CONTENTS
History
Scope of Removable Appliances
Classification
Indications
Advantages
Disadvantages
Limitations
Design Components
Patient instructions and Appliance Care
Conclusion
HISTORY Victor Hugo Jackson
Chief proponent of removable appliances in the US
Charles Hawley
Introduced Hawley’s appliance in 1908
Martin Schwartz
In mid 20th century developed a variety of split plate appliances
Philip Adams
Modified arrowhead clasp into ‘Adams Crib’ Became the basis for English removable appliances Still the most effective clasp for orthodontic purpose
George Crozat
In early 1900s developed a removable appliance entirely in precious metal Heavy gold wires as framework Lighter gold finger springs for desired tooth movement
Norman W. Kingsley (1879) Described his plate for “Jumping the bite” Pioneer in orthodontic therapy for the forward positioning of the mandible.
Monobloc by Pierre Robin(1902) Passive positioning device Modified from bite jumping v u l c a n i t e ma x i l l a r y g u i d e p l a n e s designed by Norman Kingsley
Indicated in patients with severe
Scope of removable appliances
The quality of outcome is not as high as with fixed appliances
Higher chances of discontinuation of treatment associated with the use of removable appliances
The use of removable appliances still varies widely between clinicians, but it is possible to achieve adequate occlusal improvement with these appliances, provided suitable cases are chosen.
It is vital to emphasize that cases suitable for removable appliance treatment are those that require simple t i p p i n g m o v e m e n t s o n l y, a n d surprisingly few malocclusions will fall i n t o t h i s c a t e g o r y.
Definition: REMOVABLE ORTHODONTIC APPLIANCE: An appliance which can be removed for cleaning by the patient or for adjustment by the orthodontist.
Classification Given by Graber for removable appliance
Group A :- tooth supported appliances E.G.- Catlans appliance, inclined planes, etc.
Group B :-tooth/tissue supported E.G.-Activator, bionator, twin block, etc
Group C :-vestibular positioned appliances with isolated support from tooth/tissue Frankel appliance, lip bumper,etc
Indications At present removable appliances are indicated for three major uses
Growth modification
Limited (Tipping) tooth movements Retention
Advantages Majority of malocclusions which require simple tipping of teeth can be satisfactorily treated with removable appliance
Can be incorporated with bite platforms to eliminate occlusal interference and displacement Manufactured in the laboratory and adjustments takes less chair side time.
Can be removed by the patient for cleaning both teeth and appliance.
Damaged appliances that apply undesirable forces can be removed.
They
are aesthetically better accepted than fixed appliance.
They
can also be used as a muscle exerciser. They are Inexpensive
fixed
removable
Disadvantages
PATIENT COMPLIANCE Uncooperative patient may sometimes leave out the appliance which prolongs the treatment and uncontrolled drifting of teeth occurs.
Rotation of one or two upper incisors can be dealt but multiple rotations cannot readily be treated.
Lower removable appliances are not well tolerated due to encroachment on tongue space and retention problems.
If the appliance is not adjusted carefully it brings about uncontrolled tipping of teeth.
Patients
may
salivation initially
have
have
excessive
LIMITATIONS
Removable Appliances permit only TIPPING movements Patient will have difficulty in speech initially
Appliance can be easily damaged if care is not taken
Components of removable appliances
Retentive Components Baseplate Active components
Retentive Components
IDEAL REQUIREMENTS
Should not impinge Close contact to the tooth Usable in both deciduous and permanent dentition. Adequate retention No active force on the anchor tooth Should be rigid Easy to fabricate and also replace if needed Not interfere with the growth of jaws and eruption of teeth
Circumferential Clasp
Fabricated using wire 0.8 mm -Also known as „C‟ clasp or Three Quarter Clasp Simple clasp used to engage buccocervical undercut Adequate retention. Easy to fabricate.
Easy to replace.
Disadvantages
Cannot be used in partially erupted teeth Decalcification of cervical margin. Gingival irritation. Plaque accumulation enhanced. Can easily distort.
Jackson’s Clasp
- Fabricated using 0.8 mm wire - Also known as Full clasp or „U‟ clasp - Engages both bucco-cervical and proximal undercuts Offers adequate retention X Inadequate retention in partially erupted teeth X Difficult to adjust
Triangular Clasp
Fabricated
using 0.6mm wire Used between adjacent posterior teeth Indicated for additional retention Elastics can be engaged Not usefull if adjacent tooth is
ADAM’S CLASP Also known as Liverpool Clasp, Universal Clasp, Modified Arrowhead Clasp Parts Bridge Arrowhead Retentive arms
DESIGN CHARACTERISTICS Bridge
The bridge is 2/3rd the mesio dital width of the tooth, or slightly less then the distance between mesiobuccal and distobuccal undercuts, or length should be equal to the intercuspal distance.
Is 1-2mm away from the buccal surface of the tooth.
o Angulated at 45 to the long axis of the tooth.
Arrowheads They
should lie in the disto- and mesio buccal undercuts. Shaped according to the curve of the gum margins into the interdental papilla. Long enough to keep the bride at a proper distance. Should not touch the adjacent teeth
ADVANTAGES Small,
neat, occupies minimum space Rigid, offers excellent retention Used on any tooth in the arch If broken can be repaired by soldering Permits modifications in design
DISADVANTAGES Extensive
wire bending incorporates stresses in the wire Unwanted palatal tipping if it gets activated. Can be repaired only if fractured through the arrowheads. Cannot be given on proclined anteriors.
Modifications
Adams clasp with single arrowhead
Adams clasp with J hook
Adams clasp with helix
Adams clasp with additional arrowhead
Adams clasp with soldered buccal tube
Adams clasp with distal extension Double clasp on maxillary central incisors
Schwarz Clasp
Designed by C. M. Schwarz One of the oldest clasps and is considered as the predecessor of the Adams Clasp
Can be used in deciduous or permanent teeth Skill to fabricate
Eyelet Clasp
Similar to triangular clasp
Used as single eyelet or multiple eyelet clasp Eyelets placed in embrasures
On single tooth does not have firm grip so multiple eyelet clasp is preferred
Southend Clasp
Spans two adjacent margins of anterior teeth Esthetically more pleasing
Ballend Clasp
•
Wire having a knob or ball like structure on one end • utilizes interdental undercuts • Indicated when additional retention required
Crozat clasp It
resembles a full clasp but has a additional piece of wire soldered which engages into the mesial and distal proximal undercut
Offers
better retention than full clasp
Baseplate
Greatest portion of removable appliance and is 1-2mm thick It serves 3 main purposes 1. Act as vehicle to carry all parts of the appliance 2. Serve as anchorage 3. Become an active part of appliance itself
Anterior biteplane
Platform behind upper incisor teeth with a 60degree inclination
Height enough to separate posterior teeth by 1.5-2mm
Reduces overbite of anterior teeth and causes opening of the bite
Sved Biteplane
Introduced by Sved in 1944 Covers incisal edges of upper anteriors Pressure transmitted axially Provides reinforces anchorage
Posterior Biteplane
Can be used for treating Posterior crossbites Anterior crossbites Anterior openbite after correction appliance acts as a retainer
Lower Inclined Plane
Introduced by Catlan more than 200 yrs ago
Used for treating Anterior crossbite
Inclined at 45 degrees to the occlusal plane
If used for more than 6wksanterior open bite results
Active components
LABIAL
BOWs SPRINGS ELASTICS SCREWS
LABIAL BOWS Parts of labial bow 1. Incisor segment 2. Vertical loops 3. Cross over section 4. Retentive arm
May have 2 functions 1) Serve as active element for movement of teeth 2) Hold the plate in place & retain the teeth
Incisor segment U s u a l l y i n t h e j u n c t i o n o f m i d d l e t h i rd a n d i n c i s a l t h i rd . Right angle bend at the distal third of lateral incisors or mesial third of canine Contacts only the most prominent teeth
Vertical loops
Consists of parallel vertical legs joined by a smooth curve. It is usually 9-12 mm in length, extending 2-3 mm. At the gingival level the loop is 11 . 5 m m a b o v e t h e g i n g i v a l m a rg i n
The various types of labial bows are
Short labial bow Long labial bow Split labial bow Reverse labial bow Robert’s retractor Mill’s retractor High labial bow with apron springs Fitted labial bow Begg’s retention bow
Short Labial Bow
Fabricated with a 0.7 mm wire Flexibility depends on vertical height of „U‟ loops Used when only minor overjet reduction or incisor alignment required Retentive arm distal to canine.
Adjustment : Compressing of ‘U’ loop so that the incisor component is displaced palatally by only 1mm
Long Labial Bow
Used
to close space between canine and premolar Provides better control over the position of the canine Used for retention purposes
Split Labial Bow
• •
The flexibility of the wire is increased Used for incisor retraction and Closure of diastemas Adjustment : at the „U‟ loop 1-2 mm at a time.
Labial Bow with Reverse Loop
Prevents buccal drifting of canine
Mills Bow /Extended Labial Bow
•
Made of 0.7mm wire • Extensive loops- flexibility greatly increased Indications -Reducing large overjets -Alignment of irregular incisors Lighter forces, longer range of action Due to extensive loops less comfortable
High Labial Bow with Apron Spring •
• •
Used mainly for carrying Apron Springs Heavy base arch made of 0.9-1 mm wire Apron spring are made of 0.3-0.4mm wire
Used
for retraction of teeth with severe proclination Lighter forces Longer range of action
Not well tolerated by the patient Time consuming to fabricate Cannot be used in patients with shallow sulcus
Roberts Retractor
Flexible bow constructed of 0.5mm wire
Steel tubing in the form a buccal sleeve to give support
Fitted Labial Bow
Fabricated with a 0.7 mm wire Adapted closely to labial surface of anterior teeth Used for retention
Beggs Retention Bow
•
0.7mm wire extends till last erupted molar • ‟U‟ loops made between I & II premolars Allows better settling of occlusion
Other Modifications
The labial bow with retractive canine loop
The modified labial bow Function: Engagement of elastics and soldering of springs
The labial bow with vertical M-loop Function: Alignment of the canine, if it is labially
SPRINGS These are the most commonly used active elements. Requirements: springs should deliver optimum force should possess high degree of elasticity should have long range of action and apply light forces.
0.5mm
or 0.6mm wires are used to move single teeth or groups of teeth
Constructed
in 18/8 austenitic stainless steel
The
more wire incorporated, the greater the range of the spring and the lighter the force
Classification of Springs Based on direction of tooth movement 1. Springs for mesio-distal tooth movement 2. Spring for labio-lingual tooth movement 3. Springs for expansion of arches II. Based on nature of support 1. Self supported springs 2. Guided springs 3. Auxiliary springs III. Based on presence of loop or helix I.
Single Cantilever Spring active arm Parts coil retentive arm • Fabricated with a 0.5-0.6mm wire • coil with internal diameter of 3mm • used to move teeth labio-lingually or mesiodiatally
Double Cantilever Spring / Z spring •
Constructed using 0.5 or 0.6 mm wire • Spring perpendicular to palatal surface of tooth • Indicated where incisors are to be proclined Activation: Done by opening both coils If not perpendicular to palatal surface of teeth, it tends to intrude teeth.
‘T’ Spring •
Constructed using 0.5 mm wire • Used for buccal movement of premolars and molars
Coffin Spring
•
Described by Walter.H.Coffin in 1881 • Made of 1.25 mm wire • Can be used for slow dentoalveolar transverse arch expansion
Canine Retractors •
used to move canine in distal direction CLASSIFICATION
I.
II. III.
Based on location -buccal -palatal Based on presence of helix or loop Based on mode of action -push type -pull type
Buccal Self Supported Canine Retractor
• •
•
Fabricated with a 0.7 mm wire Used when buccally placed canine is to be moved palatally and distally coil just distal to long axis of tooth
‘U’ Loop Buccal Canine Retractor
•
Can be used in shallow sulcus
Requires frequent adjustment
Palatal Canine Retractor
-Used for canine placed palatally requiring distal movement
Screws Types of screws The 2 types of expansion screws are Skeletal expansion screw Dental expansion screw
PITCH OF THE SCREW When the expansion screw is given one complete turn, i.e., four one-quarter turns, the two halves of the removable orthodontic appliance advance a distance equal to the space between the neighbouring lines often called as threads. The distance moved is called the pitch of the screw.
Activation Whenever the screw is turned 90 degrees it will drive the parts of the plate apart by 0.2 mm which narrows periodontal ligament by 0.1 mm on each side. •In the case of adult patient – 1 quarter turn/week 0.2mm approx which is less than width
of
periodontal
ligament
fibre
Uses : Baseplate divided into sections driven apart by one or more screws 1)
Split along midline – For correcting Bilateral crossbites
2)
Split into a larger and a smaller part
Y-Plates – For saggital and lateral expansion
Elastics
Resembles rubber band Made of latex rubber Available in various diameters – force applied depends on their diameter Colour coded for easy identification Uses : For movement of singe teeth and groups of teeth For intermaxillary traction
Molar intrusion with removable a appliance
Intermaxillary elastics with removable plates can be used for the treatment of Class II and Class III
Instuctions to the patients and Appliance Care Appliance
should be worn all
the time. Remove the appliance using the clasps only. Remove the appliance only during brushing and for
Never wrap the appliance in napkin or in pocket The
patient should avoid playing with the appliance using the tongue. Initial problems faced by patient like discomfort, pain ,excessive salivation ,plastic taste and difficulty in speech. Storing the appliance in a proper
PROBLEM 1: UPPER INCISOR INSIDE BITE
RETENTION: Adams cribs 6/6 and 4/4
Active component: Z-spring to 1/
BITE OPENING: Posterior bite capping to 654 / 456 (more comfortable for patient)
BASEPLATE: to connect everything together, also some anchorage
ACTIVATE THE Z-SPRING....
PROBLEM 2: All four incisors inside bite, with deep reverse overbite
RETENTION: Adams cribs 6/6 and 4/4
ANTERIOR RETENTION: Southend clasp 1/1
ACTIVE COMPONENT: Expansion screw to section 21/12
BITE OPENING: occlusal capping posteriorly
Screw is opened by one quarter turn twice a week and pushes upper incisors forward over the bite
PROBLEM 3: Increased overjet, proclined incisors
Extract 4/4 to allow overjet reduction
RETENTION: Adams cribs on 6/6 , Southend clasp 1/1
ACTIVE COMPONENTS: Palatal finger springs 3/3 with wire guards for stability
Trim acrylic
BITE OPENING: flat anterior bite plane
3/3 at end of canine retraction
Canines retracted. Now the incisors must be retracted
RETENTION: Adams cribs 6/6 with arrowhead extensions to 5/5
Metal stops mesial to 3/3 to prevent these teeth from moving forward
ACTIVE COMPONENT: Labial bow in 0.7 mm wire with large U-loops to allow activation
BITE OPENING: flat anterior bite plane
Labial bow activated 1-2 mm at each visit by squeezing vertical legs of U-loops together. Palatal acrylic must be trimmed away by the same amount.
End of incisor retraction
Where canines are bucally placed, use buccal canine retractors, made in either 0.7mm wire or 0.5mm wire supported by 0.5mm internal diameter tubing where it emerges from the acrylic
Canines can be pushed palatally into the line of the arch as they move distally
The labial segment can be retracted also with a 0.5mm labial bow with tubing support.
ACTIVATION OF LABIAL BOW: Press the vertical leg towards the tubing
PROBLEM 4: /5 deflected palatally, /6 has drifted mesially
RETENTION: Adams cribs 6 / 46 , southend clasp 1/1
ACTIVE COMPONENT: Screw section to /6 , Z-spring to /5
PROBLEM 5: Buccally placed canine /3
Retention: Adams cribs 6/6 and 4/4
ANCHORAGE REINFORCEMENT: Headgear tubes on 6/6
ACTIVE COMPONENT: Screw section to distalise /456
ANCHORAGE REINFORCEMENT: headgear to tubes on 6/6
Problem 6: Class II div 1, and both upper first permanent molars are carious
Adams cribs on 73/37, finger springs 5/5 and 4/4, fitted labial bow 21/12
Extract 6/6
Retract 5/5 (with or without headgear support)
Retract 4/4
Adams cribs 74/47, finger springs 3/3, Southend clasp 1/1
Upper 3/3 retracted
URA with labial bow to retract 21/12
Conclusion Removable and fixed appliances are the two facets of the orthodontic world. The science and art of designing and constructing removable orthodontic appliances forms the basis for managing most of the orthodontic patients Sound theoretical knowledge of orthodontics helps us in designing a removable orthodontic appliance where as the construction of removable appliance is more of an art which has to be learned meticulously following the procedure and by repeated practice.
References
Orthodontic treatment with removable appliances- W. W.J.B. Houston, K.G. Issacson The Design, construction and use or Removable Orthodontic Appliances – C. Philip Adams Removable Orthodontic Appliances- T.M. Graber, Bedrich Neumann Orthodontics Principles and Practice- T.M. Graber Contemporary Orthodontics- Proffit
