) Do not festoon too deeply in the interproximate spaces between the teeth. Smooth the wax around the teeth and on the palatal surfaces. (Fig. 172.) Soften a piece of 26-gauge blue casting wax between the palms of the hands and adapt over the palatal surface. (Fig. 173.) Trim the blue casting wax on the palatal surface, seal with heated spatula and festoon around the teeth with a penknife. (Figs. 173, 174, .175 and 176.) Eliminate all pits and other imperfections in the wax, using wax spatula, or pick up the Bunsen burner and pass the flame quickly over the area to be smoothed.

I 80

MANUAL FOR DENTAL

TECHNICIANS

181

DENTURE WAXING T E C H N I C

9. Using cotton wad, polish the waxed denture after chilling and while holding under running cold water (Figs. T 76, 177)10.I n waxing partials follow the gingival contours around the remaining teeth on the cast as in making partial denture bases (Unit No. 6, 11) and in making partial biteplates (Unit No. 7) (Fig. 178).

FIG.1 7 3 . FESTOONING O N T H E PALATE AROUND

Note: The wax has been festooned around the lingual surfaces of the teeth. I I.

Keep wax away from the labial and buccal surfaces of teeth set (butted) against the gum in partial cases. Allow only a small amount, if any, wax to show in the interproximate spaces of teeth set against the gum.

Supplementary Assignment: (Information to be obtained by the learner.) I. Various waxes used. 2 . Different methods of carving wax on labial and buccal surfaces.

THE

TEETH

3. Different types of wax obtainable for waxing. 4. Rugae; application of artificial rugae. 5. Other methods of festooning wax. 6. Other methods of polishing wax. Questions : I. What happens if too much pressure is applied on wax? 2. Why should all pits and irregularities in wax be eliminated? 3. Why is wax added on the palatal surfaces of the baseplate dentures? 4. Why should wax completely cover pins on teeth? 5. Why is it necessary to have a uniform thickness on palate? 6. Why should waxing not be too thick on lower dentures? 7. Why should waxing not be too thick on upper dentures? Job Appraisal : I. Have all pits and other imperfections been eliminated? 2 . Has the wax been properly festooned around the teeth?

I 82



A-Carved

183

rugae.

(LINGUALSURFACECARVED) FIG. 175. LOWERDENTURE A-Carving

to extend lower tooth forms.

Note: Carving on lingual and palatal surface to extend the outlines of the teeth is of advantage, especially where the natural alveolar ridges of the patient have receded, because it allows more room for the tongue.

Note: T h e outline around the teeth of the cast is sharp and the buccal extensions of the denture are well finished. Where the teeth are butted against the cast, they do not show any wax a t their interproximate spaces on the labial surface.

3. Are the pins on the teeth covered and not visible on the palatal surface?

4. Are the teeth sealed tightly to the wax? 5. Is the wax carved and polished? 6. Can you wax a case in 25 minutes (average)? REFERENCES: (Books for Additional Information.) I. Nichols,

I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Company,

193'. Frahm, F. W.: Principles and Technics of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Company, 1934. 3. T u r n e r , C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea and Febiger, 1932. 4. Swenson, M. G.: Outline of Full Denture Prosthesis. N e w York: N e w York University Press, 1932. 2.

Side View

Front View

Note: T h e wax is free of pits, it is polished, and the carving is not too pran?uncecl or too high toward the rim of the denture. T h e carving at the lower anterlorr 18 not prominent. T h e wax has not been d u g out too much between the teeth. While the teeth are well exposed the wax nevertheless covers the collars of the teeth.

I 86

DENTURE FLASKING TECHNIC


187

Vocational Information: Flasks consist as a rule of three parts: ( I ) a lower (base) or shallow part which has a floor or base, ( 2 ) an upper (counter) or deeper part which fits over the lower and (3) a cover. (Fig. 179.) Flasks may be closed firmly by the use of bolts and nuts or by using flask clamps. Flasks are made of iron, brass or bronze. Bronze flasks are most desirable because they are

FIG.180. DENTURE FLASK Note: This type of denture flask is used in conjunction with a flask clamp.

not affected by sulphur, can be easily cleaned and are not distorted

i n use. I.

2.

Clamp flask. a-Cover. b-Upper part (counter). c-Lower part (base). Bolt flask. a-Cover. b-Upper part (counter). *Lower part (base). 3. Bolts and nuts for bolt flask.

Tools and Equipment: Vulcanite denture investment flask; flask press; flask clamp; plaster bowl; plaster spatula and plaster knife. (Figs. 180, I 81.)

188



189

Materials : Plaster, water, shellac, Sandarac and liquid soap. Procedure : (Follow operations in the order presented here.) CAUTIONS : a. Examine the waxed case (waxed denture and cast) carefully b. c. d. e. f. g. h. i. j.

k.

before immersing it i n water t o make sure that t h e denture is properly sealed to the cast. Examine the teeth to make sure that they are securely waxed. B e careful not to loosen t h e teeth when using wax solvent to remove excess wax. T o prevent breaking the cast during vulcanizing, do not trim too thin. Be sure that the cast clears the sides of the flask to prevent breakage of the cast. Minimize undercuts by setting t h e long axes of t h e teeth at right angles to the base of the flask. M a k e sure that the teeth are not in direct contact with the sides of the flask or too close to the cover of the flask. Keep t h e teeth free from separating media or lubricants. D o not cover the top r i m of the flask itself or the upper part of t h e flask will not fit properly. T o avoid loosening the teeth or displacing t h e base, do not jar the flask too hard when pouring plaster into the "counter." D o not cut plaster teeth lower than the wax base or too close to the gingival margin in flasking partial cases. Be sure that plaster in counter is poured well into the spaces between the teeth.

Carefully seal all around the rim of the waxed denture so that it is fast to the cast; with the plaster knife remove the cast with the sealed waxed denture from the articulator extension arm. 2. Using the plaster knife, trim the cast so that it clears the sides of the lower half of the flask. Set the cast in the lower part of the flask. (Figs. 182 and 183.) 3. Place the upper or counter part of the flask in position over the lower, place the flask cover in position. Make sure that the teeth do not touch the sides or the cover of the flask. (Fig. 184.) 4. Remove the cast from the flask and immerse the cast in cold water until nll bubhling ceases.

A-Lower

part (base) of flask. C-Lower

B-Cast, clearing sides of lower part of flask. denture sealed to cast.

FIG.183. UPPERWAXEDDENTUREI N LOWERHALF (BASE)OF FLASK A-Lower

half of flask. B-Upper

denture sealed to cast.

Note: T h e importance of making sure that the teeth are clean and firmly attached to the wax and that the denture base is sealed all around the cast-bucally, lingually, palatally in upper and linqually in lower-cannot be overemphasized.

I.

A-Lower part (base) of flask. B-Upper part (counter) of flask. &The sealed wnxed denture. This is immersed in water so that the plaster used in flasking will not lose its strength through having water absorbed by the dry cast.

Note: 111hiis ill\~str;~tion we call see that the teeth do not touch the sides of the flask IIIIII 11i:tt we II:IVC:~lnpleroom hctween the edge of the teeth and the top of the flask.

IgO



I9I

5. Make a plaster mix and fill the lower half of the flask to about two-thirds of its capacity. 6. Set the cast into the plaster in the lower half of the flask, so that the occlusal plane of the teeth is parallel with the bottom or base of the flask. (This can usually be accomplished by setting the heels or condyles of the cast somewhat lower than the anterior portion (Figs. 185, 186 and 187).

A-Denture waxed and sealed to cast. B-Plaster has been smoothed and removed from waxed surface a s well as from top rim of sides of flask. C-Lower half of flask. A-Denture

waxed and sealed to cast. B-Plaster into which cast has been invested. C-Lower portion of flask.

Note: T h e long axes of the teeth are parallel with the vertical elevation (sides) of the flasks. T h e plaster is smooth and there are no undercuts between the plaster and the waxed denture. If directions are not followed properly all the preceding work will be in vain.

Note: T h e case is centered in lower half of flask. T h e plaster comes up to side of cast, below waxed denture base.

7. Mould the plaster, removing all excess, between the rim of the denture and the rim of the lower half of the flask. Wait until plaster sets. (Figs. I 88 and I 89;) 8. Apply shellac and sandarac or liquid soap to the plaster between the periphery of the waxed denture and the rim of the flask. (Figs. r go and 191.) NOTE: Wait until separating medium is dry before proceeding. T h e preferred method is to apply tinfoil over the casts as explained in the following Unit (No. 13). T h e counter or upper part of the flask should be poured after the tinfoil is applied. Tinfoil is extended to cover this portion of the plaster between the cast and the flask and also the wax and part of the teeth. (See Unit No. 13.)

A-Lower

half (base) of flask. B-Plaster into which cast has been set. C-Waxed denture sealed to cast.

Note: I n these illustrations we note that the dentures are centered in the lower half

of the flask. T h e plane of the teeth is parallel with the floor of the flask. T h e plaster does not cover the rim of the flask or the wax the dentures.

192


9. When the separating medium is dry or after tinfoil is applied, as shown in Unit 13, and the denture is sealed to the cast, set

10. I I.

the upper or counter part of the flask in position over the lower. Make a plaster mix and fill the upper or counter portion of the flask, pour the plaster along the side of the flask to prevent the inclusion of air bubbles. Jar the flask to make sure air bubbles are excluded. Place the cover in position and wipe all excess plaster from


I93

Supplementary Assignment: (Information to be obtained by the learner.) I. Various types of flasks, advantages and disadvantages of each. 2. Separating media, types commonly used in commercial laboratories; advantages and disadvantages of each.

FLASKBD I N BOLTTYPE FLASK FIG. 190. UPPEIZDEN.TURE A-Lower

half of flask. B-Plaster into which cast was set for flasking. &Waxed denture sealed to cast.

Note: A careful examination reveals that the flask is clean, the plaster is smooth and well adapted to the cast but does not cover the waxed denture. T h e long axes of the teeth are parallel with the vertical elevation (sides) of the flask. There are no undercuts between the waxed denture and the plaster. W e can also see the details in the waxing. T w o different shades of wax were used in this case; one, a light color for the buccal and lingual surfaces, and the second, a dark color for the palatal surface and over the condyles.

the outside and rim of the flask. (Figs. 192 and 193.) If bolt type flask is used place bolts in position and tighten nuts. 13. I n partial cases, cut the remaining (plaster or stone) teeth on the cast to within 1/16 inch of the wax base. (Figs. 194 and 195.) 14. I n flasking the wax denture bases follow the general instructions for flasking full dentures. Use separating media or preferably liquid soap and pour the counter or upper part of the flask. (Fig. 185.) 12.

,

A-Lower half of flask. Note: All plaster has been removed from the outside of the flask and from the rim so that the upper part of the flask will fit accurately. B-The plaster used for flasking has been smoothed and molded around the cast and covered with liquid soap. C-The cast. Note: T h e cast is centered in the lower half of the flask. I t does not touch the sides of the flask and there is a layer of plaster between it and the base of the flask. D-The relief metal over the hard area and over the rugae. E-The baseplate of the denture base covered by a sheet of 26-gauge blue casting wax. Note: T h e baseplate has been cut in half to show the details of the relief over the hard bony areas on the cast. T h e denture base is sealed to the cast so that there are no undercuts between the cast and the denture base. F-The basewax into which the teeth have been set. Note: T h e wax has been festooned properly around the palatal surfaces of the teeth. T h e pins of the anterior teeth have been covered. G-The teeth. Note: T h e teeth are clean. All wax has been removed from them. If the teeth have wax on them they will become loose when the wax is eliminated or during the process of packing dental rubber. T h e long axes of the teeth are parallel with the side of the flask. T h e plane of the teeth at the incisal edges and occlusal surfaces is parallel with the floor of the flask.

3. Methods of removing excess wax from teeth. 4. Methods of avoidinn extreme undercuts in flasking cases. Various methods of cutting off plaster teeth in cases.

5.

= 94



I95

Note: T h e plaster teeth should be cut at a slant outward to the edge of the cast or crescent shaped in a mesio-distal direction. Never cut the teeth flush with the wax. Always allow the plaster teeth to extend higher than the wax.

A-Plaster used for flasking case. B-Upper cast. =Waxed denture (denture matrix). D-Diatoric tooth. %Upper half of flask. F-Cover of flask. GLower half of flask.

A-Plaster used for flasking case. B-Lower cast. C-Waxed denture (denture matrix). D-Diatoric tooth. E-Upper half of flask. F-Cover of flask. GLower half of flask.

Questions: I. Why are dentures flasked? 2. What precautions should be observed when flasking in the lower or base portion of the flask? 3. What precautions should be observed in pouring the counter portion of the flask 4. Why must the waxed dentures be sealed to the casts? 5. Why is it necessary to remove excess wax from tooth surf aces? 6. Why should the teeth be waxed securely? 7. How may undercuts be avoided?

A-Flask. B-Plaster used in flasking. C-"Horseshoe" shaped denture. D-The plaster teeth have been cut to about two millimeters higher than the wax of the trial denture base. Note: T h e cast is centered in the lower half of the flask and parallel with the base of the flask. T h e waxed denture is sealed securely to the cast around the edge of the denture.

8. I Y h ! arc sepal-atiiig medin used atid wh!. should scl>nratiug tncdi;~I)c kel)t ;IM.;L! (I-0111t lic tcct li l' 0 . l h u . C:III the teeth 1)e i ~ i j ~ ~ ;I ~ -i cl l ddil-ec,t co11tac.t with the sides or top of the flask? lo. il'hy should plaster teeth in partials Ile cut higher than the wax? I r . W h y is licluid soap or tin foiling better than separating ~ n e d i a in flaskingi

Job Appraisal : W a s the cast trini~ncd to fit wcll i l l the lower part of the flask.? 2 . Are the tceth out of colitact with the uppel- part alid with the cover of the flask? 3 Lloes the p l ; ~ s t e used ~ - in flaskilig clear the edge of the waxed denture? 4. il'erc ~lndct-cutsa~roidedto facilitate separatilig the flask.; 5. Can 1 0 ~ 1flask :1 case iri 1 0minutes (averagc ) ;. I.

I
1'liil.rd~~lpl~i;i: [,en & I'cbigcr,

~(lzz.

lIEI.,ATF,Il I N F O R M A T I O N :

U N I T NO.

I2

DENTURE FLASKING TECHNIC Flasks: Flasks with L>olts and nuts have been largely replaced b! clamp flasks. R r o l i ~ eflasks are most desirable because the) do not I-ust in the vulcanizer and they can easil) be kept clean. Brass flasks
Tooth Cleansing Preparations : Carboll tetrachloride (carbons) , ~ l c o h o l ,chloroforn~01-other wax s o l ~ ~ c nmay t s be used to clean wax 11-omthe tooth surfaces. I t is better to cleanse the teeth with a sharp ~ristrunient, as all tooth cleansing preparations tend to loosen thc teeth from the wax. Tooth cleansing agents should be used sparingly.

DENTURE TINFOILING TECHNIC

UNIT NO. 13 DENTURE TINFOILING TECHNIC W e have invested the case in the lower half of the flask and are about to pour the upper half. Before doing so, we shall apply tinfoil over the denture and the plaster around the cast. T h e tinfoil will serve as a shield between the plaster and the wax and will also aid us in separating the two halves of .the flask, so that the wax may be eliminated and dental rubber inserted in its place. If we foil the case properly, the vulcanized denture will be smooth and will require less work in trimming and polishing. Furthermore, the surface of the vulcanized dental rubber will be much denser. If any minute pits are present in the waxing, the tinfoil will cover them. T h e value of tinfoiling will become more apparent to us when we examine the vulcanized dentures and compare them with the vulcanized bases without teeth which have been flasked without tinfoiling. I n this Unit,we shall give our attention to the method of applying tinfoil.

Process o r Principle: No. 19. Application of Tinfoil to Flasked Dentures. a. Cutting of tinfoil for covering wax matrix. b. Method of applying tinfoil. Project o r Jobs: (To be performed by the learner.) JOB NO. 57: Foil four sets of full upper and lower flasked dentures. JOB NO. 58: Foil six partial dentures after flasking. NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definitions of new words.) Job Application: The application of tinfoil gives a hard smooth surface to the vulcanite. Tinfoil produces a cleaner denture which requires a minimum of trimming and polishing. Tinfoil is indispensable when base materials other than vulcanite are used. Vocational Information: Tinfoil in various gauges, No. 60 or 40, should be used for vulcanite. For denture base materials other than vulcanite, No. 20 foil should be used. Tools and Equipment: Soft brushwheel, scissors, pointed orangcwood stick. . 198

I99

Materials: No. 60 or 40 tinfoil, absorbent cotton, duco glue. Procedure : (Follow operations in the order presented here.) CAUTIONS : a. Tinfoil must be seczlrely burnished against the teeth to prevent seepage of plaster under the foil when pouring the counter during the flusking operation. b. Avoid folding or creasing the tinfoil to prevent its being . incorporated too deeply in the vulcanite. c. Do not displace the teeth when burnishing tinfoil. d. Do not distort the wax matrix by pressing or burnishing the tinfoil too hard. e. Be sure to cover all of the plaster in the @sk with tinfoil to facilitate the opening of the $?ask. f. Avoid puncturing or tearing the tinfoil. I. Cut two pieces of tinfoil, each to fit over approximately onehalf of the palatal surface of the upper denture from the front to the back. Then cut three pieces of tinfoil to fit around the buccal and labial surfaces. Tinfoil should be cut to extend from the beginning of the incisal or occlusal third of the teeth to the plaster in the flask. Additional tinfoil should be cut to cover the plaster in the flask to the inner edge of the rim of the flask. (Fig. 196.)

11-For labial surface. b-For buccal surface. c and d-For palatal surface. e-For buccal surfacc. Note: Adapt the parts c and d so that the sharp points of the two triangles are toward the incisor teeth and the bases of the triangles are toward the rear of the palate.

200



2.

20 I

7. After covering the cast and the plaster between the cast and

Cut tinfoil for lower cases as indicated for the upper, except the part to fit the lingual surfaces and the tongue space. These should be cut square for the lingual surfaces and the piece for the tongue space should be rounded in front. (Fig. 197.1

the rim of the flask with tinfoil, glue the overlapping edges with duco glue. 8. I n lower dentures cover the lingual space with tinfoil, otherwise follow same procedure as for upper.. (Fig. 198, No. I.)

labial surface. d-For buca- -For lingual surface. b-For buccal surface. -For cal surface. e-For lingual surface. f-For lingual surface at the incisors. Note: Cover the lingual space with an additional piece of tinfoil, extending it to the inner edge of the flask.

3. With absorbent cotton wad, burnish the tinfoil on the wax of the palatal syface of the upper denture and overlap it in the center of the palate not less than f/4 inch. Extend the palatal tinfoil to a point about % inch below the incisal and occlusal surfaces of the teeth. (Fig.. I 98.) 4. Cut "V" shaped grooves in the tinfoil covering the teeth on the palatal, labial, lingual and buccal surfaces to facilitate the close adaptation of the tinfoil in the interproximate spaces between the teeth. Use a round-edged, tapered orangewood stick for this purpose. (Fig. 198, No. 3.) 5. Remove one side of the palatal tinfoil. Apply glue to the overlapping margin and replace on the waxed case. 6. Adapt tinfoil around buccal and labial surfaces of the waxed case, extending the tinfoil from approximately inch below the incisal and occlusal surfaces of the teeth to the edge OF the flask, covering the plaster. Use a separate piece of tinfoil on the plaster used in flasking. Cut "V" shaped grooves over the teeth to facilitate adaptation in the interproximatc spaces. Seal the overlapping edges of the tinfoil with duco glue. (Fig. 198, Nos. I, 2, and 3.) U

,

I

.

applied to lower denture. 2-Tinfoil applied to upper denture. 3-Bucon buccal surface. R-Tinfoil on plaster extending to inner edge of flask. C-Plaster, tinfoil not yet applied. Note: T h e tinfoil is free of folds or creases. I-Tinfoil

cal view of upper denture. A-Tinfoil

9. I n partial cases follow the same technique but do not cover the remaining teeth on the cast itself. 10. After the tinfoil is adapted place the upper part of the flask in position, fill with plaster as indicated in the procedure in the previous U&t, No. 12 (Fig. I 99). Supplementary Assignment: (Information to be obtained by the Jcarner.) I. Uses of different thicknesses of tinfoil. 2 . Various methods of adapting tinfoil. 3. Mechanical tinfoil adapters.

202



203

3. Is all of the plaster and wax covered by the tinfoil? 4. Were the teeth and wax left undisturbed? 5. Can you foil a case in 15 minutes (average)? REFERENCES:(Books for Additional Information.) Nichols, I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Co., 1931. Frahm, F. W.: Principles and Technics of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., 1934. 3. Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea and Febiger, 1932. I.

2.

A--Lower

half of 'flask. B-Plaster. C-Waxed denture. D-Plaster upper part of flask. E-Cover of flask.

poured in

4. Various substitutes for tinfoil. 5. Silex method; glazene, cellophane; method of using; advantages and disadvantages. Questions : I. What is the purpose in using tinfoil? 2. Why should tinfoil be securely sealed? 3. How is the tinfoil prepared for an upper denture; for a lower denture; for a partial denture? 4. How is the tinfoil prepared around the teeth? 5. Why is it important not to puncture or tear the tinfoil? 6. What may occur if foil is burnished too long? 7. What may result from creases in the tinfoil? Job Appraisal : I. Is the tinfoil smooth? 2. Are the edges of the tinfoil glued securely?

IZF,LATEI> I N F O R M A T I O N :

U N I T NO.

U N I T NO. 14

I3

W A X ELIMINATION TECHNIC DENTURE TINFOILING TECHNIC Silex: Liquid silex may be used in place of tinfoil. T h e silex should be applied with a brush. Be careful not to get the silex on the porcelain teeth. Cellophane: Cellophane or ,glazene may be used in place of tinfoil. D e n t u r e Bases O t h e r T h a n Vulcanite: All of the plaster and the cast must be completely covered with tinfoil.

W i t h the assembling of the impression which was obtained by the dcntist from the mouth of the patient, we beg;~nbuilding the denture \vhicll progressed through the undel-lying processes of boxing, pouring casts, trimming casts, relieving of hard arms, biteplate building, articulating and arranging of teeth for trial. T h c denture, after being waxed, was returned to thc dentist for trial in thc 1110~1thof the patient. W h e n the dentist and the patient were satisiicd with the fit and appearance of thc denture, thc dentist returned it to the technician who began the proccsscs of conlpletion by investing the denture in a vulcanizing flask. I n this Unit we shall describe the method of eliminating the wax and baseplate trial denture base so that the matrix (the space left) may he packcd with A per~nanentdenture base such as \rulcanite.

Process o r Principle: No. 20. Elimination of Trial Denture Base. a. W a x elimination. b. Opening of flasks. c. Preparation of flasks for packing dental rubber. Project o r Jobs: ( T o be performed by the learner.) JOB No. 59: Elimi~latewax from denture base without teeth. JOB NO. 60: Eliminate wax from four sets of full upper and lower dentures. JOB No. 61: Eliminate wax from six partial dentures. NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definitions of new words.) Job Application: T h e wax matrix of the flasked denture must be clit~iinntedso that dental rubber or some other denture base material III:~!, I)c inserted or packed in the spnce formerly occupied by the wax . I I I ~ IIx~scplatetrial denture. Vocational Information : I t is thc spnce Icft :~ftcrthe wax is climtI1:1t is I-C:LII!. thc 11l;ltrix of the denture and not the wax itself. \$';I\- ~ I ~ I I I ~ I I : I ~i l~l ( ~I I I C l:~bo~-;tt~~-!' is imn1edi;ttely followed hy the I ~ , I ( ~ 1~ ~I- 0I ( (~ . 4 4 ,I I ( . ~ o I - c t l ~ cfl:~sk112s h a ~ ltimc to cool. .'iI,c,

III;I(C<~

206

W A X ELIMINATION TECHNIC


i. Do not allow overhanging particles of plaster to remain in flaJk. '

Tools and Equipment: Gas stove, two large iron pots, ladle, collander, plaster knife, pliers, canvas gloves, flask press. (Fig. 200.) Materials : Boiling water, washing soda. Procedure : (Follow operations in the order presented here.) CAUTIONS: a. T h e length of boiling time depends on the type of wax wed. Some waxes require longer heating. Too little boiling may cause a fractured cast on opening. T o prevent tooth displacement, do not tighten flask-press after immersing h boiling water.

b. Be sure the @sk-press or clamp is tightly closed. c. Do not overheat wax as it loosens teeth and the wax is hard to eliminate. (Figs. 205 and 206.) d. Separate the fiask carefully, do not w e too much force, otherwise the cast may be fr~ctured. e. Water and all utensils used must be kept clean to prevent impurities from entering the plaster in the flask. f. Do not displace teeth while removing wax. g. Be sure all wax is elim'nated from flask, otherm'se it zenzenll interfere with proper packing and vulcartization. h. Be sure all loosened teeth are replaced in their original positions.

207

I.

2.

Pour two quarts of water in each of the two iron pots. Place a level tablespoonful of washing soda in each pot. Bring water in both pots to a boil on gas stove (Fig. 203). Place the flask, in the press or clamp, into the boiling water in the first pot for three minutes (Figs. 201 and 203).

Courtesy S.

S. White Dental M f g . Co., Philadelphiu, Pa.

PRESSFOR HOLDING FLASKDURING WAXE L ~ M ~ N A T ~ O N FIG.201. CLAMP PROCESS OR D U R I N G . VULCANIZING I

and 2-Discs

to take up slack. Note: A "dummy" is placed above the flask when boiling out so that the clamp can be tightened.

3. Remove flask from boiling water, and place on bench. Instead of using actively boiling water, hot water may be used and the flask allowed to remain for five to ten minutes. 4. Using stub end of plaster knife, open flask carefully, raising the rear of the flask (heel or condyle portion) first (Fig. 202).

208


5. Using pliers or tweezers raise the melted wax matrix out of

WAX ELIMINATION TECHNIC

10.Set

the two halves of the flask in a warm place and allow to dry.

the flask (Fig. 207). 6. Place each half of flask on sieve or collander and hold over the first pot in which the flask was immersed. Pour clean boiling water from the second pot over each of the parts of the flask to remove all remaining wax. (Using the clean water in one of the iron pots while holding the flask in the

A-Stub of knife. B-Lower half of flask. C-Upper half of flask. D-Cover of flask. Note: The flask is hot. Gloves should be worn or a towel used when handling hot flasks.

collander over the other pot, eliminates pouring water containing melted wax back on the flask from which we are trying to eliminate the wax matrix.) (Figs. 203, 208 and 209.) 7. Using plaster knife and pliers, remove all small overhanging particles of plaster from flask, especially at the denture space. 8. Replace loosened teeth in proper places (Figs. 208 and 209). 9. Cleanse the plaster off the counter and the cast with scalding water.

209

FIG.203. Two POTSUSEDIN POURING SCALDING WATEROVER OPENED FLASKTO ELIMINATE WAXAROUND TEETH A-Stove.

B-Pot.

C-Flask in wire strainer. D-Ladle containing clean scalding hot water from the second pot.

Supplementary Assignment: (Information to be obtained by the learner.) I. What are escape gates; how are they made? 2. What apparatus is used for wax elimination? 3. Methods of preventing tooth displacement. 4. Methods of opening flasks containing casts with undercuts or thin alveolar ridges.

210


WAX ELIMINATION TECHNIC

211

FIG. 204. CROSSSECTION OF COUNTER(UPPERPART) OF FLASKSHOWING TRIAL DENTURE BASE WHICH IS ELIMINATED DURING WAX ELIMINATION PROCESS, SEPARATED FROM CAST A-Trial

denture base. B-Flask. C-Tooth (all of the teeth must remain in place in the counter). D-Plaster of the counter.

Fig. 205-lower cast showing wax melted and flowing all over the case. Fig. 206-The teeth are floating in melted wax; 'the plaster is covered with it. Note: Poorly vulcanized dentures will result if wax is not totally eliminated fro111 flask. If wax is allowed to melt too much, it seeps into plaster and is hard to eliminate.

I. Lower half of flask containing cast. A-Flask. B-Plaster. C-Cast. Note: T h e waxed denture sealed to the cast which was originally invested i n the lower half of the flask has now been transferred to the upper or counter part of the flask. z. Upper part of flask with waxed denture base being removed. A-Upper part of flask. B-Tinfoil which was applied on the palatal surface of the waxed denture. C-Teeth separated from waxed trial base. Note: While some melted wax is present around the teeth, most of the wax is in one piece. D-The softened wax base or baseplate being removed in one piece.

Questions : I . Why is wax eliminated? 2. W h y is the flask heated prior to removing wax? 3. W h y should we not allow the teeth to become misplaced? 4. W h y should the water be free of impurities? 5. W h y is the flask first opened at the heels? 6. Why must the flask press be closed tightly before it is placed in the boiling water? 7. W h y is it important to remove all of the wax from the flasks? 8. Why are the small, thin particles of over-hanging plaster removed? Job Appraisal : I. Has all wax been eliminated? 2. Have all loose particles been removed? 3. Are the teeth in their original positions? 4. Can you boil out wax in 2 0 minutes (average)?

I

212

1


RELATED INFORMATION: UNIT NO. 14 WAX ELIMINATION TECHNIC Heating Flasks: Dry Method. The flask is placed in a hot oven and heated evenly for five to ten minutes. This does away with soaking the plaster in the flask in the water. After the flask is heated, it is opened and the loosened soft wax is removed. Scalding water is poured over the cast to eliminate the wax remnants, or a wax cleansing preparation may be used. Washing Soda: May be added to the water for washing out the wax remnants. Use a tablespoon or more of soda to a gallon of water. Eliminate last traces of wax by gently pouring scalding water over the teeth.

FIG. 208

FIG. 209

OPENEDUPPERFLASKED CASEWITH WAXELIMINATED ' or upper part of flask, containing the teeth. b-Lower part of flask which holds the cast.

FIG.208. a-Counter,

FIG. 209. OPENED LOWERFLASKED CASEWITH WAXELIMINATED a-Upper

part of flask containing the teeth. b-Lower

part of flask holding the cast.

Note: The wax has been thoroughly eliminated and the teeth are in their original places.

REFERENCES: (Books for Additional Information.) Nichols, I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Co., I 93 I . Frahm, F. W.: Principles and Technics of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing CO., 1934. 3. Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, 1932. I.

2.

VULCANITE DENTURE PACKING TECHNIC

215

tools may be made from tapered old dental instruments. There are many different kinds of denture base materials other than rubber. Tools and Equipment: Vulcanite shears, packing tools, tile slab, packing table, flask wrench, plaster knife, linen cloth (from dental rubber), flask bolts and nuts, flask press or clamp (Figs. 2 10,2 I I and 212.)

U N I T N O 15 VULCANITE D E N T U R E PACKING TECHNIC If we stop for a moment and consider the purpose of the various procedures that we have learned up to this point, we realize that they have led to the preparation of a wax mould, as it were, for making a permanent denture base to hold the artificial teeth in a definite relationship to each other and to the jaws. T h e flasking operation enables us to retain the dental cast and the teeth in a definite relationship when the wax trial base is eliminated, leaving a matrix for the permanent denture base. I n this Unit we shall take up the method by which we pack the dental rubber into the space in the flask formerly occupied by the wax (the matrix). When dental rubber is properly packed and the flask is closed as it was originally before the wax was eliminated, we are ready for the vulcanizing or rubber "curing" process. T h e success of the finished denture depends on how well each step in its construction is performed. T h e proper packing of rubber is of utmost importance to the successful completion of the denture.

Process o r Principle : No. 2 I. Packing Vulcanite Dentures. a. Preparation of dental rubber for packing full and partial dentures. b. Packing vulcanite dmtures. c. Testing vulcanite cases. d. Use of $ask-press. Project o r Jobs : ( T o be performed by the learner.) JOB NO. 62: Pack two full denture bases without teeth. JOB NO. 63: Pack four sets full upper and lower dentures. JOB NO. 64: Pack six partial dentures. NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definitions of new words.) Job Application : I n making vulcanite dentures, dental rubber must be placed in the space formerly occupied by the wax matrix. Vocational Information: There are different types of apparatus used for softening rubber by gentle heat, after it is cut, prior to packing it in the space formerly occupied by the wax matrix. Packing 214

I

a-Shears

for cutting vulcanite. &Packing point. d r e n c h for bolt and nut flasks. d-Dental flask press.

Materials: Dental rubbers, brown base, pink gum rubber, cellophane. Procedure: (Follow operations in the order presented here.) CAUTIONS : a. Keep rubber clean at all tames. b. W a s h your hands and keep t h e m clean whenever you h a ~ d l e ru6bm.

216



A-Gas stove. B-Pot containing hot water. C-Linen cloth or tile slab on wire screen. Note: Do not overheat rubber before using. Hot water is better than boiling water for heating rubber.

,

I

A-Canvas

on wire screen (marble slab may be used). B-Wire containing hot water. D-Gas stove.

screen.

C-Pan

c. Remove the "hollana?' or linen covering from the rubber sheet before cutting the rubber. d. Replace all unused rubber between the original linen slcects and place in the origiml box. e. W a r m the rubber on the steam table before beginwing to p a d .

217

f. Keep steam table clean. If marble table is used it should be smooth. If canvas is wed, replace canvas as soon as it begins to show signs of wear or dirt. g. T h e water in the pot or tray under the packing table should be well under the boiling point (less than 200" Fahrenheit. T h e boiling point of water is 2 12" Fahrenheit). T h e rubber needs little heating if the flask is previously heated. h. Keep pink rubber away from the pins of the teeth. i. Avoid an excess amount of brown rubber'around the anterior teeth. j. Pack according to the directions given in the "Procedure." k. Be sure each piece is thoroughly united to the previous piece before adding more rubber. 1. I n folding or adding rzlbber do not allow air bubbles to become incorporated zvith the rubber. Fold pieces of rubber evenly. m. Always place a piece of the wet linen, in which the rubber sheets are packed by the manufacturer, over the packed rubber in the flask before closing the $ask for testing to jind out if suficient rubber has been packed. n. T h e flask press should not be tightened so that it strains the cast, when closing for trial. o. Tighten the clamp after the flask containing the packed case has been boiled for six to eight minutes. p. Pour hot water over the linen to facilitate removing it from the rubber h the flask, after pressing. q. Be sure the flask is as completely closed as it was originally, before the boiling out process, before you place the flask in the vulcanizer. I. Preparation of Dental Rubber. ( A ) Method of Cutting Pink ( G u m ) Rubber for Full Upper DenLure. NOTE: T h e directions given here are for average cases. T h e size and number of the pieces can be increased or decreased according to the size of the case. Place the cut pieces of rubber on the packing table. (Figs. 21 I and 212.) Keep the flask warm while cutting the rubber. I. Cut four 5" wide pieces or two I" wide pieces of pink rubber parallel with the width of the sheet of pink rubber to within %" of the entire width of the sheet. Round one end. (Fig. 213a.)

218



2.

Cut the remaining (Fig. 213b.)

%"

219

X 2" piece into 13 triangular pieces.

PATTERN OF PINK (GUM) RUBBER FOR FULL UPPER DENTURF

( B ) Method of Cutting Brown (Base) Rubber for Full Upper Dentures. I. Cut three j/4" pieces of brown rubber parallel with the width of the sheet to within 5'' of the entire width of the sheet. (Fig. 214.) 2. Cut the remaining piece g'' X H" into 8 small pieces of equal size. (Fig. 214b.) 3. Cut a piece of brown rubber to fit over the width of the palate to the crest of the alveolar ridge. The length of this piece should be the full width of the sheet of brown rubber. (Fig. 214c.) 4. Cut four S" X 1%:' pieces of brown rubber. Round one edge. (Fig. 214d.) 5. Cut a %'' wide piece of rubber parallel with the width of the sheet. . (Fig. 214e.)

GUM (PINR) RUBBFR CUT AND

( C ) Method of Cuttifig -Pink (Gum) Rubber for Full Low& Dentwe. I. Cut four g" pieces of pink rubber parallel with the width of the pink sheet to within %'' of the entire width. (Fig. 2I~ a . ) 2. Cut the %" X I piece remaining into 13 triangular pieces. (Fig. 2 I 5b.) ( D ) Method of Czlttilzg Brown (Base) Rubber for Fzcll Lower Denture. I. Cut one piece of brown rubber 5 ''wide parallel with the width of the brown sheet. Cut this piece in half and trim. (Fig. 216a.) 2. Cut three %" pieces of brown rubber parallel with the width of the sheet to within g'' of the width. (Fig. 216c.) 3. Cut the remaining piece %" X gr'into 8 square pieces of equal size. (Fig. 216b.) 4. Cut a I" wide piece parallel with the length of the sheet. (Fig. 216d.) 5. Cut a 5'' wide piece parallel with the length of the sheet. (Fig. 216e.) 6. Cut a piece of brown rubber (Fig. 216f) for lining the pink rubber before closing the flask.

st'

A-For labial and buccal surface, covering the triangular pieces which are applied first, and the edges of the teeth. B-For tooth embrasures (interproximate spaces). Note: Place the triangular pieces well down between the teeth. Keep the gum rubber against the labial and buccal surface away from the pins and diatoric openings. Grim rubber will not hold teeth securely, brown rubber should cover the pins and the diatoric openings of the teeth.

220


VULCANITE DENTURE PACKING TECH N lC

PR€PARATION OF DENTAL RUBBFR

22 I

PATTERN OF PINK(GUM) RUBBER

fULL UPPER DENTURE

fOR FULL LOWLR DENTURE

PATTERN OF BROWN (BASE) RUBBER

B 4

BAS€(€ROWN)RUBBER CUT

inF AND READY FOR PACKING

0 m I

---------- - -

GUM (PINK) RUBBER CUT AND R[ ADY IOR PACKING

Id

00000000

B

I(

FIG.214. BROWNRUBBER FOR FULL UPPERDENTURES diatoric A-Under pins and on palate against the bicuspids and molars. B-In openings. G O v e r the palate, covering the pins and diatoric openings. D-Over the condyles and against the buccal surface at the second molars. &To be stretched for lining the pink rubber. F-Excess rubber to be used over the palate and wherever needed. Note: Do not force the brown rubber into the embrasures or too high especially in the anterior region. T h e pins and diatoric openings should, however, be covered by the brown rubber because i t is stronger than pink rubber. Smaller cases and partials require less rubber.

A-For labial and buccal surfaces covering the triangular pieces, which are applied first, and the edges of the teeth. B-For tooth embrasures (interproximate spaces). Note: Place the triangular pieces well down between the teeth. Keep the gum rubber against the labial and buccal surface, away from the pins and diatoric openings. Gum rubber will not hold the teeth securely.

222



h

PREPARATION 01 DENTAL RUBBER FULL LOWER DtNTURE

PATTKRN OF BROWN (BA>€IRUBBLR .,.

FOR FULL LOWER DtNTURE

223

11. Packing Dental Rubber for Full Dentures. NOTE: Place the flask in a towel to retain the heat in the flask during the packing process. Hands should be clean when handling rubber. ( A ) Fall Upper Defitzlres. - I. Using the packing tools, carefully insert the triangular pieces of pink rubber between the embrasures (interproximate spaces) of the teeth (Fig. 213b) as far down as you can without disturbing the teeth. (Fig. 217c.)

BAS€(BROWN)RUBBFR CUT AND READY FOR PACKING

A-Brown rubber in diatoric holes. B-Brown rubber packed under pins of anterior teeth. C-Triangular pieces of pink rubber on labial and buccal surfaces. Note: T h e triangular pieces of pink rubber should be packed tightly between the teeth. Care should be taken not to displace the teeth while packing.

Fold one of the g" pieces of brown rubber (Fig. 21qa) along its greater length, cut off a piece long enough to fit from first bicuspid to first bicuspid and, using the packing points, insert the piece of brown rubber under the pins of the anterior teeth. (Fig. 217b.) 3. Pack the eight square pieces of brown rubber, using the packing tools (Fig. 214b), into the diatoric openings of the bicuspids and molars. (Fig. 2 I 7a.) 4. Take two of the 5"pieces of pink rubber (Fig. 213a) press them together carefully, one over the other without stretch-

2.

A-Over the condyles and against the buccal surface of the secontl molars. B-In djatorjc openings. C-Under the pins and on the lingual surface ngnilist the bicuspids a n d molars. D-Over the pins and dintoric opcnlngs nrlcl ng;~inattlle lingual. &Additional brown rubber where required. I"-To be stretchccl for li~iillgover or too lliglr pink r111)bcr. Note: Do not forcc the brown rl~hberinto the cml>rna~~rcs capecially in the anterior r e ~ i o n . T h e pins nntl tlintoric opeoinga sbo\~ltl,Ilowcvcr, I,c coverccl I,y tllc 1,rown ruhl>cr h r c ~ l r ~ aite is RtronRrr tllnn t l ~ ap i l ~ krul>l)cr. fimnllcr rlisc-a n~lcl~ , r ~ r f ircc(l~irc r ~ l ~ 11.s~rllld)cr.

i

?

224


ing, and place them along the labial and buccal surface over the triangular pieces and the edge of the teeth from the median line to a line mesial of the second molar. (Fig. 2 I 8.) 5. Take the remaining two %" pieces of pink rubber (Fig. 213a) place one over the other and place them on the remaining half of the buccal and labial surface (Fig. 218)

Note: T h e pink rubber is kept above the pins of the anterior teeth. T h e pins will be covered with brown rubber in the next step. This applies to upper as well as lower denture.

over the triangular pieces and the edges of the teeth, from the median line to mesial of the second molar. NOTE: T h e pieces of pink rubber should extend from about I mm. above the pins and the diatoric openings to I mm. above the rim of the denture. (Figs. 218 and 219.) 6. Fold the two %" pieces of brown rubber (Fig. 214d) along their lesser diameter and place them close against the pink rubber along the buccal surface at the second molars and over the condyles. (Figs. 2 I 8 and 219.) 7. Fold the remaining g8'pieces of brown rubber (Fig. 214a) and using the packing tools place the rubber on the palate against the bicuspids and molars. (Fig. 21 8.)


225

8. Place the rounded end piece of brown rubber (Fig. 2 1 4 ~ ) over the palate allowing it to extend over the pins of the anterior teeth and over the brown rubber in the diatoric openings to the rear of the denture. Fold over the palate the part of the brown rubber that extends beyond the denture limit. (Fig. 219.) 9. Cover the remaining part of the palate with brown rubber that is left. (Fig. 214f) and (Figs. 219 and 220).

Packed upper denture before testing.

Now test the case. (See Procedure I11 which follows.) (Fig. 222.) I I. Stretch the 5'' of brown rubber (Fig. zrqe) until fairly thin and cover the pink rubber, being careful not to place the brown rubber higher towards the rim of the denture than the pink rubber, to prevent "bleeding." Place a wet piece of cellophane over the packed rubber. Close the case immediately after applying the sheet of cellophane. (Figs. 223, 224 and 225.) NOTE: Be sure cellophane has been adapted over the packed rubber before closing the flask. (Fig. 225.) ( R ) Fa11 Lower Dentures. NOTE:Place the flask in a towel to retain its heat during the packing process.. Hands should be clean when handling rubber. 10.

226


I.

2.

Using the packing tools, carefully insert the triangular pieces of pink rubber (Fig. 215b) between the embrasures of the teeth (Fig. 217c) as far down as you can put them without disturbing the teeth. Fold one of the f/4" pieces of brown rubber (Fig. 216c) along its greater length, cut off a piece long enough to fit from first bicuspid to first bicuspid and, using the packing points, insert the piece of brown rubber under the pins of the anterior teeth. (Figs. 217b and 218.)

A-Triangular piece of pink rubber. B-Brown rubber in diatoric hole. (Note: T h e overlying rubber has been removed to show A and B.) C-Pink rubber around labial surface extending to the mesial of the second molar. D-Brown rubber over condyle. E-Brown rubber over palate. F-Tinfoil lining palate is showing. T h e rubber has been removed over this half of palate.

3. Pack the eight square pieces of brown rubber (Fig. 216b), using the packing tools, into the diatoric openings of the bicuspids and molars. (Fig. 217a.) 4. Take two of the 5 '' pieces of pink rubber (Fig. 215a), press them together carefully, one over the other without stretching, and place them along the labial and buccal surface, over the triangular pieces and the edges of the teeth, from the median line to the mesial of the second molar. (Fig. 218.)


227

5. Take the remaining two %" pieces of pink rubber (Fig. s r ~ a )place , one over the other carefully and place them over the remaining labial and buccal surface from the median line to the mesial of the second molar. (Fig. 218.) NOTE: The pieces of pink rubber should extend from about I mm. above the pins and the diatoric openings to I mm. above the rim of the denture. (Figs. 21 8 and 219.) 6. Fold the two S'' pieces of brown rubber (Fig. 216a) along their lesser diameter and place them close against the pink

A-Brown rubber over condyle. B-Pink rubber over labial surface of alveolar ridge. (Note: Before closing for vulcanization, the 'pink rubber will be lined with a stretched piece of brown rubber.) C-Triangular pieces of pink rubber. DBrown rubber against lingual surfaces of teeth. E-Brown rubber over condyle. F-Troughs ("escape gates") have been cut over the tongue space for the escape of excess rubber.

rubber along the buccal surface at the second molars and over the condyles. (Figs. 21 8 and 221.) 7. Fold the remaining g" pieces of brown rubber, (Fig. 216c), using the packing points, place the rubber along the lingual surface against the bicuspids and molars. 8. Fold the I" piece of brown rubber (Fig. 216d) along its greater length and place it over the pins, the diatoric openings and along the lingual surface of the denture space. (Fig. 221.) I t may be found easier to cut this piece of brown rubber at the median line and pack in two parts. (Fig. 221.)

228



9. If you feel certain that more brown rubber is required, cut piece (Fig. 216e) and add. from the long 10. Now test the case (see Procedure I11 which follows). I I. Stretch the 5"piece of brown rubber (Fig. 2 1 6f) until fairly thin and cover the pink rubber, being careful not to place the brown rubber higher towards the rim of the denture than the pink rubber, to prevent "bleeding." Apply a piece of wet cellophane. Close the case immediately after applying the cellophane. (Fig. 222.)

sf'

329

Apply two thicknesses of brown rubber over the palate to the crest o l the alveolar process. ( E ) Brown Rubber Lining: NOTE:All pink rubber should be covered on the surface toward the cast (the tissue surface) with a layer of brown rubber. This should be done after the final testing of the case. 2.

A-Brown rubber. B-Pink rubber to A-Brown rubber covering the whole be covered by piece of thinned-out brown tissue surface of the denture. rubber. Note: Sufficient rubber has been packed. There is little excess rubber showing. When rubber is packed in this manner escape gates are unnecessary. Escape gates may draw rubber away from the denture where it is most needed. A-The rubber shows through the weave, indicating that sufficient rubber has been packed. B-The dental rubber is not visible through the weave of the linen, indicating that more rubber should be added.

NOTE: Be sure cellophane has been adapted over the packed rubber before final closing of the flask. ( C ) Partial Dentures: I . I n partial cases pack pink (gum) rubber on labial and buccal surfaces only where indicated, as previously occupied by the wax in the denture space. 2. Use a small piece of pink rubber in the interproximate spaces where the teeth are butted (set directly against the cast). (D)1% Fall Cases Without Teeth: I . Apply pink rubber, two thicknesses along the labial and buccal surfaces from the rim of the denture to the crest of thc alveolar process.

Thin out by stretching a piece of brown rubber with your fingers. 2. Place the stretched piece of brown rubber over the pink rubber, being careful not to extend the brown rubber farther than the pink rubber at the rim (periphery or denture limit). Adapt the brown rubber carefully. (Figs. 220, 223 and 224.) 111. Testing packed cases: I. Wash a piece of linen, in which the sheets of rubber are packed, under hot water to remove the starch. 2. Adapt the piece of washed linen over the packed rubber and place the lower half of the flask containing the cast over the upper half of the flask containing the packed rubber. (Fig. 222.) 3. Close the flask carefully without straining the flask or exerting too much pressure on the rubber. I.


230


4. Place the closed flask in a flask-pressor clamp without tighten5.

6. 7. 8.

ing the press or clamp too much. Place the closed flask, in the press or clamp, into boiling water and allow to remain for six to eight minutes. Remove the flask from the water and tighten the flask-press or clamp until closed all the way. Remove the flask from the press or clamp and open the flask. Notice places where the rubber has failed to show through the weave of the linen cloth, indicating where more rubber should be packed.

9. Pour hot water over the linen sheet to make it easier to remove the linen. Remove the linen from the packed rubber, being careful not to disturb the packed rubber. (Fig. 222.) (Chloroform or carbona on a piece of cotton may be rubbed over the linen.) 10.Notice the glossy spots on the packed rubber which fail to show the imprint of the weave of the sheet of linen. Add brown rubber over the glossy areas. (Figs. 223 and 224.) I I. Replace the linen sheet and close the flask, replace the flask in the press or clamp dnd boil again for 6 to 8 minutes. 12. Tighten the flask-press or clamp and then open it to see if sufficient rubber has been packed, if not, repeat the testing and adding of rubber. If too much rubber has been packed, carefully cut away the excess with sharp scissors. Do not disturb the rubber in the denture area.

231

13. When sufficient rubber has been packed, line the pink rubber with a thinned-out piece of brown rubber. Dip a piece of cellophane in a pint of hot water containing one tablespoon of glycerine. This will allow the cellophane to be adapted smoothly without wrinkling. Escape gates for excess rubber may be cut in the plaster or a j/4" trough may be cut around the packed rubber about j/4" from the rim of the denture. (Figs. 220 and 221 .) 14. Cover the packed case with the wet cellophane and close the flask tightly, as it was originally before the wax was boiled out. (Fig. 225.) NOTE: If a bolt and nut flask is used, be sure the nuts are tight when the flask is finally closed for vulcanization. Otherwise, the clamp should be tightened. Never attempt to close a flask by means of the flask bolts only. Place the flask in a suitable press and immerse in hot water until the rubber flows freely. Close the press slowly, at the same time drawing up the bolts. When the flask is closed as far as desired, the bolts will hold the parts together indefinitely without strain. Bolts should always be drawn up alternately, a half turn at a time. This procedure holds the parts of the flask together evenly, and assists the flask-press in distributing the pressure properly. Supplementary Assignment: (Information to be obtained by the learner.) I.What do we mean by the dry method of packing dental rubber? 2. What is the wet method of packing? 3. Methods of testing. 4. Application of tinfoil, cellophane or other material over the cast before final closing of the flask. 5. Various "steam tables" and method of using them. 6. Care in using packing tools. 7. Care in handling heated flasks. 8. Prevention of "bleeding." Questions : I. W h y should the rubber be warmed before packing? 2. W h y should the pins be covered with brown rubber? 3. What is the composition of dental rubber? 4. W h y is a linen cloth used? 5. How can you tell when you have sufficient rubber?

232


6. How can you separate the linen from the rubber after it is heated? 7. What is the indication that not enough rubber has been used? 8. Why are the edges of plaster removed? 9. When do you use cellophane? 10. Which rubber is stronger, pink or brown? I I. Name two other colors of dental rubber; give their use. 12. H o w may "bleeding" be prevented? Job Appraisal : I. Was the rubber cut according to directions? 2. Was the rubber kept clean? 3. Was the pink rubber adapted well around the anterior teeth? 4. Did the imprint of the linen cloth show all over the packed rubber? 5. Was the flask closed as tightly as it was originally, before the wax was eliminated? 6. Can you pack a full case in 20 minutes (average)? REFERENCES:(Books for additional information.) Nichols, I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby CO., 1931. 2. Frahm, F. W.: T h e Principles and Technics of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., 1934. 3. Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, I 93 2. 4. Skinner, E. W.: T h e Science of Dental Materials. Philadelphia: W. B. Saunders Co., I 936. I.

R E L A T E D I N F O R M A T I O N : UNIT NO. 15

VULCANITE DENTURE PACKING TECHNIC Caoutchouc: A light yellow, creamy, odorless juice obtained from tropical trees (Sephonia elastica) and other plants. I t is imported chiefly from Brazil in the form of dark, tough, fibrous masses, possessing a high degree of elasticity and many impurities incorporated during the solidifying process. Crude rubber is purified by cutting it into fine shreds, washed, dried and kneaded, then rolled into sheets. Ingredients of Dental Rubber Red rubber:

Caoutchouc 48 parts by weight Sulphur 34 parts by weight Vermilion 36 parts by weight Pink rubber: Caoutchouc 48 parts by weight . Sulphur 24 parts by weight White oxide of zinc 30 parts by weight Vermilion 10parts by weight Brown rubber: Caoutchouc 48 parts by weight Sulphur 24 parts by weight

Proportion of Ingredients in Dental Rubber I n a I 6-02. mixture: Dark Elastic-15 oz. of rubber and I oz. of sulphur Jet Black-I 15oz. of rubber and 4 5 oz. of lamp black Red--9 oz. of rubber and sulphur and 7 oz. of vermilion Pink-5 oz. of rubber and sulphur and I I oz. of vermilion

Dental Rubber of Various Colors Light Red, Dark Red, Maroon, Brown, English Base, Olive Base, Lower Base, Weighted Brown, Metallic Weighted, Casco Golden, Tmproved Black, Light Pink, Medium Pink, Granular Gum (Walker's), etc. 233

234

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IJXI.

FOR

1)IINTAI. TJ7CII NICI:\NS

Aged Dental R u b b e r : If dental rubber is kept too long, it beconies "aged" and unfit for use. Do not huv more dental rubber at orle ti~riethan L J I ~be used i l l unr ~rionth. D r y Method of Packing Dental R u b b e r : 'The flask is heated in Fahrenheit. T h e rubber is packed and an oven at 213' to "8' tehtcci without boili~lg. D E N T U R E BASE MATERIALS Vulcanite-vulcanized dental rubber. Metal-gold, platinum, stainless steel, etc. 3. Celluloid compounds-not much used. 4. Synthetic resins-(a) thermo-plastic, (b) thermo-curing. 5 . Porcelain bases. Celluloid Compounds : These compouncls are not satisfactory because of the camphor odor from the camphor used to make the celluloid plastic. T h e fluids of the mouth affect the celluloid and the denture loses its color. Celluloid dentures warp easily because they :II-ethermo-plastic. (They are made plastic or soft by heat.) Synthetic Resins: T h e synthetic resin compounds may be thermo curing (a chemical reaction takes place when heated) or thermo1)lastic (softened by heat and molded to the desired shape which is supposed to be held on cooling) which do not undergo any chemical I-enction or heating. Thermo-plastic resins warp easily and are less desirable than thcrmo-curing resins. I.

2.

DEN'I'URE

BASE MA'VERIALS

23 5

Tissue Tolerance: T h e low heat capacity and irlsulatirig propert! of vulcanite, together with its springiness under pressure, frequently. is the cause of irritated tissues. I t is generally conceded that its tissue tolerance is quite low. T h e tissue tolerance of the ~ h e n o lformalde hyde resins is considered to be the best of all the materials. L e n g t h of Life: T h e length of life of a denture is dependent upon many properties, such as strength, stability of form, and texture. Experience has shown that the length of life of rubber dentures is all that can be desired, while as a class, that of all thermo p1;istics is comparatively short, due to change of form, texture, discoloration, or breakage. T h e length of life of the phenol formaldehj~desas a class has been little more than that of the thermo-plastics because of the short color life and low strength. T h e phenol-formaldehyde resins, however, with their greatly increased color life and strength, have a life equal to that of rubber. Ilrhile the color at the end of twent) years would probably not be the same as when it was made, it would be a better color than that of a rubber denture at any time. T a s t e and O d o r : With the exception of those cellulose materials containing camphor, plastics or resins-if compounded properly-will have no taste or odor when first inserted in the mouth. I11 time the softer materials, or thermo-plastics, which stain and which have poor xdhesion, will, like vulcanite, become foul. .I phenol-formalcichjde I-csindenture has absolutely no taste or odor. With phenol-forinalde hpde resin dentures, since there is no seepage around or between the tccth and denture base, and no appreciable absorption in the resin itself, there is no possibility of taste or odor from embodied decn) ing organic matter.

Permanency of F o r m : Thermo-curing materials being molded ill the licluid form and then by means of additional heat changed into the solid form, are not subject to warpage, since their natural fortli is the form to which they have been moulded, and they will retail) this form.

Pleasing Color: Vulcanite beilig opaque and lacking e~ltirclyin tl.nnslucency and transparency, all efforts to produce a lifelike color in it have not proved entirely successful. Since the resins and cellulose compounds are practically transparent in the natural state, it is possible to produce almost any color desired.

Absence of Absorption: Most plastics exhibit a fairly low ahsc>i-1) I ~ O I I ;tt roo111tcn~l>cratures.Vulcnnite shows pr;~ctic:~ll~ tio w:ttcr al, sol.l)tiorl for scvcl.al nloliths. LYhilc tlic I-csi~is( ~ ~ h e n o l - f o i - m : ~ 1 ~type) i ~ l i ~ ~:t~-c c ~:ttt:tck~:cl c I)y C O I I cc~~t~.:ttc(l aci(1s :111d: ~ l ~ s o l:~lcof~ol, ~ ~ t c tiicy :trc i l l ~ i o\ir;t), :tlTr~.tc(ll)y IIIC.Iluicls J>I-L.SL.II~ i l l tlic 111oilth. 'l'lic 1v:ttcl- ;tl)so~-l)tio~i i \ :11)0iit I I X , I . I (.lit :t11[1 [ h i < is 1 ~ c ~ : 1 c ~ l 1\t\x, li t I ~ i t iS V \ . V I I
Rase Metal D e n t u r e Bases: Stainless steel has the advantages of low cost, light weight and less hulk. Cobalt-chromium alloys can be 11\r(1ill colnl>in.ltioll with v~~lc:t~iite or other materials.

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VULCANIZATION TECHNIC


m.

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239

...-...-.......

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FIG. m 8 a . FIG. 2 2 8 b FIG. 228a. BLOW-OFF CAPAND PIN (CROSS SECTION)

*

Note: T h e blow-off is opened by unscrewing the cap one or two turns only. T h e cap and pin are riveted together and the action of unscrewing the cap lifts the pin from its seat. T h e pin or valve has the customary pointed end with a large flange on its upper end to bear against the inner surface of the cap. I t is riveted on the outside, so i t is held securely from movement either way. I n closing it, use no more force ihan necessary to make it steam-tight. Attention must be paid to this point to avoid damage. T h e blow-off will become leaky much sooner if opened when the steam pressure is high, than if used as directed above. T h e vulcanizer should be allowed to cool slowly for at least 15 minutes. Never relieve the steam pressure by opening the blow-off.

FIG.228b. IMPROVEDSAFETYVALVE*

Note: Do not tamper with the safety valve. Care should be taken to remove all deposits and uneven surfaces on the top of the stud before mounting a new disk. Put the thin safety disk on the stud, the flanged 'poition down-wards; then the brass washer, broad side down. Screw on the cap only hard enough to prevent leakage. Buffalo Dental M f g . Co.

FIG.227.

VULCANIZER COVERSHOWING THERMOMETER AND MANIFOLD SAFETY VALVE( I ) AND BLOW-OFFVALVE( 2 )

WITH

Procedure: (Follow operations in the order presented here.) CAUTIONS : a. Make certain that all gas tubing and other co.ranections are secure between gas jet and time clock. b. Make sure vuZcanizer pot is clean. c. Always pour aboiwt foozlr ounces of warm, clean waLer i n vulcanizer pot. V~lcanizermust always have water for generaling steam. ( T h e vulcanizer pot should h a v ~walor to r/t(, depth o j one inch.) d. Avoid resting flash on boltom of vulcanizer pol. USL*clar~rj) eoitl~holt ring with clamp flask. U s e empty $a.rk on ho//of~c

L

h'olu: T h e Time Regulator has a metallic w i v e which is gas tight whether the ylta

nupply jet be open or closed. T h e time device is operated by the minute arbor

o f tlrc clock. T h e No. I T i m e Regulator is used in connection with the Lewis Gnu Regulator No. 4 and No. 4A. (Buffalo Dental Mfg. Co.)

240


$asks. D o not drop flasks into vulcanized pot. (Place gently.) Flasks and clamp nwst not extend ahove th.e top of the vulcanizer pot.


241

h. Avoid tampering with saf ety-valve cap unless replacement of disk is required. (Fig. 228b.) i. Be sure time clock regulator is wound and set before lighting gar. (Figs. 229a and b.) j. Mercury in thermometer should be at the bottom when vulcanizer burner is liglited.

Note: T h e Regulator is capable of being set for temperatures varying from 280" to 320°. TOvulcanize at any of the degrees of temperature marked on the graduated base, all that is required is to turn the milled hand-plate until the pointer is over the degree desired. T h i s should be done before lighting the gas under the vulcanizer. A small screw is inserted in the base, which acts as a stop for the pointer, and prevents the regulator from being set, either by design or accident, to maintain a higher temperature than the highest graduation on the base, which would endanger the safety of the vulcanizer.

e. Make sure vulcanizer patking and cover are in proper posi.. tion over rim ( t o p ) of vulcanizer.

(Fig. 226.)

f. Make sure cross-bar is in proper position and cross-bar bolt is tight when closing vzclcanizer. g. Always open steam blow-of valve one or two turns only bcfore lighting gas. (Fig. 228a.)

k. Be sure to set gas regulator to 320' in Btvfalo Dental Valcanizer, or accordi~gt o vulcanization directions. (Fig. 230.) 1. Make sure gas is properly lighted. Hold lighted taper or match over gas burner before opening gas jet. m. Do not allow flame. to extend beyond the bottom of the vulcanizer pot. If too much $ame is turned on, the latent heat m.11 sometimes cause the temperature to rise several degrees .a;fter the regulator has acted, and thzls confuse the operator.

242


n. Make certain gas @me is blue and not a yellow carbonizhg flame. o. Be sure to close steam blow-of valve so that it is steamtight after all air has been expelled from the vulcanizer and steam has begun to escape. p. After an interval of about one-half hour make sure that thermometer gauge is not above 320"; otherwise turn off gas because the gas regulator is out of order. q. Be sure to allow a su@ient interval of time for vulcanization. I t is better to vulcanize over a longer period of time at a lower temperature than otherwise. r. After the time clock has indicated that the vulcafiization process is completed and that the flow of illumimtkg gas to the vulcanizer burner has been stopped, be sure to close the gas supply jet immediately before proceeding. s. Allow vulcanizer to cool for about 15 minutes, after the gas is turned off before opening the steam blow-off valve. ( B e sure you are opening blow-off valve and not attempting to open safety valve.) t. Do not keep your head too close to the top of the vulcanizer when opening blow-off valve, when removing vulcanizer cover or at any other time. u. Never loosen cross-bar bolt until all steam has escaped through the steam blow-of valve. v. Carefully place vulcanizer cover on a shelf provided for this purpose wothozlt cliipping or marring the cover, regulator or thermometer. w. Use tongs, wear canvas gloves and exercise care k removing flasks from vulcanizer. x. Remove water from vulcanizer pot and clean the vulcanizer. y. T h e thermometer should be kept clean. (Fig. 231.) I . Pour four ounces of warm water in the vulcanizer pot. (Water should be to a depth of one inch.) 2. Place the closed flasks in the vulcanizer pot, being careful that the flask clamp (ok bolts, if bolt flasks are used) are properly adjusted. 3. Examine the graphite packing on the bottom of the vulcanizer cover to see that it is free from dirt and plaster. Adjus~ the vulcanizer cover on the vulcanizer pot. 4. Open the blow-off valve. (See directions.) This vnlvc is marked "blow-off ." (Fig. 227.)


243

T h e bulb of the thermometer is set in a mercury bath. T h i s is a small cup, forming a part of the vulcanizer cap, to which the thermometer is screwed. l'his cup should contain sufficient mercury to insure its surrounding the bulb of the tube when the thermometer case is screwed down properly. T h i s makes a metallic connection between the thermometer bulb and the vulcanizer cap which is absolutely necessary for the proper indication of heat by the thermometer. Should the mercury column separate, it can usually be reunited by removing the thermometer case, holding it perpendicularly and striking the bottom of the case with some force upon the palm of the hand. If the vulcanizer is used with the mercury separated, it should be remembered that it is the whole column that denotes the heat, a n d allowance should be made for the broken part, i. e., if there is enough mercury separated to fill the space of ten degrees, the remainder of the column should rise only to ten degrees less than the temperature desired. T h e thermometer do:s not give a correct indication of the heat inside of the vulcanizer. It gives only the temperature of the vulcanizer top, which may not be the same as that in the flask.

5 . Set the time clock regulator which shuts off gas at the desired interval. (See directions.) (Fig. 229.) 6. Set the gas regulator which controls the time limit for attaining the maximum temperature. (See directions.) (Fig. 230.1 7. Using a taper, light the burner under the vulcanizer pot. Be sure flame is blue. Turn on only enough gas to cover the bottom of the vulcanizer pot. T h e flame should never be allowed to reach up on the sides of the pot. This rule must be observed, particularly when natural gas is used. 8. Wait until all air is expelled and steam begins to escape, then close blow-off valve, using wrench. 9. Vulcanize at 320° for 1% hours from time blow-off valve is closed. 10.When time regulator denotes that the supply of gas to the vulcanizer burner has been stopped, shut off gas supply at gas jet. I I. Allow vulcanizer to cool for 15 minutes, then open blow-off valve, using wrench and turning cap until steam begins to escape.

244

After all steam has escaped through blow-off valve, unscrew cross-bar nut, using wrench, and remove the cross-bar and vulcanizer cover. Place vulcanizer cover carefully on shelf. (This is better than to disconnect gas tubing when removing vulcanizer cover.) 13. Using flask tongs, carefully remove flasks from vulcanizer pot. (Wear canvas gloves.) D o not drop flasks. (Fig. 233.) 14. Allow flasks to cool for 15 minutes, then place in cold water until thoroughly chilled. (At least I 5 minutes.) I S . Empty the vulcanizer pot and clean thoroughly. I 6. Lubricate cross-bar bolt threads. 17. Replace vulcanizer parts. Supplementary Assignment : I. Various types of vulcanizers used. 2 . Methods of using different vulcanizers. 3. Attachments and types of vulcanizers for denture base materials other than vulcanite. 4. Care of vulcanizers. 5. Advantages and disadvantages of vulcanizing at various temperatures. Questions : I. What are the main parts of a vulcanizer and what is the purpose of each? 2 . Describe the blow-off valve and give its use; how may it be repaired? 3. Describe the safety valve; how is it repaired? 4. H o w do you set the gas regulator? 5. How do you set the time regulator? 6. How is the vulcanizer and its accessories attached; where is the time clock attached? 7. What precautions should be observed before lighting the gas burner under the vulcanizer? 8. Give the various temperatures and time intervals used in vulcanizing. 9. What precautions should be observed before opening the vulcanizer? 10. What care should the vulcanizer receive? Job Appraisal : I. Did you examine the gas connections? 2 . Did you set the time clock regulator? 12.



245

3. Did you set the gas regulator? 4. Was the safety valve opened to allow the air to escape? 5. Was water put in the vulcanizer? 6. Can you name the various parts and give a detailed account of the operation of a dental vulcanizer? REFERENCES: (Books for Additional Information.) Skinner, E. W.: T h e Science of Dental Materials. Philadelphia: W . B. Saundcrs Co., I 936. 2 . Buffalo Dental Mfg. Co., Dcntal Vulcanizers: Buffalo, N. Y. 3. Turner, C. R. and Anthony, I,. P.: American Textbook of Prosthetic Dcntistry. Philadelphia: Lca & Febiger, 1932. 4. Nichols, I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Co., 1931. 5 . Frahm, F. W.: T h e Principles and Practice of Full Denture Construction. Brooklyn: Dental l t c n ~ sof Intcrcst Publishing Co., 1934. I.

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VULCANITE DENTURE CLEANSING TECHNIC


IN FIG. 236. FLASKHASBEEN OPENEDAND DENI-UREHASREMAINED UPPER PART OF FLASK

A-Plaster

has been cut a w a y a: rear of flask. B-Tissue C-Rim of denture.

surface of denture.

Note: If cellophane is applied over packed case before closing flask for vulcanizing, tissue surface of denture will be clean and glossy. T h e rim (periphery) of denture, denoting denture limits, can be seen plainly in the above.

FIG.237.

FIG. 237 FIG.238 UPPER DENTUREAFTER REMOVAL F R O M FLASK BEFORE T I N F ~ I I . Is STRIPPED

FIG. 239. A-Surface

259

METHODO F STRIPPING TINFOIL F R O M VULCANIZEDDENTURE of vulcanized denture. B-Tinfoil being stripped away. excess of vulcanite.

C-Extreme

Note: T h e extreme excess, if not more than ]A6'' thick, can be cut away with scissors, provided you do not cut too close to the denture limit.

erly applied and the rubber properly packed, it will be found that there is little trimming to be done. (Fig. 242.) 10. Remove all remaining plaster from the flask. Scrub and dry the flask and reassemble the parts. I I. Partial dentures are removed from flasks and cleansed in a manner similar to full dentures, except that partial dentures require greater care because they may be more easily broken. Supplementary Assignment: (Information to be obtained by the learner.) I . Methods of removing dentures from flasks. 2. Denture cleansing preparations. 3. Methods of removing tinfoil. 4. Removal of closely adhering tinfoil particles from vulcanite. 5. Care of flasks. 6. Methods of avoiding warpage of vulcanite dentures. 7. Methods of avoiding marring denture or breaking teeth while opening flasks. Questions : I . What is the first procedure in opening flasks to remove dentures after vulcanization?



HASBEENOPENED A N D DENI.URE HASREMAINED IN FIG. 236. FLASK UPPERPARTOF FLASK A-Plaster

has been cut away at rear of flask. R-Tissue C-Rim of denture.

surface of denture.

Note: If cellophane is applied over packed case before closing flask for vulcanizing, tissue surface of denture will be clean and glossy. T h e rim (periphery) of denture, denoting denture limits, can be seen plainly in the above.

FIG. 237 FIG.238 AFTER REMOVAL F R O M FLASK BEFORE TINFOII. FIG. 237. UPPERDENTURE Is STRIPPED

%-59

O F STRIPPING TINFOIL F R O M VULCANIZED I)ENTUKE FIG. 239. METHOD

A-Surface

of vulcanized denture. B-Tinfoil being stripped away. excess of vulcanite.

C-Extreme

Note: T h e extreme excess, if not more than 1413' thick, can be cut away with scissors, provided you do not cut too close to the denture limit.

erly applied and the rubber properly packed, it will be found that there is little trimming to be done. (Fig. 242.) 10.Remove all remaining plaster from the flask. Scrub and dry the flask and reassemble the parts. I I . Partial dentures are removed from flasks and cleansed in a manner similar to full dentures, except that partial dentures require greater care because they may be more easily broken. Supplementary Assignment: (Information to be obtained by the learner.) I . Methods of removing dentures from flasks. 2. Denture cleansing preparations. 3. Methods of removing tinfoil. 4. Removal of closely adhering tinfoil particles from vulcanite. 5. Care of flasks. 6. Methods of avoiding warpage of vulcanite dentures. 7. Methods of avoiding marring denture or breaking teeth while opening flasks. Questions : r. What is the first procedure in opening flasks to remove dent,urcs after vulcanization?

260



Note: There is a glossy surface left by the tinfoil on the palate of the upper denture.

261

7. H o w can you remove tinfoil which adheres closely to the vul. canite? 8. What method shoulc; be followed in stripping the tinfoil from the denture? 9. What care should be given the flask after the denture is removed? Job Appraisal : I . Is the vulcanite of the denture free of knife marks or other injuries? 2. Have any of the teeth been fractured? 3. H a s all of the tinfoil been removed? 4. Is the denture clean? 5. H a s the flask been cleansed and reassembled? 6. Can you remove a vulcanized denture from its flask in 10 minutes? REFERENCES: (Books for Additional Information.) Skinner, E. W.: T h e Science of Dental Materials. Philadelphia: W. B. Saunders Co., I 936. 2. T u r n e r , C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, 1932. 3. Nichols, I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Co., I 930. 4. Frahm, F. W.: T h e Principles and Practice of Full Denture Construction. Brooklyn: Dental I t c n ~ sof Interest Publishing Co., 1934. I.

DENTURE AFTER TINFOIL IS FIG.242. APPEARANCEOF CLEANSED STRIPPED AWAY

A and A'-vulcanite

between the teeth. B - d i v i d i n g line between pink and brow11 or base rubber over heels of denture.

Note: T h e denture has an even glossy surface; little trimming is required aror~ntl the necks of the teeth. There is a straight line dividing the pink gum rubber fl.0111 the brown rubber over the second molar. 2.

3. 4. 5.

6.

W h y should the flask not be hammered to remove thc denture? What should be done to avoid cutting the denture or break.. ing teeth? H o w is warpage avoided? What procedure should be followed in removing dcnturcs remaining on the casts? H o w may extreme excess of vulcanite bc removed?

266

DENTURE TRIMMING TECHNIC


267

BEFORE FIG. 244. LOWER DENTURE PARTLY FIG. 245. UPPERDENTURE TRIMMED TRIMMING PERIPHERY

A-White-colored

section indicates excess to be trimmed.

Note: T h e periphery of the denture is plainly visible in the upper and lower dentures.

A-Dental lathe. B-Abrasive band mounted on lathe chuck (arbor band chuck). C-Denture. T h e denture is held so that the abrasive wheel does not touch the carving about the teeth.

N o t e : T h e denture should be held securely but in such a manner as to afford a n unobstructed view of the part to be trimmed. I t is not necessary to use more than one method of trimming around the periphery of the denture.

3. Remove all roughness on labial and buccal surfaces of denture by using the tip of the scraper. (Fig. 250.)

4. Festoon vulcanite around teeth by using right and left vulcanite chisels. Do not cut vulcanite too thin over the teeth. (Fig. 251.) 5 . Sandpaper denture to a smooth finish only where scrapers are used. (J?igs. 252 and 253.) 6. Use an abrasive wheel, with a mandrel mounted on a bur chuck on the lathe, for final trimming around the palatal and lingual surface of the teeth which should be made to follow the outline of the teeth. OF HOLDING D E W ~ U RWHILE E USINGHALF-ROUNL) FILE FIG. 246. METHOD

A-Denture.

B-Half-round

vulcanite file.

C-Bench

block.

Note: T h e denture is held securely in the left hand, with the index finger slipporting the buccal extension of the denture. File in an outward direction with a slightly

sliding stroke. D o not file too close to the denture limit. Leave the rim of thc denture rounded by scraping gently with a scraper or with fiuc s r ~ ~ i t l l ) ~ ~ l w r .

Supplementary Assignment: (Information to be obtained by the learner.) I . Mcthods of trimming vulcanitc. 2 . Mcthods of trimming denture bascs other than vulcanite.

268

DENTURE T R I M M I N G TECHNIC


Job Appraisal : I. Was the denture properly trimmed at the periphery? 2 . I s the vulcanite smooth and of even thickness over the palate? 3. Were the teeth festooned to show the maximum amount of porcelain without weakening them in the vulcanite? 4. Was the carving preserved? Are the pins covered? 5. Can you trim a denture in 30 minutes (average)?

3. Method of using sandpaper in trimming dentures. 4. Methods of carving vulcanite. 5. Methods - of trimming around tooth embrasures. Questions : I. How do we trim to the denture limits? 2. What method do we follow in using vulcanite files? 3. How are scrapers used?

A-Rat-tail

file used with a pushing motion from lingual surface. denture.

B-Partial

Note: Never use rat-tail file over tissue surface of denture. Do not file beyol~tl denture limit indicated by ridge on g u m tissue surface of denture, that fits betweell patient's teeth and gum.

4. How should the chisels be used around the teeth? 5. H o w are partial dentures trimmed around the remaining natural tooth outlines? 6. How may the gum rubber be carved? 7. Why is proper trimming important?

A-Dental lathe. B-Abrasive wheel on lingual surface of denture. C-Lower denture. T h e denture should be held securely but in such a manner as to allow a clear view of the surface to be trimmed.

Note: A half-round vulcanite file can also be used for the lingual surface. T h e half-round side of the file should be used a t the anterior part. All peripheries of denture should be rounded to prevent cutting the patient's gums.

REFERENCES: (Books for Additional Information.) T u r n e r , C. R. a n d Anthony, L. P.: American T e x t b o o k of Prosthetic Dentistry. Philadelphia: Lea & Febiger Co., 1932. 2. NicIiols, 1. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Co., 1930. 3 . I:r:th~n, 1:. W.: T h c Principles and Practice of Full D e n t u r c Construction. Ilrooklyn: 1)cntal Jtcms o l Intcrest Publishing Co., I 934. I.


270

DENTURE TRIMMING T E C H N I C

271

N o t e : T h e vulcanite is smooth and the carved elevations over the teeth have not

A-Scraper

directed away from teeth to prevent breaking them.

been trimmed away. T h e festoons are almost at right angles to the long axes of the teeth and the vulcanite over the teeth is not too thin nor cut out too deeply between the teeth. T h e original gloss left bv the tinfoil can be seen around the carving over the teeth.

Note: W h e n tinfoil is used over a properly waxed denture there is little need for scraping. Only rough spots should be scraped away. T h e teeth on the denture should not be allowed to press against the bench-block, to prevent breaking or loosening them.

FIG. 2 5 I . A-Denture.

B-Chisel

METHOD OF FESTOONING TEETH

in palm grip. Notice the thumb is used as a fulcrum to control the force exerted on the chisel.

Removc the excess volcanite around the necks of the teeth so that :I smooth even few too^^ is seen while the tooth is exposed ;IS much ns possible. 1)o not rrlnove thc vulc:~nitr heyond the "coll:~r" of the teeth. T h i s \roultl I(loscn th(: cc-ct11. Ilsc 111tr r i ~ h t:I II(I left chisels for ;~ltcl.l~;lte ~nrai:ll : I I I ~ (1ist:ll ~ I : I I I ~ S 011 ill(: f c s t o o ~o~f (:i1(.11100111.

N o t e : Do not cut too deeply into the interproximate spaces of the teeth.

FIG. 253.

TRIMMED DENTURES READYF O R I'OLISHING

I-Lingual view of lower denture. 2-Lahial view of lower denture (the labial uum is usually shorter than shown here). 3-Palatal view of upper denture. 4Labial view of upper denture. Note: ~ 1 ; cvl~lcn~litc is smooth. All scratches have been eliminated. T h e r e is little work required i n polishing thesc tlent~~rcs.

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DENTURE POLISHING TECHNIC.

276

M A N U A L FOR D E N T A L TECHNICIANS

q. Mfear a muslin face n?ask when polishing. r. Avoid bringing denture in contact with the rotatifig chuck. I . Mount the two-row brush wheel on the cone or spindle chuck of the lathe, apply pumice of a creamy consistency, mixed with water or liquid soap and water, at the tooth embrasures of the denture and a r o u ~ ~the d carved elevations, over the teeth on the buccal and labial surfaces. Holding the denture

277

vations over the teeth. Regirl applying the pumice at the second molar on one side and continue polishing and applying pumice until the vulcanite over the second molar on the opposite side is reached. 3. Mount the linen (6-inch) wheel on the cone or spindle chuck and apply the creamy mixed pumice to the periphery of the denture. Bring the periphery of the denture against the linen wheel in a manner already described in steps I and 2 of the "Procedure." (Fig. 257.)

METHODOF USINGTWO-ROW BRUSH WHEELWHEN POLISI
FIG..2 5 6 . AROUND

Note: Pumice is applied to the denture. T h e denture is held firmly and rocked in n semi-circular manner to prevent making deep grooves between the teeth. Rernovr the denture from the brush wheel a t short intervals to apply fresh pumice and to prevent overheating the denture. Avoid holding the carved surfaces at rigllt angles to the brush wheel so that the carving will not he polished away.

2.

firmly with both hands, but in a manner that enables you to see the denture in actual contact with the wheel, press the denture gently against the lower front quarter of the wheel and with a rocking or rotating motion continue to remove all scratches, always keeping the surface wet with punlice and adding pumice as needed. (Fig. 2 5 6 . ) T o pi-event the obliteration of the carving, hold the dc~iturr so that the whecl is never at right angles to thc c11.vcd clc

Note: Pumice is always applied to the denture. Wheels are always mounted so that they rotate in the same direction to prevent the wheel from pulling the denture out of the hands of the technician. Avoid holding the denture in one position; always rock it from side to side or in a semi-circular motion. Dentures should not be held too long against the polishing wheel, to prevent overheating the vulcanite.

4. Apply the creamy mixed pumice on the palatal surface of upper dentures or lingual surface of lower dentures and continue to remove all scratches, using the linen wheel (6-inch) and felt wheel. 5. Mount the large felt cone on the cone or spindle chuck of the lathe. Apply pumice to the denture and continue to remove scratches on the palate and around the buccal and labial

27 t?

MANUAL F O R DENTAL TECHNICIANS

surfaces, which were not removed by the two-row brush wheel or the linen wheel. Change from large to small felt cones as needed. (Fig. 258.) 6. Wash the denture with soap, brush and cold water, using a dabbing motion.

FIG. 258.

DENTURE POLISHING TECHNIC

279

cone or spindle chuck of the lathe and polish all surfaces of the denture. (Fig. 260.) 1 1 . Wash the denture thoroughly with soap and water. Use a dabbing motion. I 2 . Oxide of tin powder on a soft flannel wheel may now be used for final polishing. 13. Again wash the denture thoroughly. 14. Place t.he denture in a glass dish containing alcohol and expose to sunlight for about one hour, to solarize the pink

METHODOF USINGFELT CONEON PALATE

Note: If the denture is held in one position it may be warped or a hole may be polished through the denture. Always agitate the denture when polishing. Use plenty of pumice mixed to a creamy consistency.

7. Mount the cotton wheel on the cone chuck of the lathe. Apply Tripoli to the wheel. Buff the denture in a manner described for the use of pumice. 8. Mount small felt cones on the cone or spindle chuck, apply Tripoli to the felt cone and continue to buff the denture until all scratches have been eliminated and all surfaces have been buffed. T o avoid making the denture too thin or puncturing the vulcanite of the palate always rock the denture but do not press too hard against the wheel. (Fig. 259.) 9. Wash the denture thoroughly with soap, water and brush, using a dabbing motion. 10.Coat the denture with vaseline and dip or dust it with fine chalk, or the denture may be covered with chalk and water of a creamy consistency. Mount the soft flannel wheel on thc

FIG. 259. METHODO F USINGFELT WHEELFOR ROUNDING THE PERIPHERY Note: The rim or periphery of the denture should be rounded to prevent sharp edges which are likely to cut the tissues in the patient's mouth.

rubber and bring out its luster. (Figs. 261, 262, 263, and 264.) 15; Dry the denture and coat the tissue surface with mineral oil. Supplementary Assignment: (Information to be obtained by the learner.) I. Various fine abrasives used in polishing.

280


DENTURE POLISHING TECHNIC

28 I

Note: T h e dentures have a high polish. T h e natural tooth margins are sharply defined. All scratches have been eliminated. Note: If rouge is used it should be applied sparingly to a chamois wheel. Keep the rouge away from the teeth as much as possible. Tepid water and soap with a small soft denture brush should be used to brush the rouge and other polishing agents off the denture.

Note: Denture base9 are ol1c11 uuctl I)y tllc tlcnli%~:Is illdivitlu~~li ~ ~ ~ p r c o n iIrr~y* on for tnking irnpreeuiol~afor tlcnturcn. 'rllc nl~nve1)11ncnwrrc ~,ncl(ccl wit11 brown n~rtl light pink dr11t111r~~l>l)rrn.

282

MANUAL FOR DENTAL

2.

3. 4. 5. 6.

TECHNICIANS

Various wheels used in polishing. Use of rouge in polishing; removal of rouge from teeth. Various types of polishing machines. Speeds of electric lathe used in polishing. Polishing agents for dentures other than vulcanite.

Questions : I . H o w should the denture be held during polishing? 2. H o w should wheels be mounted? 3. What is the purpose of the pumice? 4. What does the Tripoli do to the vulcanite denture? 5. What purpose does the chalk serve? 6. H o w are the labial and buccal surfaces of the denture polished? 7. H o w do we polish the palate? 8. Give the use of four different wheels in polishing. 9. W h y is the denture washed when changing from fine abra sives to buffing agents? 10. What is the purpose of solarization? I I. H o w do we know when the denture is properly polished? 12. What purpose does polishing of vulcanite dentures serve? Job Appraisal : I. Were all scratches removed? 2. Were all trimming tool marks removed? 3. Is the carving intact? Are the pins on the anterior teeth covered by the vulcanite? 4. Does the denture have a high polish? 5. Have all polishing agents been thoroughly washed away fr(1111 the denture surface? 6. Can you polish a denture in 20 minutes (average) ? REFERENCES: (Books for Additional Information.) Turner, C. R. and Anthony, 1,. P.: American 'I'c~thook of P ~ o ~( 1 , ~ l i ~ Dentistry. Philadelphia: Lea & Febiger Co., 1932. 2. Nichols, I. G.: Prosthetic Dentistry. St. Louis: C. V. hloshy Co., I j o 3. Frahm, F. W.: T h e Principles and Practicc of Full 1)cntnrc Con\tt ( 1 , tion. Brooklyn: Dental Items of Interest I'ublishing Co., I c ) ~1. Ip1ii.1~Lt'. 1; 4. Skinner, E. W.: T h e Science of Dental Matcrinls. I'l~il,~~lc Saunders Co., I 936. I.

RELXTEI) INFORMATION:

U N I T NO. 19

DENTURE POLISHING TECHNIC Solarize P i n k Dental Rubbers: T o develop the full tone in pink (gum) dental rubbers, after they have been vulcanized and polished, expose the denture to sunlight for thirty minutes to one hour. I n the absence of sunlight a powerful artificial light may be used. Pumice: A material of volcanic origin, used as an abrasive as well ;IS a polishing agent. Tripoli: A mild abrasive and polishing medium found in the form of porous rocks, first found in northern Africa. Chalk: Calcium carbonate or precipitated chalk used as a polishing agent. T i n Oxide:

A white powder used as a polishing agent.

OPERATION AND CARE O F A SUCTION POLISHING MACHINE A. Operation : I. Before starting the polishing machine, prepare all polishing tools and materials such as pumice, whiting, brushes, Tripoli, rouge, etc. 2. Mount the wheel that you are going to use on the spindle tip, while the electric current of the machine is off. 3. Warn others working on the machine with you to keep their hands off spindle tips before you start machine. 4. Push lever to "on" as marked on the lever box. 5. Turn on dust-pan light. 6. Before stopping the machine to adjust a new wheel, warn others using the polishing machine to stop work and to keep their hands off the spindle tips. 7. Alw:l!,s stop the motor on the polishing machine before reI I I ~ \ ~ ~ 01. I I , :1
284

M A N U A L ]'OK

DI.N'I':II.

'I'ECIiNICIANS

B. Care of Machine : I.

2.

3. 4.

5.

6.

Always keep the machine clean. Daily, remove lint from steel wool filter. Every other day during the summer and every week during the winter fill the water pan so that, at all times, it contains 1% to I inches of water. Once each week lubricate the motor that operates the spindle heads, pour oil in oil cups on the right and left sides of the motor shaft. Once each month, lubricate the spindle bearings and remove the spindle head covers. Pour machine oil over felt around the spindle bearings. Once a year pack grease in the three transmission bearings on the pulley shaft.

U N I T NO.

20

DENTURE REPAIR TECHNIC Rubber uscd for p.lcking d e n t ~ u closes its elasticity ~ f t e rit undergoes vulcanization. Dentures are occ'~sionally accidentally broken. Sometilnes a denture is fractured bccnuse of uneven stress of the teeth of the opposing jaw. I n this unit we shall discnss the repair of vulcanite dentures and the replacement of old, worn vulcanite denturcs by new vulcanite bases without changing the fit of the denture or the relationship of the artificial teeth to the denture base.

Project or Jobs: ( T o be performed by the learner.) a. Repairing simple fractures. b. Repairing fractures irtvolving teeth artd clasps. c. Replacement of new palate. d. Replacenzent of buccal and labial ( g u m ) vulcanite. e. Replacr7nent of entire vulcanite denture bast,. Project or Jobs: ( T o be performed by the learner.) JOB NO. 77: Repair simple fractures of one full upper and one full lower denture. J O B NO. 78: Repair fractures involving loose teeth of one full upper and one full lower denture. J O B No. 79: Repair a partial denture with loose clasp. J O B No. 80: Replace palatal vulcanite of one full upper denture. J O B NO. 81: Replace buccal arid labial vulcanite of one full lower denture. J O B No. 82: Replace the entire vulcailite denture bases of two full upper dentures. N w r ~ :(Read the entire Upbit carefully before beginning work. Co~isultthc glossal-!, for definitions of new words.)

jol) Application: Vulcnriite is l>~-e;~kable hut call bc repaired by : ~ , l t l i n ,FI-csh ~ clcnt:~l ~-ul>berslid I-cvulca~lizing. T h e revulcanized , l c . ~ ~ t ; I~ IlI I , I I ~ I - is thcri trimmed 2nd polished. Although the repaired I ~ ( . I I I \isI I: -I~~. : S~~ I~~ V I~ CIC ' : L I > I Cthc , new L ' u I c ~ I ~ ~ :ip~>cars ~c lighter t h x r l ."5

286

MANUAL FOR DENTAL

DENTURE REPAIR TECHNIC

TECHNICIANS

the original vulcanite of the denture which becomes darker. Den tures may be repaired several times as occasion demands. However, it is better to replace all of the old vulcanite if extensive or repeated repairs become necessary. Vocational Information: The parts of the broken denture are assembled into their original relationship, a matrix (cast) is made under the denture and the edges of the parts are prepared for receiving additional vulcanite. The denture may then be "cold packed" or "wet packed" and revulcanized. Special rubbers or the regular dental rubbers may be used for repairing vulcanite dentures. Tools and Equipment: Plaster bowl, plaster spatula, plaster knife, glass slab, wire nails, articulator, flask, wax, spatula, penknife, vulcanizer and attachments, all trimming and polishing tools. NOTE: (Tools and equipment used in waxing, flasking, boiling out wax, packing, cleansing, trimming and polishing are used in denture repairing.) Materials: Sticky wax, petrolatum jelly, basewax, plaster, water, dental rubber, sandpaper, pumice, chalk. NOTE: (Materials used in waxing, flasking, boiling out wax, packing, cleansing, trimming and polishing are used in denture repairing.) Procedure: (Follow operations in the order presented here.) CAUTIONS: a. T h e fracture-edges must be accurately approximated to prevent distortion oj the denture. b. Avoid applying sticky wax on the tissue surface of t h e denture. c. Be sure to lubricate the tissue surface of the denture before pouring the stone or plaster cast. d. A strip of vulcanite of about g" must be filed or ground away between the fracture-edges after making the matrix ( a stone or plaster cast or foundation on which the fractured denture is repaired and revulcanized). e. All of the polish should be removed from the denture for a distance of g" beyond the edges to be repaired. f. Dove-tails should be between %" and g" i n size and no/ over g" apart. g. W h e r e dovetails are not used, the vulcani~eskould he rlS of its original thicknrs.~N / /hr e/l.ec.s l o hn join/,,/, duced to n ~ tken d m7h.chened wit11a h f ~ r .

287

h. Only the waxed surfaces s h o d d be expo~edin investing the dmtzcre to be repaired in fEasKs. i. Handle the denture carefully while trimming and polishing. j. Be careful to keep the artificial teeth in the exact positions hdicated by the index ( a plaster wall used to peserve the

A-Loose

tooth. B and C-Broken of lower denture.

parts

A-Clasp in place after the vulcanite has been ground out to receive the clasp extension. B-Plaster matrix.

A and B-Parts

of upper denture.

A-Dovetails. B-Loose tooth in position. C-Vulcanite thinned and honeycombed with a bur.

Note' Either dovetailing or the thinning and roughening method may be used. T h e cast poured to hold the denture is known as the "matrix."

288

MANUAL FOR DENTAL

TECHNICIANS


289

relationship of the teeth to the denture base) when replacing vzllcanite dentare bases. k. I n remakes, avoid changing the original relationship of the teeth to the denture base (keep the articzllator set-screw seczlrely locked). 1. Cover the teeth v i t h a layer of basewax before passing the dentzlre through the flame to soften the vulcanite so that the teeth can be removed without fracturing. NOTE: (Observe all cautions indicated for waxing, flasking, boiling out wax, packing, cleansing, trimming, and polishing.)

I. Simple denture repair: I. Approximate fractured edges and seal the broken parts with sticky wax and wire splints, laid at right angles over the line of fracture. (Figs. 265 and 266.) 2. Lubricate tissue surface with petrolatum. 3. Apply a basewax or carding wax strip around the periphery of the denture as in boxing impressions. 4. Mix plaster and pour a matrix (cast) of the denture as in pouring impressions. (Figs. 267 and 268.) 5. When the plaster of the matrix has set, remove and cleanse the fractured denture parts. 6. Using vulcanite burs, separating discs and abrasive files and wheels, as found necessary, dovetail and remove polish for a distance of S'' parallel with the fracture-edges. (Figs. 269, 270 and 271.) 7. Replace fractured parts on the cast, fill in missing parts of vulcanite with basewax, waxing somewhat thicker than thc original vulcanite denture itself. 8. Trim the plaster matrix (cast) and invest in flask, covering all surfaces except waxed areas. (Fig. 272.) 9. Proceed with flasking, packing, vulcanizing, finishing and polishing as described in the respective units. (Fig. 273.) 11. Denture repair involving loosened teeth: A. When the same artificial tooth can be replaced. NOTE: Where the denture base indicates the exact position of the loose tooth, cut a dovetail in the lingual or palatal surface of thc vulcanite adjacent to the tooth, replace the tooth in its original posi tion, wax it securely with sticky wax and proceed as in simple repairs. B. Where the loose tooth is broken and a new tooth is to bc used but the denture base at the site of the tooth is intact.

A-Matrix (cast). B-Assembled bro- A-Wax rim around broken denture. ken denture showing wire reenforcement. M i r e reenforcement.

Note: T h e wax rim reenforces the denture so that the parts are not disturbed when the matrix is poured. T h e wax rim helps to obtain a more evenly rounded matrix.

A-Prepared edges of fracture, honeycombed with bur. B-Trough on matrix around denture after removing the wax rim placed around the denture before the matrix was poured. N o t e : Dental rubber may be heated on the packing table and worked into the space to be repaired by using a clean hot spatula.

\


290

291


NOTE: T h e dentist supplies the technician with a wax "bite" indicating the relationship of the teeth of the opposing jaw, and a new artificial tooth, or the make, shade and mould number of the tooth to be used. I. Proceed as in simple repairs until the matrix is poured. 2. Mount the wax "bite" on the denture, fitting the teeth of the denture into their tooth depressions on the "bite" as indicated, and seal the wax "bite" securely to the teeth of the denture. (Fig. 274.)

Note: T h e denture is covered with plaster excepting over the area to be packet1 with dental rubber.

A-Denture.

B-Teeth

on denture.

&Bite

mounted over denture and matrix.

Note: The plaster mix for pouring the "bite" should be looser than for other purposes.

B e sure plastei fills the tooth depressions before building up the plaster on the "bite."

3. Fill with plaster the tooth depressions left in the "bite" by FIG. 273. REPAIRED UPPERDENTURE Note: T h e lines of division between the old and new vulcanite can be seen the palate.

on

the teeth of the opposing jaw. 4. Mount the matrix with the denture and poured "bite" on an articulator. 5. Remove the "bite" from the denture and the poured "counter" or cast of the opposing. teeth. (Fig. 275.) 6. ,Place the new tooth in position as indicated by the bite and

292

MANUAL -FOR DENTAL TECHNICIANS

DENTURE REPAIR T E C H N I C

Lubricate the tissue surface of the denture and impression or apply separating media to the impression part (if the impression part consists of plaster.) 2. Apply a wax rim around the periphery of the denture and impression. 3. Pour the matrix (cast). 4. Apply the wax "bite" to the denture and wax it securely. (Fig. 274.) 5. Pour the "bite." 6. Mount the matrix with the denture and "bite" on an articulator. 7. Remove the "bite" and add teeth as in adding new teeth to broken denture and proceed as in simple repairs. (Fig. 275.) 111. Repair of partial denture with loose clasp. NOTE: (The dentist takes an impression of the clasped tooth with the clasp and denture in position.) I. Pour the impression and denture as directed for adding teeth to a partial denture. 2. Cut out the vulcanite of the denture base around the extension (tail-piece) of the clasp. 3. Proceed with waxing,' flasking, packing, etc., as in simple repairs. IV. Replace entire vulcanite on palate of a n upper denture. (Fig. 276.) I. Assemble the broken denture parts and pour a matrix as in simple repairs. 2. Using separating disks on a mandrel mounted on the bur chuck of the lathe, cut away the entire palatal vulcanite flush with the palatal (lingual) surfaces of the teeth. (Fig. 276.) 3. Using round burs, roughen the vulcanite under the teeth by honeycombing it with the bur. 4. Wax the denture and proceed as in simple repairs. V. Replace entire buccal and labial (gum) vulcanite of a n upper o r lower denture. I . Assemble the broken denture parts and pour a matrix as in simple repairs. 2. Using an abrasive wheel reduce the gum vulcanite to about one-half of its original thickness. 3.. Using a vulcanite bur, honeycomb the remaining gum rubber with the bur to roughen it. (Fig. 277.) I.

Note: T h e bite has been removed. T h e denture, the matrix and the counter of opposing teeth are shown mounted on an articulator.

tllc

the arrangement of the adjacent teeth of the denture to 1)c. repaired. NOTE: [It is often necessary to grind the incisal or cervical edgcs of the new tooth to be added, in order to fit it into position. l'hc gum rubber at the neck (the collar) of the tooth should not I)c ground away. T h e denture, especially when an anterior tooth i s being replaced, will look better if the original gum rubber is prc served.] 7. After the tooth or teeth are arranged in proper position, ~ M - I I ceed as in simple repairs. C. Where additional teeth are to be added to partial denturc.~. NOTE: (The dentist takes an impression and wax "bitc" 01' the part where new teeth are to be added and supplics thc tc.c,l~ nician with the teeth or specifies the make, shade, and moult1 ( 1 1 the teeth to be used.)

293

294


4. Carefully cut away the gum rubber around the necks of the teeth. 5. Wax the buccal and labial surfaces. 6. Flask the denture by filling the lower part of the flask with plaster of a fairly stiff mix and set the denture with the teeth down, while on the matrix, into the newly mixed plaster,


I

295

ing the plaster of the index about j/4" away from the indsal and occlusal surfaces of the teeth. (Figs. 280 and 28 I .) 4. Cut a dent on the index opposite each of the cuspid teeth of the denture, to weaken the plaster, and remove the index from the denture and cast. 5. Remove the denture from the cast and remove the teeth from the denture by first covering the teeth with a layer of melted basewax and passing the denture quickly several times through the flame of the Bunsen burner to soften the vulcanite. 6. Arrange the teeth in position as indicated on the plaster index and secure them with sticky wax.

METHODO F REPAIRING FIG. 2 7 7 . METHODO F PREPARING UPPER DENTUREFOR NEWPALATE RUBBER OF LABIALSURFACEOF DENTUREFOR APPLICATION OF NEW RUBBER

FIG. 276.

A-The vulcanite under the teeth has been honeycombed with a vulcanite bur. T h e pins on the anterior teeth have been exposed.

A-Plaster matrix. B-Gum rubber thinned out and honeycombed for new applied to desired rubber. C-Wax thickness.

Note: Plastic rubber or heated dental rubber may be applied directly without waxing.

being careful to have the teeth at least g''from the bottom of the flask. (Fig. 278.) 7. Smooth the plaster around the teeth and over the cast at the rear of the denture, making sure that all of the waxed part has been exposed. Lubricate the plaster. 8. Pour the upper part of the flask and continue as in simple repairs. (Fig. 279.) VI. Replace the entire vulcanite denture base. NOTE:(Proceed as in simple repairs until the matrix is poured.) A. When the matrix is not to be mounted on an articulator. I. Make a groove on each and in front of the matrix at right angles to the base of the matrix and the denture. 2 . Lubricate the teeth and the buccal and labial surfaces of thc denture and matrix. 3. Build a plaster index around the denture and matrix, extend-

A-Plaster matrix. T h e denture is flasked with teeth toward the base of the flask. B-Wax to be boiled out after the upper part of the flask is poured.

7. Construct a baseplate over the cast (the matrix) and arrange the index containing the teeth around the matrix with the baseplate. 8. Flow basewax into the separations between the teeth and the baseplate. (Fig. 284.) 9. Remove the sticky wax holding the teeth to the index and remove the index. 10. Finish the waxing where necessary without disturbing the position of the teeth. I I.. Proceed as in flasking a newly waxed trial denture.

1

296



297

NOTE: (Basewax may have to be used instead of the baseplate to avoid disarranging the teeth in the index.) B. Where an articulator is to be used: I. Proceed as in simple repairs until the matrix is poured, then lubricate the teeth on the denture. 2. Deposit a stiff plaster mix on a glass slab and press the teeth of the denture on the matrix into the plaster mix which now , becomes the tooth index.

FIG. 279. FLASKOPENED FOR BOILING OUT I-Counter.

2-Denture

flasked in lower part of flask.

A-Lateral part of index. B-Anterior part of index. C-The matrix, showing the trough left by the wax rim. D-The denture base to be replaced. E--Part of index, showing method of extending above the occlusal surfaces of the teeth.

Note: T h e trough on the matrix around the denture made by the wax rim and a vertical cut on the matrix help to replace the index in the same position. T h e index is higher than and extends over the incisal edges of the teeth.

A-Reenforcements

on fractured denture.

B-Index.

C-Matrix.

Note: T h e matrix and denture should be lubricated in order to make the separ:~ti~)~l of the index from the matrix and denture easier. T h e plaster wall around I I I ~ . denture and matrix is known as the "index."

3. Trim the tooth index and mount the denture on the matrix and the tooth index on an articulator, securing the set-screw to hold the relationship of the index to the matrix when the denture is removed. (Fig. 282.) 4. Cover the teeth of the denture with a layer of basewax, pass through the Bunsen flame until the vulcanite is soft, remove the teeth from the denture, arrange on the tooth index and .fasten them with sticky wax. (Fig. 283.)

29 8



299

5. Make a baseplate or basewax denture base over the cast. 6. Adapt a wax roll over the denture base and wax the teeth to it securely. (Fig. 285.) 7. Remove the sticky wax holding the teeth to the index and complete the waxing. (Fig. 286.) 8. Proceed with flasking, boiling out wax, packing, etc., as with wax trial dentures, until completion. Supplementary Assignment: (Information to be obtained by the learner.) I. Various methods followed in repairing dentures. 2. Various methods of adding new or additional teeth. 3. "Jumping the bite."

X-Tooth

depressions on index.

T h e index poured for teeth and the denture on the matrix are articulatetl. All of the denture base is to be replaced without disturbing the relationship of tllc teeth to the cast. T h e set-screw of the articulator must be properly adjusted.

Note:

FIG. 283. TEETH ARRANGED IN THE INDEX A-Matrix. B-Teeth. &Index. Note: T h e matrix of the original denture is now ready to receive a denture base. T h e teeth are then waxed to the denture base and separated from the index.

4. "Rebasing." 5. Different rubber preparations for cold packing. 6. Various methods of flasking. 7. Methods of removing teeth from vulcanite dentures. 8. Methods of grinding teeth. 9. Method of reenforcing assembled parts.

DENTURE R E P A I R T E C H N I C


300

WAXEDIN INDEX FIG.284. DENTURE WAXEDI N INDEX FIG.285. DENTURE WITHOUT

A-Index.

ARTICULATOR

B-Waxed Matrix.

denture.

WITH

C-

ARTICULATOR

A-Matrix. B-Basewax with teeth waxed to base. C-Index. D-Teeth held in index with aid of sticky wax but not yet joined to base.

Note: When the case is articulated be sure the set-screw is tight. T h e teeth shoultl be arranged in their proper positions in the index before waxing them to the w a x denture base.

30'

Questions : I. Why must the broken parts of the denture be accurately assembled? 2 . Why should the assembled parts be reenforced? 3. Why are the teeth secured to the index? 4. Why is it necessary to secure the set-screw firmly when an articulator is used? 5. What are the advantages and disadvantages of cold packing? 6. What precautions should be taken in removing teeth from dentures? 7. How should the teeth be secured to the denture base in "jumping the bite." 8. What is the purpose of dovetailing? 9. Why should the polish be removed from the denture near the edges to be repaired?. 10.What is the purpose of roughing the vulcanite with burs? 11. What methods other than dovetailing may be employed to secure old vulcanite to new rubber? 12. What effect does revulcanization have on vulcanite dentures? Job Appraisal : I. Were the parts accurately assembled? 2. Were dovetails and grooves cut according to the directions? 3. Were the teeth accurately replaced in the index? 4. Were the teeth removed from the denture without breaking them? 5. Was the denture properly vulcanized, trimmed and polished? REFERENCES: (Book for Additional Information.) > .

C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger Co., I 932. 2. Nichols, 1. G.: Prosthetic Dentistry. St.. Louis: C. V. Mosby Co., I 930. 3. Frahm, F. W.: T h e Principles and Practice of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., 1934. 4. Skinner, E. W.: T h e Science of Dental Materials. Philadelphia: W . B. Saunders Co., I 936. I. T u r n e r ,

Note: The denture is an exact duplicnte of the origillnl as f a r :IS IIN. ti1 :111tl 1111. relationship of the teeth to thc matrix are concc.~.~~c.tl.

KEI,ATEI> I N I ~ O K M A T I O N : U N I T NO.

20

D E N T U R E REPAIR TECHNIC Plastic rubber: Compounds of plastic rubber are sometimes used in repairing vulcanite dentures. T h e plastic rubber is used instead of wax. After flasking the cast: is placed in the vulcanizer without the necessity of boiling out or packing. Removal of teeth from vulcanite denture: Place the denture into a tin box containing sand. Heat the box until the sand is red hot. Allow the sand to cool, remove the denture and the teeth will be found loose and easy to remove. Properties of repaired vulcanite: T h e repaired denture is not strong as it was originally. Revulcanization causes a slight shrinkagr of the vulcanite. Dry-Packing: Instead of waxing the part to be repaired, dental rubber may be heated on the packing table and inserted with a hot wax spatula into the part to be repaired. Care should be taker! to pack the rubber tightly. T h e spatula must be kept absolutely c l e a ~ ~ to prevent foreign particles from becoming incorporated with thy rubber.

1

r

I n. .a . u r. n . .

ux.

3 0 ~

n07

APPENDIX I1

APPENDIX I1

( C ) Related Information (a) Vocalional Informalion

ANALYSIS O F U N I T NO.

I:

I.

( A ) Processes and Jobs No.

I.

a. b. c. d. e.

(a) . . Process or Princiblc Dental waxine: Handling and-cutting basewax Melting and sealing basewax Manipulation of carding wax Use of wax spatula Use of Bunsen burner

4. Modified plasters 5 . Method of storing plaster plaster tools and equipment

&. Care of

( b ) Project or Jobs No.

I:

a. Construct a sealed wax box 4 5 x 4 5 I I I ~ L I . b. Construct a wax art-base form t o g i v r ~ t dimensions

,lNALYSIS O F U N I T NO. 3: I'KEPARATION O F P I A S T E R 1MPRI':SSIONS F O R CrlSTS--1 (.4)

( B ) Laboratory Instruclion (0) Tools. Equipmen1 and Malerials I . Laboratory hench 2 . Bunsen hurner with gas tu1,~ng 3 . Wax spatula 4. hllllimeter ruler 5. Penknife 0. Pink basewax 7. Carding wax 8. Absorbent cotton

(b) Operations Using mm. ruler Handling andcuttingwax Using wax spatula Melting and sealing basewax Handlinrr. cuttinp and sealinn cardrne wax -

I. 2.

3. 4.

s.

(6) Laboratory Pracliceh Cutting waxes and using u., spatula 3 . Polishina basewax 4. Sealing 6asewax I.

z . Heating

(a) Process or Principle So. 3. Assembling impressions: a. Application of sticky wax b. Handling broken parts of plasterimpresslnns c. Arranging broken parts in dental im~ ~ r e s s i otrays n (1. Assembling impressions without using trays

(b) Projecl or Jobs No. 3 . Assemble four sets of full (edentulous) upper and lower impressions in trays No. 4. Assemble four sets of full (edent~llons) upper and lower impressions without using trays No. 5. Assemble six partial (partially edentulous) impressions in trays KO. 6. Assemble six partial (partly cdentulo~is) in~pressionswithout using trays

( R ) Laboratory Instruction

( C ) Related Information

ANALYSIS O F U N I T NO.

(b) Subblenrenlarr .. - Assianmenl~ I . Ingredients of wares 2. Degrees of heat attained by Bur~st:rtl , i ~ t flame j . Analysis of Bunsen burncr flamc 4. Physical changcs in heating and chilii~ir:n s. Gauaes (thicknesses) of different w : i h s usesof each

I. 2.

4.t

2:

PI,ASrl'EK

1

3.

4. 5.

.C

6. 7. 8.

(a) Tools, Eguipmenl and Materials Camel's hair brush Wax spatula Bunsen burner Paper towel Tweezers Sticky wax Basewax Upper a n d lower full and partial impressions

TECHNIC

( A ) Processes and Jobs (a) Process or Prindfile Plaster work: a. Handling, mixing, shaping and trinlming mixed plaster b. Use of plaster spatula, knife. bowl and saw c. Use of sandpaper. chan~oiscloth anrl chalk in polishing plaster 2.

Processes and Jobs

-

-

(a) Vocalionol Informalion I. Kinds of waxes and uses 2 . Types of wax spatulas 3 . Types of Bunsen burners

Nu.

(b). Subblementar~ Assiannrenls -Origin and development of plaster for dental use 2 . Physical and chemical properties of plaster 3 . Con~positionof various plaster eompounds 4. Duties of plaster technician

WAX TECHNIC

No.

2.

(b) Projccl or Jobs Construct upper and lower a r t - i , : ~< .-. , I be used as wax trays

I.

(b) Operalions Arrangipg broken parts of impressions

2.

Brushing parts

of

debris from

3. Use of tweezers for hand-

ling plaster parts 4. Arranging plaster parts of impressions in trays 5. Fitting parts of plaster impressions 6. Application of sticky wax 7. Fitting of parts without trays 8. Reenforcing with sticky wax

(c) Laboralory Praclices Using sticky wax Opening packages containing plaater impressions 3. Arranging parts in relative positions 4. Handling parts of plaster impressions 5. Cleansing of dental impression trays I. 2.

( C ) Related Information r. 2.

3.

4.

5.

(a) . . Vocalional Informalion Different types of impressions Types of sticky wax used Types of dental impression trays Use pf reenforcements in assembling im. presslons Types of tweezers used for holding plaster parts

(b) . . Subblemenlarv .- Assiannrenls Various imnrcssion materials Care of deGtal impressions Ingredients of sticky wax Precautions in assembling What to do when parts are missing

( B ) I , ( ~ b o r ~ ~ / 1o ~i,\trii(./~oi~ ry (a) l'ools, Equipmen1 onrl Malerials ( b ) Upcrol~otr\ (<) I . n / , o r t ~ / o ~1y' ) ,jC I , , , I . I'laster saw I . M < ~ ~ > i p ~ ~ l~: I~;tL i tS~LgV : I I . 1'I:~strrwo! k 2. Glass slab 2. Usir~gpIa\tcr <,t,tt~~l.s 2 . Mixi111: l~l,~:,lc~~ 3 . Plaster spatu1:i ,I. U S ~ I I~V ~ l :\:cw ~ ~ ~ l ~ ~ r .$. l ' < n ~ r i~~> >l .~~ :~ , l t ~ ~ 4. Plaster knife 4. US~IIS! r)l:<\~<,r kt111~ 4. ' r r i l > l ~ t l i l t > I: I ~ , I V . I < . I 5. Plaster bowl 5. 'l'rirni!~\tii:1,1.#..lt,r 5 . I ' ( ~ I . , / I 1I ~~1 .I~ )~ :. I r - I 0 . Chamois clotlj 0. S:tnd[~:t(~c MII,: I>I., . I * ! 7. Mi~rkingrwnril 7. l',nli\l~if~j* 1t1.t .f<.r 8. Mens~lrirlcct11, n l l ~ , , ~, ~I I , ~i I I I, C > ~,, I. , , I I ~ 9. Dcnt.iI j > l ; v , t < , ~ to. W:1t rr 1 1 . S : L ~ ~ I N~w~ , . ,(I L,tr(sl I ~I ~ ~ ~ 1 a. 'r,,I,

ANAT;YSIS O F U N I T NO. 3 : P R E P A R A T I O N O F DENTAIL IMPRESSIONS-I1 ( A ) Processes and Jobs Process or Principle .I Il*,\incdental impressions a. Clsc of c : ~ r < i i n ~ , w a x h. I'<.<:/IIIIC: o I I,r,xlng ~l~lprcssions , A l ~ l , l t < : ~ t iofo ~ stlell?~ ~ and Sillrdi~rac v:iro~isll;other sepnrntlng rrle11i:l (11)

(b) Projecl or Jobs No. 7. Boxing of assembled impressions No. 8. Application of shellac and Sand:~mct o boxed irnprcssio~~s

,2Nr\T,YSIS

017

ITWIT NO. 4 : I.)ICNT;\ I, CAST TECFINIC- I I I .I 1

I . L\',,\ S\I:LIIII:I A . I ~ I I I I S ~ II JI ~ I ~ I II C . ' I 1 I 4. I ' c ~ l k r ~ ~ l r 5. R:~scw;~s 6. C:~rdirlg wirx 7 . Sticky rvax 8 . Shellac g . Sandi~rnc ro. V1,rlatur~ilalcnll<~l

111gO.rsc~~v;i\ C u t t ~ n gy:~r<1111g \\:t\ j. Scaling basr.n.:~h 4. Sealing c;trrli~tgiv:~x 5. Using n:tx s1~;ttul;i 0 . Using shel1;ic 7 . Using S:t,ndnrac \wrnisIi 8. Applic:tt~nn of seoarating media ('1111

I . 2

(C)

I. 2.

13osilig imprcssinr~s Applic;ltiol~ of *el,;iratt181: 1nc6i:~

1j;triaus lnnterinls nsed for boxing irnprcss~ons 2 . Various s e p a r a t i n ~mcdi'i .A.Various methods nf applying sep;\rating ~ncdia j. Care of hrushes 5. Care of separating n ~ e d l n 0 . Why irnprcssior~snre boxrd

(ti) Tr~olr,Equipt,ienl linil Jl~iirri~ri 1'l;lstcl- knilc L. Pcnklrifc 3 . Alrvh,,l 4. .2bsc>rl!rnt c o t t r , ~ ~

Precautions in boxing 2 . hfethorls I I boxing ~ j. l n g r c d i r ~ i t scr1 scparatinz media 4. Prcc:tutions ill using separating media

(b) Project or Jobs

.

((1).

No.

I.

2. j.

4. 5.

6. 7.

(b) Opt:rolio?zz ( ( 1 Laburulr~ry/'roc 1 1 , < I . ['<,urir~gplaster < , , t , - l > M i x ~ l i gplaster 2. Pouring :irt~li(.i:~I. . I , * I hfixing artilirinl stunt. Pouring plastcr ~ r n ~ ~ r e s s i r ~ ~ i sr;rsts Pouring artifici:il stone 1121.r. Vil,r:~tingc:lst:press~ons 4. I < e c n l u r c i ~ ~ [)!.ISIC.I g I I : ;. Sctrini: ~ , ~ I ~ I R .
(C)

R e l a l e t l Zi?f,~rnrr~lzr~ii

(a) Vocational Injornralion r . Kinds ot plzister a n d purposes of each K ~ n d sol vltjrators a n d purgiises of cncli 3 . Method of reenr,,rcing tccth I r l li.rrtial c;isls L. Kinds uf 11ent:ii artifici:ll ,torre 2.

9. Pour in plaster four sets 01 full I , I I I ,I ,

a n d lou.cr impressions Kc,. lo. Pour in artificial storle four sets
~~

2.

,111 \r,ppl,,,,,,,,i~,tr~1 , \ , I : ? r!,, I I I K I C V I H,115 , , I , C I I I 5.I8~ 1 ,, I , , ~ > c (l,crc. "1 1 1 1 1 1,1.1.\11,>11..

,{

\It

:

I I I ~ c I \, , I

, , ~ , , I I I > : , ,1 1 8 1 , r t

\ , ~ I ~ I I ~ \~ ~, . , $ I I ,L;,,

,.I,,!#

,,,I

(b) Oorralions Kcinoval of poured imprrssioli.; from t r a y s 2. Rcmuval of boxiiig material from pourcd casts 3 . Separation of plastcr ilnprcssinn from casts 4. Removal ijf pl:+ster iinpl-essinn from t ~ e t hof partial casts j. Using knife blade i n scp:trating 6 . Cleansing casts I.

(C)

TECHYIC- I

and J o h s

Processes

Pro(rss or Princbple Xr, . n..a dentn! casts ( 1 . P c , u r i n ~plaster casts b. Pouring artificial stone casts c. Usc of mcchurtcal viijrator rl. Recl~forrlngt c ~ t t hin pi+rti:rl casts

I.

I.

01" ITNIT NO. 4: I)EP\;T['XT, (:.\ST

(u) Tools, fiqrtipmeni nnd Jfalerzals I . Plaster bowl 2 . Plastcr s l ~ a t u l n j. Glass slab 4. Mechanic:il vibrator 5. Llcntal l a t h e 6. P l a s t r r of Paris 7 . Water 8. Artilicial stonc 9. Iron ~i-ircip:lpcr clip)

(111 l ' ~ o j r , l or J o b ) S c ~ ~ ~ l a t c fsets o ~ (i er i ~ ~ h(1111 t ) ~jljl)cra i ~ i l Inwer plaster casts r I . Scparatr l'mr sets (right) 11111~ l p p c r;ind It,wer ;trtificial s t o ~ i ecasts 15. Separate six partial plaster casts 1 0 . Scparatc sis partial artificial stiinc casts

1.3.

R r l u l r d Znfornztltiu~

I.

jil)

.

i c 0 I ' r , ~ ( t, or l'?!??,ipl, C ~ iI lI l I, l ~ ~ . ( \ ~ . i c ~ ~ - . 11. Sc.par:iti!,p plastcr casts b. S e y a r a t i n ~:irtifvial strlllt caath Separatinr full Iedrt!tulc!~rs)c:lsth d . S ~ p n r n t i n gg:rrtinl (parti:illv edrnti:lous) rosts

Nc,. 0. S e l ~ d ~ . i ~ riists t i ~ ~ l~: ~

( i .

, ,

;\N.\I.YSIS

/'r(ur.~.~<..\ ~ i ~ i .Iul1.5 i l

(a) r . Scparatiuz matrrials 2 . Sep:ir:iting j. Separating 4. Separating

(c) Luhorulory Pracli
Z2elated Znforwrc~tion

IToculion(~l Inj(~rmalion casts front v : r r i o ~ ~ isn ~ p r r s s i r , ~ i

(b) Supplemenlury Arsig?rtirr?r/* 1001s used in s r p a r a t i n g Care ni casts pourrd i n v a r i n ~ i sc r , m y t ~ ~ ~ ~ ~ r i s 3 . P r e c a u t i i ~ n sin scgar;iting casts f r l ~ r nrlilstiv a n d other compounds I.

.

,

2.

elastic uiiiterinls soluble p1;ispr "Dcntocoll

'

AN.\LYSIS OF UNIT S O . 4: l)ENTA\T, C.\ST TECHNIC-TIT

(A)

P r o t e s ~ e su n d J o h s (b) Projecl or Jobs S o . 1 7 . Trim full upper a n d Iowrr plaster < rrsts 18. T r i m full ~ ~ p p rand r lo\vrr arti1ici:rl stone casts 1 0 . Trin, partial plastcr c:lsts 20. Trim pnrti:il artiiirial stinlc r a < t s

(R) Tool*, It,lr 1,. s : , , l ~ l , > : , l ~ < ~ l r

L a b o r u l o r y 1~1.slricc-lio11

(ir)

( O ) Operation.? Marking casts Sawing plastcr j. S a y i n g stonc 4. L s ~ n zrasp 5. Using sandpnpcr

(c) Laboralury Prriciirt:b

I.

I . Marking casts

2.

l'rimn~ingplastrr c.;rsts 3 . Trimming stolie casts 4. Sandpapering c : i s ~ s

(C)

2.

R e l a t e d Znfornznlion (/I) Supplemenlary Assignrne?zls I . Various methods of making art-bases 2 . Opc,ration 01 patentt,d t r i r r ~ t ~ t i ~ 111:tr11i11rs rg .i. Mctl~orlsr ~ ~i , i ~ l i s I ~ i:~rt-l>:8h~s ~~c: .I. L',.,, <,I ,. \l<.II\ll

31°

I\NALYSIS O F U N I T NO. 5: P R E P A R A T I O N O F D E N T U R E BEARlNC; AREAS-I (-4) Processes and Jobs (a) Process or Principle N o . 8. Outlining denture bearing and rclicf areas on casts o. Location of anatomic landmarks b . Outlining edentulous and partial dcnturc bcaring areas

No.

21.

Xo.

22.

(b) Projecl or Jobs Locate landrnarks and outline dcntul-n arcas on eight sets (sixteen) ol c d ~ n t t ~ lous casts Locate landmarks and outline denture, areas on twelve partial casts

ANALYSIS O F U N I T NO. 6 : T R I A L D E N T U R E BASE TECHNIC--I

( A ) Processes and Jobs (a) Process or Principle No. l o . Construction of baseplates on casts a. Construction of baseplates with lapped margins b. Construction of baseplates with trimmed margins

(b) operation^ I . Outlining dentures 2 . Outlining landmarks 3 . Outlining hard areas 4. Outlining suit areas 5. Outlining alveolo-buccal fold

I. 2.

(6) Laboralory PrncLicr\ Denture dcsigning Outlining relief areas

( C ) Related I~~j'ormation (a) Vocalional 1 njormulion I . Various methods of denture dcsignixlg 2. Horseshoe" dentures 3. Metal a n d vulcanite combinations 4. Partial denture designing

(b) S~rpplemenlaryAssignmenls I . Openings in boncs nf palate covercd by < I < , # turcs z. Openings in honcs of mandible (lower j:lv I covered by denturcs A . Muscular a t t a c h m ~ n t sin upper jaw rt!:llL,! t o dentures 4. hluscular a t t a c h ~ n c n t sin lower jaw rcl:clr I t o dentures

(a) Tools. Malerials and Eouibmenl - I. Bunsen burner i. Plate-shears 3. Wax spatula 4. Penknife s. Rat-tail vulcanite file 6. Half-round vulcanite file 7. Baseplate material 8. Boiling water 9. Cold water 10. Absorbent cotton I I . Paper clip wire I z. Sandpaper 13. Plaster howl

I. 2.

Britltania metal (22 gauge)

3 . Absorbent cotton 4. Shurt straight pins 5.

Scissors

6 . Orangewood stick

(b). Ofieralions Cutting relief metal 2. Cutting ti~riui! 3. Applying reliei metal 4. Applying tinfoil 5 . Using cement 6 . Using pins

z. 3.

4. 5. 0.

7.

(6) lJrojecl or Jobs No. 28. Construct wax bases for four sets oi edentulous tinfoiled plaster casts No. 29. Construct wax bases for six trnfoiled partial plaster casts

(a) Tools. Maleriuls and Equipmenl Bunsen burner Wax spatula Shears Orangewood stick Basewax Wire (zo gaugej Copper platc (2R or 30 gauge)

I.

z.

3.

4. 5. 6.

(b) Operalions Softening basewax Cutting basewax Adapting basewax Making copper recnforccments Adapting wire strengtheners Polishing basewax

(c) Laboralory Practzces Making wax bases a. Reenforcing wax hases (copper) 3. Polishing basewax 4. Reenforcing basewax (wire) I.

( C ) Related Inj'orn~nlion

( b ) S u / ~ P I ~ : n r c , t l ~ r. I r y\~r,:rr,,~,.ni

l)<.,;,rril,ti<,~~ ( 8 1 I I > C J \ V I IS I I , A ,:.tw~,, I,~ .!. ' 1 ' 1 ~ 1 > 1 ~ .llii,.ll 1 1 1 :1,1,11,111/:l l l i l I . . j . ' 1 , 1 1 1 I 1 > 1 1 :,cI:lllIlll/: I.

(b) . . Subblemenlarv .. - Assimnment5 .. Composition of baseplate Tuols used for trimming trial haseplatcs 3. Different methods of adapting and indications for variations I.

2.

( B ) Laboratory Instruction

( C ) Rel(~te(1I ? L J ' O ~ ~ I I I I ~ L O I L (a) Vocalional Injorn. aiion G a u g ~ sof relief mctals 2. Gauges uf tinfoil 3. Methuds of applying rcllcis 4. Mcthods of i ~ l ~ l ~ l yl ii l~~l gf ~ i l 5 . I ' u l c ~ ~ t c relicfs d 0. "Suclivns"

9.

( A ) Processes and Jobs

7. Two-row brush whecl 8. Bernard pliers

I.

6. 7. 8.

(a) Process or Principle Nu. I I. Construction of wax trial denture lnscs a . Construction of full a n d partial wax trial bases b. Application of strengtheners t o wax trial bases

I.

I.

4. 5.

ANA1,YSIS O F U N L T NO. 6 : TIZIAI, D E N T U R E HASI': 7'1SCRNIC-11

( B ) Laboralory I n s t r z ~ ~ t i o ? ~ (a) 1'uoIs. Eguipment and Maleriuls Tinfoil i.001 and .ooz

2.

3.

(c) . . Laboratory Praclices Makinefull trial b a s e ~ l a t e s I. ~ a k i G - p a r t i a ltri$ baseplates 3. Preparation of trial haseplate for denture bases other t h a n vulcanite I.

( C ) Related Information

( A ) Processes a72d Jobs (b) Project or Jobs Xo. 23. Apply relicfs on eight sets of cdcntr1111 casts. (8 casts.) S o . 24. Apply tinfoil on four scts or e c i e l l t ~,lI plaster casts. ( 4 casts.) Ko. 2 5 . Apply tinfoil on six partial pl;iti,r < . , , . I

(b). Oberalions . Softenina b a s e ~ l a t ein Bunsen flamz * Cutting haseplate Adapting baseplate Applying reenforcing wire Filing baseplate Softening baseplate Repairing baseplate Using rat-tail file Using half-round file

I.

(a) Vocational Infurmulion I . Various con~puunds used for trial denture bases z. Methods of adapting trial base materials 3. Methods of reenforcing trial bases

AN,2T,E7SIS O F U N I T NO. 5: PREPllRATION O F D E N T U R E BEARING AREAS-I1 (a) Process or Princrple No. 9. Application of relief metal a n d tinfoil to-casts a. Application of reliefs on edentulous casts b. Application of tir~foilon partial casts a n d full casts

(b) Project or Jobs No. 26. Construct baseplates with lapped margins on four sets of edentulous stone casts No. 27. Construct baseplates with trimmed margins of six partial stone casts

( B ) Laboratory Instruction

( B ) Laboralory Instructio~r (a) TOOLS,Equipment u nd Muleriuls I . Marking pencil 2. Llrawing paper 3 . Sixtpen edentulous casts 4. Twclve partial casts

311

APPENDIX I1

APPENDIX 11

1.

2.

i.

.I.

.,.

O.

(a) Vocalional Informoliun IJiflcrc~ltwaxes used Mc?Iiods of adapting wax V;~rlcr,~s rnethods of reenforcing wax 11:ises hi<:tl~uds of adapting copper reenIorcemerrt Mc,tliods of adapting strengthening wire I':ltc~lted wax melting apparatus

(b) Supplemenlory As5ignrnenl~ Ingredients of basen-ax z. Gauges of copper for recnlurcing 3 . Materials uscd for polisl~ingwax 4. Gaages of wax I.

.\.U.\I,YSLS

O F U N I T N O . 7 : L3l'rE I'L,\TE

( C j Relufrd

TECHKIC

It~for~ri~~tiori

(('1 1 ' 0 ~ ~ ~ 1 i i o11zfort1!~11;0?1 nul I yi,cs ,,f articulators used

1.

\,1.

rl.

( ( I ) Process ur Principle Construction of wax biteplates

a . Biteplates f o r e d e ~ i t u l o u scasts

6. Biteplates f ~ , partial r casts c. Construction of modeling cc.~npc,tlr~d biteplates

(H) 7'1~ol.s.~ 1 u l c r i ~ 1~z 7l ds EquiPmenl \V:bx s p a t u l a I'<,nknifc 'l'crnplate (flat o r c u r v e d ) 1l1111scnburner (:i:~ss s l a b I
( b ) Projec! or Jobs Nil .lo. (',instruct ivax lliteplates o n t w o s c k . uf e d e n t u l ~ casts ~ ~ ~ swith bascplnte bast,, Nu. 31. Construct mucleling cumpound bit,uplates o n two sets of e d e n t u l o ~ i sca.1.. with bascplate 11;iscs S o . jz. Construct \\.axbiteplate,~o n four scth , ,' edentulous casts wit11 basc~\-:rx base, KO. 3 3 . Construct six partial biteplates on I,:<\c plate bases KO. 34. Construct six partial l ~ i t e y l a t e s i t , , . bases

Laboratory Instructio~l

. .\drantages 01 various a r t i c ~ ~ l a t u r s

('uard:; nfr;tinst d i s t i ~ r h i n g bitcl~latc rc.l:ltinnship

i

,; 1 .\

I1

APPENDIX

I. 2. j.

( h ) S~tPp/e,?rrnlurg. l r i i ~ , ~ n , r n / ~ Kelatiilfi partizil c a s t s Methods of adjusting articulators Alethorls of protecting articolator sct-screw f r c ~ ~accidental n ope~ling

l\NALYSIS OF U N l T NO. 8. tlRTIC'UL,\TING TECHNIC-11

(A)

P ~ o c e s s e so t ~ dJobs

( u ) PIOCF\Sor Pt iizciple Xi,. 14. hluuntillg c:~sts o n adjustable articuIators u . F a c e bow transference 6. Mounting e d r n t , ~ I < ~c al s~tss

( b ) Projecl or Jobs KO. 3 8 . M o u n t edentulous, related casts o n Gysi or Han;iu articulator

(81)

I.

2. 3.

4. 5.

6. 7. 8.

9.

( 6 ) OPeralions Construction of wax roll Sealing wax roll t o baseplate Use of glass slab Use of t e m p l a t e Shaping biteplates Marking lower c a s t s Construction of modeling c o m p o u n d roll Sealing modeling c o m g o u n d t o baseplate Shaping modcling conipound biteplnte

(C) Related V ~ ~ c ~ ~ L i o1izfort~z~1lio11 tzol \' I I I O I I S tli,~tcrialsuqed f o r biteplates \/,~l.ir)lls tVT,CS I J ~temylatcs \ ' . I ~ ~ ~> I #I UI ~II S I ~ ) I \of ~ S making bitcplates

I.

z. 3. 4. 5.

( c ) I.aburalory 1'1acliria Construction oI base wax biteplates Construction of nlurlr,': c o m p o u n d biteplates Using t e m p l a t e Polishing w a x biteplatc:. Using biteplate formcr

I

Lnborolnry I~lstr~iction

( b ) Operulions jc) Laborulory Praclices Sctting articulntor in ccnI . Fncc bow transfrr t r i c occlusion 2. h l o m ~ t i l i gon :irlnptable arA d j i ~ s t i n gface bow ticul;itc~r Mountirig ilgper cast 3 . Ailjustir~gcolrdylc yatlls h l o u n t i n g lu\\er cast 4 . A d j ~ ~ s t i nir~cis:~l g ~~ii,l:~nr.r. Adjusting condyle ~ l n t h s . A d j ~ ~ s t ~i I~I C~I g S : ~~~ ~ ~ r i ~ l e ~ ~ i i i A d j r ~ s t i n ginrisal tnlilr

I.

.I.

2.

.3.

4. 5. 1 ~

7.

I1zfori7zatio11

((L)

I

(R) Tool?, dfaleriysi o r H a n a u ;xrtic~slntors I'laster bowl .i. I'lzister s p a t ~ ~ l . + I. 1'l;ister k ~ ~ i f e j . P a c e bow r > . l'lastcr ;. XVntcf $. \ ' a s r l ~ n ? (a)

I.

Advantages a n d disadvantages of materials Ingredients of m a t e r ~ a l s 3 Advantages a n d disadvantaces u i templates 1.

\

I

L.

r

( u ) K o ~ ~ ~ l i o nI naf lo r m r ~ l i o n Types ilt a
(bj S~rpplernenlory.Issignmrnls Xlethorls uf nsirrfi adjust:rl~le i i r t i ~ ~ ~ I : i t r > r s z. ~ I e t h i ~ r ili fs u s i l ~face ~ t,otvr; 3 . Yletlro~lsc l i tralisic,rru~ji con(1ylc rr.:irlil'gs I.

3.

11,

.\UI\I,YSIS OF U N I T NO. 9: hIORPHOLOG1' OF .\lITI1"ICIA\I. TI3ETTT ANALYSTS O F {'NIT NO. 8: ARTICULATING TECHNIC--I

(11j Proce, yes n n l l Job.\

( A ) l'rncesses and Jobs (11) l'rocess or Principlr r.,.1.5. I \ l < ~ ~ ~ [~~ t1i ns oxtn ~plairl line a n d m n v :!I,Ic iir111arliculdtors ,I. h l o ~ ~ n t ci dn c~r ~ t ~ i l o uc:isls s 1,. h l o l ~ ~ > ~t ~ i ~: i lr t~i ic:zsts tl

( h l. Proiecl - or Jobs So. 35. h l o u n t three s r t s of casts 011 ~l':,ir, artic~llators A , , . .iG. M o u n t f o n t s t t s of ~ ~ 1 on s t I!!,,~ . I .irm articul:rtr~rs SCI.. j 7 . M o u n t six r~;irtials o n n ~ o v ; ~ l , l, ~

( a ) Process or 1'r:nczPle

1,). 1 5 . hlurpl~ulogyol artifici:~l tcetli Nonienclature h. T o p u g r s p h y r . Identificntion

d.

(B) ( u ) Tools, M1zlerirzls lind IiquiPrnenl I.

l'f~~ic,il

2 . L1a1>cr ,r. S1.t of artifici;+l teeth I . ( ' : ~ r ~ l i z\V;IK ~g

, 1

, 8

I I I ~ ~ ~ : ~ ~ I I . 1.1, ~ ~i hIj ,~: , ~ ~ ~ : I I I I c

,C.Ctl.,ll~.

I,aborcl/ory I n s / r z r c l i o r ~

[ b ) Operalions Arrnnxing teeth z . Drawing of teeth 3 . Labcliny p a r t s of t e e t h 4. Recogniring i n d i r i d i ~ a l teeth

((11 V ~ C U ~ I OInfor?nnIiun ILU~ ' I ' V ~ N \ ,,I :~rtificixlteetli I\l,~mlillc*l tertll I t ~ 8,l ~
( b ) I'rojecl or J o h ~ Arrange teeth Label parts of tceth Recognition of i~ldividual

I.

(Cj 8

So. No. i i (1

( c ) Laboralory l'raclice~ Nomenclature of t c r t b 2 . Sequence of teeth 3. Rccognitiun I J ~tcctlr I.

Related Information ( b ) SuPPlemenL,rry A s s t g n t t ~ e n h C o n ~ p o s i t i o nof artificial tretlr Colors of t e e t h .i.Staining t c c t h . I . 'l'llror~rs ~ ~ n i l c r l \ ~ , , I, I:I O I I ~ I I C I I ~ > o * t c r l o l t~~~~t11 q . ~ ; r ; t ~ , l i ~,irttIi< ~ ~ : i . ~ lI , . ~ I ! I I.

2.

-

2 k W

$2

H

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0.

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(13) L a b o r u t o r y I n s t r ? ~ c r i o i i l < r ) Tools, l
. . stick

1,.

I'ij~lil~g cases 'rir~f<,iI 111!rnisl1i11~ j. F e ~ t u u n i n gtinfoil q . P u u r i n ~c u u n t e r s i l l 11.1~1. I.

Applying tinfoil 3. Burnishing tinfoil a. Use of orance\r.,,r,d stick fllr 2.

. I . 'l'infoil S o . bn or 40 i

1.

.

I. C u t t i ~ ~ tinfuii g

Suit brushwheel

I .

. Scissnrs ,i. Orangewood

Jd~llerials V u l ~ . a n i t es h e a r s P a c k i n g tools Tile s l a b Packing table Flask w r e ~ l r h P1:lstcr knifc Idinen c l v t l ~( H r ~ ; l a n dcuve r i n g r u l ~ l ~ schr e e t ) F l a s k press or clarnp F l a s k l ~ o l t sa n d n u t s Dental rubher Cc!lophane

2.

:211sorhent r o t t o i l 1)1ic0 glue

2.

.r.

4.

5. b.

i. S. I).

( C ) Relrrt(vf I ~ z f o r n z u l i o ~ r ( a ) T'oco1,onol fnJar,,rulion of tinfoil hl,,thods i l i a p p l y i n g fvil : I'ittcnted tini,iilers 1 . I1;ltented rugaes

. \ ' . ~ r ~ u ug sa u g r s

i

.\h.\T,YSIS

I.

lo. r I.

( b j Slrpplcnienrury Assip~l11it.111.~ 'l'infoil s u b s t i t u t e s (11)

j. Fc~ilin):tor d e n t u r e s othpr t h a n vulc;initi 4. L i q ~ ~ scparatlrig id mcdia

EI,IMIN.2TLC)N

r. 3. J.

5. h.

7. 8.

(C)

r . Uses o i d i f f c r r n t tinfili! g a u g c s

OE' UNIT NO. 14: \V.\X

( h ) Operalio~rs Cuttin%rubber Packing rubber T e s t i n g p a c k e d c;ises Using l i n e n s h e e t Using cellophane C l o s i n ~flasks Using flask presses Using flask c l a m ~ ~ s

I.

Kelulrd Infornzatioi~

I ~ O C ~ I / ~ O NInformulioti ~LI

M e t h o d s of cuttin:: d c l ~ t a ruhlier l :. h i e t h o d s vf packing dci1t:il r1111ber .i. Various flask presscs 4 . V:irii~us lacking t a b l c s ,, ,,Various ,?. .... d e n t u r e hases E S L ~ I J gate$" C advant;iges a n d disad, allt aces J " E s c a p c tr-ougl!" 1.

TECHSIC

( c ) Luboralory Prrri1i~r.s Packing vulcanite 2 . test in^ vulcanite cases 3 Using flask presses J. Cutting dental rubber I.

(b) S l r p p l e ~ ~ l e n l n r.4i~ignme,zls y C ~ ~ r n p o s i t i oof n dental r ~ r b h c r 2 . Properties of d e n t a l r u b h e r j. Origin of d e n t a l r u h h e r J. Composition of o t h e r d e n t u r e hascs 5 . Special rnLber uscd i n d c n t a l w o r k h . Soft vulcanized rtrL1bt.r 7 . h l a t e r i a l s u s e d for l i n i n c r a s t s I.

.\SALYSlS OF U K I T NO. 16: TTUl~CANIZXTIONTECHNIC Z'ro~elis or I ' r i ~ ~ c i p l e S , I .2 0 . 1Eliniinatiun i ~ ft r i a l d e n t u r e l ~ a s e n. W a s a n d I ~ a s e p l a t eeliniinatiun b. Opening of flasks c. P r e p a r i n g flask f u r gncki~,:: r l r r ~ t a l rubber

t h ) f'rojecl or .lobs

(li)

(R) .\f
I .

.. :. 1. \. 0.

; X

\,I.

1

(B)

fcj Lobor,~l,~r?I'r,,< t i , I . Boiling o u t casts 2 . Opening flasks .i.E l i i r ~ ~ n a t i nmelt< g ( I \ $ t L. 4 . C l c a n s i n ~d e n t u r c . , I c . t f,

. 1-~~lcanizer

I L.

J.

.t. j.

0.

7.

8.
l ~ o ( o l 1 ~ 1 1I ~ ~ 1J 1o r ~ n u ~ i o n \',IN iLo:. H I , , I l,,,
h1c.I l ~ o r l s, > I ~ , v c \ > : ~ r ricntrlr? i,~g sllncc. " I , : , , c . , I I , ~ . j:;~lcs'.

Jobs

( b ) Project or .lobs S o . 65. Vulcanize d e n t u r e h a s r s r r i t h o ~ ~Lcct!~ t Xo. 60. Vulcanize f o u r s c t s of full d c ~ i t u r c s Xo. 0;. Vulcanize six p a r t i a l d c n t u r e s

Equipmenl

(b) O p e r , ~ / i o n . ~ I . H r a t i n g flasks L . Opening flasks .i. l i e m o v i n ~wax 4 . K e r n o v i ~ ~baseplatc fi j . E l i m i n a t i n ~,\-ax : rennr;illt> 6. R e l ~ l a c i nlousc ~ teeth 7. Clcnnsing d r n t u r e s p a r e

P r o c e s s e s ulrd

Lclborutory Iizstrzictiot~

i o ) T o o l s , J l a l r r i i ~ l sond

y'OO/.\,

(,I)

I 1

(11 j f'ruces.i or I'rirzciplc,: 2 2 . V ~ ~ I t ~ : ~ ~ ide11t11res izing o . Using vu!c;i!~izer b. S a f e t y i~istruoticins r . C a r e of rulr:tnizcr (ul

T,nborc~toryI i i . x / r r ~ r t i o ~ ~

( C ) Kelnlril I

S o . 5 ' ~ . Eli,rlin:rte wax frrim 1111ppra1111 i i , \ r , t d r n t u r r L~nscsw i t h o u t t e e t h S o . 60. Eliniinatc w a r frorrl f o u r sets o i I . : ' dentures Sn. ( 1 1 . I%!iminatcwax froin siu p a r t i a l 11c111rir

1 ' 1 i l r a n i ~ r rt o n g s l'imt~-clock Thernirj~nctcr (;as regulator Vulcanizer p;lnkin): irin!: Manifold w i t h blou,-<>ff ;ind s a f e t y valves \l'rcnches Vulc. p o t lifting h a n d l e Water

Ii7fornzi1fio~i

( b ) Operolions I . Att;icliing a n d s r t t i n g tinlc1.

3

4. .j.

6. 7.

8.

cluck S c t t i n g g a s regulator O p e r a t ~ nblow-vff ~ valrt. C l o s i ~ i gv u l c i i n ~ z e r L i g h t i n g vulc. b u r n e r C a r e of thrrn2nmcter Opening vulcallizcr C a r c of vulcanizer

(C)

i b j .Suppirr?~t~t,/ur? .L.\.sitr~tt!r~~~/.~ I . W<,t ~11rthoc1 of n ; > x ~ ~ I i ~ , , i ~ ~ ; a t i c a ! ~ 3 . 1)ry n ~ c t t i n i ~ ~ : t t i c t ~ > 3. A v s I I : I : 1 , . g;rtcs 4. ( I l 8 c ~ ~ iI\,,! ~ l tk,: \ t i 1 1 1 t ~ ~ ~
'

( c ) Trlrrie I'ru
2.

accessories

Krlnlecl I n f o r r i ~ a f i o i z

( u ) T'occltioniii 1 n/orn!uliun r . l'y13.i~of r u l e a n i z c r s 2 . 131cxctricvulcanizer o p r r a t i o u i. I'ressure g a u g e s 1. \':~ri
( b ) S,upple~ncnlary .-lssijin?~~enls Vulcanizing processes 2 . Vulcanizing I~henol-form;ilr3rhy~le resills 3 . T r m p c m t u r e a n d s t e a n i press~ll-e ril:lti',lrsI7i11s I.

.I\ \I,PSIS OF KNIT 90. 1 7 : \7LrL('A\NlTE T)ENTUKE CI,I.:L\NSIIUG TECHNIC

\ ( , .

, i .I < (

l ' r , , r c , \ \ ur l'ri,~c.iple 1111>~:11 1,i \ i ~ l c . i ~ ~ I~~ Ci I~I IeI ~ I I lI - r; r t l l l l

I b ) J'rt~je~lor .lob$ X,.). 118. O ~ C I flasks I a11d c l c i ~ n s rt.40 d c i ~ ~ t l i r e

APPENDIX I1

( B ) Laboratory Instruction (a) Tods. Materials and Equipment I. Plaster knife 2. Hand brush 3. Soap A. Water

( B ) Laboratory Instruction (c) Laboratory Practices

(b) Ogerations

(a) Tools. Materials and Equipmenl I. Dental lathe

flasks

4. Removal of tinfoil

5. Care of flask

7. Glass tray 8. Pumice (xxx)

9. 'Ifipoli

(C) Related Information (a) Vocational Information I. Methods of opening flasks 2. Methods of removing dentures from flasks 3. Methods of cleansing dentures 4. Methods of removing tinfoil 5. Methods of removing from flasks dentures of materials other than vulcanite

(b) Supplemenfary Assignments I. Properties of vulcanite 2. 'Optimum vulcanization 3. Comparison of vulcanite and other denture base materials 4. Compounds for cleansing dentures

ANALYSIS OF UNIT NO. 18: DENTURE TRIMMING TECHNIC ( A ) Processes and Jobs (a) Process or Principle No. 24. Trimmine vulcanite dentures a. Establishing denture limits b. Use of various trimming tools

(b) Prqecl or Jobs Job. No. 71. Trim 2 vulcanite denture bases ob. No. 72. Trim 8 full vulcanite dentures ob. No. 73. Trim 6 vulcanite partial dentures

10. Chalk 1 I. Oxide of tin 12. Water 13. A I C O ~ O I 14. Soap IS. Denture brush 16. Mineral oil

z. Lathe 3. Dustpan for lathe 4. Rat-tail file s. Half-round file 6. Abrasive bands 7. Sandpaper wheels 8. Lathe chuck 9. Bur chuck 10. Mandrels I I. Vulcanite burs rz. Vulcanite chisels 13. Vulcanite scrapers 14. Burlew abras~vewheels 15. Sandpaper

(b) Operations I. Use of files 2. Use of sandpaper wheels 3. Use of scrapers 4. Use of chisels 5. Use of sandpaper 6. Mounting chucks 7. Use of burs

(c) Laboratory PracliCes I . Filing dentures z. Scraping dentures 3. Festooning teeth 4. Sandpapering dentures 5 . Finishing dentures

(C) Related Information I.

2. 3.

4.

5.

(a) Vocational Informalion Various methods of trimming dentures Various abrasive wheels Advantages of vulcanlte files A d v a n t a ~ c sof sandpaper Determining denture I l m ~ t s

(b) SupPlemenlary Assignments I. Shrcypening of cutting tools

2. Vanous methods of trimming denture pcriphery 3. Methods of using combined trimming and

pol~shlngwheels 4. Operation of various chucks

ANALYSIS OF UNIT NO. 19: DENTURE POLISHING TECHNIC ( A ) Processes and Jobs No. 25. a. b. c.

(a) Process or Principle Polishing vulcanite,dentures Operation of pollsh~ngapparatus Use of polishjng materials Use of polish~ngtools

(b) Project or Jobs No. 74. Polish two vulcanite denture bi~scs No. 7 5 Polish ejght fu!l dentures No. 76. Polish SIX p a r t ~ a ldentures

(b) Operations I. Mounting wheels 2. Mounting chucks on lathe 3. Using umice 4. Using Fripoli 5. Using chalk 6. Pollshlng denture 7. Holding denture during polishing 8. Cleansing polished dentures

(c) Laboratory Practices Applying pumice on dentures 2. Applying Tripoli 3. Removal of rough trimming marks 4. Solarizing rubber 1.

(C) Related Information (a) Vocalional Information I . Types of polishing machines 2. Types of polish~ngwheels 3. Types of polishing materials 4. Methods of polishing

1.

2. 3. 4.

5. 6.

ANALYSIS OF UNIT NO.

. . Su*plementary (bl Assignments Composjtjon of different poliHhing media Com~qsltlonof pumice Ingred~entsof Tripoli Action.of chalk Ingfedlents of pther polishing materials Action of solarlzat~onon vulcanite

DENTURE REPAIR TECHN'IC ( A ) Processes and Jobs

( B ) Laboratory Instruction (a) Tools. Equipment and Materials

3I 9

APPENDIX I1

No. 26. a. b. c. d. e.

20:

(a) Process or Principle Repairing vulcanite dentures Simple repairs Repairs involving teeth and clasps Replacement of new palate Replacement of gum rubber Replacement of entire denture base

(b) Prq.ed or Jobs Repair of simple fracture Tooth repair Clasp repair Rebase palate 81. a s r "gum" rubber --. R - -e-h- -82. Replace a denture base

No. 77. 78. 79. 80.

-

(B) Laboratory Instruction (a) Tools. Equipment and Materials I. Plaster bowl 2. Plaster knife 3. Plaster spatula 4. Plaster 5 . Water 6. Bunsen burner 7. Wax spatula 8. Base wax 0. Stickv wax 16. Artic;lat& I I. Dental rubber 12. Vulcanizer 13. Pumice 14. Felt cones IS. Polishina wheels 16. Glass slab 17. Penkn~fe 18. Scrapers 19. Petrolatum 20. Chalk zr. Flask

(b) . . Operalions broken denture 2. Pouring matrix 3 . Gnndigg broken denture 4. Flasking repalrs 5. Packing repairs 6. Trtmm~ngrepairs 7. Polishing repairs 8. Pouring index 9. Removlng teeth from denture 10. Waxing teeth t o denture 11. Cold packing 12. Clasp repairtng I. Assembling

(c) Laboratory Practices I. Assembling repairs 2. Pouring matrix 3. Articulatinn dentures

4. Dovetailing 5. Flasking repairs 6. Packing plastic rubber 7. Removing teeth from dentures 8. Clasp repairs 9. Duplicating dentures

( C ) Related Information (a) vocational Information I. Repair of denture bases other than vulcanite 2. Methods of flasking 3. Methods of packlng 4. Methods of removing teeth from dentures

(bl SubDlemcnfary Assignments

indi din te;ih 2. Klnds of rubber used for repairs I.

3. Rebasing

4. Methods of adding clas s 5. Methods of adding t e e 8

APPENDIX I11 GLOSSARY A ABRASIVE (ab-ra'siv). Substance containing sharp particles, used to render a surface smooth, an abradant such as emery, carborundum, etc. .4BUTMENT (a-but'ment). A tooth used as a support or anchorage for a bridge or other prosthetic appliance, a solid support. .kCCELERATOR (ak-sel'e-ra-tor). T h a t which hastens action ; as the use of sodium chloride (table salt) in the setting of plaster. ADAPTABLE (a-dapt'a-bl) , or ADJUSTABLE (ad-just'a-bl). Articulator that permits adjustment of extension arms to which casts are attached to simulate movements of the mandible. ADHESIVE (ad-he'siv). Sticky, such as wax used to unite parts. AGAR-AGAR (agl-ar-ag'-ar). A gelatinous substance made from seaweeds. .4LPHA GYPSUM (al'pha gyp'sum) Nonporous crystals of plaster of Paris used in quick setting stones for dental casts, etc. ALUM (a1'-urn). Combination of sulfate of aluminum, manganese, chromium and other non-alkaline metals with sulfate of potassium, sodium and other alkalinc metals. An accelerator of plaster of Paris. 4LUMINUM (a-lo'-min-um). A silver-white, light, non-tarnishing metal of brilliant luster. ALVEOLAR RIDGES (al-ve'-o-lar) . T h e raised rounded arches surrounding the palate and on the lower jaw, covered with gum tissue and formerly contained the roots of the natural teeth.

.

I

ALVEOLAR TISSUE (tish'oo). The structure (gum) covering the ridge formerly mntaining the of the teeth. ALVEOLO-BUCCAL FOLD. T h e fold formed between the alveolar ridge and the cheek, covered by gum tissue. AMALGAM (am-al'-gam). A plastic metallic dental material may contain silver, zinc, tin, in addition to merANATOMIC (an-at-om'-ik). Pertaining to anatomy, the science of structure of organisms. ANATOMIC LANDMARKS. Marks serving as guides, as in denture construction, when located on the gums or palate. ANATOMICAL ARTICULATOR (artik'-u-la-tor.) See adaptable or adjustable articulator. ANATOMY (an-at'-o-me) T h e science of the structure of organisms, their parts and relations one to another. ANTERIOR (an-te'-re-or). Situated in front. A term commonly used to denote the incisor and cuspid teeth. ANTERO-POSTERIOR (an-te'-ro poste'-re-or). In a direction from the front to the rear. ANTIMONY. A silver-white, hard, crystalline, metallic element used in chemistry, medicine, and in the arts. APPROXIMATE SPACES (ap-prok'sim-ate). Spaces (the gum) between two adjacent teeth. ARRANGING ARTIFICIAL T E E T H . T h e setting of artificial teeth on the denture base over the alveolar ridge. ART-BASE FORM. A form following the outline of a n artistically constructed base of a dental cast.

321

.

GLOSSARY

A R T CLAY. A n earthy substance used for modeling purposes. ARTICULATOR (ar-tik'-u-la-tor) A mechanism for holding in correct anatomical relationship the casts of the uDper and lower jaws when arrangiAg artificial teeth: ARTICULATOR EXTENSION ARMS. T h e Darts to which the casts are attached when mounted on the articulator. ARTICULATOR SET-SCREW. T h e screw which holds the extension arms of the articulator apart a t any desired distance. ARTIFICIAL STONE. Plastic stonelike material used in making dental casts. ARTIFIClAL T E E T H (ar-te-fish'al). Teeth made of porcelain in form, color and texture to imitate the natural organs; contain silica, feldspar and quartz. ARTISANS. Skilled hand workers. ASSEMBLING IMPRESSIONS. Fitting together broken parts of plaster im~ressions. A ~ I A L(aksJ-e-al). Pertaining to the axis; the long or vertical dimension of a tooth.

.

BALANCED ARTICULATION (bal'anst ar-tik-u-la'-shun). T h e placing of porcelain teeth on a denture base in a manner to render the denture stable or stationary when used in eating or speaking. BASE O F CAST (kast). T h e part beyond that formed by the impression taken from the gums and palate. BASE. OF DENTURE (den'-chur). T h e portion of an artificial denture which covers the roof of the mouth or ridge of the mandible to which artificial teeth are attached. BASEPLATE (bad-plat) A temporary form of wax or compound to represent the plate or base of a denture. BASEPLATES W I T H LAPPED MARGINS. Temporary denture forms with the margins turned over on the baseplate around the limits of the denture bearing area.

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GLOSSARY

BASEPLATES W I T H T R I M M E D MARGINS. T h e margins a t the limits of the denture bearing area are cut or filed away. BASEWAX. A wax used for baseplates or temporary bases for dentures. BEESWAX (bez'waks). W a x secreted by bees when constructing the honeycomb. BENCH-BLOCK. A wood o r rubber extension on the work-bench used for supporting the hands o r the dental cast while working. BERNARD PLIERS. A pincher type instrument used for holding and cutting metals. BEVEL (bed-el). T h e slope of a surface from the horizontal or vertical; an angle less than a right angle which leads to the cutting edge of tools. BICUSPID ( b i - k ~ s ' - ~ i d ) .A tooth having two cusps. There are eight in the human or artificial set. They are placed two on each side of a set of teeth between the cuspid and first molar. They are designated as the first, second, right, left, upper or lower. B I T E (bit). T h e forcible closure of the lower against the upper teeth. A wax impression of the relationship of teeth when in occlusion or contact. BITEMARKS. T h e impressions left by the teeth in wax or oiher mzterial. BITEPLATES (bit'-plites) Rims C O ~ I structed over the alveolar ridges o f dental casts, used by the dentist to obtain the relationship of one jaw to the other; used by the technician a s an aid in arranging teeth. BLEEDING (bleed'-ing) Loss of blood. I n artificial dentures, whc.11 the brown or base rubber show^ through the pink or gum rubber after vulcanization. BLOW-OFF VALVE (valv) Tl~c valve on the vulcanizer cover used 10 allow a i r to escape before closing t l ~ r vulcanizer and to eliminate the Yt(.illll in the vulcanizer pot after the vtrl canization process is completed. BLOWTORCH. A blowpipe: 1\11 i r l strument by which compressed nir i n blown through the flame, used for IIIR ing o r soldering.

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BOILING O U T WAX. Boiling out the trial denture base before packing permanent denture base material. BOXING. Arranging a retaining wall around a dental impression. BOXING IMPRESSIONS. Arranging a retaining box or wall around the outside of dental impressions to hold the cast material in position until it sets o r hardens. BRASS. A n alloy of copper and zinc, having varying proportions, but containing usually 6 ~ 7 5 % of copper. BRIDGE (brij). I n dentistry, a fixed or removable prosthetic appliance made of metal or porcelain which replaces lost teeth. BRIDGEWORK (brij'wurk). I n dentistry, an appliance supplying artificial teeth attached o r supported by natural teeth. T h e construction of dental bridges. BRITANNIA METAL. A n alloy containing tin, 82%; antimony, 12%; zinc, 2.5%; copper, 2%; bismuth, 1.5%. BROWN-SHARPE G A U G E (gige). A gauge plate or measure used to determine the thickness of wire o r metal plate. BUCCAL (buk'-al). Pertaining to the cheek; the surface toward or facing the cheek. B UCCO-LABIAL. Pertaining to the cheek and l i ~ s . BUFFING A ~ E N T . A material used for buffing or fine polishing; to obtain a luster o r gloss. BUNSEN BURNER (bun*-sen). A gas burner generating a high degree of heat, due to complete oxidation of gas and air, admitted through an opening in the metal burner, before ignition. BUR. A small rotary excavating instrument of steel for cutting tooth structure, metal, cement, etc., operated in the dental engine or lathe. BURNISHING. Polishing by friction. Burnishing tinfoil in order to adapt it to cast or trial denture before flasking. B U T T E D T E E T H . Teeth supported or set directly against the alveolar process, a denture without labial gum.

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CALCIUM SULPHATE (kal'-se-um su1'-flt). (See Plaster of Paris.) CaSO,, gypsum. CALIPER (kal'-ip-er). A pair of compasses with curved legs used to measure the thickness, diameter, or bore of a solid object o r tube. CANINE (ka-nin). T h e third tooth from the median line of the dental arch; the cuspid. There are four canines in the human or artificial dentition. CAOUTCHOUC (koo'-chook). The whitish exudate (elastic) obtained from several tropical trees of South America and Africa. CARBON TETRACHLORIDE (carbona). A cleaning fluid. CARBORUNDUM (kar-bo-runJ-dum). An abrasive; a synthetic carbide of silicon. CARDING WAX. A black wax used for boxing impressions and for displaying artificial teeth. CARIES (ka'-reEz). Decay of teeth; cavities are formed by the gradual destruction of enamel and dentin. CARMICHAEL (kar'-mi-kl). A type of partial cast gold cap o r crown consisting of a hood covering the prepared lingual, proximal and occlusal sides of the natural tooth. Named after . . J. P. Carmichael, an American dentist. CARVING KNIVES. Instruments used for modelling, sculpturing, carving or trimming. CASTING (kas'-ting). T h e process by which a molten substance notably metal, is poured into a mold. CASTING MACHINE (kas'-ting masheen). A n instrument used for casting (see casting). CASTING MAN. A dental laboratory technician who specialized in making cast dentures. CAST P L A S T E R Plaster of Paris used for pouring impressions to construct dental casts or counters. CELLOPHANE (sel'o-fin). A white transparent cellulose product used in sheets for wrapping and other purposes.

324

GLOI

GLOSSARY

CELLULOSE (se1'-u-10s). A carbohydrate, chief constituent of vegetable membranes, cotton fiber and chemical filter paper. CEMENTUM (se-ment'um). T h e bony layer which covers the roots of the teeth. CENTRIC OCCLUSION (sen'-trik okloof-zjon). T h e relation of the inclined planes of the teeth when the jaws are closed and a t rest. CERAMICS (se-ram1-iks) . Porcelain; the art of making porcelain substitutes for the replacement of teeth and parts of teeth. CERVICAL (ser'vik-al). Pertaining to the neck or constricted part of an organ, as of a tooth. CHALK (chawk) Calcium carbonate; a white insoluble earth; used as a polishing agent. CHISEL (chiz'-el). A n instrument used in dentistry for cutting, shaping and trimming. CHUCK. (See Lathe Chuck.) CITRIC ACID (sitt-rik). A sour tasting substance derived from citrus fruits. CLASP (klasp). A partial band or loop of spring metal, of alloyed gold or steel, fitted to grasp the sides of a tooth. CLASPED T O O T H . A tooth on which a clasp is fitted. (See Clasp.) COBALT-CHROMIUM ALLOYS (ko'balt kr6'mi-um). Stainless (silvery) metal used for denture bases. COLD PACKING. Inserting a plastic mixture of dental rubber to repair dentures. COLLAR O F T O O T H . T h e porcelain extension a t the gum line or cervix of an artificial tooth. COLLODION (ko-lo'-di-un) . A preparation of soluble gun-cotton with ether. COLLOIDAL IMPRESSIONS (kol-oid'al). Dental impressions taken with a colloidal, elastic material which contains gelatin, agar-agar, chalk and coloring material. A glue-like or jelly-like substance. COMPENSATING CURVE. An imaginary line in contact with the tips of the buccal cusps of the bicuspitla,

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and molars extending to the condyles of the lower jaw. COMPENSATING PLANE. A curved plane which bisects the crests of the upper and lower alveolar ridges. COMPOUND (kom'-pound). A mixture composed of two or more ingredients. Dental compounds or modelling compound, an impression material containing chalk, stearin, gum and coloring material. CONDYLE (kon'-dil) A rounded eminence or protuberance a t the articular extremity of a bone. T h e rounded end of the mandible which articulates with the skull. CONDYLE BARS. T h e extensions on the Snow face-bow which fit on .the condyle tips of adaptable articulators. CONDYLE PATHS. T h e path followed by the mandibular condyle during opening and closing of the mandible. I n an adaptable articulator slots are provided to establish the condyle paths. CONDYLE READINGS. Notations indicating the degrees of condylar inclination in opening and closing thc lower jaw. CONE CHUCK. (See Chuck.) A conical shaped chuck. CONTOURING (kon'-toor-ing). Thc restoration of lost form. CONTOURING PLIERS. Pliers having specially formed beaks for bendi~lg and shaping mire and sheet metal. CONVECTION. Transmission of he:~t in liquids o r gases by heated particles below rising and cold particles abovc descending and in turn becomi~lc heated. CORUNDUM. An abrasive; a hn~cl crystalline aluminum oxide. COUNTER. T h e opposite of an i n pression; the dental cast obtained I I ~ filling a dental impression with a ~ I : I terial which hardens or sets ant1 I V tains its shape whcn the imprcsait,~~ is removed from it. CRES'V OF CONDYLE. T h c Iliglic.~f point on thc contlylc. (:IZICS'L' OF RIDGI?. 'I'hc r~ppcr ctll:c. or sllmmit of a ritlgc of tiwar~c-. ' I ' l l ( highcnt point on t l l i elveolnr ritlg(..

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CROSS-BAR BOLT. T h e bolt used to stabilize the bar which fits across the cover of the vulcanizer. CROSS-BAR NUT. T h e nut which tightens the cross-bar bolt of the vulcanizer. CROWN (krown). T h a t part of a tooth which is covered with enamel and normally projects beyond the gum line. T h e part of an artificial tooth that projects from the denture base. A meltingCRUCIBLE (kroo'si-bl) pot for metals. CRUDE RUBBER. Unrefined rubber as shipped after the rubber sap is coagulated by boiling. CRUSHING STRENGTH. T h e ability of a substance to withstand a load or pressure before being crushed. C R Y S T A L L I Z A T I O N (kris'tal-izashun'). Forming crystals or a crystalline structure. CURVE O F SPEE. An imaginary curve passing through the condyles and the cusps of the teeth ending at the incisal edges of the lower central incisors. CUSP (kusp). A pointed or rounded elevation on or near the masticating surface of a tooth which is designed to occlude in the sulcus of the antagonizing tooth of the opposite dental arch.

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DABBING (dab'-bing) Striking gently, pecking. DAVIES PROCESS D E N T U R E BASES. A moldable metal base is used. T h e denture is tinfoiled, flasked, packed with dentaI rubber and vulcanized a t a lower temperature (288" F.) for five hours. DECIDUOUS T E E T H (de-sidf-u-us) T h e first set of teeth in the infant which are gradually displaced beginning at about six years of age and ending a t about thirteen years of age. DENTAL ARCH (artsh). T h e curve formed by the teeth in position. DENTAL IMPRESSION (see Impression). T h e negative left by the dental tissues in a plastic material such as plaster o r modelling compound.

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DENTAL LABORATORY (lab'-or-ator-e). A workship o r place where inlays, crowns, plates, bridges and other artificial dental appliances are made. DENTAL MECHANICS (me-kan*-iks) T h e art which deals with the construction of dental prosthetic appliances. DENTAL PLATE. A denture; an artificial or prosthetic appliance to provide artificial teeth when the natural teeth are lost. DENTAL RUBBER. A combination of rubber, sulphur and coloring matter. DENTAL TECHNICIAN. A skilled artisan of dental prosthetic appliances. DENTIN (denf-tgn). T h e osseous tissue forming the body of a tooth, underlying the cementum and the enamel. D E N T I S T (den1-tist). One who practices dentistry. A doctor of dental surgery: a D.D.S. or D.M.D. DENTOCOLL (den-to-col) A colloidal impression material used in dentistry. DENTURE BEARING AREA. T h.-. e area which is covered by an artificial denture or plate. DENTURE FLASK. A box-like metal frame, usually consists of a base, a counter and a cover, used for investing or holding dentures during vulcanizing process. DENTURE LIMITS. T h e boundary beyond which the artificial denture is not extended. DENTURE SPACE. T h e space left after the trial denture base has been eliminated before the permanent denture base material, such as vulcanite, is inserted. DENTURE (den'chur) . T h e entire set of teeth, whether adult or deciduous. A name applied to a dental artificial appliance which rests on a base and can be removed from the mouth by the person wearing it. DIATORIC T E E T H (di'-a-tor-ik) Teeth having a recessed opening in the shut or tissue surface in which rubber is packed. DISTAL. Pertaining to the surface away from the median line. DISTO-BUCCAL. Pertaining to the surface facing away from the median line and toward the cheek.

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DISTO-INCISAL (dis'to-in-sip-zal). A designation used for a surface or angle of a tooth which is at the incisal edge and faces away from the median line of the dental arch. DOVETAIL. A flaring anchorage form in a tooth cavity locking in place a filling or inlay. A flaring cut to hold the new vulcanite in repairing dentures. DUPLICATING CASTS. Making duplicates of dental casts. A n impression of the original cast is made with a colloid of elastic material and a cast is poured. DUST-PAN. A receptacle for abrasive material used in trimming and polishing metals on dental lathes.

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EDENTULOUS (e-den'-tu-lus) Toothless. ,EDENTULOUS CAST. Cast of a mouth without teeth. E D G I N G WIRE. Reenforcing wire used on baseplate and base wax in making trial denture bases. ELASTICITY (e-las-tis'-it-e). The quality of being elastic or stretchable. EMBRASURES (em-bra'-zhurs). The spaces between adjacent teeth, covered by gum tissue. ENAMEL (-am'el). T h e dense white substance of the teeth. ESCAPE GATES. Grooves in the plaster of a flasked denture to allow excess rubber to escape. ESCAPE TROUGH. A concentric groove in the plaster around the flasked denture. E S T H E T I C (es-thet'-ik). I n accord with the principles of harmony in form and outline. EXCURSIONS O F CONDYLE. T h e range of movement of the condyle. EXCURSIONS O F MANDIBLE. Range of movement of the lower jaw. EXODONTIST (eks-o-don'-tist). A specialist in extracting teeth. EXPANSION (eks-pan'-shun) The process of widening. EXTENSION ARMS O F ARTICULA'TOR. T h e projections of the articula-

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327

GLOSSARY

GLC

tor to which the casts are attached when mounted on the articulator. EXTRACTION (eks-trak'-shun). T h e surgical removal of a tooth from its alveolar socket.

FLASK CLAMP. A clamp used for holding together the parts of a flask. FLASKING (flask'-ing). T h e process of investing a trial denture in plaster within a metal flask. FLASK PRESS. Apparatus used for pressing packed rubber into the denture space of the flasked case. FLINT. A variety of quartz. FORMALDEHYDE ( for-mal'de-hid) A disinfectant and antiseptic. FOSSA (fosl-ah). A shallow depression, concavity or hollow on the occlusal or chewing &face of a tooth. The FRACTURE EDGE (frak'-chur) edge along which any substance has been broken. FRENCH CHALK (chawk). Talcum powder. FRENUM (fret-num). A membranous fold which joins two parts and restricts the individual movement of each. I n the mouth it is a fold of gum tissue extending from the lip or cheek to the alveolar ridge. FUNCTIONAL STRESS. T h e pressure exerted on a denture during use, as when chewing food. FUNCTIONAL (funk'-shun-al) Pertaining to or affecting use.

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FACE BOW ADAPTOR LUGS. T h e extensions at the condyles of the articulator on which the face bow is adapted in mounting the casts. FACE BOW. A mechanical device to record the relationship between the alveolar ridges of the upper and lower jaws and the temporomandibular joints and to insure reproduction of this relationship on an articulator. FACE-BOW TRANSFERENCE. Transfering the face bow measurements and relationship from the face to an articulator. FAHRENHEIT (fah-ren-hit). The series of graduations on the Fahrenheit thermometer upon which the boiling point of water is designated as 21z0 and the freezing point is 3z0. FELDSPAR (fe1d'-spar) A crystalline silicate of aluminum and potassium or aluminum, potassium and sodium, one of the important ingredients of the porcelain body of mineral artificial teeth. FESTOONING (fes-toon'-ing) The shaping of the interproximal gum rubber which fills the buccal and lingual embrasures, following the cervical curves of the teeth at the interproximal space. FINAL SET. When plaster or stone reaches the maximum hardness. FINISHER. Any implement, material or instrument used in finishing a filling, denture, bridge, etc. A dental technician who specializes in trimming dentures before polishing. FISSURE (fishf-ur). A deep ditch or cleft as on the occlusal or chewing surface of a tooth. FLAMING T H E WAX. Passing a fine blue flame quickly over a waxed surface in order to make it smooth.

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G U M DAMMAR (dam'-ar). A resin derived from pinaceous plants of the genus Dammara. G U M LINE. T h e line formed by the gum around the necks of the teeth. G U M SECTIONS. Artificial teeth with porcelain extensions which make up the gum portion of the denture. G U M VULCANITE. Dental Rubber used for the gum portion of a denture, after it is vulcanized. GUMS. T h e dense, coral pink, fibrous tissue which covers the alveolar processes of upper and lower jaws and invests the necks of the teeth. G U T T A PERCHA (gut-ah per'-tchah). A tenacious gumlike material obtained from the thick milky juice of various Malaysian trees. GYPSUM (jip'-sum) Hydrous calcium sulfate. Plaster of Paris. GYSI (geesee). A Swiss dentist, inventor of Gysi adaptable articulator. GYSI ARTICULATOR. An adaptable articulator invented by Dr. Gysi.

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GINGIVAL (jin'-jiv-al). Pertaining to or affecting the gingivae or gum around the neck of the tooth or teeth. GOLD. A bright yellow, lustrous, soft, malleable, tenacious, metal usually found uncombined, but mixed with various impurities. GOLD CAP. A crown made of gold, shaped to reproduce and fit over a natural tooth. G R A P H I T E P A C K I N G (graf'-it) A black lead ring which fits into a depression around the edge, under the cover of the vulcanizer and makes a tight seal with the vulcanizer pot when the cover is adjusted on it. GRINDING STONES. Abrasive stones made of carborundum or corundum. GROOVE (groov) A developmental linear depression or furrow in a tooth surface.

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HALF-ROUND VULCANITE FILE. A double-ended file, half round in shape with coarse teeth generally used for reducing vulcanite dentures. HANAU (hanow). A n engineer of Buffalo, N. Y., invented the Hanau adaptable articulator. HARD AREAS. T h e parts of the palate or alveolar ridges where the bone is close to the surface. HARD W A X W a x containing a high percentage of rosin or a hydrocarbon which does not melt readily and hardens on chilling. HASTENER. (See accelerator). HEEL. T h e posterior part of the alveolar ridge on the dental casts. HOLLAND. T h e cotton cloth in which sheets of rubber are placed when manufactured to keep them from sticking together. HORSESHOE DENTURES. Partial upper dentures in which the vulcanite of the palate is omitted at the center; suggesting a horseshoe.

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IMPRESSION (im-presh'-un). T h e impressed reverse o r negative of the surface of any object in a plastic substance. A s an imoression of the pums in plaster of Paris. IMPRESSION PLASTER (im-preshu n ) . Strong but quick setting plaster of Paris particularly adapted to taki n g impressions. INCISAL (in-si'-zal). T h e cutting edge of a tooth. INCISOR GUIDXNCE PIN. A pin of an adaptable articulator which guides the arrangement of the incisal edges of the teeth. I N I T I A L S E T (in-ishf-al). Pertaining to the beginning or first stage of hardening of plaster or stone. INLAY (inf-IS). A cast dental filling, shaped to the form of a cavity and secured therein by cementation. INLAY MAN. A technician who specializes in construction of inlays. F A C I N G S. INTERCHANGEABLE Porcelain teeth used chiefly in bridgework, so constructed as to be easily replaced when broken. I N T E R D I G I T A T E . T o interlock. I N T E R P R O X I M A T E SPACE (in-terprok'-sim-at). T h e space between adjoining teeth, covered by gum. INVESTMENT. A material or process of enveloping or embedding. I N V E S T M E N T MATERIAL. A material used for embedding a denture for flasking or an inlay or metal denture for casting.

KAURI. A resin used in compound and sticky wax.

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J A W RELATIONSHIP. T h e relationship of the jaws to one another and to the condyles of the mandible. J U M P I N G T H E B I T E . A process of retaining the tooth relation to the jaw when substituting new denture base. An index is used to preserve the relationship of the teeth to the gums.

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KAOLIN (ka'o-lin) A hydrous silicate for china or porcelain.

329

GLOSSARY

GLOSSARY

LABIAL (la'-be-al). Pertaining to the lips. LABIO-AXIAL R I D G E O F CUSPID. T h e line on the canine tooth which divides the labial surface into mesial o r labial and distal or buccal parts. LANDMARK. A fixed mark which limits an area. LATEX. A milky fluid, the natural rubber usually kept in a state of solution in ammonia. L A T H E CHUCK. A device which fits over or on the end of the spindle of a dental lathe and holds a wheel used for abrasive or polishing purposes. LABORATORY BENCH. T h e workbench or work-table used in the dental laboratory. LATERAL MOVEMENT. Sidewise movement. A machine for uroL A T H E (15th). ~, ducing rotary motion, propelled' by electricity. LINE-ANGLE. T h a t formed bv two surfaces, as mesial. and buccal, the junction being called mesiobuccal angle. L I N G U A L A S P E C T O F ALVEOLAR RIDGE. T h e surface of the ridge facing toward the tongue. L I N G U A L BAR DENTURE. A narrow, usually half-round gold bar running across the inner anterior surface of the mandihle, beneath the tip of the tongue, connected with saddles of n partial denture. LINGUAL SPACE. T h e space occupietl by the tongue usually a part of the lower cast. L I N G U A L (ling1-gwal). Next to or toward the tongue. L I N G U A L SURFACE. T h e surfacc particularly of a tooth, which is nearest to the tongue. LINGUO-BUCCAL. I n :I tlircctio~~ from the cheek to the t o ~ ~ g u c . LONG AXIS o l tlic tooth. 'I'lie I:CIIII.:I~ lengthwise line, thro11g11 cro\rfn : I I I ~ ~ root.

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MANDIBLE (mand'-dib-1) T h e lower jaw bone. MANDIBULAR (man-dibl-u-lar). Pertaining to or affecting the mandible. MANDRELS. A shank or spindle designed to fit a lathehead or dental engine handpiece, for the purpose of carrying a revolving instrument, such a s a brush wheel, stone or bur. -O VALVE A N D SAFETY VALVE. T h e attachment on the cover of the vulcanizer to which are attached the blow-off valve and safety valve. M A S T I C (mas1-tik). A resinous exudation obtained from the lentisk. M A T R I X (ma'-triks) Used to denote the cast poured into a denture to be .repaired. T h e space left in the flask after the trial denture base is eliminated and into which the permanent denture material is packed. MECHANICAL D E N T I S T R Y (mekanl-ik-al). T h a t branch of dentistry which includes the construction of artificial dentures, crowns, bridges, gold inlays, etc. MECHANICAL SPATULATORS. Devices used for mixing water with plaster of Paris or artificial stone. MECHANICAL VIBRATOR (vi'-brator'). A device or apparatus used to produce vibrations in placing mixed stone into dental impressions. M E D I A N LINE. T h e vertical, central line dividing the body or the jaws or dentures into right and left. M E D I A N SUTUEE. T h e middle line of the palate in a n antero-posterior direction. M E D I C I N E (medl-is-in). T h e science of the treatment and prevention of disease. T o w a r d the MESIAL (me'ze-al). median line or situated in the middle. MESIAL INCLINE. T h e leaning of a tooth or surface of a cusp facing mesinlly. ,MESIAL SLANT. T h e incisal edge of n cuspitl or bicuspid which faces ~ o w n r t lthe median line.

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MESIO-DISTALLY. In a distal direction from the median line. MESlO-INCISAL. T o w a r d the cutting edge and the median line. M E T A L BASES. T h e foundation or support of a denture made of gold, platinum, aluminum, steel or other metal. METALLURGY (met1-al-ur'-je). T h e science which treats of the properties and uses of metals and their refinement from natural ores. MILLIMETER RULER. A measuring instrument divided into thousandths of

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-.-a.

MODELING COMPOUND. A preparation which may be softened by dry or moist heat and which becomes rigid on cooling, used for impressions and biteplates. M O D I F I E D T E E T H . Porcelain teeth that have been changed anatomically to increase their stability. MOLAR (mo'lar). A grinding tooth, with multicuspid crown. T h e r e are twelve molars in the natural set, three on each side of each jaw. There are only eight molars in an artificial set, the third molars are omitted. MORPHOLOGY O F ARTIFICIAL T E E T H . T h e study of the shapes of artificial teeth. M O R T A R (mor'-ter). A strong bowl in which substances are crushed or rubbed by means of a pestle. MOULD-GUIDE. A set of forms of various sizes and shapes of artificial teeth. MOULD O F T E E T H . T h e shapes of the teeth. M O U T H . T h e entrance to the alimentary canal which extends from the lips to the pharynx. M O U N T I N G . T h e arrangement of a dental model, die, impression, etc., on a suitable support, or on an investment in order that i t may be observed, studied or worked upon. M O U N T I N G ON ARTICULATOR. T h e setting up or act of attaching casts t o an articulator. MUSCULAR A T T A C H M E N T S . T h e points to which the must:les are joined to the bones.

GLOSSARY

330

PALATAL BAR DENTURES. A metal bar constructed or cast to fit the surNECKS O F PLASTER T E E T H . T h e face of the palate and connecting two ginvival outline of the teeth on casts lateral sections of a denture. of partially edentulous mouths. PALATE. T h e roof of the upper jaw. NICKEL (nik'l). A greyish white, malPALM GRIP. Holding the instrument, leable and ductile metal. Ni. as a chisel, scraper or carver in the NOMENCLATURE. T h e method of palm of the hand; the thumb is used naming or designating objects. as a guide. A white, PARAFFIN (par'-af-in). tasteless, odorless, waxy, translucent 0 hydrocarbon. PARTIAL DENTAL CASTS. Casts or models of jaws from which only some OCCLUSAL PLANE (0-klool-zal plin). of the teeth are missing. T h e plane established by the occluding surface of bicuspids and molars PARTIAL DENTURE (par'-shal den'chur'). Pertaining to or constituting of both jaws, in opposition; (see curve only a part of the whole denture. of spee). A prosthetic appliance which supOCCLUSAL SURFACE (0-kloo1-sal plies teeth for a partially edentulous sur'-fice). T h e grinding surface of jaw. molars and bicusp~ds. OCCLUSION (ok-loo1-jun). T h e act of PARTIAL IMPRESSIONS. Pertaining to or constituting only a part of the closing or shutting, as of the teeth. whole impression of the mouth. ORAL (0'-ral). Pertaining to the PARTIALLY EDENTULOUS (e-den'mouth. ORAL TISSUES. T h e gum or mucous tu-lus). Partially toothless. P A T E N T E D SUCTIONS. Small soft membrane of the mouth. rubber cup-like attachments on the ORTHODONTICS (or-tho-donp-tiks) tissue surface of a denture; supposed T h e science which has for its object to help in keeping the denture against the production of normal occlusion and the palate or gums. jaw relationship. ORTHOPEDIC SURGEON (or-tho-pep- PELLET (pelf-et). A small mass of fibrous substance. dik). One who specializes in surgery PEN GRASP. A term denoting the of the joints and spine. manner of holding an instrument beOXIDIZING (oks'-i-dizing) Combintween thumb and fingers similar to ing with oxygen. holding a pen. OXIDIZING FLAME. T h a t part of PENKNIFE. A smal! pocket knife. the ...- flame which will cause oxygen to T h e excombine with metal, usually p r o d ~ ~ -PERIPHERY (per-if'-er-e). ternal surface. T h e periphery of a ing a black oxide which covers the denture, the rim or extreme outer limmetal and interferes with soldering. its of a denture. PERMANENT DENTURE BASE. A material used as a permanent base for a denture:. eold, " . vulcanite, phenol-formaldehyde resins, celluloidi nickel-coPACKING RUBBER. Inserting dental balt metals, stainless steel, etc. rubber in the denture space or matrix PHENOL-FORMALDEHYDE RESINS formerly occupied by the wax trial denture base. (fe'-nol-for-mal-de-hide). "Bakelite" ; used as a permanent denture base. 11 PACKING TOOLS. Pointed steel inis light, translucent and thermo-curing struments used in packing pieces of (cured by heat). rubber around the teeth in the matrix of the flasked denture. PESTLE (1~s'-I). An implcmcnt (I(:PALATAL (pal'-at-al). Pertaining to signed for c r u s l l i ~ ~substnnccs g in iI mortar. o r directed towards the palate.

.

.

33I

GLOSSARY

PHARMACIST (far'-ma-sist). An apothecary or, drugpst. PHYSICIAN (fiz-ish -an). One skilled in the art of healing. A medical doctor; an M.D. PINLESS T E E T H . Anterior or other teeth without metal pins. Diatoric teeth. PLAIN LINE ARTICULATOR. One that permits upward and downward movement of the extension arms only. PLANE O F OCCLUSION. T h e plane established by the occluding surfaces of the teeth of both jaws in oppositioc. PLASTER (plas'-ter). See plaster of Paris. PLASTER CORE. A removable plaster reenforcing wall to retain teeth in a desired relationship to a cast. PLASTER INDEX (in'deks). A plaster imprint of the teeth which helps to retain them in their original relationship to one another in making new denture bases for old dentures. PLASTER KNIFE. A knife used for cutting set plaster of Paris. PLASTER M I X I N G BOWL. A bowl adapted to the proper mixing of plaster of Paris; usuallv made of semisoft vulcanized rubbkr. PLASTER O F PARIS. Calcium sulfate from which water of crystallization has been evaporated by heat. (CaSO,)zH20 3H.O +2CaS042H20. A white powder used in the dental laboratory. PLASTER SAW. A saw used for cutting plaster of Paris. A round barbed blade. PLASTICENE (plasl-te-seen') . A modelling clay. PLASTER-WORKER. A plaster technician; one who specializes in operations involving the use of plaster. PLASTIC RUBBER (plas'-tik). Moldable rubber; a compound of rubber that can be packed on the cast and condensed without a flask. Used in repairing dentures. PLATE-MAN. A denture technician. PLATES. A common expression for artificial dentures. P L A T I N G APPARATUS. A n apparatus used to deposit a coating of metal ~

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on dentures by means of an electrolyte. POINT-ANGLE. T h e junction of three surfaces a t a point forming a corner of a tooth. POLISHER. A dental technician who specializes in polishing work. A n agent used for smoothing and producing a glossy surface. POLISHING A N D GRINDING MACHINES. Lathes with suction attachments used for polishing and grinding purposes. POLISHING DENTURES. Putting a high gloss or finish on a denture. POLISHING WHEEL. A wheel or brush, designed for attachment to a lathe and useful in polishing metals, ~ulcanite, porcelain, dentures, dies, etc. POLISHING STONES. Fine stones used for polishing. Tripoli, a porous rock. PORCELAIN (por'-se-lain). T h e fused product of the combination of various minerals, such as, silica, feldspar and quartz. PORCELAIN BAKING FURNACE. An electric oven used for fusing porcelain. PORCELAIN CROWN. A crown composed of porcelain. PORCELAIN T E E T H . Mineral teeth, teeth made of porcelain. POROSITY (po-rob-it-e) T h e quality or condition of being porous; in vulcanite by heating too fast or if the rubber is too thick. POROUS (PO'-rus'). Possessing pores or spaces; permeable by liquids. PORTLAND CEMENT. A limestone cement used for building purposes. POSTERIOR T E E T H . Those teeth of either jaw behind the incisors and canines. PROTRUSION (pr8-tru'-shun). The condition of being thrust forward as, the protrusion of the incisor teeth or of the jaw. PRESCRIPTION (pre-skript-shun). A written formula for the preparation, dose and method of administration or application of a medicinal remedy. PROCESS PATENTS. A patent on a method of manufacturing or constructing an article.

.

332

GLOSSARY

PROPHYLACTIC (pro-fil-ak'-tik). Anything that guards against disease. T h e cleansing of the teeth by a dentist or dental hygienist. PerPROSTHETIC (pros-thet'-ik). taining to artificial substitutes for lost members of the human anatomy. I n dentistry; of an appliance that replaces lost teeth by artificial means. PROSTHETIC APPLIANCES. Artificial appliances such as artificial arms, legs, dentures, etc. PUMICE (pump-is). Used in powder form as an abrasive and polishing agent. A powder from volcanic rock.

GLOSSARY

RHEOSTAT (re'-o-stat). A n instrument which regulatesrthe strength of an electric current by interposing a graded and known resistance within the circuit. RIDGE (rij) A narrow, elongated elevation or crest, as on the surface of a tooth or a bone; the ridge which formerly contained the roots of the teeth is known as the alveolar ridge. RIDGE-LAP. T h e surface of artificial teeth which faces the alveolar ridge. RIDGE-LIKE ELEVATIONS. Rugae ; elevations on the mucous membrane of the palate. RIM O F T H E W A X E D DENTURE. T h e periphery; the denture limits. ROACH CARVER. A n instrument for carving wax by the combined use of heat, suction and

.

RASP FILE. A file with rough teeth used in trimming plaster and stone ROCHELLE SALT (TO-shel') Sodium casts. potassium tartrate. RAT-TA1L VULCANITE A ROSIN. Any member of a classof exround, tapering file, like a rat's tail. udates from various trees and plants. Making a new denture ROTARY DIRECTION. Pertaininv0 to base. rotation ; a circular movement. RE-CRYSTALLIZES. Forms crystals ROTATION CENTER O F LATERAL agaln. MOVEMENT. T h e fixed point of the FLAME (re-do'-sing)' radius of the arc described by the T h e soldering flame; the melting teeth when the jaw is moved sideflame; area below the luminous cone. .a=. RELIEF AREAS. Parts of dental casts R O U ~( rooj) ~ , Red oxide of iron conwhere the bone is close to the overlytaining chalk. gum. Areas which require a ~ ~ l i -RUBBER (rub'-er). India rubber or cation of relief metal. caoutchouc, especially in a commercial RELIEF O F BONY AREAS. T h e adrurrrl. dition of metal or tinfoil over bony RUBBER PACKING. T h e act of inareas on dental casts. troducing rubber into the denture RELIEF METAL. Metal used for respace; the space formerly occupied by lieving hard areas on casts; tin, tinthe waxed or trial denture base. T h e foil, lead, Britannia metal, etc. gasket of a vulcanizer cover. RETAINING WALL. A wall formed RUGAE (roof-gah) Irregular ridges by wax to keep the plaster or stone on the mucous membrane covering within the desired limits on an imthe hard palate. pression. RUGAPAKS (roo1-gah-paks). An apRETARDERS. Substances which lengthparatus that reproduces the palatal en the time required for plaster or rugae in vulcanite dentures. stone to set or harden. Citric acid, lemon juice, vinegar. RETRUSION. T h e act of pressing s teeth backward. A backward posiSALIVA (sa-li'-va). T h e mixed tligcstion of the teeth or jaw. REVULCANIZATION. Putting vultive fluid secreted by the paraotid, sulicanite through vulcanization a second maxillary, sublingual and Inllcotls glands of the mouth; spit. time.

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S A G I T T A L CONDYLE P A T H (sadjri-tal). T h e (median) path of the condyle when the jaws are openetl. T h e path in a11 anfero-posterior tlirection. SAND. A loose mass or accumulation of grains of silicic oxide. SANDARAC. A white transparent resinous secretion ; a varnish. SCORING. Cutting grooves on the base of casts, scarring. SCRAPERS (skraf-pers) Implements for scraping or abrading a surface. SEPARATING DISKS. Emery or carborundum wheels used for cutting or separating teeth, vulcanite or metals. SEPARATING MEDIA (me-dja). Any coating upon the surface of plaster of Paris which serves to prevent another stratum of plaster from adhering to the first. SETTING. Hardening. SETTING-TIME. T h e time required for plaster or artificial stone to harden. SHADE O F T E E T H . T h e hue or color of artificial teeth. SHELLAC (shel'-ak). A resinous deposition from the lac-insect. SHELLAC BASEPLATES. Trial or temporary denture bases made of shellac and gutta-percha. SHUT. T h e part of an artificial tooth which holds the metal pins. SILEX (si'-leks) . Sodium or potassium silicate. SILVER ALLOY (al'-oi). A n alloy containing silver, zinc and tin. SIMPLE REPAIRS. T h e repair of a denture broken in two, not involving teeth or clasps. S O F T AREAS. Areas covered by gum and underlying tissues. Non-resistant, flexible areas. SOFT PALATE. T h e soft or movable portion of the roof of the mouth, located beyond the hard palate. SOFT VULCANIZED RUBBER RELIEFS. See patented suctions. SOLARIZING RUBBER (so'-lar-iExposing vulcanite to sunzhing) light~torestore its color. SOLDERING APPARATUS (sof-der). Tools used for , ioinine hieher melting metals bv means of lower m e l t i nmetals.

.

333

SOLDERING TWEEZERS. A pincer used for holding or placing snlder. SOLVENTS OF CAOUTCHOUC. Agents which dissolve rubber. SPATIJLA (spat'-u-lah). A flexible, knife-like instrument with blunt edges which varies in size and shape, and is employed in the mixing, spreading or shaping of ointments, cements, plaster of Paris, amalgams or waxes. SPATULATION. Mixing with a spatula. SPINDLE (spin'-dl). A shaft or rod upon which anything is wound. STABILITY. Steadiness, immobility. STAINING O F PORCELAIN T E E T H . T h e addition of metallic stains to artificial teeth to give them a more natural appearance. STAINLESS STEEL. A rustless steel compound. STEARIN (ste'-ar-in). A white, crystalline compound found in animal and vegetable fat. STICKY WAX. Adhesive wax, usually beeswax, resin and gum. STIPPLING (stipt-ling). T o spot or dot. SUCTION MACHINES. Machines which suck in dust when grinding and polishing. SUCTIONS. Attachments on a denture which help to keep it in place by creating a vacuum between the denture and the tissues. SULCUS (sul'-kus) A Iong-shaped depression on the surface of a tooth, the inclines of which meet at an angle. SULPHUR (sul-fur). A yellow nonmetallic chemical element occurring in nature both in a free state and in combination, in volcanic regions and in certain stratified rocks. SWAGER (swa1-jer) (swedger). A device for shaping metal accurately to a desired form by the simultaneous use of pressure from every angle. SWEDGED. Same as swaged.

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TAILPIECE EXTENSION. A metal extension of a clasp, which is incorporated in the den&re base of a partial denture.

334

GLOSSARY

GLOSSARY

T E E T H (t&th). T h e set or group of hard, calcified organs in two, opposed, arch-like arrangements, imbedded in the alveolar process of the mandible and the maxillary bones. Artificial teeth are made of porcelain. TECHNOLOGICAL. Pertaining to technical advancement. TEMPLATE. A metal plate used to aid in obtaining the occlusal curve when setting teeth or making biteplates. THERMAL. Pertaining to or characterized by heat. THERMOMETER. An instrument used in determining and registering variations of temperature. THERMOPLASTIC DENTURE BASE. Denture base material which is softened and shaped with the aid of heat. There is no chemical change in the material itself. THUMB-NUT. T h e nut which keeps the set-screw of an articulator stationary. TINFOIL. Pure tin prepared in very thin sheets of standard sizes. TISSUE (tish'-00). Cells and other elements united and arranged to produce a recognizable structure; gum tissue, skin tissue, etc. TISSUE SURFACE.' T h e surface of a dental impression which shows the imprint of the tissues. T h e surface of a cast which shows the reproduction of the tissues; gums. TISSUE TOLERANCE. T h e ability of the tissues (gums, etc.) to tolerate certain metals, vulcanite or other compositions used in constructing prosthetic appliances. TONGUE-SPACE. T h e space occupied by the tongue. T h e space between the alveolar ridge of the lower cast. T O O T H DEPRESSIONS. T h e imprints of the teeth in an impression. T h e imprints of the teeth in a wax "bite." T O O T H INDEX. A n imprint of the teeth in plaster; used to obtain a record of the relationship of the teeth to each other. TRANSLUCENCY. Partially transparent. TRANSVERSE RIDGE. Formed by the union of two triangular ridges and

crossing transversely the surface of an upper molar tooth. T R A U M A T I C (traw-mat'-ik'). Pertaining to or resulting from an injury. TRAYS, DENTAL ( t r l ) . T h i n shallow metal receptacles for holding dental impression material during the process of taking impressions. T h e impressions are assembled in trays. T R A Y SURFACE O F IMPRESSION. T h e surface toward the tray; opposite the surface toward the tissues. T R I A L BASE. A baseplate, basewax, metal or vulcanite base used for arranging the teeth for trial before completion. T R I A L DENTURE. A denture constructed to be fitted in the mouth of the patient before the permanent denture base is completed. TRIMMING VULCANITE DENTURES. T h e process of removing excess vulcanite from the denture base. Rottenstone. A TRIPOLI (trip-0'-lee) soft stone found in Tripoli, Northern Africa, used as a mild abradant and polishing agent. TUBERCLE. A small nodule or elevation. T U B E T E E T H . Porcelain teeth held in place by metal pins which fit into tubes in the teeth. Cement is also used. T U R P E N T I N E (tyr'-pen-tin) A volatile, concrete or liquid oleoresin which exudes from trees. TYPODONT. A metal cast of the teeth and dental arches.

.

.

UNDERVULCANIZED VULCANITE. T h e state of vulcanite when it has not received sufficient heat over a long enough period during the vulcanizing process.

VACUUM CHAMBER. A depression o r concavity sometimes prepared on the inner surface of a denture by adding a heart shaped piece of metal over the hard area of the palate of the dental cast.

VULCANITE. A chemical combination of caoutchouc and sulphur which has been subjected to the process of vulcanization. VULCANITE BASE (vul'-kan-it) T h e base of a denture composed of vulcanite. VULCANIZED DENTURE. A denture which has been vulcanized. VULCANIZED RUBBER. R u b b e r which has been cured in a vulcanizer. A VULCANIZER (vu1'-kan-iz-er) . strongly constructed metal vessel which confines and withstands the concentrated steam pressure that is generated during the process of vulcanization, the curing of rubber. VULCANIZER COVER. T h e lid of the vulcanizer pot to which are usually attached the thermometer, gas regulator and manifold holding the safety and blow-off valves. VULCANIZER PACKING RING. T h e graphite ring which fits into the bottom of the cover and helps to obtain a steamtight seal between the cover and the vulcanizer pot. VULCANIZER POT. T h e pot holding . the water into which the flasks containing packed cases are deposited for vulcanization. VULCANIZER TONGS. T h e tongs or pliers used for depositing in, or removing flasks from the vulcanizer. VULCANIZING CAOUTCHOUC. Rendering flexible caoutchouc inflexible so that it will retain a desired mold. VULCANIZING PERIOD. T h e duration of time required to cure dental rubber. VULCANIZING POINT. T h e degree of temperature a t which vulcanization takes place. VULCANIZING PROCESS. That process by which a combination of caoutchouc and sulfur is made flexible o r hard, as desired, by means of steam pressure in a vulcanizer.

.

335

WARPAGE (warpr-lj). T h e process of, or condition resulting from warping. WARPING DENTURES. Overcuring or heating vulcanite dentures causing them to change their shape. W A T E R O F CRYSTALLIZATION. T h e water contained in the molecule. If this water is eliminated the molecule is changed. T h e water contained within the granules of dry plaster powder. W A X (waks). A product of the honeybee or made of a hydrocarbon as paraffin. W A X SPATULAS. Instruments used for holding, melting and applying wax. W A X BITE. T h e impression of upper and lower teeth brought to closure in a mass of wax. W A X ELIMINATION. T h e elimination of wax from the flask before packing rubber in its place. WAXER. A technician who specializes in waxing dentures. WAXING. T h e process of applying wax to dentures. W A X MATRIX. T h e space left after the wax base is eliminated into which rubber is packed. A name erroneously applied to the wax trial denture. W E T METHOD. A method of packing rubber where the flask is boiled in hot water to soften the rubber during the testing stage. Wet method of wax elimination is the method of boiling the flask in water to soften the wax in the flask. W A X SOLVENT. A chemical which dissolves wax; carbona, ether, chloroform, etc. W I R E SPLINTS. Wire used for holding fractured portions of a denture or an impression which is assembled with the aid of sticky wax.

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332

GLOSSARY

PROPHYLACTIC (pro-fil-ak'-tik). Anything that guards against disease. T h e cleansing of the teeth by a dentist or dental hygienist. PerPROSTHETIC (pros-thet'-ik). taining to artificial substitutes for lost members of the human anatomy. I n dentistry; of an appliance that replaces lost teeth by artificial means. PROSTHETIC APPLIANCES. Artificial appliances such as artificial arms, legs, dentures, etc. PUMICE (pump-is). Used in powder form as an abrasive and polishing agent. A powder from volcanic rock.

GLOSSARY

RHEOSTAT (re'-o-stat). A n instrument which regulatesrthe strength of an electric current by interposing a graded and known resistance within the circuit. RIDGE (rij) A narrow, elongated elevation or crest, as on the surface of a tooth or a bone; the ridge which formerly contained the roots of the teeth is known as the alveolar ridge. RIDGE-LAP. T h e surface of artificial teeth which faces the alveolar ridge. RIDGE-LIKE ELEVATIONS. Rugae ; elevations on the mucous membrane of the palate. RIM O F T H E W A X E D DENTURE. T h e periphery; the denture limits. ROACH CARVER. A n instrument for carving wax by the combined use of heat, suction and

.

RASP FILE. A file with rough teeth used in trimming plaster and stone ROCHELLE SALT (TO-shel') Sodium casts. potassium tartrate. RAT-TA1L VULCANITE A ROSIN. Any member of a classof exround, tapering file, like a rat's tail. udates from various trees and plants. Making a new denture ROTARY DIRECTION. Pertaininv0 to base. rotation ; a circular movement. RE-CRYSTALLIZES. Forms crystals ROTATION CENTER O F LATERAL agaln. MOVEMENT. T h e fixed point of the FLAME (re-do'-sing)' radius of the arc described by the T h e soldering flame; the melting teeth when the jaw is moved sideflame; area below the luminous cone. .a=. RELIEF AREAS. Parts of dental casts R O U ~( rooj) ~ , Red oxide of iron conwhere the bone is close to the overlytaining chalk. gum. Areas which require a ~ ~ l i -RUBBER (rub'-er). India rubber or cation of relief metal. caoutchouc, especially in a commercial RELIEF O F BONY AREAS. T h e adrurrrl. dition of metal or tinfoil over bony RUBBER PACKING. T h e act of inareas on dental casts. troducing rubber into the denture RELIEF METAL. Metal used for respace; the space formerly occupied by lieving hard areas on casts; tin, tinthe waxed or trial denture base. T h e foil, lead, Britannia metal, etc. gasket of a vulcanizer cover. RETAINING WALL. A wall formed RUGAE (roof-gah) Irregular ridges by wax to keep the plaster or stone on the mucous membrane covering within the desired limits on an imthe hard palate. pression. RUGAPAKS (roo1-gah-paks). An apRETARDERS. Substances which lengthparatus that reproduces the palatal en the time required for plaster or rugae in vulcanite dentures. stone to set or harden. Citric acid, lemon juice, vinegar. RETRUSION. T h e act of pressing s teeth backward. A backward posiSALIVA (sa-li'-va). T h e mixed tligcstion of the teeth or jaw. REVULCANIZATION. Putting vultive fluid secreted by the paraotid, sulicanite through vulcanization a second maxillary, sublingual and Inllcotls glands of the mouth; spit. time.

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S A G I T T A L CONDYLE P A T H (sadjri-tal). T h e (median) path of the condyle when the jaws are openetl. T h e path in a11 anfero-posterior tlirection. SAND. A loose mass or accumulation of grains of silicic oxide. SANDARAC. A white transparent resinous secretion ; a varnish. SCORING. Cutting grooves on the base of casts, scarring. SCRAPERS (skraf-pers) Implements for scraping or abrading a surface. SEPARATING DISKS. Emery or carborundum wheels used for cutting or separating teeth, vulcanite or metals. SEPARATING MEDIA (me-dja). Any coating upon the surface of plaster of Paris which serves to prevent another stratum of plaster from adhering to the first. SETTING. Hardening. SETTING-TIME. T h e time required for plaster or artificial stone to harden. SHADE O F T E E T H . T h e hue or color of artificial teeth. SHELLAC (shel'-ak). A resinous deposition from the lac-insect. SHELLAC BASEPLATES. Trial or temporary denture bases made of shellac and gutta-percha. SHUT. T h e part of an artificial tooth which holds the metal pins. SILEX (si'-leks) . Sodium or potassium silicate. SILVER ALLOY (al'-oi). A n alloy containing silver, zinc and tin. SIMPLE REPAIRS. T h e repair of a denture broken in two, not involving teeth or clasps. S O F T AREAS. Areas covered by gum and underlying tissues. Non-resistant, flexible areas. SOFT PALATE. T h e soft or movable portion of the roof of the mouth, located beyond the hard palate. SOFT VULCANIZED RUBBER RELIEFS. See patented suctions. SOLARIZING RUBBER (so'-lar-iExposing vulcanite to sunzhing) light~torestore its color. SOLDERING APPARATUS (sof-der). Tools used for , ioinine hieher melting metals bv means of lower m e l t i nmetals.

.

333

SOLDERING TWEEZERS. A pincer used for holding or placing snlder. SOLVENTS OF CAOUTCHOUC. Agents which dissolve rubber. SPATIJLA (spat'-u-lah). A flexible, knife-like instrument with blunt edges which varies in size and shape, and is employed in the mixing, spreading or shaping of ointments, cements, plaster of Paris, amalgams or waxes. SPATULATION. Mixing with a spatula. SPINDLE (spin'-dl). A shaft or rod upon which anything is wound. STABILITY. Steadiness, immobility. STAINING O F PORCELAIN T E E T H . T h e addition of metallic stains to artificial teeth to give them a more natural appearance. STAINLESS STEEL. A rustless steel compound. STEARIN (ste'-ar-in). A white, crystalline compound found in animal and vegetable fat. STICKY WAX. Adhesive wax, usually beeswax, resin and gum. STIPPLING (stipt-ling). T o spot or dot. SUCTION MACHINES. Machines which suck in dust when grinding and polishing. SUCTIONS. Attachments on a denture which help to keep it in place by creating a vacuum between the denture and the tissues. SULCUS (sul'-kus) A Iong-shaped depression on the surface of a tooth, the inclines of which meet at an angle. SULPHUR (sul-fur). A yellow nonmetallic chemical element occurring in nature both in a free state and in combination, in volcanic regions and in certain stratified rocks. SWAGER (swa1-jer) (swedger). A device for shaping metal accurately to a desired form by the simultaneous use of pressure from every angle. SWEDGED. Same as swaged.

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TAILPIECE EXTENSION. A metal extension of a clasp, which is incorporated in the den&re base of a partial denture.

3n8

INDEX

INDEX

IIIZSIIPI.A~.T:(Cont'd) I ~ ~ X I N C(Cont'd) : I.;i[ll~ingedges of, 8 1 , 82 1)t:lltal impressiorla I\il;ltel.ials for, 80 ~woccclurr for, 33, 34, 1 5 . 16 I':~l-tial cnsrs, 83, 84 rl11esti1111\ 1111, 31, I'roced~~rc,,811-83 rrasnrls for, 32 U ~ l e s t i o ~ lorl, s 85, $0 1001s fill., 32 Kelatrtt inforrnatin~lO I I ,87 R K t ' I A N K L A MICTAI., 72, 78 Rc.p:lir of, 82 I t ~ g r c t l i r r ~ tof, s 78 ... S:~lety inst. for, X X V I I I HlJ?iSI:N IlIJRI\'I..K Shaping, 81 Flamr, arlalqsis of, 4 Shell:lc crrm[>oul~tls,use of, 87 S:lfcty ir~structions for, x x r i i 'l'in, nse of, 87 \'trlcarlite, use of, 87 (scc VIJI.CANITE) CAI.CII!hI SUI.PIIKI'E, 1 0 II.\SI. \\'AX C.\OUTCEIOIJC I 011, 104, l)~.eparationof d c l i t u r ~:I re;[ I ~ I I ,1 I < ~ . I : I I ~ , ( I ~ I I ~ I I ~ I ~ : I O~I II, ~ ro8, I I I 109 78 (see I)I:VTI~~KI:S) I < I ~ ~ I I ~ O I I . I . I , I I I ~use ~ I I ~ ,II[, 105, loft ["'"cc'lurc~, + 1-40 I < I , I ; I I ~ I I(st,c ~ I07 , re1:11111. (\l.(. 11111~.1'1..\11'S,\ < . I ' l < l l \ 1 0 1 : S ( . ; t l i l ~0g1 , I I I I I ; I \ I ~ I ~ ~1112 :III~, w l ) : i r : ~ l i ~ I~I ~gI I I I ~ I I I ~ I I ( , ~ > ~ I I, ,I I I, \ , < , ' I ' I ~ I ~ I ~[or, I I ~ yI .5 - I O O 57 (Sl,t, l~rl~lICI ,111' . . ill, 1 0 3 104 l
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nl: CIIABIANT,x v 1)FhTAL Apl)li:rnces (see APPI.IAN~:ES) Arc.hes, cor~sistof, 64 C'asts (see CASTS) L:~hor;ltorv (see L A R ~ R A T . O K Y ) a ~ ~ a l j . sof, i s 303 tlivision o t lal)or ill, xii lnrchanic (see ~ ~ I ~ . C I I K I C I A N ) t r c l ~ n i c i a (see ~ ~ .I.I:CIIYICIAN) ~ v ~ ~ rwhere li, p ~ . r f o r ~ n e dxviii , contlitions of, xviii I~ygienic~ne:lsur~.s,xviii seasorla1 F:l~.tors, xviii l.;l!ll~ (see l,,\,l111:) Mech:~riic ( ~ c .MI:crrt\xrc, sce vclr~lC1,lU) Mt,rh:~~lic~.: ( ~ c cMECHANICS) 111.fit1iti1111 of, xi origi11 o r , xiii, xiv \ ~ I I I ~ ; I I ~ O I I ;1ti:1l~si5 :I~ of, xviii-XYV tl('\('IO~)lll(.lltllf, X V R111)lvr (<,,I,K I I I I ~ E R ) ' l ' c c l l l ~ i c i :(~\ ~r e~ ~ ~ r c r r ~ ~ r ~ n x ) \irol-l;~llll~l :cllnlysi.; of, uviii clivisio~~.i ill, uxiii-XXY 111'NI'IST Relati1111to t t , ~ . l ~ n i c . ixi-xiii :~~~, Rrsponsihility of, xi I)liNTISTK\' C o n t r i h r ~ t i o ~ i \ 1)y teclrlricians to, xiv Origin, in America, xi\. Practice 1)y t c c h n i c i a ~ ~ sxiv , forhidden, x i v Revolutionary W a r , in, xiii l l ~ : N T O C ( l ~ . l .49 , nENlnFORhI ( S ) , 23, 24 Kelatnr ( w e REI.ATOR) IIEN'I'UKE ( s ) Area, p r e p : ~ r a t i c ~of, l ~ 6+-78 Artificial (ser ARI.IFICIAI.) Rase (sce n.\slc) Basrl~l:ltc, for trial, 79-87 (see RASF.PI.:\.I.E, scc .I.KI.\I.D E N . L U I < F ) I ) c l ) : ~ r t r ~ i cill ~ ~ Inlr., t xxiv F i l ~ i r h i n g (
DEN'I'IJRll ( s j (Cont'llj Polislling (see P O L I S ~ ~ I N ( ; ) Pnsitio~lin mouth, 274 Preparation of casts tor, 61-78 ('.~,c CAS'I'S) Relation to hrad, 20 to j a ~ \ - s 274-275 , Relirf o f , 65, 71-78 (see I < I I . I ~ I . ) Krpair of (see REPAIRS) S o l a r i z i r ~ gof, 283 T e s t i n g (see 1.1:srrscj ,1 ~ r ~ f o i l i ncasts, g 71-78 (see CASIS,see TINTOIL.IUC) trial dcntt~res,198-204 (sce .IUI.*I.) l ' r i a l hase, 79-87 (scc TRIAI.) irule:~nite (see VIJI.C.INITE) L)IJCTII\TEAU, X Y

..

EIIUIPMENT r)(~llt:l1 l;ll~llratory I ~ ~ ~ s i n32g , colnrnonly 11sc.11,xx plaster, rz I.'.\~.'tIBOW, 119 <;Js~ ?'l.llh~te, 125 (SCCM I ~ I J N I ~ I N I ~ ) ~ n o u l l t i n\ \~i t h , 121-123 (see hIollNIINC;) Gysi l'rohyte, 125 (scc M ( I u x . I . I ~ ( ; ) 1:~1.lSc Ilnscplatc (sec n.~sirr~r.a.~l:) Vulcanite (scr \'III.C~ZNI'II..) 1.IX 1SIIING

U e r ~ t u r r s (see .I.KIMMINC) l.'I.Ah.lli

H u n s e l ~I)nrner, :~nalysisof, 4 Flaming baseplate, 80-92 \Tax, 91 1-I.AShBolt type, method of closil~g, 197, 23 I Clalnp, 187 C l o > i ~ ~lnrthotl g, of, 23 I Denture, 186, 187 (see I I . . \ S K I \ I : ) FIratillg I J ~2, 13 d r y methi~tl,2.13 011rni11gof, 208, 254-255 l'rec~>, 207 Rcrr111v;11( I [ I ~ I , I I ~ I I [rorn, I.~ ~ ~ + - (:\ I ,o( ' ~ CI,I~.ZWSISI;J ' I ~ < > l l 2~ 51, ~ ,

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3 40

INDEX

I.I,ASKING Denture cautions in, 188 cellophane, use of, l o 4 details of, 193, 194, 195 equipment for, 187 escape gates in, 23 I job appraisal of, 196 materials for, 188 partials, 195 (see ~ 4 K l . l A l . ~ ) procedure for, 188 questions on, 194-196 rrasons for, 185 rrlated information on, 197 s e l ~ a r a t i n gmedia ill, 197 ( s r e sr:~'.\K.\IINC, M e d i a ) tool\ for, 187 W:IK e l i m i n a t i o ~ ~in, 205-213 (sce \v.~x, Elimination) l:llN~I,x v

IMPRESSIONS (COtltJd) Dental (Cont'd) pouring of (see I ~ O U R I S ~ ; ) preparation for casts, 19-31 (see CASTS) rluestions on, 30 related i n f o r m a t i o ~011, ~ 31 scraping of, 78 separating from casts, 50-57 ( w c SEPARATING) soluble plaster, 49, 50, 51, 57 (5cc PLASTER) sticky w a x , application of, 19-30. 27-29 (see W A X ) storing of, 25 trays, 22, 3 r ( w e ~11.41's) use of, 2 0 vibrating, 42, 43, 44

(;AS lll~~mi~~:~ti~~g safety i~~str-11cti1111s for, xxvi tubing, 2 (:ALICE (s) I3rown & Sh;irpe, 71, 73, 78 Relief, 74 r:l,i\ss s r m , 12, 13 I:OOL)YI:I\R, CII,\RLES,XV, x v i I:OOIIYI~~ZK,NI:I.SON, x\.i 1 .I
JAWS Details, of, 21 L a n d m a r k s on, 21

I"I"\-I'I ~ I P , 124-127 1.[I

INIIFX

Denture, const. of, 298-300

KNIFE C a r v i n g (see CARVING) Plaster (see PT.AS.I.FR) care of, xxvii .. . carving, method of il>ing, xx\,llr g u a r d s , xxvii use of, ro, 17 wax, method of u s i ~ ~ 25 g , (see \ \ \ \ I.AUOKATORY 1)rntal a d v a ~ ~ c . eill, s xv, xvi :~nalysis of, x\riii-xx-vii, 303 I ) o o k k c c p i ~ ~in, g xxii (.c,r;~mies(lcl):~I llnc.lrl, x x \ , (ICI~III~ I -(e . ~ : I I I I I ill, ~ ~ .xI\ iI \I " l ) i \ , i \ i o ~ U~I I ~ , ; I ~ I < I I , " it), \ i i c I i \ . i \ i o ~ t ~ \ 01, \ \ i i i

I

MOUNTlllG (C07lt~d) hlriC1lINk:S A d a p t a b l e Articulator, on (Coaf'd) Polishing (see POI.ISIIINC) (;psi Simplex, 120-123 c a r e of, 284 adjustment of, 122 grinding, safety inst. for, xxvi ~ y s Tir u h y t e , 124-127 g u a r d s for, xxvi face bow, with, 125 operation of, 283-284 job appraisal of, 128 safety instructions for, xxvi (iurstlons on, 127 MA'I'ER1AI.S use of, 125-126 D e n t a l Lahorntory H a n a u , 128, 129 b o x i t ~ g ,33, 31) ('re BOXING) materials for, 119 buying, s s i i i ~ x o c e d u r efor, 119-128 c:ists, for, 41 (hce CASTS) theory of. 118, 119 commonly usrtl, xxii tools for. 1 19 elastic, irnl)rc.s>io~~, 49 ( s r e I M P K P S u w of, I 18, I 10, 120-128 sros) A ~rtic~ilatol-s, (111 ( w e ~ K ' l . l ~ l ~ l .IA N'(l; ) I)ellt11rcs, R:Iw.. iol- ( s t c I ) ~ ~ N ' I ' U K I I S ) (':~\ts, 011 ( w e .\KI~CUI.ATIN~:) ILI.\IRIS, COY5 I . 0 1 2 q 0 , 297 11;111:111,118, 129 MECII.\SIC Plain lit~c,articl~lator,011, I 10-1 17 l)tat~t:~II , : I ~ > o I - : I I I I (lefi~~etl, I-~, xi ( w e casts, attnchrnrnt of, 113-115 ~l'l~CllN1C'l~\\~) c a u t i o l ~ sin, r I r Ml<<:Il:iSIC~S c q l ~ i p m c n tfor, I I I 1)ental ( w e '1'1:(.11vrCi\ N ) jol) al;prai%il of, I 16 I>:~sis~ I Ci115tl-uctio~~, 305 r n a t e r ~ a l sfor, I I I ('oloni:~l daxs, in, x i v procedure, 111-115 tlcfi~ritionof, j , 14 related information 011, I I 7 dentist relatiol~,14 technic for, 110-129 development of, r r tools for, 111 Eighteenth Century, x i v MOUllI European countries, x i v G e n e r a l vie\\, of, 65, 66 France, in 17th Cent., xiii origin of, xiii, x i v Ol! I'LINE public relation, xviii l > r l ~ t ~ i r e ( s 66-69 ), vocational analysis of, xviii-xxv c a u t i ~ ~ nill, s 66 hl E'C4.1. iob appraisal ol, 7 0 Denture, 235 ( w e DENTURE) procedure for, 66 Melted, safety inst. for, xxviii cli~estic~ns 011, 67, 68 MODELING COMPOIJSD, 48, 49 r u g a r , 66 Riteplates of (see BITEPI..~TI:S) tools for, 65 Ingredients of, 49 Specifications for, A.1>..4., 108, loo MORPHOLOGY, I 33- 146 l'.\CKING IJel~turcs,v ~ ~ l r a n i t ezo7-zj5 , 'I'eeth, Artificial, 131-146 (see T E K I I I ) caution, ~ q r caution5 for, 215-217 c h a r a c t r r i ~ t i c s of, r33-i42 (src d e n t u r e bases, 228-229 TEETIL) etluipmrlrt for, 215 ;ol> ;~l)l)raisal011, 132 full dentnrrs, 223-228 jol, a p p r a i m h f , 232 j)roc.ctlr~~-c., 13 I materials for, 215 clltrstions 011. 132 partial d e l ~ t u r e s ,228 MoIIN'I'IN(: A ~ l : ~ l ~ t ; ~ lAArti<~~tlator, )lr 011, 118-121) I ) r o c e d ~ ~ for, r e 215-217 (\c'l, b l l l ~ ~ K ' 1 1 ~ ~ ) IlLll'pOSC OF, 2 14 ; I ( ~ ~ ~ I \ I 0I1 I, I ~I 10, . I I 1I 2 0 1 ll~'\lloll\ llll, 23 1.232 I .' C . , I I I I ~ iOl l ,I II \ 1 0 1 2 1 1 IV\,I:IIC.II ~ I I ~ I I I I I I :I III II, ~2I1I: I I

.

1 1 1 l 1 1 1 1 ~ 1 ~('1.1.

I11111111 I:)

342

INDEX

( Co7lf'cf) I)rlltrlrcs (Corrt'd) materials for, 274, 2x3 nartinls, 281 procedr~srfor, 274-279 ~ ~ u m i c eclsc , of, 276 or:~torv, 10, 20 I),-111111 I . ( \ ) o r 1.1 \sl'lPl< 'l'l:('ll NICl,\Y (SIT' '1 1:CIl K l Y l ) \ \ ) l):lsl~,rl~,~l;ll~l~llll~lll ,,I, .,()I .!I15 1,l A'l'l' (sl'(' l l l ~ N ~ l ' 1 l l < l : ,S1.c. l!ASl'lBl,,\ 11,) l ) i ~ t , l o t , 2<,1 2 0 , 1 ' 1 \ I I SI 1 1 . ,\I
(Cont'd) Dentures, vrllcanite (Cont'ii) table for, 216 testing (see TES.I.ING) tools for, 215 I'AKTIAL A r r a n g i n g teeth on (see I\KKAN(:IN~:) Raseplate repair, 82-84 (see BhSllPLATE,see REPAIR) Riteplate, 104, 105 (see BITEPLATE) Casts, 41-44 (see CAS~S) I)rnture. 2 0 [see D E N T U R E (s)] Imprr\sions (see IMPRESSIONS)

I~ACKING

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KI<~,AIK(S) (Cont'd) I)el~tuve(s) of (Cont'd) p:~late, replnccrncrlt of, 293 procedure for, 286-300 (111c.stionson, 301 rcl;~tctlir~rol-ln:rtionon, 3oz simple, 288 technic of, 285-302 trcth, i ~ l v o l v i l ~ 288-293 g, l
SEPi\RATISG Media dried out impressiolls, 34 illgredients of, 39 method of application, 33, 34, 37 ]>laste~.impressions, for, 32 reasons for using, 39 remove fro111 casts, 51, 53 from plaster teeth, 51, 54 S1:l'AKA'I'INC

IMPRllSSIONS

Drlltal, 50-57 .[ ( 1 ~ 1 0 c:~~rtions, 5I Kllltlll..K DentocoII, 57 De~ltal elastic material, 57 colors 01, 133 job appraisal, 55 cutting, rllctliod of, 217-222 materials, 51 clrv l ] ; ~ r L i ~of, ~ g 302 (see P A C R I N C ) modeling cornpou~ld, 57 fnr full tlclltu~-rs,217-222 questions on, 5s i n g ~ - c ( l i c . ~of, ~ t \233 scoring, method of, 51 ~ ~ v c r v ~ ~ l c : ~262 ~~ized, tools used, 51 11:i(.Li11got (sce PACKIKG) S I C Y ~ I N G - TEETII UP, (see ARRAPI'GING) ~)l:~stic, 302 SllliI.I.AC ~ I I I ~ I oS, J S ~262 I~' Baseplate compou~rtl, 87 (see BASEh c ~ l l ) I ~O~~i rI I I in, 262 PI.,\TE) 1csti11g(see .rlisl-~xc) SIL.ES u~~tlcreul.etl, 262 Fl;lsking in, 204 (see FLASKING) vulcanizi~lg (see \ vr.cnvlLlvc) SYOW'S STUDENT AR'I.ICUI.ATOR, I23 (See tliscovery of, x v ARTICULATING) patent for, xvi SO1.VENTS KUGAE, 184 Grease, safety inst. for, xxviii [)EN-

SPATULA

SAFETY Dental tcchnicinr~s,for acids, xxviii baseplate, xxviii ... basewax, X X \ ~ I I I hefore closing lab., xxvii Runsen burner, xxvii I)nrs, xxviii chisels, xxviii files, xxviii grinding a n d polishing machine, xxvi illnminating gas, xxvi instructions for, xxv-xxviii lathes, xxvi lnachilre guards, xxvi spvrifir inst., xxvii-xxviii \.l~lc:rnizrrs,xxvii \\.lrrcls, xxviii Sl1.11I N 111. I 1 1,:l 11, 1.~8-1j 3 (stY, , I 1. !..I I I) \I I I IN(:

I ) ~ ~ I I I . I II . I I B ~ I I , I Ix O h i Ii ~ ,

Plaster care of, xxvii use of, xxvii Wax care of, xxvii guard for, xxvii heating, method of, h use of, xxvii, 17 Sl'A I.lll.ATlON lJl:lster of Paris cautions, 13 closed bowl, 18 hastenets, 12 mechanical, 18 ope11 bo\vl, 18 procedure for, 13 retarders, 12 SPEE, CUKVE OI:, 174 (see i\KK,\NCING) SOlJ~\Sll Fl1.1'1.: ( s r r Kl~l,~\'lllK,s(,(%~11~11.IP1,A~ l l ) S l 11.hl. M ' t h ( s , ~ \j.,lh) s;11,.ly i l t \ l . lor, xhviii

INDEX

S'I'ONE, DENTAL. Artificial (see AK.I,IFICII\I.) s c t t i ~ l gof, 12, 40, 41 use of, 12 Casts (see CAsrs) Ingredients of, 41, 48 P o u r i n g of, 40-49 (see cnsrs,

see

POURIBG)

Scoring of, 46 I IFCIINIC

I

(Cont'rl) Artificial (Co7ztJd) g r i n d i n g of, 167-1651 illcisor, 133, 135, 138, 142 ingrrdier~tsof, 131, 143, 145-146 matching of, 144-146 modified, 174 molar, 137, 138, 140 morphology of, 130-146 (see MORPHOLOGY) n o r ~ n a lpositions for, 173 number of, 135 occlusion of, 141, 142 pins of, 143 posterior, details of, I 64 removal f r o m vulcanite, 302 retention in v ~ ~ l c a n i t 162 e, selecting, aids in, 144, 145, 146 selection of. 148-153 setting u p (see ARRANGING) shade guitles, 143-146, 148-153 Spec c u r v e of, 174 (see ARRI\NCIN(:I I I I I I ~ ~ 133, I I , 134 color of, 133 crowns of, 133 number of, 133. 134 occlvsion of, 135 TEMPLATE Hiteplatrs, for (see BITEPI.;ZTF:S) lJse of, lo8 'I'IIS~ING(see PI.ASKING,see P A C K I Y ~ : ) For excess rubber, 229-230 Packet1 dentures, 229-231 Questions on, 230-232 TEETH

Plaster (see PLASTER) IVax, 1-9 (see w a x , see WAXIXC) cautions for, 3 e q u i p ~ n e n tfor, 2 job appraisal of, 8 materials for, 2 proretlure, 3-8 cluestions on, 8 tools for, 2 IbCIINICIAN, DIINTAI. Attributes of, xii Cor~tributionsto dentistry, x i v I)efinition of, xi ])if. bet. dentist a ~ i d ,xi, xii, xiii I)enture, duties of, xxiv lirnployment of, xii ITorbitltlen practice dentistry, xiv Illjuries to, x x v I.:~ck of schools for, x v i I.rg:~l rtstrictions, x i s Mct;ll, tluties of, xxiv R;I(:tl~otlof o l ~ t a i ~ ~ iwork, ng xviii NITTI for, xi, xviii I'(.rso~1:11l i y g i e ~ ~of, e xxv I'it.h-ull mc-thod in, x v i I'I:~stt.r, drlties of, 2 0 I<~.~:II~ toI Idcrltist, II xi-xiii! xviii ( 1 1 1111l>li1,, xviii I < ~ . ~ l u i r clrwz, c~l x r v , sx\.i S:11(,ly i l ~ s l r ~ l c t i o ~f i~s ~ xxv-xxviii r, S I . I I I ~111, \\ark, xi-xiii ' I ~ I - : I I I I ~111, I I ~ x i , xii, xvi 11.1 111

A~~iIi~.i:ll .II.I:III~ I I~~I147, ,I ~ 154 160 (st,<,,\I
'IIN

Baseplare, trial, use for, 87 (st.,, FOIL, see TINFOII.INC) '1'1 s 1:nl I, A l ~ l ' l i r a t ito ~ ~c.:~.;ls, ~ ~ 7 1 -78 I ~ ~ I - I I ~ S I of, S 71, 7 2 , 7 3 , 7s JIIII : I I I I I ~ : I ~or, S : I70, ~ 77 hT:~~(,vi:lIs ~ I I I 72, - , 73 I'1~0~~1~1111rl~ 101. ;! ( ) I I I , S I ~ I1 1I1 1I, ~71, Y I<1~11111v:1I lr11111 ll~~111111,~,. c.I.I..\NsIN(;)

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TINFOII.ING (collf'd) Job appraisal of, 202, 203 Xlaterials for, 199 Questions on, 202 Reasons for, 198 Related information on, 204 , 1001s for, 198 TO0I.S L.abor;ltory, Dental ;~ssemblingimpressions, for, 22 baseplate, const. of, 80 (see BASEPLATE) basemax, 88 (ser BASEWAX) biteplates, for, 80, 96 hoxing, i~npressions,32 (sec BOXING) c:lsts, for, 41 c o ~ n m ~ ~ rused, ~ l \ , 16 I I I ~ I ~ I I ~ for, ~ I I ~I 1, I p1a\tcr, 12 \ I I : I ~ I I ~ I I ~ of, I I ~ 272 l l l l ~ l ~ l (st,(: l ~rl~I~l.11)

.

I KAY

Art-l~:rse, plastelc:on\trurtion of, I S jol) apjuais:~l of, 16 plan for, 11 111~'stions011, 15, 16 I r n p r c ~ s i o n s(ser IMPRESSIONS) TRI:\L DENTURE B a s e w a x for, 89-94 (see BASEWAX) adapting, rntathod of, 89, 90 applied, w l ~ r r r ,88 a r r a n g i n g (see ARRANGIYG) cautions for, Sg denture (see DENTURE) equipment for, 88 flaming of, 91 job appraisal of, 92 materials for, 88 partial cascs, in, 91 reenforcrment of, 91, 92 polishing of, 91 procedurr for, 89-91 q u e s t i o ~ ~on, s 92, 93 reenforcement of, 89-99 related infornlation on; 0 4 S(:t-lIp (See . ~ R R A N C I N G ) tools for, 88 I I S C of, 88

(Cont'd) Casts, dental (Coni'J) equipment for, 58 file, use of, 59, 61 job appraisal, 61, 62 knife, use of, 59, 60 materials for, 58 procedure, 59 questions, 59, 61 rel:~ted information on, 63 sandpapel-, use of, 59 s a w , use of, 60 tools for, 58 r i b r a t i n g of, 41-45 IJenturts, vulcanite abrasive ~vheels,use of, 267 cautions on, 264 chisels, use of, 270 festooning of, 271 file, use of, 266, 268 job appraisal of. 269 materials for, 264 procedure for, 264-267 questions on, 268 reasons for, 263 related i n f o r m a t i o ~on, ~ 272 scraping of, 270 tools for. 264, 265

TRIMMING

VUL.Cr\YITE Baseplate of, 87 Change in volume, of, 262 LJenture, packing of, 214 (see PACKIXG) cautions on, 255 cleansed, appearance of, 254-262 job appraisal of, 261 procedure for, 255-260 questions on, 259-260 related information on, 262 removal f r o m flask, 255.262 removal, teeth from, 302 Properties of, 262 Repaired, properties of, 302 Retention of teeth in, 262 T r i a l base, use for, 87 (see TRIAI.IIASI:) .'UI.CASI%A'l'ION

Caoutchouc, x v , x v i Patents, x v i Rel:~tctl inforrnatiorl, 246-253 'l'c~nlwratt~rein, 252-253 T11ic.k tlcnturcs, 2 5 1-251 'l'i1111, in, 252-253 ~ I l l l l , ~z1,2 r,

Manual for Dental Technicians

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