Ld retention and relapse

Retention and relapse in orthodontics

Introduct ion The problem of “retention and relapse” was born with the science of Orthodontics and continues to persistently plague Orthodontic researchers and clinicians. Most authors of Orthodontic textbooks, from ngle to the present!day writers, ha"e included the chapters on retention and relapse in their publications. #n spite of all the ad"ances in the acti"e treatment procedures, "ery few practitioners underrate u nderrate the significance of retention. $e are yet pu%%led how to sol"e the problem& $ith the establishment of concept of normal occlusion and the classification scheme that incorporated the line, by the early '())*s orthodontics was no longer +ust the alignment of irregular teeth, instead it had e"ol"ed into the treatment of malocclusion. ince precisely defined relationships re-uire a full complement of teeth in both arches, maintaining an intact dentiti dentition on become becomess an impor importan tantt goal of orthodo orthodonti nticc treatm treatment ent.. ngle ngle and his follow followers ers strongly opposed extraction for orthodontic purposes. Treatment goal during this period was “#deal Occlusion.”' $ith the entry into 'st century, the goals ha"e somewhat appeared to change. The goal of Modern Orthodontics is creation of best balance among occlusal relations, dental and facial esthetics, stability of the results and its long term maintenance and restoration of dentition /T$0012'. ims of orthodontic treatment ha"e been summari%ed by 3ackson as 3ackson*s triad. triad. The three main ob+ecti"es are4 /a2 5unctio 5unctional nal efficacy efficacy /b2 tructural tructural balance balance /c2 0sthet 0sthetic ic harmon harmony y Retention is that part of orthodontic treatment during which a passi"e appliance is used used to maintai maintain n orthod orthodont ontic ic correc correctio tion n of dental dental and skelet skeletal al struct structure uress and thereb thereby y counteract relapse or the tendency for return of characteristics to original malocclusion. Retention was defined by Moyers6 as “the holding of teeth followed by orthodontic treatment in the treated position for the period of time necessary for the maintenance of the results.”

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Riedel7 defined retention as “the holding of teeth in ideal esthetic and functional position.” Relapse may be defined as return of the corrected malocclusion towards the original condition. Moyers6 defined relapse as loss of any correction achie"ed by orthodontic treatment. The retention period has e"en been called “econdary orthodontic treatment.”8 lthough it has been stated that correct diagnosis and planning of treatment, followed by a careful stabil stabili%a i%atio tion n of the final final result result,, would would minim minimi%e i%e the impor importan tance ce of retent retention ion,, relaps relapsee tendencies still exist in a fairly high percentage of cases treated. 0"en if these precautions are taken, taken, howe"er howe"er,, relaps relapsee after after tooth tooth mo"eme mo"ement nt still still remain remainss a comple complex x proble problem, m, with with a "arying number of factors in"ol"ed. Orthodontists ha"e been concerned by relapse process for decades. e"eral studies ha"e been carried out to determine the changes taking place se"eral years after orthodontic treatment and the influencing factors. 5actors including growth, periodontium, age, third molars, molars, tooth dimensions dimensions etc ha"e been held responsible responsible for post treatment treatment relapse. relapse. e"eral procedures ha"e been de"ised de" ised to ensure stability and pre"ent or at least a"oid post treatment changes so as to reduce relapse. To achie"e this purpose, a proper understanding of the changes occurring, "arious factors affecting relapse and retention procedures is important. Thus our Orthodontic forefathers faced the problems of retention and the continued trend, which owes to the biological and mechanical limitations, demands e"ery Orthodontic student to go through the state of art of this perineal problem “Retention and Relapse” which also is the purpose of this library dissertation.

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Historical background background 9  look back at the origins of orthodontics orthodontics (Weinberger) has (Weinberger) has shown that the necessity of retention was not mentioned until about '( centuries after the first treatment modality was described and would pro"ide a clue to establishing the priority of the esthetic needs of the prospecti"e orthodontic patient. s Weinberger states, states, “lthough orthodontics had its origins in medicine, it had its beginnings beginnings in aesthetics aesthetics”. ”. :ikewise, :ikewise, the modern modern well!trai well!trained ned clinical clinical orthodontist has recogni%ed that the most desirable facial!dental esthetics may be +ust as important as excellent posterior occlusion and good function!possibly more so from the standpoint of the patient*s needs. ;owe"er, there appears to be as much contro"ersy o"er the present treatment methods of achie"ing facial!dental ob+ecti"es as there was in the Case, Dewey, Cryer extraction!nonextraction extraction!nonextraction contro"ersy in '('', which still persists three fourths of a century later in the writings of Tweed, Tweed, Ricketts, Begg, Ten Hoeve, and Williamson. dditional insight into the retention problem may be gained and our present day limitations in achie"ing predictable stability appreciated when we learn about the anti-uity of some of our still current modes of orthodontic treatment. #n the beginning, says Weinberger , “people sought relief because of the disfigurement of the crooked and irregular placed teeth”< the first century Roman writer Pliny writer Pliny  !alen, !alen, his countryman in the second century who was the founder of experimental medicine, both recommended filing when a tooth pro+ected from trauma trauma and other reasons. reasons. 5i"e centuries centuries later, later, Pa"l o# $gina (%&'%*), the (%&'%*), the classical =reek author, was first to consider that if “supernumerary teeth cause irregularity of the dental arches, they may be corrected by resection of each tooth or by extraction”. #t was not until ten centuries later that Pierre that Pierre Diones (+%'+-+) appeared (+%'+-+) appeared to be the first “to open or widen the teeth when they were set too close together”. #ndeed, while significant works on orthodontic etiology, classification and mechanical treatment techni-ues were published by Pierre by Pierre a"c/ard (+-&), Bo"rdet (+-'-), o0 (+*1), Delabarre (++), 2c/ange (+3+), (+3+), and Harris Harris (+3&), we gained little, if any, knowledge as to the concern about stability of treatment until '>9). #n that year 4merson year 4merson C. $ngell (+%*), as (+%*), as a byproduct of his palate!splitt palate!splitting ing procedure, procedure, mentions the necessity necessity to preser"e preser"e or retain retain space. ngell ngell

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Retention and relapse in orthodontics described his method of employing a +ackscrew for?rapid opening of the maxillary median suture or to enlarge the face in the maxillary dental arches, in order to establish occlusion without extraction of teeth?The time for this expansion need not exceed two weeks, after which which it is only only necessa necessary ry to preser preser"e "e or retain retain the space space until until comple complete te erupti eruption on and de"elopment of teeth in -uestion. Only 8 years later in 0ngland, $l#red 0ngland, $l#red Coleman (+%') wrote about restoration of the former condition by muscular pressure!in other words, the first illusion to relapse. More than a century later, clinicians still refer to abnormal muscular pressure as a dominant factor in the cause of relapse. #n the following year, C.$. 5arvin (+%%) described (+%%) described the physiologic reasons for retention. #ndeed, he went a step further in his writing and emphasi%ed the necessity of the preser"ation of correct facial expression or “aesthetics” as one of the ob+ecti"es of orth orthodo odont ntic ic trea treatm tmen ent. t. @ot @ot long long afte afterr, Brown5ason (+-&) (in 4ngland) descri described bed a retaining plate for surgically rotated teeth. Thus, after more than '( centuries of some kind of mechanical mechanical orthodontic orthodontic inter"ention, inter"ention, recognitio recognition n of the possible possible instability instability of treatment treatment emerged and the concept of a retaining appliance was born. One of the earliest retaining appliances in the Anited tates was described by 6ames by 6ames W. 2mit/ 2mit/ (++) (++) before the ;ar"ard Odontological ociety in Boston. #t was a simple "ulcanite plate with a bar extending o"er the labial aspect of the maxillary incisor teeth. #n '>>6, H.C. '>>6, H.C. 7"inbey described 7"inbey described a slightly more sophisticated maxillary retaining plate that had strips of metal extending from the "ulcanite plate o"e r the anterior teeth. 6ackson (+*3) mentioned mentioned the importance importance of retention retention and designed designed many retaining retaining de"ices!some permanent when necessary. lso, lso, to pre"ent the tendency tendenc y of the teeth to change their positions after the remo"al of the retainer, he suggested that “after they ha"e been rotated as far as desired, the soft tissue be separated from the neck of the tooth and allowed to reunit reunitee in the new locati location, on, dependi depending ng upon the cicatr cicatrix ix thus thus formed formed to pre"en pre"entt their their retrograde mo"ement!in short fiberotomy. fiberotomy. $ngle stated $ngle stated that obtaining “normal occlusion” /with steep cusp height2 during the eruption period would decrease retention time, but added that when habits are not o"ercome and the rotations and disturbance to the fibers of the periodontal membrane are "ery marked, he described cutting gingi"al fibers to counteract this in his sixth edition publication /'())2. ;e warned warned that that most most applia appliances nces were remo"e remo"ed d too soon soon before before teeth teeth were were thorou thoroughl ghly y

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Retention and relapse in orthodontics established in occlusion, and he ad"ised, “#n doubtful cases, wearing delicate and efficient appliances indefinitely may be far less ob+ectionable than a malocclusion”. 5ina 5inall lly y $ngle $ngle de"ised and described many ingenious mechanical combinations of cemented bands and spurs, the action of which were, to -uote his uni-uely descripti"e phase, “to antagoni%e the mo"ement of teeth only on the direction direction of their tendencies”. tendencies”. lso in his -uest for the ultimate retainers, it is interesting to note that ngle*s intricate pin and tube acti"e acti"e treatment treatment appliance appliance was de"eloped primarily primarily as a working working retainer to achie"e achie"e bodily bodily mo"ement or uprighting of teeth that had been tipped outward in expansion. #n his article, “Crinciples “Crinciples of Retention”, Retention”, Case listed Case listed the following principles4 Cost treatment influence of surrounding tissues would return to their former irregular position after retention primarily because of the “more important factor of hereditary”< stretched and bent fiber structures would be brought to e-uilibrium in their changed positions by the physiologic process of nature< retention should be of ade-uate force to antagoni%e reacti"e tendencies for relapse and held, often indefinitely by a fixed appliance, unless teeth are brought to positions of what wha t he called “positi"e “ positi"e self!fixation “ by b y occlusion< o"er correction and slower mo"ement of teeth< teeth< use of inconspicuou inconspicuouss fixed retainer, retainer, incorporatio incorporation n of strong strong intermaxillary and "ertical elastics with chin cups to o"ercome the reacti"e or relapsing forces of the corrected mesial or distal occlusion as well as open or closed bites< for retaining diastemata of both the maxillary and mandibular anterior teeth, gold staples were cemented into drilled preparations in all lingual cingula, which remained in place for more than ) years.  hundred years ago, Bonwill ago, Bonwill described described an ideal morphologic arrangement of teeth and +aws based on his study of more than ))) skulls. ;e placed study models in anatomic articu articulat lators ors,, used used wax set!up set!upss of plaste plasterr teeth teeth for extrac extractio tion n decisi decisions ons<< and thorou thoroughl ghly y informed his patients on the limits of treatment and the necessity of ade-uate retention. 8ormal 9ingsley (+*), who (+*), who is referred to as the “5ather of Orthodontia”, in a letter /his last published article2 to the alumni of the ngle chool of Orthodontia written 8) years after his first article appeared, had these prophetic words to say about retention. #t is not so difficult to straighten crooked teeth, to get the dental system into a position acceptable to your patients and yourself, but to hold it there until it becomes permanently

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Retention and relapse in orthodontics settled, is a much more serious problem. #t is the one important consideration in all your prognosis, and the success of orthodontia as a science and as art lies in the DretainerE? DretainerE? errar (+1+++1), also (+1+++1), also referred to as one of the fathers of orthodontics!that is, scient scientif ific ic orthod orthodont ontics ics!th !thee man who introd introduce uced d the term term interm intermitt ittent ent force force and wrote, wrote, accor accordi ding ng to Weinberger, Weinberger, the greatest text on orthodontia in his experience, said /about retention2 that when the teeth are fully regulated they should be retained in position for a year, perhaps longer. #n summary, in the little more than one half century following ngell*s use of a retaining plate in his palate!splitting techni-ue, there was general adherence to the necessity of retention retention and e"en a similarity similarity of appliances, appliances, but the knowledge knowledge gained was based solely on the clinic clinical al experie experience nce and obser" obser"ati ation on of the aforem aforement entione ioned d pioneer pioneer orthodo orthodonti nticc masters. The next -uarter century witnessed the much needed addition of a more scientific dimension to the retention literature as the clinical reports of the duration of a "ariety of retain retaining ing applian appliances ces and the obser" obser"ati ations ons and opinio opinions ns ad"oca ad"ocated ted by /'2 the follow following ing orthodontic orthodontic inno"ators inno"ators and clinical clinical scholars4 scholars4 Hawley Hawley (++) (++),, Ha/n Ha/n (+33) (+33),, :"ndst :"ndstro rom m (+&), Hellman (+1%), 5ers/on (+1%), 5arc"s (+1), 5cCa"ley (+33), Tweed (+'3), and !rieves !rieves (+33); (+33); /2 experimenta experimentally lly trained trained research!or research!oriente iented d orthodontis orthodontists, ts, 2kogborg (+&) and <==en/eim (+1') and /62 the research!orien research!oriented ted periodontists periodontists,, !ottlieb (+1) and s :"ndstrom>s (+&) clinical clinical studies on apical base limitation limitation did much to counteract counteract the dominance of the expansionists led by ngle. :undstrom*s work appears to ha"e been fundamental in helping to reduce the relapse problem created by the o"erexpansionists. Hellman, the Hellman, the leading scientific spokesman of orthodontists of his generation, admitted he “was in complete ignorance of retention in the indi"idual case”. 5ers/on (+1%), who (+1%), who is credited credited with the introduction introduction of the lingual lingual arch in clinical orthodontics, thought alternating rest periods with acti"e treatment would aid retention, but

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Retention and relapse in orthodontics likened the final positioning of teeth to an argument in which “mother nature” always had the last word. Ha/n (+33), dismayed (+33), dismayed by the “apparent lack of will of the ma+ority of the profession to study the retention problem ade-uately”, obser"ed that “retention in orthodontics is like a neglected Fstep child*”. #n anot anothe herr "iew "iew,, 5cCa"ley (+33) a prop prophe hett befo before re his his time time,, proc procla laim imed ed the the importance of canine position and referred to the canine rise as a “protecti"e mechanism for maintaining arch stability”. Goncurr Goncurrent ent with with the abo"e!m abo"e!ment ention ioned ed work work of clinic clinical al schola scholars, rs, anthropologist Hirdlieka>ss generic statement that “#f regular growth of any

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Retention and relapse in orthodontics part of the body is interfered with by any cause, related parts tend towards compensation”. Thus, isc/er Thus, isc/er belie"ed belie"ed that a “compensatory ad+ustment of facial growth would occur after orthodontics since there has been an interference in the unfolding of the face”. ;e continues4 Iery often the orthodontic forces are but an interlude in the continuous de"elopment of the face, and pre!treatment and post!treatment stability is a result of an e-uilibrium between the component parts of the dental! facial complex and in the random and dynamic changes occurring post! treatment, the denture must be protected or retained during the acti"e period of facial!dental growth changes or at least un til cessation of ma+or growth changes. 2c/w 2c/war art@ t@ reiter reiterate ated d this this theme theme and descri described bed “inter “internal nal opposit opposition ional al forces forces”” or “electric effect” that was beyond the control of the orthodontist. 1uring the posttreatment period, 2c/wart@ said said #nternal and external forces playing on the denture lead to %ero and stability. #t is only a momentary static situation, because growth and change is occurring and the e-uilibrium that results must somehow anticipate and include both growth and change to insure stability. #n dir direct ect cont contra rasst, !eorge !eorge !rieves !rieves (+33) (+33) beli belie" e"ed ed that that the the caus causee of most most malocclusions was the forward translations of teeth /in agreement with a similar proposal in the earlier earlier work of 6. of 6. 2imms Wallace, Wallace, +&- 2 and that when teeth ha"e been placed backward and upright o"er basal bone they would be stable and hence ha"e no need for retention. lthough Tweed ad"ocated ad"ocated placing teeth back and upright o"er basal bone, he prescribed 8 years retention in most cases and e"en longer periods when needed. !eorge $nderson>s (+3&) obser"ations (+3&) obser"ations led him to the conclusion that nothing was stationary in the human masticatory field. There has been stability worthy of the name in the de"eloping masticatory field or in the fully erupted denture, and that retention was not a minor but a "ery serious matter and a basic part of orthodontic therapy. therapy. 1uring this same period, the application of facial, +aw and body muscular exercises /myofunctional therapy2 with fixed appliances for successful treatment and retention was brought forth in a series of publications from '(68 to '(8' by $l#red by $l#red P. P. Rogers (+'+). (+'+). #n contrast contrast,, Dallas 5cCa"ley (+33) placed (+33) placed great emphasis on maintaining canine position, arch form, and width as related to functional +aw mo"ements to achie"e posttreatment stability. stability.

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Retention and relapse in orthodontics 2tedman 2tedman (+%+, (+%+, +%-), +%-), in a comprehensi"e approach to retention, referred to an enlarged pharyngeal space, emotionally initiated mentalis or mimetic muscle hypertension, and anterior component of force of mandibular third molars because of insufficient growth as factors in bringing about undesirable posttreatment changes or relapse. 2tedman ad"ocated 2tedman ad"ocated the use of specially constructed, fixed and remo"able retainers and he may ha"e implied their long!range use when it was not the case in his theoretical statement4 :asting occlusal changes occur only in these particular patients whose internal forces ha"e changed in such a manner during treatment and retention as to support those particular teeth in the newly ac-uired positions, with new functional and emotional habits. Riedel>s Riedel>s (+%*) (+%*) comprehensi"e re"iew of retention was a forerunner of his subse-uent ')!year post!retention relapse studies and those of his graduate students at the Ani"ersity of $ashington in eattle. These and the multitude of postretention relapse studies by others report their extensi"eness, unpredictability, and se"erity, and are the grim realities facing the orthodontic clinician. #n essence, these relapse tendencies were graphically described by !raber (+%%) and (+%%) and by 9ing by 9ing (+-3). Iery ofte often n the the chara charact cter eris isti tics cs of the the malo malocc cclu lusi sion onss by whic which h we dete determ rmin inee classification seem to reoccur in an alarming degree post!retention. Relapses of crowding, rotati rotations ons,, mesio!d mesio!dist istal al relati relations ons,, o"erbi o"erbite, te, o"er+et o"er+et and arch arch width width and form form reappea reappear r subse-uent to retention. There is no assurance that relapse will not happen e"en when surgery is combined with orthodontic treatment. 9ing describes the characteristics of post!retention relapse as an o"erall “slipping back or dental changes”, "ery much in agreement with !raber. #n specific postretention relapse studies, attention has been focused on the stability or relapse of canines and molar width, mandibular arch form, mandibular incisor crowding, rotations, o"erbite and o"er+et, and the presence or absence of mandibular third molars. #n all these studies, extraction or nonextraction, there appears to be sufficient unpredictability of which cases will or will not relapse for all but a minority of treatment procedures. The relapse tendencies reported in the abo"e!mentioned studies ha"e occurred with treatm treatment ent using using what has been consid considere ered d to be con"ent con"ention ional al orthodo orthodonti nticc forces forces.. #t is

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Retention and relapse in orthodontics important to know whether there is a difference in the effect of the orthopedic palate!splitting forces reintroduced clinically by Deric/sweiler by Deric/sweiler (+'%) and (+'%) and continued by 9ork/a"s by 9ork/a"s (+%*) in (+%*) in =erman =ermany y. oon after after !raber an and Haas reported reported clinical clinical /extraoral /extraoral and palate! palate! splitting splitting22 studies, and Mc@amara reported experimental studies. 0xperimental and clinical reports on the effect of high!pull orthopedic forces by Watson by Watson (+-&), T/om=son (+-3), 4lder and T"erge (+-3), Cleal (+-3), and Wislander (+-3) differ (+-3) differ on the extent of skeletal stability, but show high agreement to the effect that dental instability or relapse, especially mandibular incisor changes following orthopedic forces, is consistent with the continuing changes that occur in con"entional force treatment. There is a recent trend of orthodontists in the Anited tates to report the use of acti"ators andJor functional appliances, alone or as a preliminary to a secondary period of treatment, using a multibracketed fixed appliance. long with this trend, there is also the belief that the results will be more stable. Reitan>s Reitan>s (+', +%%, +%-) +%-) microscopic studies of postretention treatment changes excited the orthodontic community worldwide. ;e demonstrated in animal studies that the suprac supracres restal tal gingi" gingi"al al fibers fibers /coll /collagen agenous ous22 appear appear histol histologi ogical cally ly taut taut and direct direction ionall ally y de"iate de"iated d after after tooth tooth rotati rotation, on, and that that this this conditi condition on did not lessen lessen e"en after years of retention. #n respons responsee to Reitan>s Reitan>s work, many surgical approaches with experimental animals and human sub+ects to control or lessen rotational relapse in orthodontic treatment ha"e been reported in the literature. 9ole (+') remo"ed (+') remo"ed the buccal and lingual cortical plates on human patients before initiatin initiating g orthodonti orthodonticc mo"ement, mo"ement, somewhat reminiscent reminiscent of the septotomy of Talbot (+%) and 2kogsborg (+&-). T/om=son T/om=son (+') (+') /repea /repeate ted d by Boese Boese in '(9(2 remo"ed all the attach attached ed gingi" gingi"al al tissue tissue on experi experime mental ntal animal animals, s, lea"in lea"ing g only only the mucosa mucosa surrou surroundi nding ng rotated teeth.

4dward>s 4dward>s (+-*) clinic clinical al orthodo orthodonti nticc study study was based on on Ba"er>s Ba"er>s (+%1 (+%1)) thesis describing mesial and distal incisions of transseptal fibers of rotated teeth in experimental animals and 4dward>s and 4dward>s own similar animal study /'(9>2.

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Retention and relapse in orthodontics Parker (+-&), in (+-&), in a clinical study of transseptal fibers, states4 Rotational relapse is a normal, predictable, physiological response to abnormal forces ? The paralleling of tooth roots, discriminate transection of free gingi"al fibers and ade-uate retention time are "ery important and useful ad+uncts to stability in treated orthodontic cases. $ith the growing e"idence that the presence of intact transseptal fibers was the ma+or "illain in rotational relapse, 9a=lan relapse, 9a=lan (+-%) undertook a natural sur"ey of '))) orthodontists to determine the extent of circumferential supracrestal fiberotomy as an ad+unct to retention procedures. ;e concluded4 $hile $hile it appears appears that that this this surgic surgical al techni techni-ue -ue is not widely widely prescr prescribe ibed, d, it seems seems reasonably problem free and its use will probably be increasing in the future. D;e cautions,E There are as yet no follow!up studies of the efficacy of this treatment procedure. 5ina 5inall lly y, 2c/acter 2c/acter and Bernick> Bernick>ss (+-3) conclu conclusio sion, n, in an experi experimen mental tal study study on nonhuman primates “that their study did not answer the problem of why certain rotations do not not occu occurr e"en e"en afte afterr sur surgica gicall tran transe sect ctio ion n of the the fibe fibers rs”” must must be pert pertin inen entt to all all aforementioned fiberotomy studies. lmost in lieu of retention or in retreatment, there ha"e been studies of stripping eith either er to pre"e pre"ent nt rero rerota tati tion on of the the mand mandib ibul ular ar inci inciso sorr or to corre correct ct the the rela relaps psee of the the mandibular incisors, followed with or without retaining appliances. K elston elston (+%) presented (+%) presented a techni-ue for realignment with wires and ligatures after stripping of crowded lower incisor teet teeth. h. Paskow (+-*) reported reported self!alignm self!alignment ent following following interproxi interproximal mal stripping stripping of lower incisors and was indefinite about retainers. Boese retainers. Boese reported reported a combined procedure of stripping and circumferential supracrestal fiberotomy with no lower retainer placed. #n his 7!( years follow L up, he noted that the lower incisor segment did mo"e, but mo"ed in a unit rather than each tooth indi"idually. ;e concluded4 G5 and reproximation is not a guarantee for permanent ideal lower anterior tooth alignment, but was percei"ed as a useful process, which appears to work within a framework of natural changes that ine"itably will occur.

Williams (+'), in (+'), in addition to stripping, added fi"e other treatment “keys”, which he said will eliminate the need for lower retainers, but he showed a !year follow!up of one case. These approaches and that of Peck Peck and Peck>s (+-&) reproximation studies are seemingly

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Retention and relapse in orthodontics based upon the theoretical concept of polished broad contact areas described by Begg by Begg in tone ge men. Begg made the deduction that it was the primiti"e rough diet of the ustralian ustralian aborigines aborigines that was responsible responsible for well!align well!aligned ed teeth. On the other hand, it was belie"ed that failure to achie"e polished broad contact areas during and following orthodontic treatment of modern ci"ili%ed man with a lack of comparable attrition would re-uire a techni-ue for realignment and stripping of crowded lower incisors to pre"ent or correct relapse. Waldron (+3&) (+3&) designed his retaining appliances on the basis of the rationale of <==en/eim, the researc researcher her,, and 5ers/on, 5ers/on, the clinician, who had emphasi%ed the need to allow for functional adaptation of muscles and bones during the retention period. $aldron ad"ocated remo"able appliances, empirical retention time, myofunctional therapy, bilaterally balanced occlusion based on true centric denture and +aw relationship, and extraoral appliances in many class ## and class ### cases to supplement the customary remo"able retainers. Ten Ten years after Riedel>s Riedel>s classic re"iew article on retention /'(9)2, and nearly three decades after Ha/n> after Ha/n>ss (+33) reference (+33) reference to the neglect of the importance of retention, 5"c/nic retention, 5"c/nic (+-*) informed (+-*) informed his patients4 #n most cases the retention period was planned with expected growth and maturation in mind, because the forces which work so efficiently in treatment to inhibit growth in one area while allowing growth to continue in another should not necessarily be discontinued because the bands ha"e been remo"ed and the teeth are in proper occlusion. #n '(H), ogel '(H), ogel  5cgill carried carried out a retrospecti"e study on progressi"e dental!facial changes after treatment and retention of ' cases!se"en nonextraction and '7 extraction showing good stability. #t was a small sample with some mandibular and maxillary crowding, although of a degree not entirely ob+ectionable. #n an inter"iew by Brandt, by Brandt, Tweed (+%) replied (+%) replied to -uestions on orthodontic relapse that the crowding of lower incisors can and does occur especially in type G growth trends! that that is where where the mandib mandibular ular growth growth direct direction ion is downwa downward rd and forwar forward d and usuall usually y outspaces the maxilla, although not to the extent that it becomes a class ###. #n anticipation of this growth trend, Tweed ad"ocated a lower canine!to!canine lingual bar retainer and replacement of the labial bow of the maxillary remo"able retainer with

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Retention and relapse in orthodontics anterior hooks using latex elastics and a bite!plate, which would permit the maxillary incisor teeth to tip slightly labially. Tweed referred referred to a retrospecti"e study /8 years posttreatment2 on retention that he had conducted on a follow!up group of his own patients consisting of ')) extraction and ')) nonextraction cases. ;e said that in general while “many patients /had2 lo"ely faces  teeth, in others, the picture DwasE the opposite” and that the extraction cases seemed to be “nicer” than nonextraction cases many years after treatment. Tweed acknowledged acknowledged that in his opinion “abnormal muscle function was a ma+or factor in relapse” e"en though he did not know how much one could change muscle function as a result of orthodontic procedure. @e"ertheless, he said he would try to “o"ercome the per"erse muscle and tongue habits”. 2and"sky (+3) reported (+3) reported a postretention relapse study /')!year a"erage2 of >8 Tweed treated cases!78 by Tweed himself himself and 7) by Tweed #o"ndation members. members. The mandibular incisor relapse was shown to be -uite small less than ')N using the :ittle index!but other changes occurred, namely, forward mo"ement of lower incisors and change of occlusal plane. t the same time, :ittle time, :ittle (+3) reported (+3) reported on a ')!year postretention relapse study of 78) cumulati"e cumulati"e cases from the Ani"ersity Ani"ersity of $ashing $ashington ton group at eattle, eattle, led by Riedel. by Riedel. :ittle showed that 99N of these cases exhibited mandibular incisor relapse with no statistical support of predictability of which cases would relapse and which would remain stable.

Philosophies or schools of thought of retention

'6

Retention and relapse in orthodontics 5or many years clinicians did not agree about the need for retention. O"er the years, different philosophies or schools of thought ha"e de"eloped in regard to the retention and our present!day concepts generally combine se"eral of these.H

1)

The occlusion school:

9ingsley (+*) (+*) stated, “The occlusion of the teeth is the most potent factor in determ determini ining ng the stabil stability ity in a new posit position ion”. ”. Many early early writer writerss consid considere ered d that that proper proper occlusion was of primary importance in retention and has been repeatedly stressed in the literature (Reitan, 2c/"dy, 9a/l 8ieke). $ngle belie"ed belie"ed that permanency permanency of treatment result could be ensured by creating a normal occlusion with a full complement of teeth, pro"ided there was ade-uate retention and "igorous masticatory function.

2) Th Thee apic apical al bas basee schoo school: l:

#n the middle '()*s a second school of thought formed around the writings of $0el of $0el :"ndstrom, who :"ndstrom, who suggested suggested that the apical base was one of the most important important factors in the correction of malocclusion and maintenance of a correct occlusion. ;is clinical studies on apical apical base did much to counterac counteractt the dominanc dominancee of the expansio expansionis nists ts led by $ngle. by $ngle. ;e stated that occlusal function alone could not control the form and amount of apical base rather the apical base is in largely capable of affecting the dental occlusion. Dallas occlusion. Dallas 5cCa"ley (+33) placed (+33) placed great emphasis on maintaining canine position, arch form and width as related to func functi tion onal al +aw +aw mo"em mo"ement entss to achi achie" e"ee post post treat treatme ment nt stabi stabili lity ty.. ;e sugge suggest sted ed that that interc intercani anine ne width width  interm intermola olarr width width should should be mainta maintaine ined d as origin originall ally y presen presented ted to minimi%e minimi%e retention retention problems. problems. 2trang further further enforced and substantiated this theory. 8ance theory. 8ance (+3-) (+3-) noted that, “arch length may be permanently increased to a limited extent”. This school school of thought thought sugges suggested ted that that mandi mandibula bularr interc intercani anine ne width width and interm intermola olarr width width dimensions show a strong tendency to relapse and should be considered in"iolate.

3) The mandibu mandibular lar incisor incisor school: school:

'7

Retention and relapse in orthodontics !eorge !rieves (+33) (+33) stated that cause of most malocclusions was the forward translation of teeth and that when teeth ha"e been placed backward and upright o"er basal bone they would be stable and hence ha"e no need for retention. Tweed (+33,+'&) (+33,+'&) also suggested that the mandibular incisors must be kept upright and o"er the basal bone.

4) Th Thee musc muscul ulatu ature re scho school: ol:

$l#red P. Rogers (+&&) introduced a consideration of the necessity of establishing proper functional muscle balance. Other corroborated this theory. 2trang (+'%) (+'%) stated as follow follows!“ s!“The The width width as measur measured ed occurs occurs from from one canine canine to another another in the mandib mandibula ular r denture, is an accurate index to the muscular balance inherent to the indi"idual and dictates the limits of the denture expansion in this area of treatment”. d"erse J abnormal muscle acti"i acti"ity ty has been "ariou "ariously sly proposed proposed by many many author authorss includ including ing Coleman, $ngle, Case, 2trange, 2trange, Tweed, Tweed, 2tedman 2tedman and and Rogers as, Rogers as, if not the cause, then atleast a ma+or contributing factor of relapse. Orthodontists ha"e come to reali%e that retention is not separate from orthodontic treatment but that it is part of treatment itself and must be included in treatment planning. tability has become a primary ob+ecti"e in orthodontic treatment, for without it either ideal function or ideal esthetics, or both, may be lost. Retention depends on what is accomplished during treatment. Gare must be exercised to establish a proper occlusion within the bounds of normal muscle balance and with careful regard to the apical base or bases a"ailable and the relationships of these bases to one another.

Basic theorems of retention H, >

'8

Retention and relapse in orthodontics Theorem 1: Teeth that hae been moed tend to return to their former positions!

There is little agreement as to the reason for this tendency< suggested influences include include musculatur musculature, e, apical base, transseptal transseptal fibers, and bone morphology morphology.. $hate"er $hate"er the reason, there seems to be general agreement that teeth should be held in their corrected positions for some time after changes are made in their positions. Only a few orthodontists ha"e suggested that retention is routinely unnecessary. The -uestion of why teeth ha"e a tendency to return to their former positions has, to this date, no real answer.

Theorem 2: "limination of the cause of malocclusion #ill preent recurrence!

Antil more is known about the causati"e factors that are related to particular types of malocclusion, little can be done about their elimination. Therefore, a proper diagnosis based on determining the cause of the malocclusion is in"aluable. $hen ob"ious habits such as thumb or finger sucking or lip biting or tongue thrusting are the causes of malocclusi malocclusion, on, little little difficult difficulty y is presented in diagnosis diagnosis of the determining determining cause. Anfortunately many of our malocclusions appear with apparently unknown origins or at least origins about which we can do little. Gertainly heredity plays a most important part in determining the presence of many malocclusions. #t is important, howe"er, in regard to retention, that the causati"e factors for a gi"en malocclusion be pre"ented for recurring.

Theorem 3: $alocclusion should be oercorrected as a safet% factor!

Therefore, it is well to o"ercorrect the "arious malpositions and malrelations of teeth and +aws. #t is common practice on the part of many orthodontists to o"ercorrect class ## maloccl malocclusi usions ons into into an edge!t edge!to!e o!edge dge inciso incisorr relati relations onship hip.. Orthod Orthodont ontist istss must must be aware, aware, howe"er, that these o"ercorrections may be the result of o"ercoming muscular balance rather than absolute tooth mo"ement. The unrestricted use of class ## elastics sometimes produces a mesial displacement of the mandible, which is almost impossible to detect until elastics ha"e been discontinued long enough to allow normal mandibular posture. The same phenomenon may be seen in the use of class ### elastic forces. The use of elastics must be likened to the use of traction forces in orthopedic surgery, in which muscular forces are o"ercome by constant pull. ;owe"er, absolute o"ercorrection is possible and has

'9

Retention and relapse in orthodontics been demonstrated in many instances. O"ercorrection of deep o"erbite is an accepted procedure in many practices. Gert Gertai ainl nly y, sati satisf sfac acto tory ry maint ainten enan ance ce of o"er o"erbi bite te corr correc ecti tion on depe depend ndss on the the establishment of satisfactory correction during treatment. One of the most irritating types of relapse is the tendency for a pre"iously rotated toot tooth h to rota rotate te towa toward rdss its its form former er posit positio ion. n. :itt :ittle le e"ide e"idenc ncee is a"ai a"aila labl blee to show show that that o"errot o"errotati ation on has been carrie carried d out and there there is e"en less e"idenc e"idencee to indica indicate te that that such such o"errotation is successful in pre"enting the return to the former position.

Theorem 4: Proper occlusion is a potent factor in holding teeth in their corrected positions!

n orthodontist should attempt to produce the best possible occlusion of the teeth. The influence of occlusion is a factor in retention which has often been mentioned and certainly certainly the best possible possible occlusion occlusion is a factor factor in the retention retention of corrected malocclusions malocclusions.. $hether or not it is the most important factor is certainly debatable. #n too many instances we ha"e seen teeth, e"en with high cusps, locked into normal occlusion that will still tend to return to their former positions. #t is e"ident that many orthodontists consider the denture from a static "iewpoint, i.e., with the teeth in occlusion. The functional relationships of teeth are certai certainly nly impor importan tantt factor factorss in retent retention ion and this this has been been recent recently ly emphas emphasi%e i%ed d by numero numerous us author authorss direct directing ing our effort effortss toward toward proper proper occlusa occlusall e-uili e-uilibra bratio tion. n. 5rom 5rom the standpoint of reducing the potential of irritations to the periodontium, an excellent functional occlusion is certainly to be desired. Orthodontists often blame o"erfunction or pounding of the mandibular canines by the maxill maxillary ary canines canines as a cause cause of relaps relapsee in the mandibula mandibularr anteri anterior or area. area. The e"ery e"eryday day e"idence presented by the tremendous wear that may teeth undergo would indicate that they do not mo"e in response to repeated grinding and tapping until the bone has either been so thoroughly destroyed that it allows their migration, or until fibrous tissue builds up to a degree where it actually mo"es the teeth and function on these teeth is actually not possible. Gertainly instances of mandibular anterior irregularity or collapse are common, in which canines either ha"e not yet erupted or are not actually in occlusion. @o doubt, we can say that a perfectly normal denture functions best.

'H


Theorem &: Bone and ad'acent tissues must be allo#ed to reorgani(e around ne#l% positioned teeth!

ome type of retaining appliance should be used either fixed and rigid or an appliance that is inhibitory in nature and not dependant de pendant on the teeth for some length of time. ;istological e"idence indicates that both bone and tissue around teeth which ha"e been mo"ed by orthodontic appliances are altered and that considerable time must elapse before complete complete reorgani%a reorgani%ation tion occurs. ome authors authors ha"e indicated that retainers retainers should be fixed and rigid such as $ngle as $ngle,, who suggested “=” wire, band and spur type attachments, bands soldered together etc. Others ha"e indicated that retainers should only be inhibitory and ha"e no positi"e fixation to allow for the natural functioning of teeth. #t has been suggested that the mandibu mandibular lar lingual lingual arch admir admirably ably suits suits this this descri descripti ption. on. <==en/eim suggests suggests that appliances should be only inhibitory in nature and that repair of tissues around the teeth occurs much more rapidly if no fixed type of retaining appliance is used. ll these suggestions are based on the presumption that mature bone will ensure greater stability for the teeth. Cresent!day orthodontic concepts, howe"er, regard bone as being a plastic substance and consider tooth position to result from e-uilibrium of the muscular forces surrounding the teeth. The placement of retenti"e appliances is an admission of inade-u inade-uate ate orthod orthodont ontic ic correc correctio tion n or of a predet predeterm ermined ined decisio decision n to place place teeth teeth in relati"ely unstable positions for esthetic reasons. $hether stability increases with prolonged retention is one of the most interesting points of discussion in regard to retention planning and is the phase of treatment that is most difficult to -uantify. 1ocumentation and control of such "ariables as cooperation, length of retention time, growth, and appliance design make this type of in"estigation difficult to interpret.

Theorem : If the lo#er incisors are placed upright oer basal bone* the% are more likel% to remain in good alignment!

Theref Therefore ore,, our attent attention ion should should be direct directed ed toward towardss the proper proper angula angulatio tion n and placement of the mandibular incisor segment. The difficulty in e"aluating this contention re"ol"es around proof of the fact that inci inciso sors rs ha"e ha"e been been place placed d upri upright ght o"er o"er basa basall bone. bone. The The term term upri uprigh ghtt is defin definab able le44

'>

Retention and relapse in orthodontics perpendicular to the mandibular plane, or a plus or minus 8 from mandibular plane, or a relation to occlusal plane, or 5rankfort hori%ontal plane. s to what is basal bone, there is no experimental e"idence to indicate that anyone can specify that where this bone begins or ends, and there seems to be no satisfactory method of measuring it. #t has sometimes been assumed that teeth that are upright are also o"er basal bone. ;owe"er, in certain cases the roots of mandibular incisors ha"e been mo"ed labially to a considerable degree in the process of uprighting these teeth. #t is significant that many malocclusions present with mandibular incisors upright and o"er basal bone, and yet these teeth are both crowded and rotated. ;ence the teeth that supposedly ha"e the attributes of stability can actually be in a state of malocclusion. 5rom a purely mechanical standpoint a certain amount of "irtue exists in inclining the mandibular incisors slightly to the lingual. Those who ha"e set mandibular anterior teeth during fabrication of a diagnostic set up ha"e noted that if the teeth are aligned with a labial inclination, attempts to push them lingually results in expansion in the canine area or collapse of the teeth. On the other hand, if the anterior teeth are inclined lingually, further pressure to the lingual does not cause collapse, and tipping to the labial only creates spacing. ;ence, if we are to make any errors in positioning our mandibular incisor teeth, it is probably well to err in the direction of a lingual rather than a labial inclination. #f the patient is growing, the mandibular anterior segment may exhibit a physiologic migration in relation to the mandibular body in a distal direction that is apart from the orth orthodo odont ntic ic trea treatm tmen ent. t. Mand Mandib ibul ular ar arch arch form form play playss a more more impo import rtan antt role role in stabl stablee mandibular tooth alignment than does the relati"e antero!posterior relationship of mandibular denture to base.

Theorem +: ,orrections carried out during periods of gro#th are less likel% to relapse!

Therefore orthodontic treatment should be instituted at the earliest possible age. There seems to be little possible e"idence to substantiate this statement< howe"er, it has a good deal in its fa"or from a logical standpoint if orthodontists are in any way able to influence the growth and de"elopment of the maxilla andJor the mandible. #t is certainly logical to presume that the growth of maxilla or mandible can only be influenced while the indi"idual is growing and that once growth has been completed this potential is no longer

'(

Retention and relapse in orthodontics a"ailab a"ailable. le. $hen $hen treatm treatment ent depends depends on a retard retardati ation on or change change of direct direction ion of growth growth,, treatment must be instituted early during periods of acti"e growth. 0arly diagnosis and treatment planning appear to afford certain ad"antages in long! term stability. #nstitution of early treatment can pre"ent progressi"e, irre"ersible tissue or bony changes, maximi%e the use of growth and de"elopment with concomitant tooth eruption, allow interception of the malocclusion before excessi"e dental and morphologic compens compensati ations ons,, and allow allow correc correctio tion n of skelet skeletal al malrel malrelati ations onship hipss while while struct structure uress are morphologically immature and more amenable to alteration. Much has been said about the change in muscular balance established by changing the positions of teeth, which in turn will promote rather than retard normal growth. $hether malrelations in muscle balance ha"e as much influence on growth and de"elopment as has been supposed is "ery difficult to say. say. Ghanges in muscle balance in a normal direction allow for more normal de"elopment of the dentition< in relation to retention, normal muscle balance should allow for normal arch alignment. $e can say here, howe"er, that where treatment depends on retardation or change in direction of growth such as is effected in headgear therapy, treatment must be instituted during a period of growth.

Theorem -: The further teeth hae been moed* the less likelihood of relapse!

Thus, cases in which it has been necessary to mo"e teeth a great distance are in need of less lesser er rete retent nti" i"ee atte attenti ntion on or it is desi desira rabl blee to mo"e mo"e teet teeth h fart farthe herr in the the proc proces esss of orthodontic treatment. #t is possib possible le that that posit position ioning ing far from from the origin original al en"ironm en"ironment ent will will produc producee e-uilibrium states permitting more satisfactory occlusions, but the wisdom of this rule has not yet been put to the test. 5or e.g.4 in bimaxillary protrusions produced during orthodontic treatment ha"e not shown a tendency to relapse inspite of the fact that there is a pronounced labial axial inclination of both maxillary and an d mandibular incisor teeth. #t might well be that in some of these cases the teeth are mo"ed far enough to be outside of the influence of labial musculature, actually there is little real e"idence to support the statement that the farther teeth ha"e been mo"ed the less relapse tendency they will ha"e. #n fact, the opposite may be true. #t may be more desirable through guidance of eruption and early interception of skeletal

)

Retention and relapse in orthodontics dysplasias to minimi%e the need for future extensi"e tooth mo"ement with the resultant influence on the functional en"ironment and an d such local factors as supracrestal fibers.

Theorem .: /rch form* particularl% in the mandibular arch* cannot be permanentl% altered b% appliance therap%!

Therefore, treatment should be aimed at maintaining, in most instances, the arch form presented by the original malocclusion as much as possible. The e"idence brought to the author*s attention by by 8ance that attempts to alter arch form in the human dentition generally met with failure has been accepted realistically by most orthodontist. tudies of treated orthodontic cases out of retention ha"e lent credence to this type of thinking. #n '(77, 5cCa"ley '(77, 5cCa"ley made the following statement4 “ince these two mandibu mandibular lar dimens dimension ions, s, molar molar width width and canine canine width width are of such such an uncomp uncomprom romisi ising ng nature, one might establish them as fixed -uantities and build the arches around them.” 2trang said said essentially the same thing in '(794 # am firmly con"inced that axiom of the mandibular canine width may be stated as follows4 The width as measured across from one canine to the other in mandibular denture is an accurate index to the muscular balance inhere inherent nt to the indi"idu indi"idual al and dictat dictates es the limits limits of dentur denturee expansi expansion on in this this area area of treatment. e"eral instances of three or more millimeters of expansion of intercanine width were found, but in these instances mandibular canines had been considerably constricted and were blocked lingually to the general outline form in the mandibular arch. Gertainly there are exceptions to the rule of in"iolability of mandibular arch form and intercanine width, but we cannot cannot expect expect all our patien patients ts to be except exception ions. s. 0xtrac 0xtractio tion n of two mandibula mandibularr inciso incisors rs sometimes satisfies the re-uirements of the arch form without intercanine expansion /with remo"al of two maxillary bicuspids2. Of these theorems the following seem to be the most important4 '2 Teeth Teeth do tend tend to mo"e mo"e back toward toward their their former former posit position< ion< 2 The The arch arch form form of the the mand mandib ibul ular ar arch arch cann cannot ot be perma permane nentl ntly y alte altere red d by appl applia iance nce therapy< 62 Bone and ad+acent ad+acent tissues tissues probably probably should should be allowed allowed time to reorgani% reorgani%ee around newly positioned teeth< and

'

Retention and relapse in orthodontics 72 0arly corrections corrections are less less likely likely to relapse. relapse. t this point we can be certain that orthodontic case analysis has come to include a plan for retention, not as a separate posttreatment period demanding different or unusual appliances, but rather as a part of acti"e treatment inseparable, dependent and intimately associated with the changes brought about abo ut during treatment.

0h% is rete retention ntion necessar%



Retention and relapse in orthodontics lth lthoug ough h a numbe numberr of fact factor orss can can be cite cited d as infl influe uenci ncing ng long long!t !ter erm m resu result lts, s, orthodontic treatment results are potentially unstable, and therefore retention is necessary, for three ma+or reasons4 '

'2 The gingi"a gingi"all and periodo periodonta ntall tissue tissuess are affect affected ed by orthodo orthodonti nticc tooth tooth mo"ement mo"ement and re-uire time for reorgani%ation when the appliances are remo"ed<

2 The teeth teeth may be in an inherently inherently unstable unstable position position after after the treatment treatment,, so that soft tissu tissuee pressures constantly produce a relapse tendency<

62 Ghanges Ghanges produced by growth growth may alter alter the orthodontic orthodontic treatmen treatmentt result. #f #f the teeth are not in an inherently unstable unstable position, and if there is no further growth, retention retention still is "itally important until gingi"al  periodontal reorgani%ation is completed. #f the teeth are unstable, as often is the case following significant arch expansion, gradual withdrawal of orthodontic appliances is of no "alue. The only possibilities are accepting relapse or using permanent retention. 5inally whate"er the situation, retention cannot be abandoned until growth is essentially completed.

Elastic recoil of gingival fibers

Cheek/Lip/Tongue pressure

Intra-Arch Irregularity

Changes in cclusal relationship

Differential jaw growth

,lassification of retention retention

6

Retention and relapse in orthodontics Retention planning is di"ided into "arious categories, depending on the type of case and type of treatment instituted4 9,>

1) ,ases that reuire limited minimum) or no retention

2 Gorrected crossbites /i2 /i2

nte nteri rior or44 when when ade ade-u -uat atee o"er o"erbi bite te has has bee been n esta establ blis ishe hed. d.

/ii2 /ii2

Cost Coster erio ior4 r4 when when axia axiall incl inclin inat atio ions ns of post poster erio iorr teet teeth h rema remain in reas reason onab able le afte after r correcti"e procedures ha"e been completed.

B2 ;igh canine or blocked out canines in Glass # extraction cases with no incisor crowding.

G2 Glass Glass ## cases cases slight slightly ly o"ertr o"ertreat eated ed with with headgea headgearr to restri restrict ct maxill maxillary ary growth growth with with sufficient arch length indicated by mandibular anterior spacing and absolutely no mandibular incisor rotations.

12 Gases in which maxillary or mandibular molars ha"e been tipped distally or bicuspids tipped mesially to pro"ide space for the eruption of second bicuspids. Once the second bicuspid has erupted no further retention is necessary. necessary.

2) ,ases that reuired moderate retention

2 Glass # nonextraction cases, characteri%ed by protrusion and spacing of maxillary incisors. These re-uire retention until normal lip and tongue function has been achie"ed.

B2 Glass # or Glass ## extraction cases probably re-uire that the teeth be held in contact, particularly in the maxillary arch, until lip and tongue function can achie"e a satisfactory balance, as in the nonextraction group.

G2 Gorrected cases of deep o"erbites in either Glass # or Glass ## malocclusions usually re-uire re-uire retention retention of an indeterminate indeterminate length of time with the ob+ect of attaining attaining the greatest greatest possible "ertical de"elopment in the buccal segments while the anterior teeth are held in a minimum amount of o"erbite.

7

Retention and relapse in orthodontics /i2 /i2

#f ant anter erio iorr teet teeth h were were depr depres esse sed d to achi achie" e"ee o"erb o"erbit itee corre correct ctio ion, n, a bite bite pla plane ne on on a maxillary retainer is desirable.

/ii2 /ii2

#f o"er o"erbi bite te corr correc ecti tion on was was achie achie"ed "ed as a resu result lt of bit bitee openi opening ng and and the mand mandib ible le was forced forced away away from from the maxill maxilla, a, "ertic "ertical al dimens dimension ionss should should be held held until until growth /i.e., mandibular ramal height2 can catch up.

/iii2 /iii2

e"ere e"ere occlu occlusal sal plan planee tippin tipping g may also also re-ui re-uire re exten extended ded rete retenti ntion on protoc protocols ols and and possibly additional maxillary restraint as well. well.

12 0arly correction of rotated teeth to their normal positions. /i2 /i2

Cerh Cerhap apss bef befor oree roo roott for forma mati tion on has has bee been n com compl plet eted ed..

/ii2 /ii2

#n the the mandi mandibul bular ar inci inciso sorr area area a remo" remo"abl ablee type type of appl applia ianc ncee with with a labia labiall bow is is probably best. #n this area, the occlusal splint type retainer or cast lower partial, as suggested by :ande, may be useful. More recently gingi"ectomy procedures ha"e offered hope for increased stability of corrected rotations. 0arly correction of rotations or se"ering of transseptal fibers may pro"e to be more satisfactory.

02 Gases in"ol"ing ectopic eruption of teeth or the presence of supernumerary teeth re-uire "arying lengths of retention planning. /i2 /i2

uper upernum numera erary ry teet teeth h are fre fre-u -uen entl tly y encou encount nter ered ed in the the maxi maxill llar ary y anter anterio iorr area area and on their their remo"al remo"al<< the maxill maxillary ary incis incisors ors often often erupt erupt slowl slowly y and incomp incomplet letely ely.. $hen the latter ha"e been brought to a normal le"el through orthodontic therapy, it is probably desirable to lea"e the appliance in a passi"e state for se"eral months before retaining this area because these teeth ha"e a tendency to reintrude when released.

/ii2 /ii2

0xce 0xcess ssi" i"ee spac spacin ing g betw between een maxil maxilla lary ry inciso incisors rs re-ui re-uire ress prol prolong onged ed reten retenti tion on afte after r space closure.

/52 The corrected Glass ##, di"ision  malocclusion generally re-uires extended retention to allow for the adaptation of musculature.

3) ,ases that reuired permanent or semipermanent retention in one or both arches!

8

Retention and relapse in orthodontics /2 Gases or instances in which expansion has been the choice of treatment in one or both arches, particularly in the mandibular arch to maintain normal contact alignment.

/B2 Glass ## or Glass ### relationships which ha"e been corrected by creating a “dual bite”. Muscular adaptation will allow the mandible to be positioned forward after strong Glass ## elastic therapy and the patient seemingly cannot retract the mandible any farther< yet if Glass ## therapy is discontinued, in a matter of se"eral weeks the patient will again be able to retract his or her mandible farther posteriorly.

/G2 Gases of considerable or generali%ed spacing may re-uire permanent retention after space closure has been completed.

/12 #nstances of se"ere rotations /particularly in adults2 or se"ere labiolingual malpositions particularly of the maxillary and mandibular anterior teeth and mandibular bicuspids may re-uire permanent retention, as pro"ided by bonded retainers.

/02 pacing between maxillary central incisors in otherwise normal occlusions sometimes re-uires permanent retention, particularly in adult dentitions.

4) ,ases that that reuire reuire operatie operatie procedure proceduress #ith indefinite indefinite reten retention! tion!

/2 Treatment limitations such as tooth si%e discrepancies /that is, larger maxillary teeth2 may result in increased o"erbite or super Glass #.

/B2 Re"ers Re"ersely ely,, larger larger mandib mandibula ularr teeth teeth will will result result in end!to! end!to!end end incis incisor or relati relations onship hips, s, maxillary spacing, or buccal end!on occlusion.

/G2 tripping or reproximation of o"ersi%ed teeth and esthetic bonding of malshaped or undersi%ed teeth may help to resol"e this problem.

/12  "ery "ertical incisor relationship, which for any reason cannot be corrected, will lead to deepening of o"erbite unless retained.

9


&) ,ases ,ases reu reuir iring ing speci special al cons constru tructi ction on and5or and5or rene rene#al #al of remo remoabl ablee retai retainin ning g appliances or acr%lic on the labial bo#s!

/2 Costtreatment adolescent palatal changes.

/B2 :ate mandibular growth spurt and Tweed type G growers.

/G2 To maintain maintain tor-ue and o"erbite correction.

) 6outine cases* e7traction or none7traction* should hae retaining appliancesfi7ed or remoable!

/2 tleast until the destiny of the third molar teeth is determined DorE

/B2 Antil the growth process has slowed in late teens and early twenties DandE

/G2 fterward fterward at the option of the patient. p atient.

H


Time for the initiation of retention retention “fter “fter malposed malposed teeth teeth ha"e been mo"ed mo"ed into into the desired desired positi position on they they must must be mechanically supported until all the tissues in"ol"ed in their support a nd maintenance in their new positions shall ha"e become thoroughly modified, both in structure and in function, to meet the new re-uirements” /ngle2.  R.=. lexander /'(>62 '( coined a phrase “Gountdown to Retention”, Retention”, which he ga"e to describe the time when retention should begin. The countdown begins when the patient*s teeth ha"e been properly positioned L Gentric relation achie"ed, roots at extraction sites parallel, mandibular canine width not expanded, proper buccal and labial tor-ue, normal o"erbiteJo"er+et relationships, and Glass # relationships. ny retention procedure before beginning should fulfill the following criteria4

1) ,orrection and oercorrection of the /P 'a# relationship:

Gonsiderations of anteroposterior skeletal and dental corrections are "ery essential part of any appliance systems. O"ercorrection of the Glass ## case is the greatest challenge in this area. #f corrected only to the desired end position, many Glass ## cases will show a relapse of o"er+et and a deepening of the bite. These patients benefit from o"ercorrection to an edge!to!edge position and maintenance of that position with nighttime Glass ## elastics for 9 to > weeks, followed by setting into an ideal Glass # relationship.)

2) "stablishing correct tip of the upper and lo#er anterior teeth:

#t is necessary to establish correct tip of the upper and lower anterior teeth at the end of the treatment by mode of any appliance system. 5or all teeth, the gingi"al portion of long axis of each crown should be b e distal to the occlusal portion of the long axis of each crown.)

3) "stablishing correct torue of the upper and lo#er anterior teeth:

#t is often necessary necessary to ad+ust ad+ust the tor-ue in the upper and lower anterior segments segments at "arious stages of treatment.

>


A. Moderate-to-severe Class II case before treatment. B. After overjet reduction, torque has been lost in upper anterior segment and lower incisors are angulated forward. C. Additional torque needed in archwires to recover correct incisor angulation.

The most common example is during o"er+et correction of the moderate!to!se"ere Glass ## cases, when the tor-ue is fre-uently lost in the upper anterior segment while the lower incisors are angulated forward. #n this situation, it may be necessary to compensate by adding lingual root tor-ue to the upper anterior teeth and labial root tor-ue to the lower anteriors.)

4) ,oordinating arch #idths and archform:

Garefu Garefull coordi coordinat nation ion of archwi archwires res from from the beginni beginning ng of treatm treatment ent throug through h the rectangular wire phase will pre"ent unwanted and troublesome crossbites from de"eloping. #f the patient*s archwidths are not properly coordinated at the start of treatment, this can be compensated for by narrowing or widening the appropriate archwires from the earliest stages of treatment. )

A. Cross-elastics in cuspid areas used to compensate for asmmetrical upper archform !smmetrical arch indicated b dashed

line".

B.

Modi#ed upper archform !dotted line"$ archwire canted in direction

opposite

to asmmetr. asmmetr.

&) "stablishing correct posterior cro#n torue:

(

Retention and relapse in orthodontics Gorrect posterior crown tor-ue is essential to pre"ent posterior interferences from de"eloping and to allow the seating of centric cusps. The tor-ue built into pread+usted posterior brackets usually eliminates the need for wire bending. )

6)

Retention and relapse in orthodontics ) "stablishing marginal ridge relationships and contact points:

Marginal ridges of ad+acent teeth should be at the same le"el or within ).8 mm of the same le"el. Radiographically, the cementoenamel +unctions should be at the same relati"e height, resulting in a flat bone le"el between ad+acent teeth. Croper marginal ridge relationships in the finishing stage are primarily a function of bracket height. $ith the standard edgewise appliance, the most common method of determining bracket height in"ol"ed is by placing the brackets a specified distance from the incisal or occlusal surfaces of the teeth. The brackets were thus located relati"ely more incisally or occlusally on large teeth than on small teeth, which could result in tor-ue or in!out errors.

A. Brac%ets placed &mm above incisal edges, according to standard edgewise technique. 'ith (mm central incisor !left", brac%et is )* percent of distance up crown surface. 'ith +*mm central incisor !right", brac%et is * percent of distance up crown surface. B. ame teeth with brac%ets positioned in center of clinical crowns, according to Andrews.

 more reliable guideline is the center of the clinical crown, as described by ndrews, which pro"ides a consistent bracket position regardless of tooth si%e. #ncorr #ncorrect ect bracke brackett height height becomes becomes apparen apparentt early early in the le"eli le"eling ng and aligni aligning ng stage stage of treatment. ;ence, it is effecti"e to reposition brackets as early as possible, so that time is not wasted stepping archwires or repositioning brackets during the finishing stage. )

A. pper central incisor with incorrect brac%et height and compensating step in ./+0 archwire. B. Brac%et repositioned at ne1t appointment, with ./+)0 archwire.

6'

Retention and relapse in orthodontics +) ,orrection of midline discrepancies:

Most minor midline discrepancies of 6 mm or less can be corrected with rectangular wires wires in the finish finishing ing stage, stage, wherea whereass greate greaterr discre discrepanc pancies ies re-uir re-uiree attent attention ion earlie earlierr in treatment. There are fi"e methods of elastic wear for specific situations4 /2

/2

 single class ## elastic on one side and a double class ## elastic on the other, for cases

with a bilateral class ## component. /B2

 sing single le class class ## elastic elastic on one side only only, when the o"er+e o"er+ett results results in a slight slight class class ##

relationship on that side and the opposite o pposite side is in a class # position. /G2 /G2 Glas Glasss ### ### elas elasti tics cs on one one side side and class class ## elast elastic icss on the other other, for for cases cases with with the corresponding dental relationships.

Methods of elastic wear to correct minor midline discrepancies during #nishing stage. A. Case with bilateral Class II component$ double Class II elastics on right side, single Class II elastic on left. B. Case with Class II molar relationship on right side and Class I on left$ single Class II elastic on right side. C. Case with Class II molar relationship relationship on right side and Class III on left$ corresponding interma1illar elastics.

/12

 single single class ### ### elastic elastic on one side side only, only, when that that side is in in a class ### ### position position and

the opposite side has a class # dental den tal relationship. /02

n anterior anterior cross!e cross!elas lasti tic, c, when when the discrepa discrepancy ncy occurs occurs primar primarily ily in the anterior anterior

segments.

2. Case with Class I dental relationship on right side and Class III on left$ single Class III

6

Retention and relapse in orthodontics elastic elastic on left left sid side. e. 3. Case Case with discrepan discrepanc c primaril primaril  in anterior anterior segment$ segment$ anterior anterior cross-elastic.

symmetrical elastics should be used for a minimum period of time, and only with rectangular archwires, because of their tendency to cant the occlusal plane. The archwires should be tied back while these elastics are worn so that the wires do not slide around the arch, causing unwanted space opening and distortion of the archform.)

-) "stablishing the interdigitation of teeth:

Maximum Maximum interc intercusp uspati ation on should should be establ establish ished ed betwee between n the buccal buccal cusps cusps of the mandibu mandibular lar poster posterior ior teeth teeth and the lingua linguall cusps cusps of the maxil maxillar lary y poster posterior ior teeth. teeth. 0ach 0ach functional cusp should be in contact with the opposing arch. $hen the rectangular wires ha"e been placed for a long period, the teeth are often unable to settle into an ideally finished position. #t is helpful to allow each case to settle before debonding by using a lower .)'7” round archwire and an upper .)'7” round sectional wire from lateral incisor to lateral incisor. This This is accompanied by "ertical triangular elastics.

4ertical triangular elastics used in settling phase before debonding.

#f the teeth ha"e settled properly after two to four weeks, then the patient can be scheduled for debonding. #f the teeth are not properly positioned, the patient can return to hea"ier archwires for additional finishing. The retainers will fit more properly after settling than if they immediately follow rectangular wires. )

66

Retention and relapse in orthodontics .) ,hecking cephalometric ob'ecties:

Crogress headfilms should be taken about halfway through treatment to allow time for reassessment of anchorage and possible changes in the di"ision of treatment time. Taking a headfilm in the end of treatment may be important for the orthodontist*s education and for e"aluating the success or failure of treatment, but it pro"ides no practical ad"antage to the patient. #mportant factors to e"aluate with progress and final cephalometric x!rays include the anteroposterior position of the incisors, the incisor angulations, changes in the occlusal plane, the degree to which "ertical de"elopment has occurred or been restricted, and the success of the correction of hori%ontal and skeletal components of the case. uperimposition of the progress and final x!rays on the pretreatment x!ray will help determine the orthodontic changes that ha"e occurred. )

18) ,hecking the parallelism of the roots:

=enerally, the roots of the maxillary and mandibular teeth should be parallel to each other and perpendicular to the occlusal plane, as "iewed in the panaromic radiograph. ;ence, a panaromic x!ray should be taken before debanding to e"aluate root parallelism. #f roots are properly angulated, sufficient bone will be present between ad+acent roots, an important consideration in periodontal health. #f crown!root angulation is beyond normal standards, bracket repositioning or archwire bending may be re-uired to modify the root positions. )

11) $aintaining the closure of all spaces:

ll spaces within the dental arches should be closed. #t is important that space closure be maintained, particularly in extraction cases, by using passi"e tiebacks in the finishing stage.

67

Retention and relapse in orthodontics Maintenance of lower arch space closure with passive wire tiebac% between molar brac%et and soldered archwire hoo%.

Otherw Otherwis ise, e, spaces spaces fre-ue fre-uentl ntly y open during during finish finishing ing and must must be reclos reclosed. ed. Open Open spaces not only are unaesthetic, but bu t also may lead to food impaction. )

12) "aluating facial and profile esthetics:

0sthetic e"aluation is an ongoing process during all stages of orthodontic treatment.  pro+ection of esthetic goals should be made as part of the treatment plan. The facial and profile esthetics can then be monitored clinically, clinically, as well as with progress and final cephalometric x!rays. )

13) ,hecking for T$9 d%sfunctions such as clicking and locking:

TM3 dysfunction is a broad sub+ect and the following are some of the recommendations gi"en which a clinician should take into account4 /i2 /i2

1ocu 1ocum ment ent any e"id e"iden ence ce of TM3 TM3 dysfu dysfunc ncti tion on prio priorr to trea treatm tmen ent, t, and and infor inform m the patient that such symptoms exist.

/ii2 /ii2

Moni Monito torr the the pati patien entt for for symp sympto toms ms of TM3 TM3 dysf dysfun unct ctio ion n duri during ng treat treatme ment nt.. #f problems are managed before the de"elopment of true internal derangement, then +oint function can often be re!established without permanent damage with the help of a short phase of splint and physical therapy, concurrent with the orthodontic treatment, until the symptoms are eliminated. ;eadgears and elastic forces should be stopped while managing the TM3 problems.

/iii /iii22

Moni Monito torr the the pati patien entt for for symp sympto toms ms of TM3 TM3 dysf dysfun unct ctio ion n durin during g rete retent ntio ion. n. Taking king tomographic x!rays before treatment, as well as  to 6 months before debonding, is helpful in detecting irregularities within the +oint and in e"aluating the clinical position of the condyle. A. 5atient showing anterior s%id with corresponding anterior condlar position. 6eadgear or Class II mechanics should be

68

Retention and relapse in orthodontics continued to eliminate anterior s%id and allow condle to seat in fossa. B. 5atient showing signi#cantl signi#cantl posterior condlar position with no evidence of anterior s%id. light amount of anterior s%id should be provided b ceasing headgear or Class II 3lastics, or using Class III elastics, to achieve more centered position

The orthodontic patients generally benefit from the establishment of a seated and reason reasonabl ably y concent concentri ricc condyl condylar ar positi position. on.  forward forward or retrud retruded ed condyl condylee can often often be corrected during the finishing stage, in con+unction with minor changes in antero!posterior and "ertical +aw position. )

14) ,hecking functional moements:

Before debonding, debonding, the patient should be checked for interferenc interferences es during during protrusi"e protrusi"e mo"ements and lateral excursions. #t is important that the lower eight most anterior teeth make contact with the upper six most anterior teeth during protrusi"e mo"ements. This normally re-uires a slight widening of the archform in the bicuspid area, so that the mesial of the lower bicuspids contacts the distal of the up per cuspids. #n lateral excursions, the patient should experience cuspid rise with slight anterior contact and disclusion of posterior teeth on both the working and balancing sides. econd molars should normally be banded to pre"ent interferences in this critical area during lateral excursions. )

1&) etermining if all habits hae been corrected:

;abits such as tongue thrusting will usually ha"e been corrected before the finishing stage is reached, because as the patient grows, airway si%e increases and the tongue can assume a more posterior position. lso, as the dental en"ironment that that supported the habit is impro"ed orthodontically, the tongue and lip musculature adapt to the impro"ed en"ironment and normal function begins to occur. )

1) ,orrection of rotations and oercorrection #here needed:

Most rotations will ha"e been eliminated before the finishing stage, particularly if force le"els are kept low. ny ny remaining rotations can be corrected during du ring finishing by one of three methods4

69

Retention and relapse in orthodontics /i2 /i2

Rubb Rubber er rot rotat atio ion n wedg wedges es und under er the the rec recta tang ngul ular ar arc archw hwir ire. e.

/ii2 /ii2

tei teine nerr rotat rotatio ion n wedge wedgess L these these are are usefu usefull becau because se they they can can be place placed d after after the the archwire is in position.

/iii /iii22

:ingu :ingual al elas elasti tics cs L mos mostt eff effect ecti" i"ee met method hod.. These rotations should be slightly o"ercorrected during finishing to minimi%e relapse,

particularly in extraction cases. )

1+) "stablishing a relatiel% flat plane of occlusion:

Reasons for completing cases to a relati"ely flat occlusal plane to a slight arc in the second molar region, according to ndrews, include the proper fit of the upper dentition against the lower dentition. $hen a cur"e of spee is left in the lower arch, for example, there is a tendency towards increased o"er+et, since the lower teeth occupy less room than the opposing upper teeth. 1eep bite cases also benefit from o"ercorrection of the cur"e of spee, because most deep bites tend to relapse. #f the occlusal planes are not le"eled before finishing and detailing, the archwires will not slide easily through the bracket slots during space closure with sliding mechanics. )

6H


uration of rete retention ntion ;ow long should the orthodontist continue retention& The answer to this -uestion "aries from not at all to fore"er. The answer also depends on the type of case treated, the age of the patient, patient, what the parent and the patient patient expect of the orthodontic orthodontic treatment, treatment, all of the limitations inherent in the case, and finally, what the orthodontist himself expects of his treatment. #n the a"erage adolescent, when considerable growth and remodeling of the bony en"ironment can be expected, it is reasonable to expect that retention should logically be continued continued until the effect of these changes has slowed slowed down. =enerally =enerally,, this occurs at the time the third molars erupt< hence it has been a rule for many to continue retention until these teeth ha"e erupted or ha"e been remo"ed.' o, to conclude some form of retention will probably be maintained until e"idence of comple completio tion n of growth growth is forthc forthcomi oming, ng, and consid considera eratio tion n should should be gi"en gi"en to the use of retainers on and as needed basis indefinitely to ensure maintenance of tooth relationships. #t should be4 ' •

0ssentially full!time for the first 6 to 7 months, except that the retainers not only can but should be remo"ed while eating /unless periodontal bone loss or other special circumstances re-uire permanent splinting2.

•

Gontinued on a part!time basis for at least ' months, to allow time for remodeling of gingi"al tissues.

•

#f significant growth remains, continued part!time until completion of growth. 5or prac practi tical cal purpos purposes es this this mean meanss that that near nearly ly all all pati patient entss trea treate ted d in the the earl early y

permanent dentition will re-uire retention of incisor alignment until the late teens, and in those those with with skelet skeletal al dispro dispropor porti tions ons initia initially lly,, part!t part!time ime use of a functi functiona onall applia appliance nce or extraoral force probably will be needed.

6>


Ph%siologic recoer% or relapse 5or a successful result to an orthodontic experience, retention must be anticipated and planned as a "ery important part of treatment of the dentition rather than as an apathetically undertaken aftermath or necessary e"il to the patient and orthodontist alike, which would otherwise lead to a relapse process. #n orth orthodo odont ntic icss it is impo import rtan antt to diff differ erent entia iate te betw between een rela relaps psee and and norma normall de"elopmental changes in order to resol"e our responsibilities during retention. Relaps Relapsee is a return return of detrim detriment ental al featur features es of the origin original al maloccl malocclusi usion< on< while while de"elopmental changes refer to the indi"idual*s maturation process. To make this distinction, we should ha"e a general understanding of growth, de"elopment, maturation to old age, response to treatment techni-ues, and those factors necessary for an impro"ed or healthier dentofacial en"ironment. ',  ;orowit% ;orowit% and ;ixson ;ixson', suggested that the term relapse should be replaced by the

term physiologic reco"ery as the dentition continuously changes throughout life. Biologically these changes represent a reco"ery and rebound of indi"idual dental de"elopment pattern. =row =rowth th and and remo remodel delin ing g are are =erm =erman an fact factor orss of physi physiol ologi ogicc ad+us ad+ustm tment entss afte afterr acti" acti"ee treatment< this remodeling ne"er stops, but the balance between apposition and resorption change with ageing. #n addition to physiologic reco"ery, normal growth changes must be included as contributing to continuous adaptation process that sustains the long!term stability of dental apparatus.  malocclusion represents nature*s best effort to approach balance under the handicap of asymmetric asymmetric parts and disharmony disharmony.. #t is as stable as the existing balance between muscle and bone but can change until growth and maturation, +ust as in normal occlusion. To establish establish an esthetical esthetically ly harmonious, harmonious, functionall functionally y efficien efficientt and structural structurally ly balanced balanced dental arches in the area of functional tolerance "arious cardinal points like establishment of proper static functional occlusion, archform and intercanine width maintenance, lower incisors positioning, proper understanding of growth and de"elopment etc are "ery important. Iiolation of the law of optimality is likely to re+ect the alteration imposed on an existing orofacial en"ironment leading to relapse.

6(


,auses of orthodontic relapse The complexity of the dento!maxillofacial organ, the marked changes that ha"e taken place in its en"ironment since the time it e"ol"ed to its present form, and many other influences L some of them understood and others not understood L contribute to instability of the end results of acti"e orthodontic appliance therapy. mong mong the goals goals of orthod orthodont ontic ic treatm treatment ent beyond beyond facial facial and dental dental aesthe aesthetic tics, s, functi function, on, and the health health and longe"ity longe"ity of the dentitio dentition n is the achie"eme achie"ement nt of stable stable or relati"ely stable results. The reality of our present knowledge is that no form of treatment guarantees absolute stability, nor does a well!treated case treated by the highest standards by itself assure stability. stability. tability is not an absolute, and what one tries to do for a patient is to obtain acceptable stability. The concept of acceptable stability is not an alibi for treatment but recognition of biological limitations. The success of our treatment should be measured based upon some type of ratio between the magnitude of patient impro"ement and the relapse. uccess index') P Magnitude of #mpro"ement Magnitude of Relapse 5ear of relapse is "ery real to most orthodontists and some are affected to a degree that causes them to institute retention ad infinitum to all treated cases without regard to indi"idual conditions. $hy do successfully treated malocclusions fail& The sub+ect of failure is as "ast as the field of orthodontics orthodontics itself. itself. #n fact, e"ery time time we as orthodontist orthodontist undertake undertake to treat a malocclusion we assume that the odds fa"or success but the possibility of failure, if not total, exists in some degree.6

,auses of relapse:

The tendenc tendency y of the teeth to underg undergo o change change of posit position ion immedi immediate ately ly upon upon the remo"al of the orthodontic appliances can be attributed to "arious factors like bone changes, periodontal ligament tension, general metabolism, endocrine dysfunction, functional adaptation of occlusion, inherent growth, tooth!si%e discrepancies, axial inclinations, soft tissue maturation, connecti"e tissue changes and interference with the tra+ectorial forces

7)

Retention and relapse in orthodontics established in function. $hen the aforementioned factors react fa"orably, the changes on completion of treatment actually may help as time elapses to produce better esthetic tooth arrangement and occlusion.

1) ;ate mandibular gro#th:

:ate mandibular growth may result in increased pressure at the front of the mouth. Typically, the mandible grows and displaces forward at a faster rate than the maxilla /measured to occlusal plane2 and the lower basal bone more than al"eolar bone. Tooth comp compen ensa sati tion onss incl includ udee the the tende tendency ncy of the the lowe lowerr inci inciso sors rs to mo"e mo"e ling lingual ually ly.. #f the the mandibular incisors are not free to mo"e forward because of the restraining influence of the upper arch, it is likely that they will become retroclined and, could be a contributing factor to crowding in the lower anterior region. ;owe"er, no direct relationship between the increase in crowdi crowding ng and the change change in inciso incisorr inclin inclinati ation on or positi position on has been demons demonstra trated ted.. :undstrom7 examined 8 pairs of twins between between the ages of ' and '8 years years and 6 and 9 years. ;e found no relationship between anterior growth of gnathion and increased crowding, or between changes in lower incisor inclination and increased crowding. Richardson7 measured changes in lower incisor inclination and position of the incisal edge relati"e to the maxillary plane in 8' sub+ects with intact lower arches. Between the ages of '6 and '> years, the a"erage change was proclination of +ust o"er '° with forward mo"ement of '.) mm. #ncisor inclination was measured on the most procumbent lower incisor. s contacts slip to permit imbrication, one or more incisors may procline as the others others retroc retrocli line ne in respon response se to increa increased sed lingual lingually ly direct directed ed force. force. This This may mask mask any relationship between increased crowding and incisor angu lation.

3)

1entoal"eolar adaptation tends to maintain occlusal relationships e"en when skeletal relationships change with growth. ;owe"er, if the intercuspation of the teeth is poor or if dentoal"eolar compensation is already at its limits, occlusal changes can occur, particularly where skeletal growth changes are marked. 5or e.g< class ### occlusion will often deteriorate if the underlying class ### skeletal relationship becomes more se"ere< and a skeletal open bite often often becomes becomes worse worse with with growth growth in lower lower face face height height.. ltho lthough ugh the arch arch relati relations onship hip

7'

Retention and relapse in orthodontics remains stable in most cases, increase in labial segment crowding is often associated with dentoal"eolar adaptation. Mesial drift of buccal teeth contributes to the de"elopment of labial segment crowding. Many causes of mesial drift ha"e been postulated, including the anterior component of force, tensions in the supra!al"eolar connecti"e tissues and impactions of third molars.8 @anda and @anda9 found that the pubertal growth spurt for patients with skeletal deep bite occurs on a"erage '.8 to  years later than is the case for open bite cases. 5or this reason, a longer retention period for the skeletal deep bite patients is ad"ocated to counteract the continuing effect of dentofacial growth after the completion of orthodontic treatment.

4)

$andibular incisor dimensions5 Tooth structure:

Growding is slightly more common in persons whose teeth ha"e large mesiodistal dimensions than in those with smaller teeth. mall but statistically significant correlations between crowding and tooth width ha"e been found by some. Others found nonsignificant correlations between these "ariables. @o direct relationship has been established between an increase in lower arch crowding and tooth structure. #t might be argued that teeth with large labiolingual dimensions and broader contacts would be more stable and less likely to slip under pressure p ressure or tension. The notation that mandibular incisor dimensions were correlated with lower incisor crowding was reintroduced by Ceck and Ceck 9,

H

after a study of 78 untreated normal

occl occlus usio ions ns.. They They conc conclu lude ded d that that the the rati ratio o of mesi mesiod odis ista tall /M12 /M12 to faci faciol olin ingu gual al /5:2 /5:2 dimensions of lower incisors was an important factor in producing well!aligned mandibular incisors. ;ence, they ad"ocated reduction of mandibular incisors to a gi"en faciolingualJ mesiodistal ratio to increase stability. Ceck and Ceck*s work, howe"er, was critici%ed for the following reasons. Their recommendations were based on a study in"ol"ing untreated rather than treated cases. Qoung patients with ideal lower incisor alignment were used in the study. #t is possible that these cases would show crowding if followed long term. To e"aluate whether the Ceck and Ceck ratio had long!term "alue, =illmore and 9, H :ittle9, studied '67 treated and control cases a minimum of ') years presentation. They

showed a weak association between long!term irregularity and either incisor width or the faciolingualJmesiodistal ratio. :ess than 9N of crowding can be explained by this ratio. #n

7

Retention and relapse in orthodontics addition, the actual mean difference in incisor widths between crowded and uncrowded cases was only ).8 mm. mith et al.7 found nonsignificant correlations between crowding and labiolingual inciso incisorr width width in ')) untrea untreated ted orthodo orthodonti nticc sub+ec sub+ects ts and ')) untrea untreated ted adults adults,, and low significant correlations between crowding and mesiodistalJlabiolingual incisor ratio. Cunky et al.7 found nonsignificant correlations between labiolingual lower incisor dimensions, or their labiolingualJ mesiodistal ratio and lower arch alignment in HH treated cases or >9 untreated adult malocclusions. =len et al.7 could find no relationship between mesiodistalJlabiolingual ratio and incisor irregularity in > nonextraction orthodontically treated cases, either before treatment or 6 years after!retention. after!retention. 0"idence from these studies suggests that tooth structure plays only a minor role /if any2 in the etiology of late mandibular incisor crowding. Boese >,>,

(

introduced a concept of lower incisor reproximation to pro"ide broader

contact points and increase the a"ailable arch space in the mandibular anterior region. ;e did a retrospecti"e study that in"ol"ed continued inter"ention during the retention period, e"en in the presence of minor relapse. ;ence, we are unable to compare the results of this study with results from other retention studies.

&)

=cclusal factors:

The attachment apparatus of all teeth is an effecti"e hydrodynamic damping system, like an automobile shock absorber, and is well!designed to withstand occlusal forces. #f teeth did reposition themsel"es in response to occlusal forces, it would not be necessary for dentists to be so careful with occlusal relationships. The teeth would make minor corrections for themsel"es. This does happen +ust after the completion of orthodontic treatment, when the teeth are hypermobile and the attachment apparatus is reorgani%ing. lterations in functional occlusi occlusion on may produc producee a diffe differen rentt patter pattern n of mastic masticato atory ry forces forces or an occlus occlusion ion with with premature contacts. The importance of functional and stable occlusion posttreatment is repeatedly stressed in the literature. Brodie7 suggested that with each stroke of mastication, the upper incisors recei"e a separa separati ting ng impuls impulse, e, wherea whereass the lowers lowers tend to come come into into closer closer contact contact.. This This impli implies es

76

Retention and relapse in orthodontics retroclination of lower incisors. The principle may also be applied to indi"idual teeth coming into premature contact, being displaced by the force of occlusion, and allowing ad+acent teeth to mo"e toward each other, thus creating a crowded situation. Ganine guidance in lateral excursion may cause a lingually directed force on lower canines, with a reduction of inter! canine width. On the other hand, Croffit7 pointed out that the supporting structures of the teeth are designed to withstand hea"y, short acting, forces, such as those of occlusion. @e"ertheless, it seems possible possible that these forces, in combination combination with other factors, factors, may contribute contribute to tooth mo"ement and crowding. Carafunctional acti"ity could exacerbate this phenomenon. Occlusal relations may be altered by orthodontic treatment of the upper arch. 1ifferent types of upper arch treatment may ha"e differing effects on the lower arch. :ombardi7 suggested that there may be a relationship between o"ercorrection of maxillary canines and mandibular incisor crowding. Occlusal changes may also be caused by restorations, tooth loss with drifting, or the de"elopment of grinding habits. de-uate de-uate interincis interincisal al contact contact angle may pre"ent pre"ent o"erbite o"erbite relapse and good posterior intercuspation pre"ents relapse of both crossbite and anteroposterior correction. :ess relapse of mesiodistal mo"ement occurs in the absence of occlusal stress.

)

Influence of the elements of the original ma malocclusion:

The most basic cause of relapse to occur is the persistence of the elements of original malocclusion or the etiology. #f the underlying etiology is not remo"ed, the treatment is destined to relapse. #t is mandatory for all clinicians to first diagnose a case properly, and plan the treatment and retention initially itself, keeping keep ing the etiology in mind. The remo"al of the etiologic factor before b efore finishing is mandatory. O"erbite increase postretention is related to the amount reduced during treatment, although generally 6)N to 8)N of the correction is retained. #t is suggested that o"erbite relapse tends to occur in the first  years posttreatment and maintenance of the intercanine width is thought to increase stability. #n the anterior open bite correction e"aluated in 7' patients, 7)N showed marked relapse and the other 9)N showed stability of the result. The rela relaps psee subgr subgroup oup show showed ed a grea greate terr incr increas easee in lowe lowerr ante anteri rior or face face heigh heightt durin during g the the

77

Retention and relapse in orthodontics postretention period than did the stable group, but no posttreatment "ariable could be used to predict posttreatment relapse or stability. stability. Most studies do not support a greater relapse in class ## di"ision ' cases when compare compared d with with other other maloccl malocclusi usion on groups groups,, howe"e howe"er, r, a slight slight change change in o"er+e o"er+ett toward toward pretreatment "alues was demonstrated in all malocclusion groups. :abially inclined incisors pretreatment tend to be associated with less long!term crowding. #t is postulated that the weake weakerr labi labial al musc muscul ular ar forc forces es do not indu induce ce ling lingual ual mo"em mo"ement ent of the the denti dentiti tion on and and subse-uent arch length shortening. $hen teeth are aligned by orthodontic treatment, there is a documented tendency for a return toward the original pattern of malocclusion. 5o r this reason, rotational o"ercorrection has been ad"ocated. :ittle et al., howe"er, note that there are many exceptions to this rule with greater than 8)N of the rotations or displacements relapsing in an opposite direction.9 Adhe et al.'7 formed a multiple regression analysis of o"er+et, o"erbite, intercanine width, and intermolar width changes. They re"ealed that 7'N of late lower incisor crowding could be explained by these "ariables. The relati"e contribution by these "ariables "aries between indi"iduals with a similar degree of irregularity. irregularity.

+) /lteration of arch form:

#t is gener general ally ly agre agreed ed that that arch arch form form and widt width h shoul should d be main mainta tain ined ed durin during g orthodontic treatment.H,

9

#n certai certain n cases, cases, where arch arch de"elop de"elopmen mentt has occurr occurred ed under under

ad"erse en"ironmental conditions, arch expansion as a treatment goal may be tolerated. There There is e"idenc e"idencee to show show that that interc intercani anine ne and interm intermola olarr width width decrea decreases ses during the postretention period, especially if expanded during treatment /mott, rnold, $elch, and others2. 5or this reason, the maintenance of arch form rather than arch de"elopment is generally recommended. 0xpansion is thought to be better tolerated in class ## di"ision  cases that show a significantly greater ability to maintain intercanine expansion than class # and class ## di"ision ' cases. This statement, howe"er, was based on a sample of 9 patients and was not accepted by :ittle et al6) who maintained that intercanine and intermolar width will relapse if expanded in class ## di"ision  cases as much as in other ngle classifications. nother exception to the maintenance of arch width may be found in cases of mandibular expansion concurrent with rapid palatal expansion. ;aas6' and andstrom et al.6

78

Retention and relapse in orthodontics found that maintenance of 6 to 7 mm intercanine width and up to 9 mm intermolar width was possible when expansion was carried out concurrently with maxillary apical base expansion. These two studies, howe"er, are -uite misleading. ;aas study was based on ') cases and primary canines were present in the initial records for two of these. ;ence, one cannot extrapolate on the amount of canine expansion achie"ed, when in )N of this small sample, the permanent canines were not present at the time of the original records. andstrom*s statement statement that mandibular mandibular incisor stability stability is increased when the mandibular intercanine intercanine width is expanded in con+unction with maxillary expansion is based on a sample of 'H patients only  years postretention. Moussa et al.66 reported on a sample sample of 88 patients patients who had undergone undergone rapid palatal expa expans nsio ion n in con+ con+un unct ctio ion n with with edge edgewi wise se mech mechan anot othe hera rapy py a mini minimu mum m of > year yearss postretention. Their results showed good stability for upper u pper intercanine and upper u pper and lower intermolar widths. tability of the mandibular intercanine width, howe"er, was poor with the posttreatment position closely approximating the pretreatment pretreatment dimension. 1e :a Gru% et al.67 carrie carried d out a ')!yea ')!yearr postre postreten tentio tion n study study on >H patien patients ts to determ determine ine the long!t long!term erm stabil stability ity of orthod orthodont ontica ically lly induce induced d changes changes in maxill maxillary ary and mandibular arch form. The results showed that although there was considerable indi"idual "ariability, arch form tended to return toward the pretreatment shape. They concluded that the patient*s pretreatment arch form appeared to be the best guide to future stability. stability.

-) Periodontal forces:

#n series of experiments on monkeys, Cicton and Moss 7 and Cicton7 demonstrated that the teeth are +oined together by a system of transeptal fibers under tension. Croffit7 claimed that a slight imbalance of force between the tongue on one side and the lips and cheeks on the other is normally present. ;e suggested that the teeth are stabili%ed against this slight imbalance by forces produced in the periodontal membrane by acti"e metabolism. outhard et al.7 demonstrate demonstrated d the presence of a continuous periodontal periodontal force on the mandibular dentition, acting to maintain proximal contacts in a state of compression. This force was increased increased after occlusal occlusal loading. loading. They found significan significantt correlati correlations ons between between

79

Retention and relapse in orthodontics interproximal force and mandibular anterior malalignment. They concluded that periodontal forces could contribute to the de"elopment of late lower arch crowding.

.) Period Periodonta ontall and and gingi gingial al tissue tissues: s:

Orthodo Orthodonti nticc tooth tooth mo"eme mo"ement nt to correc correctt tooth tooth rotati rotations ons is propos proposed ed to result result in stretc stretchin hing g of the collag collagen en fibers fibers.. These These stretc stretched hed fibers fibers /trans /transept eptalJ alJcol collag lagen2 en2 ha"e ha"e been implicated in rotational relapse by pulling the teeth back toward their pretreatment position.68, 69

Brain and 0dwards9 ad"ocated gingi"al fiber surgery /Gircumferential upracrestal 5iberotomy2 to allow for the release of soft tissue tension and reattachment of the fibers in a passi"e orientation after orthodontic tooth rotation. The theory of stretched collagen fibers as the cause of rotational relapse has recently been -uestioned by Redlich et al.6H who analy%ed gingi"al tissue samples obtained from rotated incisors in dog. They found that the rotational forces caused significant changes in the integrity and spatial arrangement of the gingi"al tissues, changes that are inconsistent with stretching. fter fiberotomy, reorgani%ation of the fibers similar to the control group was e"ident. They concluded that the rotational relapse may actually originate in the elastic properties of the whole gingi"al tissue rather than stretching of the gingi"al fibers as pre"iously belie"ed.

18) >oft tissue maturatio maturation: n:

#t is generally accepted that dentoal"eolar structures are responsi"e to soft tissue pressures and adapt to a position of balance between the muscles of the lips, cheeks and tongue. 5rankel and :offler 7 showed that the reduction in mandibular arch length found in an untreated control group was pre"ented in sub+ects treated with the functional regulator /5R2 appliance. They claimed that the "estibular shields of the functional regulator appliance fa"orably influence the saggital de"elopment of the mandibular dental arch by eliminating the restraining forces of the external muscular en"ironment. $oodside et al.7 and :inder!ronson and $oodside7 showed that the lower incisors of children who were mouth breathers were more retroclined and crowded compared with

7H

Retention and relapse in orthodontics controls, and proclined after adenoidectomy and a changed mode of breathing that altered the muscular en"ironment. These studies show that lower arch alignment can impro"e after the remo"al of ad"erse muscular forces and, although no direct relationship has been found between changes in soft tissue forces and increased lower arch crowding, it is likely that such changes may ad"ersely affect arrangement of the teeth. :ate mandibular growth changes may bring the lower incisors into a different soft tissue en"ironment. ubtently and akuda7 compared 8 patients who were orthodontically treated and de"eloped late lower incisor crowding with 8 patients who did not. They found a strong tendency to maintain the original intercanine width in all cases. The crowded cases had a narrower intercanine width before treatment, which returned to its original dimension after treatment expansion. They surmised that the lip musculature did not permit the necessary intercanine expansion to maintain incisor alignment. They claimed as the mandible increases in si%e, the lips exert greater pressure than the tongue, creating a lingually directed force that, counteracted the mesial forces, causes incisor crowding. Bench7 studied growth of the cer"ical "ertebrae, hyoid bone, and tongue in relation to the facial skeleton and denture. ;e found that the hyoid bone and tongue descend with age, relati"e to surrounding structures, and continue to do so after facial growth slows down. ;e claimed that this was particularly true in persons with long faces and with lack of forward growth and suggested that it could explain the de"elopment of late lower arch crowding. Gohen and Iig7 studied tongue growth on serial cephalograms of 8) sub+ects from ages 7 to ) years. They found that tongue si%e relati"e to the intermaxillary space increased with age. This might imply more forward pressure on lower teeth. They pointed out that the descent of the tongue, as it grows, may compensate for any possible increase in forward pressure because of larger tongue si%e. Iig and Gohen7 examined lip growth on the same sample and found that it continued up to '( years and exceeded growth of anterior lower face height. #n a longitudinal study of soft tissue growth, @anda et al.7 found that the lips were still growing, in height and thickness, at '> years in male sub+ects, whereas in female sub+ects the lips had reached their full adult dimensions by age '6 years.

7>

Retention and relapse in orthodontics These in"estigations show that changes in soft tissue structure are taking place during the teenage period, which may alter the pressure balance on the lower incisors, causing them to become crowded. Ghanges in soft tissue function may alter the muscular en"ironment of the teeth. Teenagers with incompetent lips, becoming more aware of their appearance, may make a conscious effort to hold their lips together causing an increase in perioral pressure.

11) 11) ,onnectie ,onnectie tissue changes: changes:

0ngel et al.7 claimed that bone and periodontal membrane are biologically labile in respons responsee to hormon hormonal al changes changes.. :askin :askin et al. sugges suggested ted that that hormon hormonal al changes changes during during adolescence or pregnancy may cause increased plasticity of bone. Bone loss as result of aging or periodontal disease may allow teeth to mo"e under pressures that they pre"iously resisted. These factors are more likely to be the cause of crowding that de"elops in later life, after a period of relati"e stability, than those responsible for increasing crowding during the teenage years.

12)

Influ Influenc encee of enir eniron onme ment ntal al fac factor torss and and neur neurom omus uscu culat latur ure: e:

trang6> theori%ed that the mandibular intercanine and intermolar arch widths are accurate indicators of the indi"idual*s muscle balance and dictate the limits of arch expansion during treatment. $einstein et al. and Mills 9 stated that the lower incisors lie in a narrow %one %one of stabi stabili lity ty in e-ui e-uili libr briu ium m betw betwee een n oppos opposin ing g musc muscula ularr pres pressu sure re,, and and that that the the labiol labioling ingual ual posit position ion of the incis incisors ors should should be accept accepted ed and not altere altered d by orthodo orthodonti nticc treatment. Reitan claimed that the teeth tipped either labially or lingually during treatment are more likely to relapse. The initial position of the lower incisors has been shown to pro"ide the best guide to the position of stability in two separate studies. #n o"er 8) N of cases the lower incisors ultimately stabili%ed at a point between the pretreatment and posttreatment positions. These result resultss indica indicate te that that if lower lower inciso incisorr ad"ancem ad"ancement ent is a treatm treatment ent ob+ect ob+ecti"e i"e,, permane permanent nt retention is essential for maintenance of the result.

7(

Retention and relapse in orthodontics 13) 6ole of deeloping deeloping third molars: molars:

The role of third third molars molars in lower incisor incisor crowding has been debated for more than a century. The literature is almost e-ually di"ided with arguments for both sides. One theory commonly reported is that of the third molars creating space to erupt by causing anterior anterior teeth teeth to crowd. $oodside $oodside6( postul postulate ated d that that in the absence absence of third molars, molars, the dentition could settle distally in response to forces generated by growth changes or soft tissue pressures. This implies a passi"e role of the third molars in the de"elopment of late crowding by hindering that ad+ustment. Broadbent7) was an early ad"ocate of the insignificant role played by third molars in late lower incisor crowding. e"eral studies show a reduction in arch length and an increase in crowding with age. ;owe"er, no difference in incisor crowding could be found in groups with impacted, erupted, missing, or extracted wisdom teeth.7' Richardson demonstrated a significant forward mo"ement of first molars between the ages of '6 and 'H years. This was correlated with the increase in lower arch crowding that occurred during the same period. There was no difference, howe"er, in the forward mo"ement of the first molar, in cases with or without impacted third molars.  recent study on 7 patients from the Belfast =rowth tudy confirmed these findings. #n summary, all of the conflicting data regarding third molars tends to indicate that if third molars were a contributing factor in the de"elopment of late lower incisor crowding, their role is likely to be one of minor importance.

8)


Proper occlusion occlusion and stabilit% Kingsley stated “That occlusion of the teeth is the most potent factor in determining the stability in a new position.” Many other earlier writers considered that proper occlusion was of prime importance in retention. The six keys to normal occlusion as put forth by ndrews7 in '(H contributes indi"idually and collecti"ely to the total scheme of occlusion and, therefore, are "iewed essential for successful orthodontic treatment and post treatment stability.

?e% I: $olar relationship:

The distal surface of the distobuccal cusp of the upper first permanent molar made contact and occluded with the mesial surface of the mesiobuccal cusp of the lower second molar molar.. The mesiod mesiodist istal al cusp cusp of the upper upper first first permane permanent nt molar molar fell fell within within the groo"e groo"e between the mesial and middle cusps of the lower fist permanent molar. /The canines and premolars en+oyed a cusp!embrasure relationship buccally, and a cusp fossa relationship lingually2.

Improper molar relationship

+, Improper molar

relationship. *, Improved molar relationship. 7, More improved molar relationship. , 5roper molar relationship.

8'


8

Retention and relapse in orthodontics ?e% II: ,ro#n angulation:

The term crown angulation refers to angulation /or tip2 of the long axis of the crown, not to angulation of the long axis of the entire tooth. The gingi"al portion of the long axis of each crown was distal to the incisal portion, "arying with the indi"idual tooth type. The long axis of the crown for all teeth, except molars, is +udged to be the mid de"elopmental ridge, which is the most prominent and centermost "ertical portion of the labial or buccal surface of the crown. The long axis of the molar crown is identified by the dominant "ertical groo"e on the buccal surface of the crown.

8ormall occluded teeth demonstrate Crown angulation !tip"9 gingiva portion of crown more distal long a1is of crown measured than occlusal portion of crown. from line :/ degrees to occlusal plane.

?e% III: ,ro#n inclination labiolingual or buccolingual inclination):

The third key to normal occlusion is crown inclination.

Crown inclination is determined b the resulting angle between a line :/ degrees to the occlusal plane and a line tangent to the middle of the labial or buccal clinical crown.

86

Retention and relapse in orthodontics Croper crown inclination should be established. The maxillary central incisors are inclined so that the gingi"al portions of the crowns of teeth are lingual to the incisal surfaces. The gingi"al portions of all the other crowns are inclined labially or buccally, although the mandibular incisor roots are inclined lingually.

Improperl inclined anterior crowns result 2emonstration, on an overla, that when the in all upper contact points being mesial, leading crowns are properl inclined the contact to improper occlusion. distall, allowing for normal occlusion

anterior points move

#n the maxill maxillary ary arch arch from from canine canine to molar, molar, all crowns crowns are lingua lingually lly inclin inclined, ed, progressi"ely increasing in inclination from canine through the molars.

A lingual crown inclination generall lingual crown inclination of occurs in normall occluded upper posterior normall occluded lower posterior teeth crow crown ns. ;he ;he incl inclin ina ation tion is const onsta ant an and sim simil ila ar progressivel increases from the canines from from the canin canines es throug through h the second second premo premola lars rs and slightl more pronounced in the molars.

;he

throug through h the the second second molar molars. s.

?e% I@: 6otations:

The fo fourth ke key to no normal occlusion is is that

the teeth should be

free of undesirable rotations.

87


A rotated molar occupies more mesiodistal space, creating a situation unreceptive to normal occlusion.

88

Retention and relapse in orthodontics ?e% @: Tight Tight contacts: cont acts:

The fifth key is that the contact points should be tight /no spaces2. Cersons who ha"e genui genuine ne toot tooth! h!si si%e %e disc discre repa panci ncies es pose pose spec specia iall probl problem ems, s, but in the the abse absenc ncee of such such abnormalities tight contact should exist.

?e% @I): =cclusal plane:

The The plane planess of occl occlus usio ion n shoul should d range range from from flat flat to slig slight ht cur"e cur"ess of spee spee.. The The intercuspation of teeth is best when the plane of occlusion is relati"ely flat.

A, A deep curve of pee results results in a more con#ned area for the upper teeth, creating spillage of the upper teeth progressivel mesiall and distall.

B, A
C, A reverse curve of pee results results in e1cessive room room for the upper teeth.

Bolton76 found that in excellent occlusions the angles of the labial surfaces of the maxillary and mandibular central incisors to their occlusal plane totaled approximately 'HH°. #n other words, the labial surfaces of these teeth in profile formed almost a straight line. #t is e"ident that the orthodontist often considers the denture from a static "iewpoint, that is, with the teeth in occlusion as seen on a study cast. #t is doubtful that proper intercuspation or interlocking is the most potent factor in retention. 5rom the standpoint of reducing the potential of irritation to the periodontium, a good functional occlusion is certainly to be desired.

89


,onsiderations ,onsiderations of dentofacial gro#th in longterm retention and stabilit% Iagary and orthodo orthodonti nticc pseudos pseudoscie cienti ntific fic ambigu ambiguity ity attrib attribute ute short shortcom coming ingss in orthodontic treatment to poor growth patterns. The terms “good” and “poor” growth patterns are orthodontic clichs and actually are meaningless crutches to support the rationali%ations of treatment inade-uacies.  “good growth pattern” is one in which the face grows in the directions in which we wish it to grow.  “poor growth pattern” takes different directions. Glin Glinic ical al

expe experi rien ence ce

supp suppor orte ted d

by

ceph cephal alom omet etri ricc

data data

asso associ ciat ated ed

the the

best best!t !tre reat ated ed

malocclusions that offered the best retention possibilities with faces ha"ing hori%ontal growth gradients. These became known as “good growth patterns”. Those malocclusions offering the poorest prospects usually grow more "ertically than hori%ontally< thus, from the standpoint of clinical achie"ement, malocclusions associated with these growth distinctions were called “poor “poor growth growth patter patterns” ns”.. The terms terms “poor “poor growth growth”” and “good “good growth growth”” actual actually ly became became associated with clinical achie"ement rather than with physical modes of growth. ;ow much can orthodontic discipline change the directions and the modes of growth& There is no real e"idence to show it to be significant.(

Aeneral facial gro#th:

The high "ariability of normal facial growth was demonstrated by B+ork in '(88 in one of the the firs firstt arti articl cles es desc descri ribi bing ng the the use use of meta metall llic ic implants. #n this limited study of only 9 patients he showed that there is great indi"idual "ariation not only with respect to the directi direction on of general general facial facial growth growth,, but also also with with respect to the growth of the maxilla and mandible and to the the erup erupti tion on of the the teet teeth h with within in each each +aw +aw. Crio Criorr to the the studies using implants the general feeling had been that growth was a fairly uncomplicated process and that the

8H

Retention and relapse in orthodontics general general direction direction of facial facial de"elopment de"elopment was downward downward and forward. forward. #t was only after these studies that their was a little change in the concept of growth.') ormal mandibular gro#th:

The normal growth changes of the lower +aw ha"e been studied extensi"ely with the use of metallic implants by B+ork and B+ork and keiller '', who examined normal mandibular growth longitudinally in a large number of sub+ects. Their studies of patients, using metallic implants showed great indi"idual "ariation in the growth pattern of the lower +aw. #n a detailed study of mandibular growth B+ork showed that the range of "ariation of condylar growth in untreated normal sub+ects may be as much as 7 with a slight upward and forward growth direction being the most common, others show an almost posterior growth direction. ssociated with this "ariability in condylar growth were distinct "ariations in the direction of eruption of teeth. #n the sub+ects with pronounced forward condylar growth, the lower posterior teeth erupt erupt and migrat migratee mesial mesially ly.. #f, anyhow anyhow,, the lower lower incis incisors ors are pre"ent pre"ented ed from from mo"ing mo"ing forward /e.g., by a deep bite2!increased crowding in the lower arch often de"elops. #n cases showing pronounced increase in the tendency of mesial migration, the intercanine width in the lower arch also tends to decrease decrease because the teeth mo"e into a more narrow narrow part of the arch. The degree to which this “secondary crowding” de"elops is dependent upon se"eral local local factor factors, s, such such as the extent extent of o"erbi o"erbite, te, o"er+et, o"er+et, a"ailabl a"ailablee space space in the arch, and inclination of the maxillary and mandibular anterior front teeth, as well as the extent of mesial migration of the posterior teeth.

=acial growth and occlusal development in an untreated subject with pronounced forward rotation of the mandible. ;he occlusion has remained stable during this si1-ear growth period without an crowding developing in the lower arch.

8>


=acial growth and occlusal development in an untreated subject with pronounced forward mandibular growth rotation and a stable anterior occlusion. ;his subject developed crowding of the mandibular incisors with time. ;he posterior occlusion change from an end-on relationship at age : ears, +/ months to a full Class II malocclusion at age +& ears, +/ months.

#n contrast, patients with upwards!backwards growth of the condyles, consistently show a more "ertical direction of eruption of the posterior teeth. ;owe"er, these patients also present secondary crowding as the lower incisors erupt in most posterior posterior direction, uprighting in the +aw base. The extent of uprighting of the incisors is influenced and modified by the balance between the lower lip and the tongue, by the space conditions in the arch, and by b y the growth changes of the mandible.')

>tabilit% of occlusion and mandibular gro#th rotation:

+) $nterior rotationA Bork in '(9( '(9(' repor reporte ted d that that prono pronoun unced ced upwa upward rd and and forw forwar ard d growt growth h of the the mandibular condyles is associated with anterior or counterclockwise rotation of the lower +aw. This rotation can occur with the fulcrum point located at incisors or further back in the occlusion. $hen the occlusion remains stable o"er time, the fulcrum point is located and maintained at the incisors, presumably by the function of the lips and tongue. ;owe"er, if the fulcrum point is lost, as a result of dysfunction of the lips or tongue or because of oral habits, a skeletal deep bite will normally de"elop.

8(


=acial growth and occlusal development in a subject with an e1treme deep bite. ;he lac% of a fulcrum point at the incisors in combination with the growth pattern has resulted resulted in continuous deepening of the bite. ;he general superimposition shows that the mandibular molars continued to upright while the ma1illar molars became more mesiall inclined over time. ;he ma1illa in this patient rotated forward, similar to the mandible. 8otice the increasing crowding in the ma1illar arch resulting from mesial migration of the posterior teeth and retroclination retroclination of the anterior teeth. ;his occlusal development is characteristic characteristic of the Class II, 2ivision * malocclusion.

#n these sub+ects, the posterior facial height is greater than anterior facial height.'6 #n patients in which anterior rotation is to be expected the goal of orthodontic treatment is to establish and maintain normal o"erbite and o"er+et relationships by creating a solid fulcrum point at the incisors. By positioning the teeth so that the interincisal angle is not too obtuse, o btuse, the lower incisors are not too upright, and there is a proper amount of tor-ue of the maxillary incisors, a more stable result can be anticipated. #n addition to creating an optimal anterior and posterior occlusion, at the end of acti"e trea treatm tment ent it is also also neces necessa sary ry to main mainta tain in and and suppo support rt this this occl occlus usio ion n with with rete retent ntio ion n appliances. #n extreme cases, retention must be continued until growth of the condyles is completed because following acti"e treatment there is often an e"en greater tendency toward anterior rotation than during treatment.

9)

Retention and relapse in orthodontics Catients with se"ere malocclusions /for e.g., Glass ## skeletal malocclusions and a deep bite2, where early treatment may be indicated and who ha"e a more extreme growth pattern, present additional stability problems. #n these cases the mandibular anterior teeth must be maintained in their new position for a long time because the continuing forward! growth rotation usually is accompanied by uprighting of the teeth. tabili%ing the lower incisors presents a practical problem, howe"er, because the stability of the anterior mandible is compromised when the primary canines are lost. $hen the permanent mandibular canines are fully erupted in the late mixed dentition, retention is often simpler. The canines can then aid in supporting the lower anterior teeth against the uprighting tendency of the mandibular incisors.')

&) Posterior rotationA #n these sub+ects, an increase in the anterior facial height exceeds than increase in the posterior facial height, which results in backward or posterior rotation of the mandible.'6 This type of growth rotation is, much less common than anterior rotation seen in the ma+ority of our patients during growth. This type of rotation has a strong tendency towards late lower crowding, because the direction of eruption of the lower incisors is more "ertical, with additional potential for retroclination of these teeth. ;ence, long!term stabili%ation of the lower anterior teeth is absolutely essential.

$a7illar% gro#th and stabilit%:

Maxill Maxillary ary growth growth shows shows simila similarr rotati rotations ons as those those obser" obser"ed ed in the mandib mandible. le. #n untreated sub+ects these rotational changes are normally in the same direction as in the lower +aw but of less intensity. intensity. There is continuous mesial migration of the upper posterior teeth concomitant concomitant with the rotation rotation of the maxilla similar similar to that seen in the mandible. imilar imilar to that of the mandible, there is often less forward mo"ement of the anterior than of the posterior teeth which ultimately leads to the increase in anterior crowding. s in the de"elopment of the lower crowding, the function of the lips may also play an important role in the de"elopment de"elopment of the maxillary maxillary anterior anterior crowding. #t may be hypothesi%ed hypothesi%ed that the lips are pre"enting the upper front teeth from following the mesial migration of the posterior teeth. nother possibility is that normal lip function, in combination with a more extreme

9'

Retention and relapse in orthodontics tendency toward anterior rotation of the maxilla, may be sufficient to redirect the eruption of the inciso incisors. rs. These These mechani mechanisms sms,, may be respons responsibl iblee for the postt posttrea reatme tment nt relaps relapsee of maxillary anterior crowding.') #n sub+ects with more pronounced forward!growth rotation of the +aws, as obser"ed by Ahde'7, there is a natural tendency for the molar relationship to become more Glass ## with time. This can also be attributed to the natural growth changes, where the posterior teeth in both arches tend to follow the growth rotations of the +aws, and therefore become more mesially inclined in the maxilla and more distally inclined or upright in the mandible. '' Because molars shift in opposite directions, the occlusion gradually shifts toward a Glass ii malo malocc cclu lusi sion on.. Thes Thesee chan change gess can can be more more or less less pron pronou ounc nced ed,, depe depend ndin ing g on the the intercuspidation and the function of the soft tissue matrix.

%splastic and compensator% deelopment:

kele keleta tall disc discre repan panci cies es are are ofte often n to a grea greatt exte extent nt mark marked ed by dent dentoa oal" l"eol eolar ar compensations.'8 #n the sub+ects, howe"er, abnormal function of the lips and tongue can cause dysplastic dentoal"eolar changes that make the dental malocclusion worse than the underlying skeletal problem. The extent of compensation not only influences the occlusal correc correctio tion n necess necessary ary to treat treat the case case but also also affec affects ts posttr posttreat eatmen mentt stabil stability ity.. 3ust 3ust as compensatory and dysplastic de"elopment is greatly dependent upon the soft tissue matrix surrounding the skeleton, posttreatment stability is dependent upon the adaptability of these structures.

entoaleolar deelopment and occlusion:

The continuous forward mo"ement of the posterior teeth in patients with forward rotation of the mandible is necessary to maintain the stability of the anterior occlusion. nteriorly this migration is reflected primarily as proclination of the lower incisors. The goal of orthodontic treatment in this type of growth pattern should be to bring the mandibular dentition forward on the +aw base and maintain the anterior teeth in their forward position so as to counteract the natural tendency tendenc y of the incisors to upright.')

>tabilit% of e7traction and none7traction treatment:

9

Retention and relapse in orthodontics #n the patient with growth pattern in which there is a pronounced tendency toward anteri anterior or rotati rotation, on, extrac extractio tions, ns, especi especiall ally y of teeth teeth in the lower lower arch, arch, should should normal normally ly be a"oided. Before any decision is made to remo"e bicuspids, the potential for saggital and trans"erse expansion must be examined carefully. $hen extractions are necessary to alle"iate crowding, they should not be carried out too early but rather during the growth spurt or e"en later when the growth pattern in the patient is more clearly expressed. 5ollowing treatment, retention is e"en more critical in these these extrac extractio tion n cases cases becaus becausee the lower incisors incisors often are more more uprigh uprightt at the end of treatment than in nonextraction cases and therefore must be maintained until growth of the condyles is completed. $here condylar growth is primarily directed posteriorly, the natural tendency of the mandibular incisors to become more crowded with time continues throughout the growth period. #t is therefore critical that extraction decisions not be made too early. #n most instances where posterior rotation is anticipated, extractions should be delayed until the patient is past maximum pubertal growth. The degree of growth rotation and associated natural tooth migration in these cases is unpredictable, and additional late crowding, resulting from growth pattern, pattern, will often de"elop de"elop e"en after extraction extraction therapy. therapy. 5ollowing 5ollowing treatment, treatment, the mandibular anterior teeth in these patients should be supported lingually until growth in the mandible is finished.')

Treatment Tr eatment timing:

The ma+ority of orthodontic treatments are carried out immediately prior to or during the pubertal growth spurt. #n some cases, howe"er, treatment during the early mixed dentition stage may be indicated. One of the reasons behind this is that these cases are often associated with e"en greater greater instability instability posttreatment posttreatment than when treatment treatment is done in the late mixed or permanent dentition stage. The lack of support from the posterior teeth in the arch, when the deciduous teeth are lost, increases the chances for uprighting of the anterior teeth, resulting in a deep bite. ;ence, the mandibular mandibular anterior anterior tooth needs to be supported supported until the permanent canines are fully erupted. The ma+ority of malocclusions are primarily related to skeletal differences between the maxilla and mandible, and this discrepancy by so!called growth adaptation. To obtain

96

Retention and relapse in orthodontics maximum effect, treatment is often carried out during the pubertal growth period, when the intensity of growth is at its greatest. $hereas facial growth can be of great help during treatment of a skeletal problem, it can also be the cause of instability of the treatment result. s growth in most orthodontic patients is not completed at the end of the growth spurt but continues for se"eral years beyond the pubertal spurt, retention of the treatment result should also continue for a period of se"eral years. The maxillary growth on a"erage is completed  to  S years prior to mandibular growth. The timepoint for completion of sutural growth again "aries by as much as 9 years, with the earliest completion of maxillary growth at age '7 years and the latest at age ) years. This differential in timing, between completion of upper and lower +aw growth, is yet another factor that influences posttreatment stability. stability.')

entofacial skeletal changes #ith gro#th:

Relapse of the corrected position of the teeth after successful orthodontic treatment is fully recogni%ed by the clinician. ;owe"er, skeletal changes that occur during retention may attenuate, exaggerate, or maintain the dentoskeletal relationship. Relapse of the teeth is a source of annoyance to all concerned< yet the outcome of skeletal changes is left to the fate of the patien patient* t*ss so called called “growt “growth h patter pattern”. n”. 1espit 1espitee the fact fact that that clinic clinical al manife manifesta stati tions ons of skeletal relationships are gi"en considerable importance before the initiation of and during orthodontic treatment, little or no consideration is gi"en to posttreatment skeletal changes due to growth and the effect on the final outcome. This attitude is based on two assumptions. 5irst of all it is often assumed that the responsibility for the skeletal super"ision is secondary to the dental relationships during acti"e treatment. 5urther, when teeth are brought into proper interdigitation, the treatment is usually terminated, regardless of the skeletal maturation status of the patient. econd, it is generally assumed that not much can be done during the posttreatment phase to modify the growth pattern of the patient. The truth of the matter is that many patients at the completion of orthodontic treatment may still be going through the pubertal growth spurt, and there may be others who ha"e not e"en entered the period of accelerated pubertal growth. This obser"ation is of particularly greater significance in boys than in girls, since boys generally mature later. ;ence failure to recogni%e the continuing effect of dento!facial growth after the completion of orthodontic treatment and its

97

Retention and relapse in orthodontics resultant fa"orable or unfa"orable effects on the physiognomy and its dental relationships may +eopardi%e long!term stability of the orthodontic result. The ma+or focus during retention is placed on maintenance of the corrected positions of the teeth, and no compensations are made for the future dentoal"eolar and skeletal growth of the +aws in either the hori%ontal or the "ertical direction. The retention de"ices should be differentially selected on the basis of dento!facial morphology and the anticipated magnitude and directions of growth instead of simply using the clinician*s fa"orite procrustean!bed retention appliance for all cases.'), '9 #n person personss with with short short face face syndro syndrome, me, the effect effect of contin continued ued growth growth after after succes successfu sfull treatment is critical.'H, '> These persons may re-uire dentoal"eolar compensations, such as an anterior bite plane during the retention phase until maxillomandibular growth is completed. 5ailure to recogni%e the dominant morphogenetic hori%ontal pattern of growth of the person may result in a “dished!in!face”, with or without extractions of teeth. ;ence the conca"e facial pattern accentuates. #n person personss with with long!f long!face ace syndr syndrome ome,, a high!p high!pull ull face!bow face!bow headgea headgearr to hold hold the position of molars and to pre"ent further dentoal"eolar growth downward and backward, autorotation, and worsening of the physiognomy may be re-uired. #t is extrem extremely ely importan importantt to pay attent attention ion to the person* person*ss growth growth pattern, pattern, and a distinctio distinction n must be made in the selection selection of retention retention de"ices on the basis of the nature nature and the extent of dentofacial dysplasia /growth pattern2. The nature and duration of retention should depend on the maturation status of the patient and on anticipated future growth. Retention guide is necessary for the ad+ustment of the dentition to late growth changes and maturation of neuromuscular balance. “cti"e retention” is a concept we accept as readily as orthopedic surgeon does for his scoliosis patients. There is some merit in the philosophy of those clinicians who ad"ocate permanent retention guidance. $ithout always being aware of the biomechanics of growth change, they are are in fact fact carry carryin ing g the the pati patien entt thro throug ugh h acti acti"e "e stag stages es of grow growth th with with thei theirr rete retent ntio ion n appliances. 5ina 5inall lly y, one one may may phil philos osop ophi hi%e %e that that noth nothin ing g abou aboutt the the hum human morp morpho holo logy gy is stat statio iona nary ry.. ging ging is a well well!d !doc ocum umen ente ted d proc proces esss of chan change. ge. :ife :ifeti time me dentitional ad+ustment changing dental relationships are known to all, e"en in otherwise

98

Retention and relapse in orthodontics healthy persons. Then why do we expect long!term stability in e"ery case& The answer to the -uestion of long!term stability is long!term retention L dynamic, not static.'9

/rch #idth changes The long!term resolution of arch length deficiencies is not easily achie"ed. illman 79 concluded that maxillary and mandibular arch length and width dimensions usually decrease with time in untreated indi"iduals. #n general, one can expect a moderate increase in width of the dental arches, particularly in the anterior region, until permanent canines erupt. fter this time, howe"er, arch width usually decreases in the transition from the deciduous to the permanent dentition and then continues to decrease with increasing age. These changes occur more markedly in the mandibular than in the maxillary dental arch and more consistently in length than in width. The intercanine width is established in the lower arch by ') years for both sexes and in the upper arch at ' years for females and '> years for males, which according to =raber acts as a safety "al"e for the final increments of saggital growth of the mandible. :ower :ower inci inciso sorr crow crowdi ding ng is a comm common on clin clinic ical al problem, which is often corrected by extraction of the premolars and retraction of the canines and thus aligning the incisors. #n cases of mild crowding, reproximation is done and hence alignment is resorted. Ceck and Ceck 77 L Mesiodista MesiodistalJ5ac lJ5acioli iolingual ngual /M.1.J5. /M.1.J5.:.2 :.2 ratio ratio and Bolton* Bolton*ss anterior tooth si%e ratio gi"e us the guidance whether the anteri anterior or intero interoccl cclusa usall proble problems ms and crowdi crowding ng could could be correc corrected ted by reprox reproxim imati ation on alone. alone. ome ome cases cases re-uir re-uiree extens extensi"e i"e treatm treatment ent by extrac extractio tion n of the premol premolar ar,, and retraction of the canine, which brings the canine into the wider part of the arch.

99

Retention and relapse in orthodontics #n many many arch arch length length defici deficienci encies, es, howe"e howe"er, r, the extrac extracti tion on of perman permanent ent teeth teeth is contraindicated due to the negati"e effect on the facial profile. #n those cases the dental arches must be expanded, thus increasing the liability for future dental irregularity. rch expansion is not always feasible and also stable solution to the intra arch and inter arch problems. #n the middle middle of the '()*s '()*s a school of thought formed around the writings of xel! xel! :undstrom who suggested that the apical base was one of the most important factors in the correc correctio tion n of maloccl malocclusi usion on and mainte maintenan nance ce of the correc corrected ted occlusi occlusion. on. McGaul McGauley ey7H suggested that intercanine and intermolar width should be maintained as originally presented to minimi%e minimi%e retention retention problems. problems. trang7> further further enforced enforced and substantia substantiated ted this theory. theory. @ance7( noted that arch length may be permanently permanently increased increased only to a limited limited extent. rch form, particularly in mandibular arch, cannot be permanently altered by appliance therapy. Therefore, treatment should be directed towards maintaining the arch form presented by the original malocclusion. ;ayesnance pointed out that alterations in the mandibular arch forms generally ended in failures. This has been accepted realistically by some orthodontists. 1all 1allas as and and McGa McGaul uley ey7H made made the the foll follow owin ing g stat statem ement ent “sin “since ce thes thesee two two mandi mandibu bula lar r dimensions, molar width and cuspid width are of such an uncompromising nature, one might establish them as fixed -uantities and build the arches around them.” trang7> said essentially the same thing as follows “# am firmly con"inced that the axiom of Mandibular canine width may be stated as follows4 follows4 The width as measured measured across from canine to the other in the Mandibular denture is an accurate index to the muscular balance inherent to the indi"idual and dictates the limits of the denture expansion in this area.” #n almost e"ery orthodontically treated cases well out of retention, the mandibular intercanine and intermolar width tended to return or maintain the original dimensions. ince '(8)*s it has been brought to the orthodontic world that the most stable and non!changeable portion or dimension of the dental arches is the arch width. Many studies carried out during du ring this period pro"ed this fact with differences found in extraction and non!extraction cases. $alters8) in '(9 was the only one to gi"e a conflicting report, who reported in 9 percent of o f both the extraction and non!extraction cases the maintenance of slight increase in

9H

Retention and relapse in orthodontics mandibular intercanine width after all retention had been remo"ed for what he termed as “an ade-uate period.” #t has fre-uently been suggested that if the mandibular canines are mo"ed into a more posterior position in relation to the mandibular basal arch, the increase intercanine width can be expected to hold. $hile this explanation may be presumed to be logical, all of the e"idence e"idence collected collected to date would indicate indicate that distal mandibular mandibular canine canine mo"ement, mo"ement, whether by tipping or bodily repositioning, has little to do with increasing intercanine width. #n this context, hapiro8' in '(H7 measured mandibular dental casts of eighty extraction and non! extraction extraction cases /') years postretentio postretention2 n2 at pretreatm pretreatment, ent, end!of!trea end!of!treatment tment,, and ') years postretention stages and changes in mandibular intercanine width, and arch length were examined. On the basis of findings of this study, hapiro hapiro ga"e the following conclusions4 '2 Mandi Mandibu bula larr inte interc rcani anine ne widt width h demo demons nstr trat ated ed a stro strong ng tende tendency ncy to retu return rn to its its pretreatment dimension in all groups, but sub+ects in the Glass ##, di"ision  group demonstrated a significantly greater ability to maintain treatment intercanine width expansion than did the Glass # and Glass ##, di"ision ' groups. 2 Mand Mandib ibul ular ar arch arch leng length th decr decrea ease sed d subs substa tant ntia iall lly y in e"er e"ery y grou group p duri during ng the the postretention period. 62 Mandibular Mandibular arch length length reduction reduction in the Glass ##, ##, di"ision di"ision  group was signifi significantly cantly less than in the Glass # and Glass ##, di"ision ' group during treatment and from pretreatment to ') years postretention. 72 5rom pretreatm pretreatment ent to postretenti postretention, on, mandibular mandibular intermolar intermolar width width decreased decreased more in extraction cases than in nonextraction cases. 1onald =ardner and Ghachonas8 in '(H9 reported essentially the same findings as regards to the intercanine and intermolar width. One more important finding in their study was that, the incisor to molar distance decreased with treatment and had a slight tendency to continue to decrease post treatment. Ahde found that intermolar and intercuspid width persisted more in the maxillary than in the mandibular arch. #n both cases, intertooth width increase was least tolerated in the cuspid region regardless of the type of extraction therapy. lthough relapse tendencies were same same for extrac extractio tion n and nonextr nonextract action ion cases cases much much of the interm intermolar olar width width increa increase se in nonextracti nonextraction on case were maintained maintained.. #n the extraction extraction cases the mean intermolar intermolar width was

9>

Retention and relapse in orthodontics only slightly increased during treatment and decreased beyond the original intermolar width after the treatment. o, it can be concluded that the original intercanine and intermolar width when intelligently and +udiciously employed, can ser"e as a "aluable clinical guide to orthodontic diagnosis.

$andibular incisor cro#ding #rregularity of mandibular incisors fre-uently occurs following orthodontic treatment. e"eral studies reported a relation between mesio!distal dimensions of lower incisors and their irregularity prior to orthodontic therapy while other studies ha"e found lack of such an associ associati ation. on. Ceck Ceck and Ceck 77 in '(H '(H stat stated ed that that rati ratio o of mesi mesiod odis ista tall to faci faciol olin ingu gual al >, dimens dimension ionss was import important ant in produci producing ng well!a well!ali ligned gned mandib mandibula ularr inciso incisors. rs. Boese Boese>,

(

ad"ocated the use of Ceck and Ceck index as a guide for interproximal tooth reduction in con+unc con+unctio tion n with with upracr upracrest estal al fibero fiberotom tomies ies so as ease ease of enhanci enhancing ng stabil stability ity of lower lower incisors.

Kuftinec78 howe"er raised the -uestion o"er interproximal stripping and found no co! relation between incisor crowding and Ceck index. ;e stated that both the cases with high and low Ceck index relapsed after treatment.

,auses of late mandibular anterior cro#ding:

The following are the different causes of late mandibular anterior crowding47

9(

Retention and relapse in orthodontics '2 :ate :ate man mandi dibu bula larr grow growth th 2 keletal keletal structu structure re and and complex complex growth growth patterns patterns 62 oft oft tiss tissue ue matu matura rati tion on 72 Cerio Ceriodo dont ntal al forc forces es 82 Tooth ooth stru struct ctur uree 92 Occl Occlus usal al fact factor orss H2 Gonnect Gonnecti"e i"e tissu tissuee changes changes >2 Thir Third d mola molarr erup erupti tion on (2 nteri nterior or compone component nt of of forc forcee

Mandibular incisor crowding is fre-uently obser"ed after retention is discontinued. This occurs in patients treated with or without extraction. There may be an intrusion of incisor teeth and an extrusion of the buccal series of teeth when the dental arch is being a le"eled. #ntruded mandibular incisors ha"e a tendency to regain their original height when pressure is released and recrowding may result. To reduce the likelihood of relapse of the lower incisors, @anda and Burstone ha"e de"eloped the following “Twel"e “Twel"e Keys to tability”4 '2 $hene"er $hene"er possible, possible, allow the lower incisor incisorss to align themsel"es themsel"es either either through serial serial extraction or the use of a lip bumper in the early mixed dentition. 2 O"ercorrect O"ercorrect lower lower incisor incisor rotations rotations as early early in treatment treatment as possib possible. le. 62 Reproximati Reproximation on of incisors incisors early in treatment treatment and again at retention retention enhances enhances stability stability.. 72 "oid "oid increasing increasing the interca intercanine nine width width during acti"e acti"e treatment. treatment. 82 0xtrac 0xtractt bicusp bicuspids ids in cases where where mandib mandibula ularr arch arch discre discrepan pancy cy is 7 mm or greate greater, r, except where facial aesthetics dictates otherwise. 92 Reor Reorga gani ni%e %e that the more more a toot tooth h is mo"ed mo"ed,, the the more more likel likely y it is to relap relapse se,, and and o"ercorrect accordingly. H2 Aprigh Aprightt lower lower incis incisors ors to to at least least () ()° whene"er the profile permits. >2 Greate Greate a flat occlusal occlusal plane during during treatment, treatment, and o"ercorrec o"ercorrectt the o"erbite. o"erbite. (2 Crescribe Crescribe upracrest upracrestal al fiberotomy fiberotomy for for se"erely se"erely rotated rotated teeth. teeth. ')2 Retain the lower arch until all growth is complete. complete. ''2 Clace retainers the same day appliances are remo"ed.

H)

Retention and relapse in orthodontics '2 Recogni%e Recogni%e that compromise compromise is often necessary in the interest interest of facial facial aesthetics aesthetics and that sometimes lifetime retention is necessary.

5ollowing these “Keys” will certainly not eliminate relapse4 The only sure way is to prescribe lifetime retention for e"eryone.

6ole of Third $olar in Post retention ,ro#ding The role of third molar in the relapse of lower anterior crowding following the cessation of retention in orthodontically treated cases has pro"oked much speculation in the dental literature o"er the past '8 years. #n a modern population, there is a strong tendency for crowding of mandibular incisor teeth to de"elop in the late teens and early twenties. Mild crowding of the incisors tends to de"elop in well!aligned arches, or it increases if mild crowding is already present. #ncreased crowding of mandibular incisors takes place at about the time of third molar eruption. lthough the mean age for third molar eruption is ) years, mandibular anterior crowding continues well beyond the eruption of third molars in both untreated and treated indi"iduals. #t is considered as a normal physiological process of maturation. #n '>8( Robinson Robinson7' wrote ?. “The dens sapientae ?. is.... fre-uently the immediate cause of irregularity of the teeth by the pressure exerted towards the anterior part of the mouth”. Broadbent7' in '(7', on the basis of the cephalometric e"idence collected by the Bolton Bolton*s *s study, study, indica indicated ted that that third third molar molar impact impaction ion was not the cause cause of mandib mandibula ular r crowding, but both were the result of inade-uate mandibular growth. ccording to @ance7', the co!incident occurrence of third molar eruption with the cessation of retention was the reason for the indictment of third molar in the relapse of mandibular crowding. s late as '(>(, Richardson7 implicated the role of unerupted third molar in lower arch crowding. e"eral studies ha"e been conducted to find out the association between the third molar and late mandibular incisor crowding and ha"e "aried findings and interpretations.

H'

Retention and relapse in orthodontics B+ork and killer '' studying facial de"elopment and eruption in sub+ects during the circumpubertal period could find on clear e"idence that secondary crowding was due to eruption of third molar. Bergstrom and 3enson /'(9'29H studied sixty dental students with unilateral third molar aplasia and found greater crowding in the -uadrants with third molars present than those where third molars were missing. Iego /'(92

9>

concluded from his study that the

erupting third molar can exert a force on approximating teeth. Rose =. Kaplan7' in '(H7 studied a sample of se"enty!fi"e orthodontically treated Gaucasian patients for an a"erage of (.6 years out of retention with a mean post retention age of 9.9 years. 6) patients had bilaterally erupted mandibular third molars, ) had bilaterally impacted third molars, and 8 had bilateral third molar agenesis. The following conclusions were drawn4 ! '2 1uring 1uring the post treatmen treatmentt period period no signif significa icant nt differe difference ncess were were appare apparent nt in the changes in arch length, lower molar position, lower incisor position or lower incisor inclinations between the three groups. 2 #t does not appear appear that the presence presence of lower lower third third molar has any signifi significant cant influence influence on post!treatment changes. 62 ome degree degree of lower anterior anterior crowding crowding relaps relapsee occurred in in the ma+ority ma+ority of cases, cases, but this was not significantly different between the three groups. 72 The theory theory that the the third molar molar exerts exerts pressure pressure on the the teeth teeth mesial to to them could could not be substantiated in this study. study. chwar%e chwar%e /'(H82 7 in a long L term study compared a group of 89 patients with third molar germectomy and 7( sub+ects whose third molars were allowed to de"elop. ;e found a signif significa icant nt forwar forward d mo"eme mo"ement nt of the first first molars molars associ associate ated d with with increa increased sed lower lower arch arch crowding in non!extraction group. :ind-uist and Thilander /'(>2 9( examined 6 boys and ( girls with impacted third molars on both sides of the mandible. The impacted molar on one side was remo"ed and the non!extraction side was used as a control. "erage age at the time of operation was '8.8 years /'6!'( years2. They noted that the space change on the extraction side was impro"ed in H

Retention and relapse in orthodontics relation to the control side in H)N of cases. They found a "ery small beneficial effect, ).'9 mm less crowding in the group without third molars compared with the group with third molars. They concluded that extraction could be recommended in se"ere crowding. The study was not able to predict which patients reacted fa"orably or unfa"orably to remo"al of third molars in cases of anticipated crowding. des = et. al., /'(()2H) conducted a long L term study to determine the relation of third molar to changes in the mandibular mandibular dental arch. The sample for this study consisted consisted of four groups and sub Lgroups. The groups consisted of premolar extraction, non!extraction with initial initial generali%ed generali%ed spacing, non!extracti non!extraction, on, and serial serial extraction extraction untreated untreated sub+ects. sub+ects. The subgroups were di"ided into persons who had mandibular third molars that were either impacted, erupted into function, congenitally absent or extracted at least ten years before post retention records. The mean post retention period was '6 years /') !> years2. The mean post retention age was > years 9 months /'> years 9 months L 6( years 7 months2. They found that mandibular incisor irregularity increased while arch length and incisor width decreased. The third third molar subgroups subgroups re"ealed re"ealed no significan significantt difference differencess in the parameter studied. @o significant difference in mandibular growth pattern was found in third molar subgroups. #ncisor crowding was not significant between third molar subgroups. They concluded that the third third molar molar remo"al remo"al with with the ob+ect ob+ecti"e i"e of alle"i alle"iati ating ng or pre"en pre"entin ting g mandibu mandibular lar inciso incisor r irregularity might not be +ustified. @ieke et. at., /'((82H' in their study of post retention crowding and incisor irregularity considered the presence or absence of third molars, di"iding the sample of 9 cases into subgroups< bilaterally erupted, impacted third molars, and bilateral third molars agenesis or extraction. :ower arch crowding was found to be influenced by the presence of third molars. #n cases with missing mandibular third molars, less amount of relapse of crowding was seen than in any case with impacted or erupted third molars. On the side of missing third molars, '. mm of less crowding was seen. They concluded that the crowding was statistically significant but clinically insignificant. :ittle RM /'((), '(((2 examined mandibular crowding during the post treatment phase and concluded that mandibular mandibular crowding is a continuous continuous phenomenon phenomenon well into the ) L 7)

H6

Retention and relapse in orthodontics years age bracket and beyond. Third molar presence, absence, impacted or fully erupted, seemed to ha"e little effect on the occurrence or degree of relapse. outhard et. al., /'(('2H measured the mesial force exerted by unerupted mandibular third molars using a techni-ue similar to measuring the anterior component of occlusal force. The sample consisted of '7 males and six female patients. Their hypothesis was that the mesial force exerted by unerupted third molar increases tightness of all proximal posterior tooth contacts and that surgical remo"al of third molar relie"es tightness by eliminating this force. They were unable to detect a mesial force exerted by unerupted third molars. They obser"ed that the change of posture relie"es the proximal contact tightness dramatically. Cirttiniemi et. al., /'((72H6 e"aluated the effect of impacted third molar remo"al on 7 indi"iduals in the third decade of life. Gasts were examined before and one year after extraction of third molar. They found slight distal drift of second molar but no significant change in the lower incisor region. s the literature indicates, there is still no agreement or definite conclusions drawn about the effect of third molars on post retention crowding or proclination of the lower anterior segment. ince at least 9)!H)N of the in"estigators belie"e that third molars could cause problems post L retention, it is ad"isable to prophylactically extract the third molars either prior to or immediately after orthodontic treatment so that it will not cause any undesirable effect on the results achie"ed by treatment.

H7


,oncept of oerbite relapse The general tendency for incisal o"erbite to “Relapse” or return toward its pre! treatment relationship is well accepted.  good diagnostic discipline is warranted in choosing the treatment modality in the correction of o"erbite.  school of thought led by chudy ad"ocates the correction of deep bite by extrusion of molars. nother school of thought consisting of Rickets, Burstone and others belie"es in genuine intrusion of incisors for the correction of o"erbite. Ghoosing the ideal line of treatment for each indi"idual case could eliminate relapse of the o"erbite. Cseudo L correction of o"erbite by extrusion of molars and proclination of lower anteriors, when a continuous arch wire is used would result in in relapse. trang86 defined defined o"erbite as the “"ertical “"ertical o"erlapping o"erlapping of the upper and lower incisor teeth.” pparently this trait has not always been present in man. Rowlett 87 described how the incisors of primiti"e man occluded in edge!to!edge relationship when the molars were in “normal occlusion”. This "ertical o"erlapping of the incisors became pre"alent in the human dentition only about ))) years ago in the axon era and may well ha"e been associated with the refinement in the diet of ci"ili%ed man. The relationship of o"erbite to post retention growth was examined by many. Cayne87 indicated that post retention ramus growth tended to decrease the mandibular plane angle, resulting in an increased posterior face height and forward positioning of the symphysis. ;e thought that these post retention growth changes were partially responsible for o"erbite relapse. ;asstedt87 found a strong tendency for the incisors to return to their original o"erbite relationship during post retention period. ;e could not, howe"er, demonstrate any correlation between o"erbite and "ertical ramus height, interincisal angulation, changes in occlusal plane or total face height. Many other studies are in agreement in finding a tendency for the incisal o"erbite to return to its pre!treatment relationship following orthodontic treatment. This relapse is associated with a number of "ariables. Gorrections carried out during periods of growth are less likely to relapse, and the maintenance of the post treatment result is dependent on amount and direction of growth during the retention and post retention periods. O"er correction of incisal o"erbite should be considered co nsidered as an aid in maintaining the o"erbite reduction achie"ed during treatment. Gonsidering the axial inclination of upper and

H8

Retention and relapse in orthodontics lower incisors Reidel> belie"ed that an upright incisor position, reflected by a higher than normal interincisal angle, is more pro"e to o"erbite relapse. Mark and imons87 studied se"enty orthodontically treated patients ') or more years out of retent retention ion.. They They tried tried to correl correlate ate incisa incisall o"erbit o"erbitee relaps relapsee with with other other cephal cephalome ometri tricc measurements. Their findings are interesting and are a "aluable ad+unct to our knowledge on o"erbite relapse. '2 Catie Catient ntss who who had a deep deep init initia iall o"erb o"erbit itee prio priorr to trea treatm tment ent also had deep deep init initia iall o"erbit o"erbitee post post retent retention ion<< howe"er howe"er,, they they also also mainta maintaine ined d the greate greatest st amount amount of correction or o"erall net decrease in o"erbite. 2  deep initial initial o"erbi o"erbite te was correl correlate ated d with with uprigh uprightt retrus retrusi"e i"e incisors incisors in both both the maxi maxill llaa and mandi mandibl ble, e, as an ngle ngless Glas Glasss # or Glas Glasss ## 1i" 1i"  malo malocc cclu lusi sions ons.. Crotrusion of the mandibular incisors during orthodontic correction of o"erbite was correlated with o"erbite relapse. This suggests that in order to enhance the long!term stabil stability ity of o"erbi o"erbite te correc correctio tion, n, unneces unnecessar sary y protru protrusio sion n of mandib mandibula ularr anteri anterior or segment during treatment should be a"oided. 62 Mandibu Mandibular lar growth, growth, contai containin ning g the signifi significant cant "ertica "erticall compone component nt both both during during and follow following ing orthodo orthodonti nticc treat treatmen mentt were were correl correlate ated d with with o"erbi o"erbite te stabil stability ity.. :ack :ack of mandib mandibula ularr growth growth in a predom predomina inantl ntly y hori%o hori%onta ntall direct direction ion was associ associate ated d with with o"erbite relapse. 72 The o"erbite o"erbite stability stability was correla correlated ted with an increase increase in anterior anterior and and posterior posterior denture denture heights during and following orthodontic treatment. 82 The occlusal occlusal plane angle angle was generally generally opened opened up during orthodont orthodontic ic treatment, treatment, and during the post retention period it returned to approximately the original angulation. This post retention closure or decrease in occlusal plane tipping should be a"oided during treatment if possible. @o correlation was found between change in mandibular plane and o"erbite stability. stability. 92 1eep initial initial o"erbite o"erbite was associated associated with a high interinci interincisal sal angle, as in ngles ngles Glass Glass # and Glass ##, 1i"  malocclusions. ;owe"er, there is no correlation between the

H9

Retention and relapse in orthodontics inter!incisal angle established following orthodontic treatment and post L retention changes in o"erbites. H2 Catien Catients ts of either either sex in whom whom o"erbi o"erbite te correcti correction on was accompl accomplish ished ed during their their respecti"e growth post retention seemed to maintain their correction ') years out of retention. >2 Cost retention retention changes changes in o"erbites o"erbites were were not related related to whether or not permanent permanent teeth teeth were extracted during orthodontic treatment. t present, genuine intrusion of incisors for the correction of o"erbite as suggested by Ricketts is most widely accepted. ngle et al -uotes =orden*s study of cases treated by Ricketts showing an a"erage post treatment relapse of ' mm for e"ery 6 mm of intrusion.

HH


6elapse related to "7traction 5 one7traction ,ases ?The last hundred and se"enty years of orthodontic history shows that, with the exception of ngle and 1a"enport, the feelings of the leaders in the profession was that extraction, like amputation of any other part of the body, was not to be a"oided if the exigen exigencie ciess of the indi"idu indi"idual al case case demand demanded ed it and no other other method method of correc correctio tion n was (1955). 88 a"ailable ! Hahn (1955).

0motional battles still rage regarding tooth extraction in orthodontic therapy< howe "er with ;ahn*s ob+ecti"ity in mind, we should search for treatment rationales to substantiate the role of tooth extraction. The contro"ersy regarding the role of extractions in pre"enting relapse of orthodontic treatment still exists after nearly a century of debate. Regarding extraction of permanent teeth, orthodontists of this century ha"e been clearly di"ided into two camps4 those who belie"ed that mechanical alignment of crowded teeth would result in the accommodation of bones and soft tissue to this new position and those who belie"ed that such adaptation did not necessarily follow. Anfortunately, Anfortunately, the extraction "ersus nonextraction debat debates es of the the pro! pro! and and anti anti L ngle ngle fact factio ions ns lack lacked ed the the ob+e ob+ect cti" i"ee docu docume ment ntat atio ion n of postretention results. The most recent studies seem to indicate that extraction is not a panacea and that long!term stability of lower incisor correction can be expected in only about )N of extraction extraction cases. Other studies are not so pessimist pessimistic ic and suggest suggest that treatment treatment techni-ues techni-ues and retention plans may be ma+or factors in long L term stability. The role of premolar extraction in orthodontics has been fiercely debated since the turn of the century. ngle, Gase, 1ewey, Tweed, Tweed, Ricketts, Begg, and Getlin ha"e each guided the pendulum of our “professional clock”. ') 0xtraction of the four first premolars enables the orthodontist to effecti"ely treat many cases of se"ere dentoal"eolar protrusion as well as many cases in"ol"ing significant arch!length deficiencies. The rationale for extraction has been extended to using it as a means of ensuring treatment stability. stability. Anfortunately, Anfortunately, many studies ha"e demonstrated that extraction cases are not immune to postretention relapse< more specifically, and most ob"ious to the practitioner, the cases are as likely as not to de"elop mandibular incisor crowding o"er the long term.

H>

Retention and relapse in orthodontics $hil $hilee ther theree appe appear arss to be gener general al agre agreem ement ent that that extr extrac acti tion onss are are +ust +ustif ifie ied d in correcting bimaxillary protrusions or se"ere arch length deficiencies, the debate continues on the role premolar extractions play in the long L term stability of incisor alignment. #n his text Gontemporary Orthodontics, Croffit' states that first premolar teeth are often extracted to allow better lip contours and to pro"ide a more stable result. Qet the most recent studies on relapse of the lower incisors in cases where the extraction of premolars was performed indicate a discouraging result might be expected in atleast two thirds of patients. patients. Many of the cases of recrowding of incisors and space opening after orthodontic treatment, which includes tooth extraction of first premolars or other teeth L can be attributed to intrinsic and extrinsic forces affecting the human den tition. mong mong these are the method of chewing and swallowing< the type, and the degree of pressure when the teeth are brought into occlusion. 1entofacial habits in"ol"ing the teeth, the tongue, the lips and other facial and masticatory masticatory muscles, muscles, psychic psychic disturbance disturbancess accompanied accompanied by certain certain orofacial orofacial tics, and other untoward habits all may be causati"e factors. tudies by little and others6), 88!8(, at the Ani"ersity of $ashington concluded that extrac extractio tion n of premol premolar ar teeth teeth has littl littlee effect effect on long!t long!term erm /')!) /')!) years years22 post post treatm treatment ent stability of lower incisor alignment. andowsky9) reported on the stability of (9 cases examined an a"erage of ) years after retention. These patients all exhibited “')) percent correction” of the lower incisor crowding present at the initiation of treatment.  comparison of long!term result to original malocclusion showed there was increased mandibular crowding in (N of the cases. t the long!term follow!up, '8N of the cases had crowding beyond 6 mm, and only 'N had crowding crowding of 9.8 mm or more. There was no attempt to distinguis distinguish h between between cases treated treated by the extraction or nonextraction approaches in andowsky*s study. #n a later article by Ahde, andowsky andowsky,, and Begole9', the the samp sample le was was brok broken en down down into into 78 none nonext xtra ract ctio ion n and and H extraction cases. The extraction sample showed more se"ere crowding at the beginning of treatment and a smaller percentage of relapse postretention. p ostretention. =lenn9' stud studie ied d > case casess of none nonext xtra ract ctio ion n trea treatm tmen entt an a"er a"erag agee of > years ears postretention. ;e found that incisor irregularity increased increased slightly postretention.

H(

Retention and relapse in orthodontics andusky') reported on postretention stability of >8 extraction cases treated by Tweed and Tweed foundation members. ;e reported less than ')N relapse of the lower incisors using :ittle*s irregularity index. ;e found the lower incisors tended to mo"e forward postretention and the occlusal plane ! 5rankfort hori%ontal plane L angle decreased. Tweed') talked in a '(9> inter"iew about a study he was conducting with ')) extraction and ')) nonextraction cases examined 8 years postretention. $hile no scientific data are a"ailable, Tweed*s Tweed*s conclusion was that the extraction cases were more stable. #n a master*s degree thesis at :oma :inda, 1a"is') reported that extraction cases experienced less mandibular incisor crowding and were more stable than nonextraction cases three to fi"e years postretention. Kuftinic and trom78 examined 8) cases, 8 extraction and 8 nonextraction, four months or more after discontinuing retention and found that lower incisor relapse was greater in nonextraction cases. Boese>, ( published a study on 7) extraction cases that were orthodontically treated but ne"er retained. ;is findings were based on obser"ations made four to nine years post treatm treatment ent.. ll ll patien patients ts had underg undergone one fibero fiberotom tomy y and reprox reproxima imatio tion n of the mandib mandibular ular incisors. incisors. Growding Growding was e"aluated by :ittle* :ittle*ss irregularity irregularity index and was found to be almost nonexistent posttreatment. #t should be noted that about one half of the cases re-uired more than '.> mm of enamel reduction, performed in se"eral stages. #t is also interesting to note that that the the lowe lowerr inci inciso sors rs were were upri upright ghted ed durin during g trea treatm tmen entt and conti continue nued d to upri upright ght posttreatment. The mean "alues for #MC />(.8 at appliance remo"al, >>.9 > >.9 postretention2 are within the range that Tweed suggested was necessary for stability. Those patients whose growth would ha"e been classified as type G by Tweed re-uired additional amounts of reproximation as growth occurred. light o"ercorrection of rotations was accomplished at least six months prior to performing the fiberotomies. >, ( Boese>, felt that the practice of not utili%ing any retention in the mandibular arch

played an important role in stabili%ing the lower anterior teeth. ;e stated that “lower retention retention eliminates eliminates the need for reproximation, reproximation, since it postpones postpones natural arch length length loss, pre"ents any compensatory lower incisor mo"ement, and allows for a build up of forces

>)

Retention and relapse in orthodontics during the retention period. The decision not to use lower retention will allow for natural arch length loss, which occurs gradually and can be dealt with immediately”. The extraction of premolars does not assure long!term stability of the lower incisors. Recent studies of postretention stability by different authors ha"e produced significantly different results. #t may be that the treatment goals and the mechanics used to reach those ob+ecti"es differed in the populations studied.

$andibular Incisor "7traction  tabilit%:

0xtraction of two mandibular incisors may satisfy the re-uirements of maintaining arch form without expansion of intercanine width. 0xtraction of one mandibular incisor usually does creates problem of deep o"erbite, at least when a normal tooth si%e relationship is present before the extraction. #f maxillary canines are related in their normal positions to mandibular canines, then maxillary incisors must naturally fall into either a greater o"erbite or o"er+et. ;owe"er, when two mandibular incisors are remo"ed, the mandibular teeth are so rearranged that the mandibular canines become lateral incisors. #f the central incisors are remo"ed remo"ed,, the mandib mandibula ularr latera laterall inciso incisors rs become become centra centrall inciso incisors. rs. The mandib mandibula ularr first first premolars assume the place of the mandibular canines and the maxillary canines must occlude occlude along along the distal distal incli inclined ned planes planes of the mandib mandibula ularr first first premol premolars ars.. $hen $hen two mandibular incisors ha"e been remo"ed, the usual relationship of the anterior teeth is end L to L end, for the mandibular arch in the anterior area is usually slightly larger than it would ha"e been with four incisors present instead of two incisors and two canines. #t is usually necessary to trim the mesiodistal widths of the mandibular centrals or laterals /whiche"er remain2, the canines, and the first premolars to create a harmonious tooth si%e relationship between these teeth and the maxillary six anterior teeth. $hen the mandibular first premolars are extracted, the simple realignment of the mandibular anterior teeth and canines in normal arch form results in a greatly increased interc intercani anine ne width, width, which which in all likeliho likelihood od cannot cannot be mainta maintaine ined. d. On the other other hand, hand, if mandibular inter canine width is maintained as presented, the arch form cannot be anything but pointed or I L shaped.  satisfactory solution in"ol"es the extraction of two mandibular central incisors. The conse-uent inter canine width is little changed, whereas mandibular arch

>'

Retention and relapse in orthodontics form has been maintained in a form similar to the original. Treatment by extraction of a mandibular incisor tooth can show a tendency to cusp!to!cusp on one side of the dental arches followed by what is known as “slippage”, or forward migration of buccal series of teeth. teeth. There is a tendency tendency for extracted extracted incisor space to reopen when the basal arch is large, large, and the tongue is large and acti"e. #n addition, it is conduci"e to maxillary incisor o"er+et and deep o"erbite. Retainers are to be worn indefinitely.7, 7, 78

,ontraindications for $andibular Incisor "7traction:

This is not to suggest that all problems of mandibular anterior crowding can be sol"ed with the extraction of mandibular anterior teeth. There are three drawbacks to such treatment4 '2 #n instances instances of minima minimall crowding crowding spaces tend tend to open between between the canines canines or centrals centrals and canines canines or latera laterals ls /which /whiche"e e"err are maintaine maintained2. d2. pacin pacing g in this this area area can be irri irrita tati ting ng to the the patie patient nts, s, for for food food impac impacti tion on is emba embarr rras assi sing ng and and esth esthet etic icss is unpleasant. 2 =enerally =enerally the most protruded protruded mandibul mandibular ar incisors incisors are remo"ed, remo"ed, and then immediately immediately the mandibular denture becomes more posterior relati"e to the mandibular base. #t is difficult, if not impossible, to mo"e the whole mandibular denture forward to assume its pre"ious relation to pogonion, and facial esthetics may suffer as a result of this recessi"e positioning of the mandibular denture. 62  third third possible possible problem includes includes the anatomic anatomic differe differences nces in shape of the mandibular mandibular canines as compared to the normal mandibular lateral incisors< occasionally there are differences in the color of these teeth as well. @on!extraction therapy in crowded cases is usually thought to lead to post retention relaps relapse. e. Mandib Mandibula ularr arch arch length length and inter inter canine canine width width typic typicall ally y decreas decreasee during during post post retention period regardless of whether they increase or decrease during treatment. Restor Restoring ing arch arch length length defici deficienci encies es with with extrac extractio tion n treatm treatment ent has not elimin eliminate ated d the problem of relapse.  number of etiological "ariables ha"e been considered including excessi"e intercanine expansion, arch from change, pretreatment crowding and length of retention.

>

Retention and relapse in orthodontics Reidel9 has sugges suggested ted that that the patien patients ts with with se"ere se"erely ly crowded crowded mandib mandibula ularr arches arches,, remo"al of one or more mandibular incisors is the only logical alternati"e which may allow for increased stability of mandibular anterior without continued retention. chwart%96 reported ) years post retention records of a patient who had two mandibular incisors remo"ed. Riedel obser"ed that the arches in these patients appeared less crowded than patients who had been treated with premolar extraction. Riedel9 stat stated ed that that L The The extr extrac acti tion on of two two mand mandib ibul ular ar inci inciso sors rs may may sati satisf sfy y the the re-uirements of maintaining arch form without expansion of intercanine width. $ith non! extraction or premolar extraction, the intercanine width usually must be increased to gain ade-uate alignment and arch form a strategy that might result in fa"orable result. #t is suspected that an increase in intercanine width contributes to incisor relapse and crowdi crowding. ng. #t was notice noticed d that that interc intercani anine ne width width decrea decreases ses after after inciso incisorr extrac extractio tion n and continued to decrease post retention. The post retention reduction was significantly less as compared to premolar extraction. The study carried out by Riedel and :ittle suggested that simply maintaining or reducing intercanine width does not guarantee completely stable long L term end result but may contribute to a lesser degree of relapse. Catien Catients ts should should be carefu carefully lly select selected ed for this this treat treatmen mentt plan plan of mandib mandibula ularr inciso incisor r extraction. uccess of treatment depends upon patient selection and mandatory diagnostic set up before making extraction decision.7

>6


>tabilit% after "7pansion lthough expansion of the maxilla is one of the oldest forms of orthodontic treatment, its use has consistently e"oked professional contro"ersy. 1ebate is being done on the stability and progress of expansion since the day the theory of expansion has been put forward. The debate seems to ha"e been all the more heated because little scientific e"idence existed to support any of these "iews.  most scientific study was carried out by kieller in '(97 who inserted metal implants into '6 girls and H boys using an expansion appliance. This was opened at the rate of ).8 mm. kieller found that both the teeth and the "ault widened during retention and thereafter the teeth howe"er commenced to relapse at the end of the expansion and continued to do so out of retention, with the relapse amounting on a"erage to about 8N of the total opening. The other finding of kieller*s study was that the dental relapse was less for the patients under ( year old.H7 Many more studies ha"e been done more recently on the stability and relapse after expansion. ccording to torey the ideal rate of expansion should be ' mm per week, which has been recommended by other authors also.H8 #n recent years ;ass /'(>)2 H7 has put forward another concept in reducing the relapse after expansion. ccording to him the retention phase after expansion is completed, should be increased. imring and #ssacson ha"e demonstrated that forces to collapse the maxillary expansion exist for approximately 9 months. ;ass also recommend the concept of o"er expansion. The en"ironmental factors play an important role in the stability of the arches after retention. ome amount of changes should be anticipated due to forces action upon the dental arches. This can be counteracted by slight o"er expansion. nother finding was that stability of maxillary arch expansion was more than that of mandibular arch and it was more easier to maintain the stability of molar expansion than canine expansion.H8 $illiam Croffit compared the amount of relapse in case of orthodontic and orthopedic expansion. ;e noted that in case of orthopedic expansion if ') mm of total expansion would

>7

Retention and relapse in orthodontics ha"e been produced, in the beginning > mm of skeletal and  mm of tooth mo"ement was seen. t 7 months the same ') mm of dental /total2 expansion could be present, but at that point there would be only 8 mm of skeletal and 8 mm of dental expansion. #f a force across the midpalatal midpalatal suture suture is applied applied more slowly slowly, total force build up is less. #t appears that approximately ' mm per week is the maximum rat at which the tissues of the midpalatal suture can adapt. o tearing and hemorrhage are minimi%ed. To produce expansion at this rate,  to 7 pounds of force appear optimal, depending on the age of patient. ;igher le"el is needed in older patients. 5rom the beginning the ratio of the dental to skeletal expansion is about ' to ', so that ') mm of expansion o"er ') week period, at the rate of ' mm per week would consist of 8 mm of dental and 8 mm of skeletal expansion. $ith expansion at this rate the situation at the completion of the acti"e expansion is approximately analogous to rapid palatal expansion  to 6 months after rapid palatal expansion is completed when bone filling has occurred. Thus the o"er all result of rapid "ersus slow expansion is similar, but with slow expansion a more physiologic mo"ement is added.H9 The farther the teeth must be mo"ed laterally and the more rapidly they are mo"e, the more longer should be the period of retention. #f a case is widened a short distance o"er a clinically long period of time with slow expansion, the chance of ma+or relapse is minimal. #f such occurs it is usually related to recurrence of the improper muscle function, which caused the problem in the first place. #f, howe"er a case is widened o"er a relati"ely short period of time with more clinically rapid techni-ue, the chances of relapse after withdrawal of the appliance are increased. light o"erexpansion is then also generally ad"isable. The amount of retention needed for a gi"en case is dependent on many factors. #n estimating the length of time re-uired for acti"e retention, it is better to o"erestimate and be sure than underestimate and suffer possible relapse due to the withdrawal of the appliance too soon. The second molar plays a key role in trans"erse expansion. $e know that the powerful mesial thrust of the second molars leads to the crowding of teeth in the bicuspid, and e"en anterior regions. $ith the elimination of this forward thrust by means of second molar extraction /when needed2, stability is gained in an anteroposterior direction. The direction of the relapse of the first molar once the second molar extraction is in the distolingual direction

>8

Retention and relapse in orthodontics rather than the mesiolingual direction. This in turn mo"es the teeth slight posteriorly back on the wider part of the arch. The age of the patient is also an important factor. The younger they are, the greater the chances of stability in lateral de"elopment. The second concept to be kept in mind is that of lateral “de"elopment” and not “expansion”. By this it means that the teeth are merely being brought out to their full genetic potential, not past the point where the limit of basal bone has been genetically programmed. ltoona et. al at the Ani"ersity of Toronto Toronto ha"e stated that though the shape of a bone may be affected by function, the "olume is genetically predetermined.HH $ith all these recent studies it is pro"ed that expansion is a biologically and bio! mechanically sound procedure. The decision to gain space through expansion or by the remo"al of teeth must be based on an understanding of the causes of the original crowding with with there there potent potential ial for future future influe influence nces, s, possi possible ble growth growth effect effectss that that may increa increase se or decrease arch length and the possibilities of functional adaptation to the proposed changes.H7

>9


Balance in the three tissue s%stems 5ailure to understand the balance between the three tissue systems of the orofacial region, namely, 1ental, keletal and @euromuscular could result in treatment failure and relapse. s =raber points out, confining oneself to only dental system, ignoring the skeletal and neuromuscular restricts the hori%on h ori%on of Orthodontic philosophy ph ilosophy.. Most Orthodontic treatment is aimed at correcting skeletal and dento L al"eolar mal! relationships and Orthodontists ha"e generally become -uite adept at achie"ing functionally balanced occlusions. ;owe"er, one concept con cept is often o"er looked when considering co nsidering the nature of malocclusions< the craniofacial complex maintains a state of homeostasis regardless of its structural configuration or whether or not it is skeletally balanced. bnormal skeletal or dento!al"eolar configurations are counter!balanced both by atypical or abnormal patterns of perioral and masticatory muscle function and by passi"e pressures of the other associated associated soft tissues.98

bnormal skeletal Gonfiguration

bnormal muscle function B/;/,"

bnormal 1entoal"eolar relationship

Cassi"e soft tissues pressures

Therefore, the o"erall form function relationship is stable, e"en though each of the indi"i indi"idua duall compone components nts may ha"e an abnorm abnormal al config configura uratio tion n or patter pattern n of acti"i acti"ity ty.. This This stability is demonstrated by the relati"e consistency e"ident in the o"erall skeletal and dento! al"eolar relationship during growth period, for example, though maturation changes occur, an indi"idual at age '> years generally resembles himself as he appeared at age 9 years. Most current orthodontic therapy, particularly practical in the Anited tates, is aimed at correcting of skeletal and dento!al"eolar mal!relationships with little or no attention paid to the accompanying accompanying abnormal functional functional patterns. #t is often assumed assumed by the clinician clinician that

>H

Retention and relapse in orthodontics these abnormal functional patterns will be corrected automatically if structural balance is attained. ;owe"er, in patients in whom such unilateral treatment is undertaken, the hard and soft tissues of the face often do not achie"e a state of balance, the result of which is a relapse of the skeletal and dento!al"eolar configurations toward their original relationships.

Treated skeletal and 1entoal"eolar

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Relationships

bnormal Muscle 5unction

Original nal skel keletal and dentoal"eo "eolar

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Relationship

Cassi"e soft tissue pressures

#n planning the ideal therapeutic regimen, the goals of treatment should include the achie"ement achie"ement of long!term long!term stability stability,, which can be obtained obtained only if the balanced balanced skeletal skeletal and dento!al"eolar configuration exists in harmony with associated musculature and other soft tissues after treatment.

Balanced skeletal configuration

;armonious Muscle function :O@= L T0RM TB#:#TQ

;armonious 1entoal"eolar Relationships

Cassi"e soft tissue pressures

#f this goal is achie"ed, relapse, as used in Orthodontics, can be limited primarily to alterations in tooth positions. Theoretically there should be no need to mechanically retain a stru struct ctur ural al rela relati tion onsh ship ip that that has has been been achi achie"e e"ed d conco concomi mita tant nt with with the the elim elimin inat atio ion n of compensatory muscle function. Mc @amara*s experiments on muscle adaptation following muscle muscle length lengtheni ening, ng, surgic surgical al detach detachmen mentt and surgi surgical cal re!att re!attachm achment ent are a conclud concluding ing e"idence of not ignoring the muscle factor in the stability of orthodontic surgery cases.

>>


>tabilit% and efficienc% of the $asticator% s%stem lteri ltering ng the form form and relati relations onship hip during during Orthodo Orthodonti nticc treatm treatment ent could could alter alter the delicate delicate balance between between the "arious "arious factors, which results in the form of the dental arches, and their relationship to one another. The stability of the result will depend on the efficiency of the masticatory system in the new relationship. The 1ental arch in man lies between the tongue and cheeks and lips. $hen teeth erupt into the oral ca"ity they come under the influence of these soft tissues and, therefore, it is commonly belie"ed, into a position of balance. There are two distinct "iews regarding the influence of the soft tissues on the teeth and the +aws. One was summed by Tomes /'>H62, who said, “The action of the lips and tongue is that which determines the position of the teeth”. The contrary point of "iew is put forth by cott /'(9H2 who said, “The arch form was determined prior to any muscular de"elopment and was independent of the functional acti"ity of the oral musculature”. #n order to consider the effect of the soft tissue en"ironment on the dental arches, the "arious factors, which make up the oral en"ironment, must be identified. #t would appear that e-uilibrium position of the teeth is the result of the influence of se"eral factors994 ! '2 The The chee cheeks ks and and the the lip lips. s. 2 The The tong tongue ue.. 62 The soft soft tissue, tissue, which suspend suspend the teeth in in the bone. bone. 72 The erupti eruption on of of the the teeth. teeth. 82 The morph morpholo ology gy of the the crowns crowns of the the teeth. teeth. 92 The forces forces from the muscle muscless of masticati mastication. on. H2 The The grow growth th of of the the +aws +aws.. The periodontal membrane, which differentiates as a result of the presence of the dental structures, has a function of maintaining the integrity of the dental arches by keeping teeth in contact with one another.

>(

Retention and relapse in orthodontics The cuspal interdigitation of the teeth is also important for transmitting the forces of the muscles of mastication to the teeth, as ngle puts it, “to gi"e one another the greatest support in all directions”. The muscles of mastication also work to pre"ent the disruption of the intact dental arch, and and studi studies es in "ari "ariou ouss group groupss of pati patient entss indi indica cate te that that bala balance nce and and harm harmony ony of the the musculature and the effort of patients with a malocclusion maintain the arch relationship. 0xperiments in adult animals indicate the adaptability of the system, which endea"ors to pro"ide an efficient masticatory system, e"en when the arch form is altered by mo"ing indi"idual teeth.

()


6eorgani(ation 6eorgani(ation of >upporting Tissues Tissues Bone Bone and and ad+a ad+ace cent nt tiss tissue uess must must be allo allowe wed d time time to reor reorga gani ni%e %e arou around nd newl newly y positioned teeth. The post L treatment reaction of the periodontal structures structures /fiber system2 has been demonstrated by experimental e"idence on human and partly on animal material. #t has been shown that a certain amount of contraction and re!arrangements of fibrous structures occurs in e"ery case. This contraction "aries according to the type and degree of tooth mo"ement carried out.  factor to be considered in this connection is the highly indi"idual reaction of the fibrous structures of the supporting tissues. There are "ariations between young and adult patient tissues, but there is more between the type of fibrous tissue obser"ed in "arious patients of the same age group. Iariations in tissue beha"ior are also apparent in practical orthodontics. #n some patients, the tooth tooth mo"eme mo"ement nt may be complet completed ed without without any apprec appreciab iable le degree degree of relaps relapse, e, i.e., i.e., without contraction of pre"iously stretched fibrous tissue. The periodontal tissues of these patients are more readily transformed. The contraction of displaced and stretched fibrous struct structure uress is less less pronoun pronounced ced in some some areas areas of the suppor supportin ting g tissu tissues es than than the others others.. =enerally, in such cases, there are two areas in which the fibrous tissue reaction is somewhat different. '2 The fibrous fibrous structures structures of the the newly formed formed bone, including including the principle principle fibers fibers of the periodontal ligament. 2 The supra!al"e supra!al"eolar olar and and trans!sept trans!septal al fibrous fibrous systems systems..

Post C treatment changes in e# Bone ;a%ers: 

The reaction changes following tooth mo"ement "ary according to how the tooth has been mo"ed. 5or example, there is no marked displacement of the fibrous structures of the new bone formed as a result of gradual migration of a tooth, or the fibrous structures of the new bone formed around an erupting tooth. s in the case of the erupting second premolar that is brought gradually into position following extraction of the first premolar. #n this case the fibrous structures of the bone will remain relaxed and re!arranged according to the new

('

Retention and relapse in orthodontics position of the tooth mo"ed. fter treatment the three teeth L canine, second premolar, and first molar will remain in contact and there will be little or no tendency to secondary migrat migration ion.. Thus, Thus, relaps relapsee of the teeth teeth approxim approximate ated d follow following ing extrac extractio tion n may be largel largely y a"oided by early treatment during tooth eruption and al"eolar bone growth. Gontrary to this, when fully erupted teeth ha"e been approximated after extraction, there is always a certain tendency to secondary change in tooth position. The cause of this relapse is contraction that occurs not only in the supra!al"eolar tissues, but also as a result of early re!arrangement of harpey*s fibers of the newly formed bundle bone as well as the principle fibers of the periodontal ligament. Anlike the supra al"eolar structures, howe"er, the fibrous tissues of the new bone and the periodontal ligament will be arranged following a fairly short retention period.

The /pical base: 

The circumferential lamellae of the bone and the supporting fibrous tissues are so arranged as to withstand any great tooth mo"ement in a labial or lingual direction. $hen mo"ed into imbalance, these structures tend to contract and relapse occurs. This reacti"e mo"ement of the teeth mo"ed becomes dominant particularly after expansion of the dental arches. #n this connection, the apical base concept has gi"en rise to a cardinal principle of orthodo orthodonti nticc philos philosoph ophy y, namely namely that that treatm treatment ent of malocc malocclus lusion ion must must not be based based on expansion if relapse is to be a"oided. The apical base concept is correct as a principle. ;owe"er, a detailed obser"ation of the beha"ior of the structures in"ol"ed may disclose that after retention there is less relapse tendency in the apical base area than in the structures of the marginal third of the root. Tor-ue of the root may be performed in either a labial or a lingual direction.  gradual tor-ue mo"ement and also tipping of the tooth may result in compensatory bone formation along the outer bone surface corresponding to the apical third of the tooth. #f the tor-ue or tipping mo"ement is carried out rapidly, the apical portion of the root may be mo"ed through the bone and partly outside the apical bone. #n both instances, the positional stability o f the tooth mo"ed is determined largely by whether the tooth is retained or not. #f the in"ol"ed tooth is retained for a period of approximately  to 6 months, there is relati"ely little relapse of the apical portion of the root. 0"en a root that has been mo"ed

(

Retention and relapse in orthodontics thro through ugh the the bone bone tends tends to rema remain in outs outsid idee the the bony bony area area.. s in a bodi bodily ly mo"em mo"ement ent,, rearrangement and calcification of the new bone spicules on the tension side will result in a fairly dense bone tissue, which initially resists any appreciable degree of relapse. The most persistent relapse tendency is caused by structures related to the marginal marginal third of the root. 5rom a practical standpoint it may thus be stated that only when retention is omitted does any appreciable relapse tendency exist in the bone ad+acent to the apical base area.

Post C treatment changes in the supra aleolar structures: 

The free gingi"al and trans!septal fibers, which some decades ago were termed the circular ligament, seem to ha"e a special function. They are more acti"e than other fibers in maintaining the tooth in proper positions. The free gingi"al fibers interlace with the supra! al"eolar soft tissues of the proximal teeth and thus form a continuous fibrous system. There are in addition, elastic and oxytalan fibers in the supra!al"eolar tissues. These elastic fibers will add to the contracti"e force of the fibrous system after displacement or stretch. The effect of this contraction is obser"ed on the tension side of the tooth, particularly in cases where the tooth is tipped or rotated. #f a tooth is tipped and not retained at all e"en surgical remo"al of the supra al"eolar tissue does not pre"ent some relapse from occurring. 5iber bundles of the middle and apical thirds of the root will then enter into action. ;yalini%ed areas may be obser"ed as a result of tipping of human teeth without subse-uent retention. #t is shown that most of the relapse occurred during the first 8 hours after the appliance had been remo"ed. #t is a fact that re!arrangement of the al"eolar bone and the principle fibers occur when the fixed appliances are left on the teeth for atleast two months. The supraal"eolar structures, howe"er, will not become rearranged until the tooth has regained its physiological e-uilibrium. Relapse caused by the trans!septal fibers is a result of their mode of attachment from cementum to soft tissue. $hen connecti"e tissue fibers under stress attach to soft tissue, there is apparently no mechanism for their rearrangement. $ith bone ser"ing as an attachment, re! adaptation is made possible.

(6

Retention and relapse in orthodontics Reitan68 demonstrated this on orthodontically rotated teeth. ;e compared the time re-uired for fibers in "arious areas of the root to reco"er from displacement. Reco"ery was considered complete when the fibers were perpendicular to the root surface.  period of >6 days was re-uired for re!arrangement in apical region. '7H days for the middle segment and no physiologic physiologic re! arrangement occurred occurred after 6 days retention retention in the marginal marginal areas. On the basis of these reports some authors ha"e said that the retainers should be only inhibitory in natu nature re and and ha"e ha"e no posi positi ti"e "e fixa fixati tion on to allo allow w for for the the natu natura rall func functi tion onin ing g of teet teeth. h. Oppenheim''9 argued that appliances should only be inhibitory and the repair of tissues around the teeth occurs much more rapidly if no fixed retaining appliance is used. ll these suggestions are based on the presumption that mature bone will assure greater stability for the teeth. Cresent day orthodontic concepts, howe"er, regard bone as being a plastic substance and consider tooth position. The placement of retenti"e appliances is then, an admission of inade-uate orthodontic correction correction or of a pre!determ pre!determined ined decision to place teeth in relati"ely relati"ely unstable unstable positions positions for esthetic reasons. $hether stability increases with prolonged retention is one of the most interesti interesting ng points points of discussion discussion in regard regard to retention retention planning, planning, and is the phase of stability stability about which we know least.

(7


The ;ong C Term >tabilit% of =rthognathic >urger% The The ad"e ad"ent nt of orth orthog ogna nath thic ic surg surger ery y has has gi"e gi"en n the the pract practic icin ing g orth orthodo odont ntis ist, t, in con+unc con+unctio tion n with with the oral oral surgeo surgeon, n, the abilit ability y to correc correctt skelet skeletal al deform deformit ities ies that that had pre"iously been camouflaged by orthodontics alone. Often these orthodontic treatment results were unsatisfactory since they re-uired se"ere dental compensations to accommodate the poor skeletal relationship. $ith the recent ad"ances in orthognathic surgery, howe"er, it has become become possib possible le for the surgeo surgeon n to address address many many deform deformiti ities es that that were were pre"io pre"iousl usly y untreatable. :ong L term stability following these surgical procedures has been of ma+or concern since the early days of orthognathic surgery because the final long! term result, both aesthetic and functional, is directly related to the post surgical stability. The early studies of mandibular ad"ancementH>, H( and maxillary :e5ort # osteotomies re"ealed that mandibular relapse tended to be greater than maxillary relapse. Therefore, many studies of stability in the '(H)s concentrated on mandibular ad"ancements utili%ing follow! up cephal cephalome ometri tricc radiog radiograp raphs hs in an attemp attemptt to identi identify fy the relaps relapsee patter patterns ns and their their etiology.>) These studies, as well as studies in the early '(>)s by chendel and 0pker >' and by :ake et. al> demonstrated that relapse primarily occurred during intermaxillary fixation and immediately following the release of fixation, so that the long L term results were not alway alwayss predic predictab table. le. ome ome studie studiess of the relaps relapsee patter patterns ns follow following ing maxill maxillary ary :e5ort :e5ort # osteotomies were also reported during this period>6 and demonstrated greater o"erall stability than than seen seen for mandib mandibula ularr ad"ance ad"ancemen ments, ts, but documen documented ted instan instances ces of instab instabili ility ty for indi"idual patients. #n the late '(H)s further ad"ances in surgical techni-ues allowed surgical procedures to be performed simultaneously in both the maxilla and the mandible. 0arly studies of double +aw surgery reported lesser amounts of mandibular relapse and greater maxillary relapse than for single +aw procedures performed independently.>7 @umerous theories regarding the primary etiologic causes of relapse ha"e been ad"anced and studied. These include4! '2 stretching stretching of the muscles muscles of mastic mastication ation and the suprahy suprahyoid oid musculature, musculature,H( 2 condylar condylar distracti distraction on during during surgery surgery,,>',>8 62 counterclockw counterclockwise ise rotation rotation of the mandible, mandible,H> and

(8

Retention and relapse in orthodontics 72 rotational rotational positio position n changes between between the the proximal proximal and distal distal segments. segments.> imultaneously, "arious surgical techni-ues and postsurgical therapies were ad"ocated in order to minimi%e relapse, and numerous studies were conducted to e"aluate their results. These techni-ue included suprahyoid myotomies>9 and cer"ical collars utili%ed to reduce muscle tension following surgery. surgery.H>, H(, >7 @umerous fixation techni-ues ha"e been ad"ocated to reduce relapse post surgically. surgically. These ha"e included4 ! '2 upper and lower lower border wiring wiring of the mandibl mandible, e,>H 2 teinm teinmann ann pins pins to stabil stabili%e i%e the the maxilla maxilla,, >> 62 skel skelet etal al wire wire fixa fixati tion on,,>' and 72 rigi rigid d fixa fixati tion on..>( Recently studies in"ol"ing isolated mandibular ad"ancements() and maxillary :e5ort # procedures(' ha"e indicated a strong potential for reduced relapse using the two most popular of these alternate techni-ues4 skeletal wire fixation and rigid fixation. lthough numerous papers ha"e been published e"aluating the stability of the ma+or surgi surgical cal procedu procedures res /i.e. /i.e. sagitt sagittal al split, split, :e5ort :e5ort # osteot osteotomy omy2, 2, no clear clear pictur picturee has as yet emerged as to their o"erall long!term stability. Most of the studies on stability ha"e concentrated their e"aluations on the short term /i.e., the first six to eight weeks2 postsurgical period. 5ew studies ha"e e"aluated relapse out to one!year post surgery. mong those who ha"e examined stability at one!year post surgery, many ha"e used small sample si%es with heterogeneous groups, often including patients with clefts or other including patients with clefts or other congenital deformities. #n addition, the fact that different surgical procedures were fre-uently carried out on patients in the same sample has further reduced our ability to e"aluate long L term result.

(9


$andibular /dancement:  /) 0ire fi7ation:

Asing the well L conducted :ake /'(>'2 > study as a baseline, one sees that there was '.9 mm of posterior relapse during fixation and little change from eight weeks out to one year. Kohn in '(H>, with a larger mandibular ad"ancement while seeing a similar amount of short L term relapse, also encountered a considerable amount of long ! term relapse. The total relapse relapse seen o"er one year in these two studies /7N and 6>N2 is reflected reflected of many studies carried out during this period that utili%ed only interdental wiring for fixation. s reflected by changes seen in the andor study /'(>72 (, when skeletal fixation using circum%ygomatic and circumandibular wires was utili%ed the amount of relapse seen was considerably smaller. Recently, $atske(6 has noted a different pattern of changes, with the initial posterior relapse being almost counterbalanced by a long ! term forward mo"ement, thus producing only a small /9N2 net relapse. $hether this pattern will be found in other contemporary studies or is due to some specific feature of the surgical techni-ue remains to be determined. uthor

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Retention and relapse in orthodontics $hen comparing the stability of mandibular ad"ancement with rigid fixation to that of wire fixation some differences are immediately apparent.(6, (7!(9 Of prime importance is the finding that the net changes for the rigid studies are in an anterior direction rather than in the posterior direction pre"iously noted for the wire fixation samples. The magnitude of the relapse is less than half of that seen with the earlier interdental wire fixation studies, but it is only moderately better than the contemporary co ntemporary skeletal wire fixation studies. uthor

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;abular ;abular and graphical representations representations of the the changes during and after mandibular advancement with rigid #1ation as measured at B-point

;owe ;owe"e "err, when when the the inci incide denc ncee of rela relaps psee in $atske tske**s matc matche hed d samp sample less of contemporary skeletal wire and rigid fixation groups are compared some interesting findings emerge. 1uring the first 9 weeks following surgery approximately 7)N of the wire fixation sample demonstrated between  and 7 mm of posterior relapse. n additional 8N showed greater than 7 mm of posterior relapse, whereas a similar number underwent !7 mm of anteri anterior or relaps relapse. e. Thus, Thus, approxi approximat mately ely 8)N of the wire wire fixati fixation on sample sample demons demonstra trated ted instability during fixation, with the preponderance of change being in the posterior direction. #n contrast, only 8N of the rigid sample demonstrated significant relapse, with most of the changes being between  and 7 mm in an anterior direction.

;he incidence of relapse relapse in 'ats%e> 'ats%e>s s rigid and

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Retention and relapse in orthodontics wire #1ation samples over the #rst si1 wee%s post-surger

5rom 9 weeks to ' year somewhat different findings were noted. bout 7)N of the wire fixation sample now demonstrated a tendency to come forward whereas in the rigid sample 8N of the cases continued to come forward and )N were mo"ing posteriorly. posteriorly.

;he incidence incidence of relapse relapse in 'ats%e 'ats%e>s >s rigid and wire #1ation samples from si1 wee%s to one ear post-surger

The past past decade decade has seen a conside considerab rable le impro" impro"eme ement nt in long long L term term stabil stability ity following mandibular ad"ancement as the transition from interdental to skeletal wiring for postsurgical fixation occurred. The introduction of rigid fixation, while ha"ing hal"ed the incidence of relapse, has offered only a moderate impro"ement o"er current skeletal fixation techni techni-ues -ues in those those cases cases showin showing g postsu postsurgi rgical cal instab instabil ility ity.. Of prime prime impor importan tance ce to the clinician clinician is the fact that the mandibular mandibular ad"ancement ad"ancement cases with rigid fixation that undergo relapse fre-uently do so in an anterior direction rather than in the posterior direction usually seen with wire fixation. Gare should therefore be taken with the long L term use of Glass ## elastics in rigid fixation cases if a high relapse potential is suspected.

$andibular >etback: 

((

Retention and relapse in orthodontics The "ast "ast ma+ori ma+ority ty of studie studiess e"alua e"aluatin ting g mandib mandibular ular setbac setbacks ks ha"e utili% utili%ed ed wire wire fixation. Kobayashi(H and Rosen-uist(>, with moderate setbacks of 8.7 and >.7 mm, noted '>N and N, respecti"ely, of anterior relapse after one year. 5orward mo"ement was seen during both the short L and long ! term periods and totaled between '. and '.8 mm. #n contrast, strand and Ii+ayaragha"an reported considerably larger mean setbacks and noted anterior relapse of .7 and 6.' mm, respecti"ely, after one year. This greater absolute amount of relapse translated into )N and 6'N net change for the two studies and is reflecti"e of many studies suggesting that larger setbacks are more likely to undergo greater postsurgical changes. uthor

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Recently Chillips et al compared skeletal stability following sagittal split and transoral "ertical ramus osteotomies. Their findings indicated different patterns of relapse< with the sagittal split coming forward post!surgery whereas the transoral "ertical ramus osteotomies showed continued continued posterior change. lso, lso, the relapse seen in the sagittal sagittal splits splits /6>N of the surgical change2 was considerably greater than that seen for the transoral "ertical ramus osteotomies /6N of the surgical change2. Anfortunately, comparison comparison with setbacks carried out with rigid fixation is not possible due to the lack of studies of this type. Of note, howe"er, is the study by 5ranco et al,

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Retention and relapse in orthodontics which, with a sample of '7 patients, patients, the researchers researchers showed an a"erage of .' mm, or 76N, anterior relapse following a mean of 7.( mm of surgical setback. lthough it has recei"ed less publicity than mandibular ad"ancements, the relapse of mandibular setbacks with wire fixation appears to be similar both in incidence and amount. :arger setbacks in particular seem to be prone to greater relapse, and as yet there are insufficient data on the effects of rigid fixation to tell if it will ha"e a significant effect. The initial findings of different relapse patterns between saggital splits and transoral "ertical ramus ramus osteot osteotomi omies es need need furthe furtherr in"est in"estiga igati tion on because because they they ha"e ha"e consid considera erable ble clinic clinical al implications, particularly in cases in which future mandibular growth g rowth is a possibility.

ince the early days of orthognathic surgery it has been hypothesi%ed that the greater the amount of mandibular surgical mo"ement, the greater the relapse. lthough reported numerous times in case studies and generally accepted to be true, little scientific data are a"ailable to confirm this concept. :ake> and Ian ickels(9 as well as many other authors ha"e felt that ad"ancements greater than ') mm showed less stability and that factor such as a high mandibular plane angle and poor proximal segment control during surgery were significant predisposing factors to increased mandibular instability. instability. #n her e"aluation of the two techni-ues for mandibular setback, Chillips noted that the sagittal split group showed a somewhat higher correlation between the magnitude of surgical change and relapse than did the transoral "ertical ramus osteotomies group. #n general, considerably more in"estigation of these interactions appears to be necessary to allow for the identi identific ficati ation on and possib possible le future future control control of factor factorss likely likely to precip precipita itate te mandib mandibula ular r instability.

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Retention and relapse in orthodontics superior superior settling settling following surgery. surgery. $hereas $hereas some studies suggest minimal long L term change /=reebe )N, Croffit HN'))2, others reflect a significant degree of relapse /chendel 'N>6, Bishara 6)N')'2, although the actual amounts are -uite small ! often around only ' mm.

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$hen single "ersus multiple segment maxillary impactions with wire fixation were compared by Croffit')), little little difference difference was found between between their long L term stability stability.. Both groups showed continued superior settling in the short term followed by long L term inferior mo"emen mo"ement, t, result resulting ing in a net of less less than than 'J mm of long!t long!term erm superior superior relapse. relapse. This produced o"erall relapse percentages of (N for the one L piece maxillas and ''N for the segmental procedures.>', ')'

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Retention and relapse in orthodontics $hen $hen maxil maxillary lary impacti impaction on is carrie carried d out as part part of a simult simultaneo aneous us double double +aw procedure a different pattern of relapse is found than that pre"iously seen in isolated '), ')6 maxillary impactions. #n the wire fixation studies >7, '), there was a small but consistent

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tabilit% of =rthodontic Treatment C =cclusion as a ,ause of Temporomandibular isorders The orthodontic concept of occlusion is bound by the same physiologic parameters and facts that bind all segments of dentistry dentistry.. n important important long L term ob+ecti"e ob+ecti"e of orthodontic orthodontic treatment is to pro"ide an oral en"ironment, which will promote health of the periodontal tissues, neuromuscular system, and temporomandibular +oints. tability of occlusion may be defined in either structural or functional terms. tructural stability is the criterion used in assess assessing ing the presen presence ce or absenc absencee of post!o post!orth rthodon odontic tic relaps relapse. e. The absenc absencee of post post L

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Retention and relapse in orthodontics treatment relapse is an indication of structural stability, both occlusal and skeletal. ndrews*7 ix Keys of Occlusion are examples examples of structura structurall criteria. criteria. nother nother concept of stability stability,, fre-uently used in dentistry, is that of good intercuspation, with multiple tooth contacts, so that there are no “slides in centric”. This is a statement of functional stability. 5unctional stability is a criterion used to assess a potential or presumed cause of dysfunction due to a neuromu neuromuscul scular ar maladap maladaptat tation ion.. =natho =natholog logica ically lly orient oriented ed orthodo orthodonti ntists sts emphas emphasi%e i%e the importance importance of functional functional stability stability in pre"enting pre"enting maladaptati maladaptations ons to occlusal occlusal interferenc interferences. es. lthough orthodontists ha"e attempted to treat cases to an ideal static dental relation, it is now genera generally lly recogn recogni%e i%ed d that that orthodo orthodonti nticc treatm treatment ent should should also also attemp attemptt to achie"e achie"e a func functtiona ionall

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temporomandibular +oints. The criteria for such an ideal functional occlusion, according to most current concepts, ha"e been described. #t has been stated that failure to produce occlusal harmony after orthodontic treatment, especially failure to eliminate centric prematurities and nonwork nonworking ing contact contactss on mandib mandibular ular excurs excursion ions, s, may subsesubse-uent uently ly contrib contribute ute to TM3 disorders. ;owe"er, no long L term follow L up of orthodontically treated patients has been carried out to e"aluate the status of TM3 function and its relationship to the functional occlusi occlusion. on. lso, lso, the idea idea that that untrea untreated ted maloccl malocclusi usions ons ha"e ha"e a marked marked potent potential ial for the de"elopment of TM3 problems has not been ade-uately in"estigated. @ow, two -uestions arise in one*s mind that4 ! '2 Gan occlusal occlusal interferenc interferences es cause relapse relapse of dental dental and J or skeletal skeletal relationshi relationships& ps& and 2 Gan occlusal occlusal interfer interferences ences cause cause temporomandi temporomandibular bular disorder disorders& s& ,an occlusal interferences cause relapse of dental and 5 or skeletal relationships

Respons Responses es to occlusa occlusall interf interfere erence ncess take take se"era se"erall forms forms.. #n the absenc absencee of a reflex reflex response the interfering tooth may be mo"ed out of the offending position. 0"idence in supp suppor ortt of this this asse assert rtio ion n come comess from from an unpu unpubl blis ishe hed d in"es in"esti tiga gati tion on exami examini ning ng the the conse-uences of a mild working L side interference carried out in the laboratory of Crofessor ;ans =raf in Berne, wit%erland. The hypothesis to be tested was that o"er a period of se"eral weeks hypernormal biting forces on a mild working L side interference would elicit a reflex a"oidance of the interference. The study entailed building up the buccal inclines of the

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Retention and relapse in orthodontics ling lingua uall cusp cuspss of a lowe lowerr right right first first mola molarr crow crown n that that had had been been plac placed ed on a postc postcor oree preparation. The sub+ect was e"aluated before /' day and immediately prior to2 insertion of the interference, 9 hours and , (, and '9 days following placement, and 6) days after remo"al of the interference. Gonclusions drawn from this in"estigation on this patient were that '2 The mild mild working working L side interferen interference ce was not reflexly reflexly a"oided. a"oided. 2 The interfe interferen rence ce did not gi"e rise to any signs signs or symptom symptomss of temporom temporomandi andibula bular r disorder. 62 The tooth tooth became became mobile mobile and subse-uently subse-uently intruded. intruded. 0arlier studies by chaerer, tallard, and ander, '') using switches recording intercuspal and interference positions, had established that mild working L side interferences were not reflexly a"oided L that is, closure into intercuspal position was guided solely by the occlusal inclines. The adapti"e response to mild working L side interferences would appear to be by tooth mo"ement. /2

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noth nother er pass passi" i"ee adapt adaptat atio ion n that that coul could d acco account unt for for reduc reducti tion on of mild mild occl occlus usal al interferences is wear of the tooth in sub+ects eating abrasi"e diets. Ganine!guided occlusions grad gradua uall lly y beco become me “gro “group up func functi tion on”” occl occlus usio ions ns due to wear wear of the the maxi maxill llar ary y cani canine ne.. 5unctional abrasion /in contrast to parafunctional abrasion2, while considered normal by anthropologists and paleontologists and crucial to hypothesis of +aw function in ancient man, is considered pathological by gnathologists. 5unctional wear in another possible adaptation to occlusal interferences.

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Retention and relapse in orthodontics molars, with e1posure of the pulp in the molar in a s%ull of a 8ubian of the earl dnastic period. 'ear of teeth is common in s%eletal remains of persons living along the 8ile.

#n contrast to these passi"e forms of adaptation to occlusal interferences are the a cti"e or reflex responses. Ander certain circumstances occlusal interferences are a"oided. uch an acti"e response to occlusal interferences resulting in “occlusal instability” is used to explain functional functional malocclusions malocclusions L for example, functional posterior posterior and anterior anterior cross bites. bites. #t has been claimed that these functional malocclusions will become skeletal malocclusions and theref therefore ore should should be treate treated d immedi immediate ately ly.. 0"iden 0"idence ce for a learne learned d respon response se to occlusa occlusall interferences was first clearly demonstrated by chaerer, tallard, and ander.'') Bridges were constructed with switches in bridge pontics that would signal tooth contact in the intercuspal position and on balancing L side interferences during mastication. 5ollowing contact with the balancing interference, muscle acti"ity stopped for about ) ms /“silent period”2 followed by asymmetric +aw muscle acti"ity, acti"ity, presumably leading to a"oidance of the interference. 7)N of the balancing L side interferences showed silent periods L that is, nearly half of the closures following contact on a balancing L side interference were reflex modulated as a conse-uence of occlusal feedback. On initial contact with the interference, the le"ator muscles fell silent and then shifted the mandible laterally so as to a"oid further contact< the occlusal guidance was acti"e. The response to initial contact is unlearned or unconditioned. 5ollowing multiple contacts on the interference, the offending contact may be a"oided through conditioning. There is a clinical perception that repeated a"oidance of interference may lead to a skeletal response in growing indi"iduals. Occlusal interferences may also gi"e rise to acti"ely mediated response. $hen reflex adaptat adaptation ionss occur occur,, the mandib mandible le shifts shifts to a"oid a"oid the interf interfere erence nce/s2 /s2 produc producing ing condyl condylar ar displacement/s2. This acti"e response may lead to condylar cartilage proliferation and mandibular growth in growing animals.

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Retention and relapse in orthodontics ;ere one sees the interaction between structural and functional instability. #n the absence of neuromuscular adaptation, structural adaptations to occlusal interferences occur in the dentition4 $ith $ith neuromuscular adaptation structural adaptations occur in the skeleton. Gonclusions that may be drawn from these experiments ex periments are that4 '2 Occlusa Occlusall interf interfere erence ncess may result result in passi" passi"ee adaptat adaptation ion such as tooth tooth mo"ement mo"ement or tooth wear, and 2 Occl Occlus usal al inter nterfe ferrence encess may resul esultt in acti acti"e "e adap adapttatio ations ns!! that that is, cond condy ylar lar displacement/s2, with the potential for condylar and fossa remodeling in the growing indi"idual. @ow, the answer to the -uestion L Gan occlusal interferences cause relapse of dental and J or skeletal relationships is is yes L occlusal interferences ha"e the potential to cause relapse of yes L dental relationships and potentially alter skeletal de"elopment.

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Temporom Temporomandibul andibular ar disorder disorder.. tatements tatements in the merican merican 1ental 1ental ssociat ssociation ion Cresident* Cresident*ss report''' and the Gonsensus tatement of the merican cademy of Cediatric 1entistry'' trongly de L emphasi%e and occlusal etiology. @umerous studies /e.g., 1roukas, :indee, and Garl Garlss sson on22 ha"e ha"e docu docum mente ented d as high high a pre" pre"al alen ence ce of occl occlus usal al inte interf rfer eren ence cess in the the asymptomatic population as in patients suffering from Temporomandibular Temporomandibular disorder. This has led some people to belie"e that occlusal factors do not play a role, or play only a minor role, in the causation of Temporomandibular disorder. $hereas absent or low correlations between occlusal factors and signs and symptoms of dysfun dysfuncti ction on indica indicate te a minor minor role role in the etiolo etiology gy of Tempor emporoma omandi ndibul bular ar disord disorder er,, weaknesses in most of the epidemiological studies need to be recogni%ed and corrected in future studies. 0"en though multiple etiologies for Temporomandibular disorder are now uni"ersally acknowledged, most studies ha"e not attempted to segregate patients or sub+ects so that those of possible occlusal etiology are not greatly outnumbered by those of traumatic and parafunctional etiology.

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Retention and relapse in orthodontics #n response response to the -uestion, -uestion, Gan occlusal occlusal interferen interferences ces cause temporomandibul temporomandibular ar disord disorders ers&& The answer answer is yes yes for 8)N of the sub+ects in which occlusal interferences are artifi artificia cially lly create created. d.  logical logical extens extension ion of this this -uesti -uestion on regard regarding ing etiolo etiology gy is that that of orthodo orthodonti ntics cs causing causing Tempor emporoma omandi ndibul bular ar disord disorders ers.. Costtre Costtreatm atment ent,,

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interferences ha"e been implicated as a cause by Roth, ''6 as ha"e lingually tor-ued maxillary incisor crowns by Berry and $atkinson. Maxillary bicuspid extractions /supposedly leading to excessi"e dorsal positioning of the Mandibular conse-uent to maxillary incisor retraction2 ha"e been claimed as a cause of Temporomandibular disorder. 5our 0uropean and three @orth merican''7,

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Temporomandibular disorders is the same in patients ' to ') years following orthodontic treatment as in the general population. The study of 1orph, olow, and Garlsen on the pre"alence of orthodontic treatment in a Temporomandibular Temporomandibular disorder clinical sample found more orthodontic treatment among Temporomandibular disorder cases than in the general population. This obser"ation agrees with the less well L controlled studies of 5ranks and Berry Berry and $atkinso tkinson. n. The finding finding may be due to the probab probabili ility ty that that patien patients ts seekin seeking g Temporomandibular disorder treatment are more likely to ha"e sought orthodontic treatment. 5ran 5rank* k*ss stat statem emen entt that that “the “the ma+o ma+ori rity ty Dof Dof the the pati patien ents tsEE regul regular arly ly "isi "isite ted d thei theirr dent dental al practitioner” supports this hypothesis. The study of 3anson and ;asund found fewer signs and symptoms of Temporomandibular disorder in their non!extraction group compared to their extraction group. necdotal claims of nonextraction patients being at lesser risk ha"e been made in the literature. Both the study of =old and that of 1ahl et al document fewer self L reported signs of Temporomandibular Temporomandibular disorder in treated compared to untreated sub+ects and no difference in clinically recorded signs and symptoms. =old speculated that untreated sub+ects o"er reported symptoms in the hopes of obtaining orthodontic treatment. $hile the collecti"e data suggests that pre"alence is the same in treatment samples as in nontreatment samples, the data do not rule out the possibility that these totals are the algebraic sum of some some sub+ sub+ec ects ts who who are are de"el de"elopi oping ng Tempor mporom oman andib dibul ular ar diso disord rder er and some some who who are are reco"ering form Temporomandibular Temporomandibular disorder.

''6


Incidence of T$ H%pothetical) /0pidemiological tudies J :ongitudinal2

$orse $orse

Total Total

=eneral Copulation

Orthodontic Copulation

0pidemiological studies ha"e shown the pre"alence of Temporomandibular disorder to be similar in patients who ha"e recei"ed orthodontic treatment compared to the general population. $ere $ere these sub+ects to followed longitudinally, longitudinally, it is postulated that the totals will be

made

up

of

sub+ects

de"eloping

symptoms

and

sub+ects

reco"ering

from

Temporomandibular disorder. The proportions of those getting worse and those getting better need not be same for both treatment and control samples. s in the the gene generral popu popullatio ation, n, some ome pat patients ents can can be expe expect cted ed to de"e de"ellop Temporo porom mandi andibu bula larr

diso disorrder ders.

$hil hile

ort orthodo hodont ntic ic

trea treatm tmen entt

may

prec preciipit pitate ate

Temporomandibular disorders, it is important to remember that other factors may predispose the the pati patien entt to Tempor mporom oman andib dibul ular ar diso disord rder er,, wher wherea eass othe otherr fact factor orss can can perp perpet etua uate te Temporomandibular disorder. #n order to clearly identify orthodontic treatment as a cause of Temporomandibular disorder it will be necessary to follow orthodontic cases prospecti"ely. The known cyclic pattern of Temporomandibular disorders is a complication also in need of control control.. Garefu Garefull monito monitorin ring g of trauma trauma and parafu parafunct nction ion as initia initiator torss during during and after after treatment will also be necessary.

,oncept of oercorrection Orthodontic treatment begins with the teeth in a malaligned occlusion, most often under abnormal function within disproportionate skeletal structures. Treatment proceeds to alig align n the the teet teeth h and and norma normali li%e %e the the funct functio ion n with within in the the limi limits ts allo allowe wed d by the the skel skelet etal al framework. Bony ad+ustments are occurring in the distant basic supporting structures, as well

''7

Retention and relapse in orthodontics as the local remodeling occurring around the indi"idual teeth. #n unlocking the malocclusion and establ establish ishing ing a more more normal normal function function,, it is necessary necessary for the clinic clinician ian not only to appreci appreciate ate the changes changes necessary necessary to bring bring the teeth teeth into into a proper properly ly aligned aligned functi functiona onall occlusion, but to anticipate changes that follow when all appliances are remo"ed and the post L treatment ad+ustments begin to occur. These ad+ustments and subtle changes cha nges will continue under under the the dynam dynamic icss of funct functio ion. n. #n order order to help help o"er o"erco come me the the tend tenden ency cy for for rela relaps pse, e, pro"isions for the post!treatment rebound as well as post L treatment growth changes chan ges need to be appreciated and planned for. There are certain cases where under treatment may be need ed in light of special growth or deformity problems. There are 7 areas suggested where the conce concept pt of o"er o"er trea treatm tmen entt may may help help comp compen ensa sate te for for the the anti antici cipa pate ted d post post L trea treatm tment ent ad+ustments.97 1) To oercome muscle forces against the tooth surfaces:  The muscular influence of the

tongue, lips and cheek against the surfaces of the teeth often re-uire o"er treatment to compensate for the post L treatment changes, that are a result of the continued influence of this musculature as it “learns” to support the new occlusion. $hen the narrow, collapsed upper arch is being expanded out of crossbite, o"ertreatment is necessary considering the relapse that may occur across the palate by the influence of the buccal musculature. O"er expansion is also needed to encourage the tongue to ele"ate and function in support of the dental arches in their new occlusion. n anterior open bite needs to be o"er!closed whene"er possible to anticipate the rebound rebound effect effect of abnorm abnormal al tongue tongue functi function, on, and the excessi excessi"e "e lower lower face face height height that that increases in the growth patterns of the extreme "ertical facial types. This excessi"e lower face height has the effect of encouraging the open bite tendency. O"er L treatment of the incisor incisor o"er+et back to a proper inter!inci inter!incisal sal angle is critical critical in cases where lip sucking has influenced the protrusion of the upper incisors and retracted the anterior portion of the lower arch, arch, and where where short short upper upper lip, lip, mental mentalis is habits habits,, or sublab sublabial ial contra contracti ction on continu continuee to influence the position and stability of the incisors. 2)! 6oot moements moements needed needed for >tabilit >tabilit%: %:  O"ertreatment of the tooth mo"ements in

locating the roots beyond the ideal in a position of o"ertreatment anticipates rebound change in "arious areas. #ncisor deep o"erbite treatment benefits in its stability by o"erintrusion and

''8

Retention and relapse in orthodontics o"ertor-uing. Caralleling the roots of the teeth ad+acent to extraction sites is important to the stability of space closure. Gompressed tissue and fibers re-uire time to reorgani%e to the new alignment. e"ere rotation, where periodontal ligaments exhibit elastic action that can ha"e prolonged post L treatment influence, needs o"er L rotation of o f the roots to help compensate for the relapse effect. Reorgani%ation of the fibers often re-uires extended time, unless surgery is also used to assist or support the stability. 3) To oercome orthopedic rebound:  $here hea"y forces ha"e produced orthopedic

changes, the basic supporting structures are sub+ected to rebound as these hea"y restricti"e forces are lessened or eliminated. These structures ad+ust as they are allowed to come under the influence of normal growth and function in the new en"ironment. These may still persist functional influences that compounded this original malocclusion. e"ere con"exity in the extreme "ertical facial types has additi"e effects, which seem to re-uire more o"ertreatment and concern for stability of results. Mandibular rotation or bite opening usually occurs in orthopedic correction by the extrusi"e action of the posterior teeth. #n Glass ## treatment, the rebound effect, which closes the bite and rotates rotates the chin forward, will help in the Glass ## correction correction and, therefore, therefore, this rebounding is beneficial. #n Glass ### treatment, forward rotation of the chin and closure of the mandible would compound the Glass ### problem and make it worse. ome rebound ad+ustments can be beneficial, but most tend to complicate or return to the original problem. Therefore, o"ertreatment is in anticipation of these post!treatment ad+ustments. 4) To allo# >etting in 6etention:  O"ertreatment of the indi"idual teeth within the arches

allo allows ws them them to “set “settl tle” e” into into a func functi tion onin ing g occl occlus usio ion. n. The The conce concept pt of rete retent ntio ion n at the the completion of acti"e treatment or debanding is not to hold or retain that which has been achie"ed, but to allow the teeth to settle back into occlusion from a point of o"ertreatment. Retainers then are considered acti"e appliances and are ad+usted to allow this settling action to take place, rather than to +ust hold or maintain the status -uo. This not only anticipates the expected rebound that will occur because teeth ha"e been mo"ed, but encourages it by allowing them the freedom of mo"ement back into their desired functioning position. #t would be almost impossible to prescribe the exact delicate location and function of each incline, while this concept of guided ad+ustment anticipates it by o"ertreatment.

''9

Retention and relapse in orthodontics O"er treatment of the typical Glass ## correction begins with the molars by o"er treating them into a “super class #” through distal rotation of the upper first molar behind an uprighted distally rotated lower molar. O"er!treatment proceeds along the buccal occlusion where the upper bicuspids and cuspids are distal to their opponents in the lower arch. The incisor o"er+ o"er+et et and and o"er o"erbi bite te are are o"ert o"ertre reat ated ed by intr intrus usio ion n of whic whiche he"er "er arch arch is o"er o"er erupt erupted. ed. O"ertor-uing of the upper incisors is necessary in those deep o"erbite cases where function would allow the deep bite to return.

Post Treatment >tabilit% Cost treatment stability can be achie"ed either by fixed or remo"able retainers gi"en o"er a considerable period of time or by positioning the teeth in harmonious relationship with their surrounding.

''H

Retention and relapse in orthodontics The fre-uency with which lower retainers are used after treatment to pre"ent lower incisor or cuspid collapse suggests there is little understanding of how to a"oid these posttreatment e"ents. ;owe"er, se"eral steps can be taken during fixed appliance treatment to eliminate the need for retention in the lower dentition. ccording to the study carried out by $illiams R ''H in which for the patients all the lower retention was eliminated and constant obser"ations were made to see what had to be done to create post!treatment stability, especially in the lower incisors. ix treatment keys ha"e emerged as essential if lower retention is to be eliminated.
The incisor edge of the lower incisor should be placed on the !C line or ' mm in front of it. This is the optimum position for the lower incisor stability. stability. #t also creates optimum balance of soft tissues in the lower third of the face for all the "ariations in apical base differences within the normal range.

;o ;o achieve stabilit and and soft tissue tissue balance in the lower third of the face, optimum position of lower incisal edge is on or + mm in front of A-5 line.

To achie"e stability and soft tissue balance in the lower third of the face, optimum position of lower incisor edge is on or ' mm in front of !C line.

''>


A. Moving lower incisor bac% mm to A-5 line provided stabilit without lower retention and improved facial harmon. B. Dower incisor was moved forward *mm to produce facial harmon. Because it moved onl to A-5 line, the incisor remained stable and no lower retention was needed.

pplian ppliance ce control control is re-uir re-uired ed to achie"e achie"e optima optimall posit position ion of the lower lower inciso incisor r consistently at the end of treatment. Coint  on the upper end of the !C line can be retracted. Coint C, at the lower end, will mo"e forward or not depending on mandibular growth. $ith experience, the clinician will know how each end of this line changes, which procedures will place the lower incisor ' mm in front of the line, whether extractions are necessary, and which teeth should be extracted. #f the lower incisor is ad"anced too far beyond the ! C line, relapse and crowding will will occur occur.. :ower :ower inciso incisors rs that that are o"erly o"erly procli proclined ned in treatm treatment ent!! beyond beyond one standa standard rd de"iation L can only be maintained in such an untenable position with a fixed retainer. $hen the retainer is remo"ed, the incisors will mo"e lingually and become crowded.

>econd ?e%: 

The The lowe lowerr inci inciso sorr apice apicess shou should ld be spre spread ad dist distal ally ly to the the crow crowns ns more more than than is generally considered appropriate, and the apices of the lower lateral incisors must be spread more than those of the central incisors. ''(


Convergent Dower Incisor roots before being spread distall for stabilit .

oot apices in tpicall convergent position !top". oot apices insu?cientl spread to assure stabilit without retention !middle". oot apices su?cientl spread so that, if other treatment %es are attained, stabilit of lower incisors without retention can be e1pected !bottom".

The Begg techni-ue is geared to achie"e the necessary progressi"e spreading, but none of the current straight wire systems pro"ides ade-uate lower incisor slot angulations to bring about ab out sufficient progressi"e spreading of lower incisor apices. $hen the lower incisor roots are left con"ergent, or e"en parallel, the crowns tend to bunch up and a fixed lower retainer is usually needed to pre"ent post! treatment relapse.

')

Retention and relapse in orthodontics Third ?e%: 

The apex of the lower cuspid should be positioned distal to the crown. The occlusal plane, rather than the mandibular plane, should be used as a positioning guide. Ase of the mandibular plane might indicate that the apex is not sufficiently distal to the crown, when in fact it is if the occlusal plane is used. uch a circumstance could occur when there are highly di"ergent occlusal and mandibular planes in a steep mandibular plane angle case.

Ape1 of lower cuspid positioned distal to crown for protection of lower incisor stabilit after treatment.

This angulation of the lower cuspid is important in creating post L treatment incisor stability because it reduces the tendency of the cuspid crown to tip forward into the incisor area. #f this happens, the lower incisors crowd up, e"en if their roots are spread and the incisal edges are on the !C line or ' mm in front of it. 1istal inclination of the lower cuspid should be a standard treatment ob+ecti"e and is easily accomplished with the Begg or any straight straight wire techni-ue. techni-ue. traight traight wire systems systems agree within within 7!9) of inclination of the lower cuspids to the occlusal plane.

ll four lower incisor apices must be in the same labiolingual plane. preading the apices of the lower incisor roots distally causes a strong reciprocal tenden cy for the crowns to mo"e mesially. Moreo"er, as the roots are spread, the contact areas between the incisor ''

Retention and relapse in orthodontics crowns mo"e upward toward the anatomical contact points, which are small, rounded, and near the incisal edge. Because of the strong mesial pressure on the crowns during the root spreadi spreading ng proces process, s, there there is a tendenc tendency y for these contac contactt points points to displa displace ce each other labiolingually. labiolingually. This results in a re"erse mo"ement of the apices linguolabially.

A. Dower incisor apices well aligned in same labiolingual plane. If other treatment %es are attained stabilit of lower incisors without retention can be e1pected. B. Crowns aligned but lower incisor apices not aligned in same labiolingual plane. nless this is corrected, there is little li%elihood of lower incisor stabilit.

The displacement forces are considerably augmented by the increasing width of the lower incisor crown toward the incisal edge and contact point. This means that pro"ision for the additional space must be made during the spreading process. Otherwise, labiolingual apical displacement of the lower incisors will tend to occur, and the degree to which it occurs will affect lower incisor posttreatment stability. stability. 0xperience has shown that the labiolingual apical displacement of the lower incisors can occur easily if round wires are used during the spreading process, because round wires forfeit forfeit labiolingual labiolingual control. To maintain maintain labiolingua labiolinguall apical control during the spreading spreading process !

using uprighting springs in the third stage of Begg treatment ! an edgewise

sectional auxiliary in the incisor region along with the main round archwire is effecti"e. $ith the edgewise techni-ue, spreading begins at the start of treatment, so any labiolingual apical displacements occurring from the initial use of round wires can be corrected later when rectangular arches are used.
'

Retention and relapse in orthodontics The lower cuspid root apex must be positioned slightly buccal to the crown apex. This is extrem extremely ely import important ant becaus becausee of its influe influence nce on post!t post!trea reatm tment ent stabil stability ity.. ll ll sorts sorts of occlusal forces await their chance to exert lingual pressure on the lower cuspid crown. #f the apex of the lower cuspid is lingual to the crown at the end of treatment, the forces of occlusion can more easily mo"e the crown lingually toward the space reser"ed for the lower incisors because of these functional pressures plus a natural tendency for the crown to upright o"er its root apex. 0"en if a lower cuspid with abnormal lingual position of the apex were supported for many years with a fixed retainer, the crown would e"entually mo"e lingually when the restraint was remo"ed.

=ault lingual position of lower right cuspid ape1. ld-stle edgewise brac%et automaticall automaticall created lingual positioning of lower cuspid ape1 unless clinician placed adequate buccal root torque in rectangular archwire.

The old concept that lower intercuspid width cannot be increased permanently is only true some of the time. fter treatment, the newly ac-uired lower intercuspid width will be maintained without retention if the lower cuspid crowns are mo"ed distally into a wider part of the +aw and if their apices are mo"ed buccally buccally so they are at least under the crown. #f the apex is not mo"ed buccally along with the crown while distali%ing the cuspid, lingual relapse of the crown into the incisor area is likely. likely. Antil the ad"ent of straight wire brackets with built L in tor-ue, there was a tendency for the old edgewise bracket to mo"e the lower cuspid apex lingually whene"er rectangular rectangular wires were used. Anless the clinician took the precaution to place appropriate buccal root tor-ue into the rectangular wire, increased lingual root position of the lower cuspid was

'6

Retention and relapse in orthodontics bound to result. :ower fixed retention was then routinely needed to pre"ent intercuspid distance from diminishing and incisors from collapsing. To tor-ue the lower cuspid apex buccally, a Begg clinician can use a simple auxiliary. n edgewise clinician can place the appropriate tor-ue in the rectangular wire. There is a bewildering range of lower cuspid buccal root tor-ues in straight wire edgewise brackets, from L '' ) to U H), a total "ariation of '> ). Between the lower right and left cuspids, the combined "ariation can be 69). Iariations in crown slopes to which the "ariously tor-ued brackets are attached compound the dilemma. >i7th ?e%: 

The lower incisors should be slenderi%ed as needed after treatment. :ower incisors that that ha"e ha"e sust sustai ained ned no proxi proxima mall wear wear ha"e ha"e roun round, d, smal smalll cont contac actt point points, s, whic which h are are accentuated if the apices ha"e been spread for stability. Gonse-uently, the slightest amount of continu continuous ous mesia mesiall pressu pressure re can cause cause "ariou "ariouss degrees degrees of collap collapse se in the lower lower inciso incisor r segment. A. mall, mall, roun round d contac contactt points points of of lower incisors.

B. mall siEe and shape of contact points ma%e it eas for pressures from the rear, or inadequate space in the jaw, to cause their dislodgment.

C. =lattening contact points and reducing mesiodistal width of lower incisors ma%es it possible to eliminate lower incisor retention, provided other treatment %es have been attained.

There are two sources for post!treatment pressure on the lower incisors that may bring about a shifting or collapse e"en though all other key treatment re-uirements ha"e been accomp accomplis lished. hed. One source source is the molars molars.. Gurren Gurrentt e"idenc e"idencee indica indicates tes that that natura naturall mesial mesial pressure is limited to the upper and lower molars. Molar pressure can cause displacement of lower incisor contact points. Remo"al of third molars does not eliminate the mesial pressure

'7

Retention and relapse in orthodontics deri"ed form the first and second molars, and “there is little rationale, based on present e"idence, for the extraction of third molars solely to minimi%e present or future crowding of lower anterior teeth”. The second source of hidden pressure is an ad"erse tooth ! +aw relationship. $ho can say that the remo"al of two, four, six or eight teeth will pro"ide the perfect solution for tooth L +aw discrepancy& #t is concei"able that the right combination to pro"ide balance and stability in some instances should be the remo"al of ' W teeth or 6W teeth. But we can only do our best by remo"ing whole tooth units when indicated. 5lattening lower incisor contact points by slenderi%ing or stripping creates flat contact surfaces that help resist labiolingual crown displacement. This treatment also helps eliminate the need for lower incisor retention. Begg said, “Anless sufficient tooth substance is eliminated from mouths ha"ing it in excess, neither artificial post L treatment retention nor factors inherent in the dental apparatus itself itself can pre"en pre"entt relaps relapsee after after treatm treatment ent.. 0"en 0"en after after reduct reduction ion of tooth tooth substa substance nce by extractions, the balance between +aw accommodation and tooth si%e may not precisely match, e"en with competent treatment, and slenderi%ing may be necessary”. #f the post! treatment dentition displays pressure signs by de"eloping irregularities among the incisors, reduction of incisor width by slenderi%ing can be the answer. Asually only minimal tooth structure has to be remo"ed if the root apices ha"e been ade-uately spread. Occasionally, more than one slenderi%ing session may be necessary to bring the tooth mass into harmony with the +aw si%e and to eliminate the need for lower incisor retention. ome post L treatment situations do not seem to ha"e a detrimental effect on lower incisor stability. One is the depth of the o"erbite, and another is prodigious mandibular growth that carries the lower incisors forward against the upper incisors and tips them out. 0xperience has shown that neither of these re-uires the protection of a lower retainer. By obser"ing the six treatment keys, it is possible to eliminate lower incisor retention followed fixed appliance therapy. Glinicians who want to eliminate lower retention may find that that they ha"e to increa increase se their their extrac extractio tion n percen percentag tagee in order order to achie" achie"ee the six keys keys ade-uately.

'8


table lower incisor segment two ears alter treatment and no retention.

Though $illiams has gi"en six keys for stability but other authors like achrisson, denwalla, rtun, xelsson, Garter etc had emphasi%ed the need for permanent bonded retention retention in the anterior arch. These authors ha"e gi"en considerabl considerablee importance importance to the post treatment retention procedures with fixed or remo"able appliances without which long!term stability cannot be achie"ed.

'9


Problems Problems =f 6etention Iarious concepts of retention re-uire scrutiny depending on indi"idual cases. The problem of retention could arise from ability of the operator, inherent tendencies present in the indi"idual patients and limitations of the science of orthodontics itself. The best of training and experience cannot be substituted for each other. $aging war against or attempting to control the biological tissues could result in its own limitations. The transseptal fibers of the periodontal ligaments demands a thorough understanding in the management of annoying problems of relapse especially in cases of closure of midline diastema, closure of generali%ed spacings and closure of extraction sites. The science of orthodontics itself, though mechanistically ad"anced to "ery high le"els, the understanding of biological basis is far from complete. @ot withstanding the remarkable instability, instability, so L called “collapse,” of treated mal!occlusion continues to elude the practicing orthodontist. I! Biological Problems of 6etention: 

The transseptal fibers are considered by many orthodontic researchers as the culprits of many of the orthodontic relapses.68, ''( The principle fibers tra"eling from tooth to tooth in the dental arch are the transseptal fibers. 5irst named by Black in '>>9, they are part of the gingi"al group of fibers of the periodontal membrane. The transseptal fibers are firmly embedded in the cementum along the con"exity of the cemento L enamel +unction, which gi"es them a strong grip on the tooth. They also attach the tooth to bone as in the third molar area and from tooth to subepithelial connecti"e tissue. The arrangement of these fibers indicate their need and function in maintaining mesio!distal relationship between neighboring teeth and in stabili%ing the tooth against separating forces. The body responds to stress by orthodontic mo"ement with increased resistance of transsepta transseptall fibers fibers as they seek to return and maintain maintain original positions positions of the teeth. This is the reason as to why good results following orthodontic treatment and retention cannot be counted as successful treatment. #t also explains why many in"estigators put them as culprits of orthodontic relapses. Relapse caused by these fibers is a result of their mode of attachment from cementum to soft tissue. $hen connecti"e conne cti"e tissue fibers under stress attach to soft tissue, ther theree is appar apparent ently ly no mecha mechani nism sm for for thei theirr rear rearra range ngeme ment nt with with bone bone ser" ser"in ing g as an

'H

Retention and relapse in orthodontics attachm attachment ent<< readapt readaptati ation on is made made possib possible le by bony resorp resorptio tion n and deposit deposition ion.. Reitan Reitan68 demonstrated this on orthodontically rotated teeth. Oppenheim /'(''2 was aware of the potential strength of these fibers. ;e stated, “The powerful fibers stretching across the septa, gi"ing off strong bundles partly to the teeth and partly to the gums, pro"e to be the most resistant tissues with which we are dealing in our operation.” Thompson described transseptal fibers as “tiny tough, resistant fibers which act slowly, slowly, but definitely to foil some beautifully treated orthodontic cases.” kogsborg a strong ad"ocate of “$alkoffs theory of tension difference” de"eloped a surgical procedure based on this theory in '(9. $alkoff belie"ed that tension remains in hard hard,, elas elasti ticc bone bone tiss tissue uess long long afte afterr the the phen phenom omen enaa of reso resorp rpti tion on and depos deposit itio ion n are are complete. ;e belie"ed that this stored tension was the ma+or cause of orthodontic relapse. The Fsepto Fseptotom tomy* y* procedur proceduree was design designed ed to relie" relie"ee this this tensio tension n and allow allow settli settling ng by remo"ing the interdental septum between the teeth of the maxillary and mandibular arches. Thompson''( in '(8( showed that the success of septotomy was not the result of bone remo"al but of indurated transaction of transseptal fibers. #n summary, nature pro"ided transseptal fibers for the maintenance and integrity of the dental arches. s a result of this function, these fibers react rapidly and definitely to interruption or stress. @o mechanism is pro"ided for the remo"al or reduction of the -uality or -uantity of these fibers. Gonse-uently, when orthodontic mo"ements place these fibers in un!natural states or under abnormal stress, the result is relapse. II $echanical problem of 6etention: 

0"en with the ad"ent of three!dimensional control of tooth mo"ement, the ideal six keys of static static occlusion occlusion cannot be fully achie"ed in extraction extraction cases. The buccolingual buccolingual root tor-ue tor-ue capabil capabiliti ities es of the existi existing ng mechani mechanical cal system systemss are limite limited. d.  prolonge prolonged d or a permanent retention is necessary where arch width is manipulated.  welcoming technical trend trend in the curren currentt orthodo orthodonti nticc field field is the popular populari%a i%atio tion n of diphas diphasic ic treat treatmen ment, t, which which incorporates an orthopedic and neuromuscular training at an earlier age to be followed by finer detail positioning of indi"idual teeth after complete eruption of the permanent dentition.

'>

Retention and relapse in orthodontics dapting the dental arches to the preformed arch planks could de"iate the archforms into the areas out of functional tolerance. The retaining of teeth in abnormal abnormal positions positions with fixed or remo"able appliances appliances can cause permanent damage to both teeth and in"esting tissues as the retainer attempts to hold them in one position, achie"ed by tooth mo"ing appliances and functional forces dri"e them towards another. The “3iggling” increases the thickness of the periodontal membrane, there is alternate bone deposition and resorption and continued mobility of teeth in -uestion. The supporting supporting structures structures sooner or later succumb succumb to the inseparable inseparable demands of the artificially artificially established occlusion, and there is deterioration of teeth o f these in"esting tissues. #n all fairness, it is not always possible for the orthodontic specialist to achie"e a satisfactory structural balance, full functional efficiency though he may achie"e the desired esthetic results.

'(


"motional >tress uring 6etention and Its "ffect on Tooth Position $hile orthodontic correction has become increasingly more reliable, more effecti"e, and more certain, confidence in the outcome of the retention period of treatment is less than absolute. 1espite the abundance of efficient retention appliances and careful super"ision, "ary "aryin ing g amou amount ntss of rela relaps psee cont contin inue ue to occur occur,, in many many inst instanc ances es with withou outt sati satisf sfyi ying ng explanation. Because correction and retention are mainly mechanical, the importance of the psychosomatic relationship of teeth and emotions, especially during the post L orthodontic treatment period, has not recei"ed ade-uate attention. By far the greatest numbers of orthodontic patients are pre!adolescent and adolescent, stag stages es in de"el de"elopm opmen ent, t, whic which h are are mark marked ed by, by, frefre-ue uent nt epis episode odess of stre stress ss,, moody moody intr intros ospe pect ctio ion, n, feel feelin ings gs of conf confus usio ion, n, anxi anxiou ouss mome moment ntss of desp despai airr. #n a pers person onal al communication, Ruth Moulton, a psychiatrist, ga"e the following description4 “dolescents “dolescents ha"e a great deal of anxiety about changes in their bodies that go with puberty which upset their pre"ious body image of child instead of adult. Many fears of adulthood and sexuality are e"oked at this time. They are particularly sensiti"e to ridicule about their bodies and this must influence their sensiti"ity about orthodontic procedures and appliances.” Throughout this time of life the stress le"el rises and falls but is particularly high and sustained high during the first semester of college awa y from home. Csychologically, there are se"eral explanations why this early period of college is so important when it in"ol"es li"ing away from home. Reasons ranging from “separation form home” to “the fear of meeting strangers” ha"e been put forth. Kenneth ;. 5ried') obser"ed changes in occlusion, which occurred in patients who were still under retention or obser"ation and in"ol"ed in a known anxiety L pro"oking situation, namely, first semester of college away from home. Crior to this time retention had been une"entful for one to three years, and oral habits, which had been present before treatment, were no longer apparent during this same one to three year period.

'6)

Retention and relapse in orthodontics Interpla% of "motions* $uscles* and Teeth: 

One psychiatrist, rnold ucker, has stated that in an anxiety state, which is intense, and of long duration there can be regression, and habits present from an earlier time in life can come back. #n retention patients /under stress2 the habit most fre-uently seen was bruxism and the occlusal changes noted in many of these patients were deepening of the o"erbite, crowding of the lower incisors, and attrition of the teeth. cti"e tongue thrusting habit and lip sucking habits were obser"ed in some of the patients of this group within six months of college life. #n addition to the effects o"erbite and the alignment of incisors, grinding and clenching are in"ol"ed in pain and trismus of the +aw by causing spasm of the muscles of mastication. lso e"ident at times during retention were periodontal abscesses in the maxillary molar region. 1espite their awareness of the importance of their retainer they tend to omit wearing them. :efer explains this as follows4 “Qoungsters with extreme anxiety want their teeth to relapse so that they can blame their failures in interpersonal relationship on their teeth rather than than thei theirr pers persona onali liti ties es.” .” :efe :eferr desc descri ribe bed d a "ari "ariat atio ion n of brux bruxis ism4 m4 “# noted noted rhyt rhythm hmic ic contrac contractio tion n of the tempor temporali aliss and masset masseter er muscle muscles, s, and a habit habit many many of them them had of protruding the lower +aw, which brought the lower anterior teeth edge to edge with the upper anterior anterior teeth back to rest position position and forward forward again.” This causes soreness soreness of the anterior teeth and slight crowding of lower anteriors, which are attributed to hard contact with the hea"y marginal ridges of the upper incisors. nother clearly "isible habit in this group of college students was sucking, which during retention generally in"ol"es the lower lip or tongue but occasionally the thumb or finger. Growding of the lower incisors and flared upper incisors are often seen in association. Cearson, a psychiatrist, accounts for finger sucking in this way4 “5inger sucking is a neces necessa sary ry part part of the the life life of young young chil childr dren en and and is a meth method od of obta obtain inin ing g inst instin inct ctual ual gratification. ome children relin-uish finger sucking "ery early of their own accord. Others

'6'

Retention and relapse in orthodontics continue for a moderate length of time. Others continue to suck for a number of years, and then of their own accord gradually gradually gi"e up first first in the daytime, daytime, later after after they get into bed, and still later after they fall asleep. 0"entually they relin-uish it entirely when they are emotionally ready to do so. #n another type of finger sucking the child has relin-uished his finger sucking himself and without any need to conform to the parent*s dislike of it. :ater, after 7 or 8 years, the finger sucking starts again. This type of finger sucking has the same etiology as any neurotic symptom. The child has met some difficulty in his present emotional de"elopment, is unable to de"elop further, goes back to an earlier form of gratification.” ucker notes that4 “Rubbing and thrusting of the tongue against the teeth occur as a manifestation of anxiety in the tense, apprehensi"e, pent!up indi"idual< it occurs particularly when the person is sub+ect to emotional stress. The response may become habitual and the sympt symptom om may be experie experience nced d as compul compulsio sion n in the more chroni chronicc states states.. Catien Catients ts often often describe an attraction of the tongue to the teeth, and particularly to dental faults. Bruxism is of a similar nature and may accompany the tongue reaction.” “Tongue tic is an intermittent, in"oluntary spasmodic mo"ement of the tongue, such as a twitch, without demonstrable external stimulus. #t represents the disguised expression of a hidden emotional conflict.” nother condition of the tongue that is found mostly in females is glossodynia or burning tongue. #n such cases there is no structural damage or loss of o f function. nxiety may produce dental symptoms by being con"erted directly into sub+ecti"e symptoms of pain or paresthesias. The symptom stands in place of an awareness of an intolerable life situation, which the indi"idual feels unable to face directly. nother category of anxiety beha"ior, hygiene neglect, can cause instability of the teeth during retention by increasing inflammatory elements in the periodontal tissues. $anagement and Preention: 

The patient under retention who will be exposed to an anxiety!pro"oking situation should be prepared in by the orthodontist.

'6

Retention and relapse in orthodontics 5irst, he should be made aware of the stressful situation he will enter and the effects it could ha"e on his teeth, and second, he should be pro"ided with retainers, which will counteract the muscular action of undesirable oral habits, should they reappear. Many people react to fears and stresses by resorting to habits, which can cause the teeth to shift. #t may be that clenching the teeth, sucking or biting the lower lip, pushing the tongue against the teeth will be happening especially before exams. Recogni%e them as a sign of tension and try to control them by talking about inner fears to a trusted friend or to an understanding teacher or to someone in the guidance department and by substituting some other form of physical ph ysical acti"ity. acti"ity. Retainers should be designed to pre"ent tooth shifting from habits that may reappear.  bruxism appliance makes an excellent retainer< it co"ers the occlusal and incisal surfaces of the maxillary teeth and pro"ides uniform occlusal contact with all mandibular teeth. #f there is a possibili possibility ty of mandibular mandibular retrusion, retrusion, a tooth positioner positioner may be indicated, although this can induce additional bruxism and temporomandibular +oint symptomology. =enerally, two ;awley retainers or an upper ;awley and a lower “three ! to L three” are effecti"e if muscle acti"ity is not o"erly strenuous. 0xcept for minor shifting, the teeth in an original malocclusion are in a state of e-uilib e-uilibriu rium, m, which which has de"elop de"eloped ed o"er o"er the lifeti lifetime me of the indi"i indi"idua duall during during period periodss of maximum growth and adaptability. lready included in this ad+ustment are the muscular balance of lips, cheeks, and tongue, and the dynamic effects of oral habits. #n contrast, the teeth, after orthodontic correction, ha"e existed in the re"ised state of balance for a short period at a time when adaptability is on the wane and habits ha"e come and gone. t best, this “young” e-uilibrium is tenuous and "ulnerable. 0motional stress during retention in the forms of anxiety and fear can reacti"ate dormant oral habits which may interrupt the maturation of this newly L ac-uired e-uilibrium, and, if of sufficient magnitude and duration, can bring about gradual relapse of the teeth. Once relapse has begun the new, desirable e-uilibrium can no longer take hold. ;ence, in those cases where there has been a history of "igorous oral habits it is especially important to establish ade-uate retention procedures as soon as acti"e treatment is concluded, and should

'66

Retention and relapse in orthodontics it be known that the patient will be entering into an anxiety L pro"oking situation, to make him aware how anxiety may affect his teeth. The orthodontist should not attempt to play psychiatrist by del"ing into unconscious material or by interpreting specific psychological mechanisms. $hen this is done, the patient looks upon it as meddling and is resentful. On the other hand, explanation of the connection between anxiety and shifting of the teeth "ia a specific mechanism can be -uite reassuring to the patient who feels that he may handle his anxiety better than when the mechanism is unknown to him. “lthough the orthodontist is in no position to suggest to the patient the answers to his life*s problems, the fact that he has helped the patient to focus his attention on the proper cause can be most useful. #f the doctor remains sympathetic with the person who is anxious or fearful, he can find a way of suggesting an emotion L physical symptom relationship without shocking or angering his patient.”

'67


6etention /ppliances or 6etainers efinition:

Retainers'' are are passi passi"e "e orth orthod odont ontic ic appl applia ianc nces es that that help help in main mainta tain inin ing g and stabili%ing the position of teeth long enough to permit reorgani%ation of the supporting structures after the acti"e phase of orthodontic therapy. The type of retainer to be used depends on "arious factors such as the type of malocclusion treated, the esthetic needs, patient*s oral hygiene, patient co!operation, the duration of retention, etc. 6euirements of 6etaining /ppliances:

ccording to =raber, ' the re-uirements of a good retaining appliance are4 ! '2 #t should should restra restrain in each each toot tooth h that that has has been been mo"e mo"ed d into into the the desi desire red d posi positi tion on in directions where there are tendencies toward recurring mo"ements. 2 #t should should permi permitt the forces forces associat associated ed with function functional al acti"ity acti"ity to act freely freely on the retained teeth, permitting them to respond in as nearly a physiologic manner as possible. 62 #t should should be as self L cleansing cleansing as possible possible and should should be reasonably reasonably easy to maintai maintain n in optimal hygienic condition. 72 #t should should be constructed constructed in such such a manner as to be as inconsp inconspicuous icuous as possi possible, ble, yet should be strong enough to achie"e its ob+ecti"e o"er the re-uired period of use. ,lassification of 6etainers:

Retainers can be classified into'4 ! '2 Remo Remo"ab "able le ret retai aine ners rs.. 2 5ixe 5ixed d retai retaine ners rs.. 62 cti" cti"ee reta retain iner ers. s.

'68


I) 6emoable /ppliances /ppliances as 6etainers:  Remo"able retainers are passi"e appliances that can be remo"ed by the patient and reinserted at will. Remo"able appliances can ser"e effecti"ely for retention against intra!arch stability and are also useful as retainers /in the form of modified functional appliances or part L time headgear2 in patients with growth problems. Iarious Iarious examples of remo"able retainers are as follows4 ! '2 ;awley ;awley Retaine Retainers rs and its modif modifica icatio tions. ns. 2 Remo"ab Remo"able le $rapar $raparound ound retai retainer ners. s. 62 @on L acryl acrylic ic remo"ab remo"able le retain retainer er.. 72 5itt 5itted ed lab labia iall bow bow. 82 Remo"ab Remo"able le plasti plasticc ;erbst ;erbst Retain Retainer er 92 0ssi 0ssix x Reta Retain iner ers. s. H2 0sthet 0sthetic ic Remo Remo"ab "able le reta retaine iner. r. >2 Cosit Cositio ione ners rs etc. etc. 1) Ha#le% 6etainers and its $odifications: 

By far the most common remo"able retainer is the ;awley retainer, designed in the '()s by Gharles ;awley, used following acti"e orthodontic therapy. The basic appliance incorporates clasps on molar teeth and a characteristic outer bow with ad+ustment loops, spanning from canine to canine. Because it co"ers the palate, it automatically pro"ides a potential bite plane to control o"erbite.

tandard design of 6awle>s retainer

'69


$hen first premolars ha"e been extracted, one function of a retainer is to keep the extraction space closed, which the standard design of the ;awley retainer cannot do.

6awle>s retainer with long labial

0"en 0"en worse, worse, the standar standard d ;awley ;awley labial labial bow extend extendss across across a first first premol premolar ar extraction extraction space, tending to wedge it open.  common common modificati modification on of the ;awley ;awley retainer retainer for use in extraction cases is a bow soldered to the buccal section of dams clasp on the first molars, so that the action of the bow b ow helps hold the extraction site closed.

Dabial bow soldered to Adam>s

lternati"e designs for extraction cases are to wrap the labial bow around the entire arch, using circumferential clasps on second molars for retention< or to bring the labial wire from the baseplate between the lateral incisor and canine and to bend or solder a wire extension distally to control the canines. The latter alternati"e does not pro"ide an acti"e force to keep an extraction space closed, but a"oids ha"ing the wire cross through the extraction site, and gi"es positi"e control of canines that were labially positioned initially /which the loop of the traditional ;awley design may not pro"ide2. The clasp locations for a ;awley retainer must be selected carefully, since clasp wires crossing the occlusal table can disrupt rather than retain the tooth relationships established

'6H

Retention and relapse in orthodontics during treatment. Gircumferential clasps on the terminal molar or lingual extension clasps may be preferred o"er the more effecti"e dams dams clasp if the occlusion is tight. The palatal co"erage of a remo"able plate like the maxillary ;awley retainer makes it possible to incorporate a bite plane lingual to the upper incisors, to control bite depth. 5or any patient who once had an excessi"e o"erbite, light contact of the lower incisors against the baseplate of the retainer is desired.' #n cases where the canines ha"e a tendency for rotation, especially toward the labial, the standard standard ;awley retainer retainer has difficulty difficulty in pre"enting pre"enting this mo"ement. mo"ement. To o"ercome o"ercome this and for better retention of cuspids, li!. Bahreman '6 has adapted extra loops to the labial bow of the ;awley retainer in the cuspid region. The loops can be made toward the mesial or toward the distal to pre"ent or correct mesiobuccal or distobuccal rotation.

31tra loop toward mesial !left" and distal !right".

The extra loops can be used in both upper and lower arches.

Modi#ed loops in both upper and lower

They can also be used as hooks for an elastic in the incisor region if minor palatal mo"ement or space closure is re-uired with a light continuous force. 5or this purpose, acrylic material should be relie"ed behind the incisors at each ad+ustment. fter using elastics for some days to retract incisors, the labial bow can be contracted to retain the new position of the incisors.

'6>


3lastic used in conjunction with

Catients wearing the con"entional ;awley retaining appliance complains that, it is too bulky and uncomfortable, causes ca uses a speech impediment /usually lisping2, causes a bad taste in the mouth, causes a loss of taste sensation, causes difficulty in mastication, occasionally discolors, occasionally warps to produce a poor fit and poor retention, occasionally in"ol"es an allergic response etc. ll of these problems, which discourage patient cooperation in wearing the appliance, are associated with the acrylic plate, which has been routine in the construction of an upper ;awley retainer. ;owe"er, the acrylic plate is not needed in cases in which pre"ention of lingual relapse is not a factor, and if stability of the appliance can be attained by proper design and construction of an all L wire, tooth!borne appliance. #n some cases, palatal co"erage is not desirable because it may contribute to relapse. 5or example, in tongue thrust cases the stability of a treated result may be related to the ability of the patient to ac-uire proper lingual proprioception for proper tongue function.

Adequate space for lingual proprioception.

This may be somewhat compromised when the palate is co"ered. Tongue spurs, rakes, and cribs can be added, or a hole placed in the plastic to influence tongue placement, but these ad+uncts may all be unnecessary unnece ssary in "iew of the alternati"e that exists. :aurance :aurance 3errold, 3errold,

'7

has design designed ed an allwir allwire, e, toothb toothborn ornee ;awley ;awley type type retent retention ion

appliance without any acrylic palate. The appliance has a modified Gro%at design. The crib and crescent clasps are made of ).)>” Cermachrome, the labial bow is made of ).)6” wire, and the transpalatal arch is made of ).)8'” wire.

'6(


;oothborne ;oothborne 6awle 6awle retainer retainer..

They are soldered with hea"y gauge. ).)8” sil"er solder. The transpalatal arch is reli relie"e e"ed d '.8 mm away away from from the the pala palatal tal soft soft tiss tissue ue.. The The abut abutme ment nt teet teeth h are are ditc ditche hed d appropriately on the model to pro"ide for undercut retention. $ith properly constructed clas clasps ps,, ther theree are are no occlu occlusa sall inte interf rfer erenc ences es,, and and spac spacee is a"ail a"ailabl ablee for for prop proper er tong tongue ue placement.

Clasps designed to avoid occlusal interference.

#n a case with a lingual relapse tendency, a lingual arch can be placed instead of a labial one. This will gi"e lingual support and still lea"e an open palate, and can be held in place by the superior retenti"e ability of properly constructed Gro%at clasps. #n properly selected cases, the all L wire toothborne ;awley type appliance may be the retainer of choice. ;awley retainers of all types, classic and modified, remain the most widely used retain retainers ers in orthodo orthodonti ntics, cs, especi especiall ally y follow following ing compre comprehens hensi"e i"e orthod orthodont ontic ic therap therapy y. #n addition to their role in retention, they can be modified to achie"e some limited acti"e tooth

'7)

Retention and relapse in orthodontics mo"ement through the acti"ation of the labial bow or incorporation of auxiliary springs imbedded into the acrylic base or soldered to the labial bow or clasps. ;awley retainers usually are worn 7 hours per day for the first 9 months following remo"al of therapeutic appliances. 0xception to the 7!hour constraint are for tooth brushing, swimming and eating. side from some slight slurring of speech, especially “” sounds, and an increase increase in sali"ary flow for se"eral se"eral days, days, patients patients find wearing wearing ;awley* ;awley*ss type retainers retainers rather benign. Because they are relati"ely small, they can be slipped out of the mouth and placed in their box for important business and social e"ents.  ;awley retainer retainer can be made for the upper or lower arch. The lower retainer retainer with the classic ;awley bow is somewhat fragile and may be difficult to insert because of undercu undercuts ts in the premol premolar ar and molar region region.. #f the ma+or reason reason for lower retentio retention n is maintenance of incisor position, a retainer for that region only is a logical alternati"e, and a wraparound design is preferred.' 2) 6emoable 0raparound 6etainers: 

 second ma+or type of remo"able orthodontic retainer is the wraparound or clip!on retainer, which consists of a plastic bar /usually wire reinforced2 along the labial and lingual surfaces of the teeth.  full!arch wraparound retainer firmly holds each tooth in position. This is not necessarily an ad"antage, since one ob+ect of a retainer should be to allow each tooth to mo"e indi"iduall indi"idually y, stimulati stimulating ng reorgani%at reorgani%ation ion of the Ceriodontal Ceriodontal ligament. ligament. #n addition, addition, a wraparound retainer, though -uite esthetic, is often less comfortable than a ;awley retainer and may not be effecti"e in maintaining o"erbite correction.  full!arch wraparound retainer is indicated primarily when periodontal breakdown re-uires splinting the teeth together.

Begg wrap-around

 "ariant of the wraparound retainer, canine!to canine clip!on retainer, is widely

retainer

the used

in '7'

Retention and relapse in orthodontics the lower anterior region. This appliance has the great ad"antage that it can be used to realign irregular incisors, if mild crowding has de"eloped after treatment, but it is well tolerated as a retainer alone.

Clip on retainer !labial and lingual views"

n upper canine!to!canine wraparound occasionally is useful in adults with long clinical crowns but rarely is indicated and usually would not be tolerated in younger patients because of occlusal interferences. #n a lower extraction case, usually it is a good idea to extend a canine!to!canine wraparound distally on the lingual only to the central groo"e of the first molar. This pro"ides control of the second premolar and the extraction site, but the retainer must be made carefully to a"oid lingual undercuts in the premolar and molar region. Costerior extension of the lower retainer, of course, also is indicated when the posterior teeth were irregular before treatment.' 3)
5itted labial bow is also known as continuous labial bow. #t is so called because in this type of labial bow the wire is adapted to confirm to the contours of the labial surfaces of the anterior teeth. The A loop is usually small. The fitted labial bow cannot be used to bring about about acti" acti"ee toot tooth h mo"em mo"ement ent.. They They are are used used as reta retain iner erss at the the comp comple leti tion on of fixe fixed d orthodontic therapy.''

=itted

labial bow

4) High labial retainer: 

'7

Retention and relapse in orthodontics Through force of habit or tradition, most orthodontists will insert a standard ;awley retainer after the remo"al of fixed bands. lthough minor ad+ustments may be made with this appliance, they are not always easy to accomplish. Therefore many operators will resort to a positioner for a final detailed tooth mo"ement prior to the placing of this “standard” retainer. The high labial appliance permits the orthodontist to achie"e both ob+ecti"es, minor tooth mo"ement plus retention, and thus is an excellent de"ice to use during the retention phase of orthodontic treatment.'8

6igh labial

retainer

/ppliance components: 

The appliance consists of the following component parts4 ! a2 dams clasps L ).)> /' gauge2 stainless steel wire. These are the clasps of choice and are usually placed on the first molars. They may, howe"er, be placed on the bicuspids if no mo"ement of these teeth is re-uired and J or if one or more of the first molars needs some correction. #deally one should clasp a first or second molar on one side of the arch, and a first bicuspid on the opposite side in order to minimi%e rocking of the appliance. b2 ;igh labial wire L ).)69 /'( gauge2 precious metal wire. This is usually soldered to the buccal hori%ontal portion of the dams clasps in order to keep keep to a minim minimum um the the numbe numberr /and /and si%e2 si%e2 of wire wiress pass passin ing g o"er o"er the the occl occlus usal al embrasures, and thus to lessen the tendency for separation of teeth. The high labial wire follows the contours of the al"eolar bone and should be kept as close as possible to the al"eolar mucosa to pre"ent lip and cheek irritation. /c2 :abial and buccal springs L ).)> /' gauge2 precious metal wire or ).)8 / gauge2 is used when springs are "ery short.

'76

Retention and relapse in orthodontics These are soldered to the high labial wire and extend to within ' or  mm of incisal edge of anterior teeth and occlusal surface /or cusp tip2 of posterior teeth. Their free end is flattened to a"oid irritation. /d2 :ingual :ingual springs L ).)8 / gauge2 stainless stainless steel steel wire or ).) /6 gauge2 is used when springs are "ery short. Occasionally ).)> /' gauge2 may be used when springs are "ery long or when considerable breakage is encountered. These springs are usually added for distal, mesial, and labial /or buccal2 mo"ement of teeth. They are also used in con+unction with the labial or buccal springs to correct minor rotations, or to maintain maintain the correction of se"ere rotations that had pre"iously been corrected with fixed appliances. :ingual springs may occasionally be used to intrude posteriors, especially second molars. /e2 Basepl Baseplate ate L Glear Glear,, self!c self!curi uring ng acrylic acrylic with with palate palate rugae rugae /ground /ground!in !in22 with with a round round "ulcanite bur2. This ser"es the re-uirements of stability and anchorage. The acrylic must be uniformly thin to minimi%e encroachment upon tongue space and to pre"ent speech problems. The rugae ser"e as a “stop” for the tongue. Occasionally, in ser"e tongue thrusters, a large opening will be made in the acrylic to expose the patient*s own palatal rugae.  bite plane may be added when necessary. /f2 uxillary components4 ! #n this category we include any further de"ices that may be added to the appliance, such as hooks for elastics, guide wires for springs, pontics, etc.'8 ,onstruction: 

'2 d+ust modelL modelL Remo"e Remo"e bubbles, and make make gingi"al cuts cuts for clasps. clasps. pply pply separating separating medium. 2 Gonstruct Gonstruct dams dams clasps clasps and and wax them them in place.

6igh labial appliance after placement of Adams clasps, lingual springs, and clearance for tooth movement.

'77

Retention and relapse in orthodontics 62 #mmerse #mmerse model in room tempera temperature ture water water until all air air is e"acuated. e"acuated. :et model damp damp dry. 72 Gonstruct Gonstruct lingual lingual springs springs.. ;old them them in place place with with red lab lab wax. 82 $ith $ith red lab wax also also block out undercut undercuts, s, and place relief relief at gingi" gingi"al al margins margins and where clearance is needed for tooth mo"ement. 92 dd self self L curing curing acryl acrylic. ic.

Appliance with acrlic

added.

H2 Clace model model /while acrylic acrylic is still still soft2 soft2 into pressure!c pressure!cooker ooker with with room temperatur temperaturee water for ') minutes. Gure at ) psi. >2 Blend high high labial wire, wire, using using no'6( and 6! prong prong pliers. pliers. older older to dams dams clasps clasps with with 78) fine solder. (2 older the the labial labial and buccal "erti "ertical cal springs springs to high high labial labial wire. ')2 Remo"e Remo"e the appliance appliance from model and wash carefully carefully with hot water and detergent detergent to remo remo"e "e wax. wax. Trim rim and and poli polish sh acry acryli licc and and wire wires, s, and and place place ruga rugaee or pala palata tall opening.'8

=inished

appliance. ;wo views showing high labial wire and labial spring construction and soldering. 8ote palatal reinforcing wire to lessen chance of fracture.

'78

Retention and relapse in orthodontics /dantages: 

The ad"antages of the high labial retainer may be summari%ed as follows4 ! '2 The orthodonti orthodontist st has complete complete control control o"er o"er each tooth tooth separately separately.. 2 The spri springs ngs are easy easy to ad+us ad+ust. t. 62 Cressure Cressure on one tooth tooth will will not appreciabl appreciably y affect affect any of the the ad+acent ad+acent teeth. teeth. 72 Glosin Glosing g of band spac spaces es is simpl simplifi ified. ed. 82 5inishing 5inishing details details are easily easily accomplis accomplished, hed, and without without the use of a positioner positioner.. 92 Rota Rotati tion onss can can be acco accom mplis plishe hed d and and J or reta retain ined ed by usin using g ling lingua uall spri spring ngss in con+unction with the labial or buccal springs of the high labial appliance. H2 ddit dditio iona nall spri springs ngs may be sold solder ered ed to the high high labi labial al wire wire for for mesi mesial al or distal distal mo"ement. >2 Aprigh Aprighti ting ng of mesial mesially ly or distal distally ly tipped tipped anterior anteriorss can sometime sometimess be accomp accomplis lished hed through the use of both mesial and distal springs on teeth with long clinical crowns. (2 Buccally Buccally erupting erupting second second or third third molars molars can be guided guided into the line line of occlusio occlusion. n. ')2 $hen desired, hooks may be soldered to the high labial wire /or to the dams clasps2 for elastic traction. ''2 The same appliance appliance can be used during both the acti"e and retention stages stages of minor tooth mo"ement cases. '2 ince the springs run "ertically "ertically /in the direction direction of the long axis of the teeth2, the appliance is actually more esthetic than one on e with a hori%ontal retaining wire. isadantages: 

The only disad"antages with respect to this appliance are the slightly higher cost of construction, the possibility of the patient inad"ertently bending the springs, and the fact that the ma+ority of patients at the present time are not educated to accept this “different” retainer.'8

'79


&) / 6emoable ,uspidto,uspid retainer: 

Retention of the lower teeth has been accomplished through many different methods4 tooth positioners, ;awley retainers, six!to!six and cuspid!to!cuspid fixed lingual retainers. There are good and bad features with each type of retainer. The remo"able ;awley works well but re-uires time and skill in its preparation. lso, in those cases tori mandibularis mandibularis are present, present, the ;awley is contraindicated contraindicated.. The tooth positioner does a good +ob of finishing and retaining, but some patients can soon find it ob+ect ob+ection ionabl ablee and re-ues re-uestt that that it be replac replaced ed by indi"i indi"idua duall retain retainers ers.. The fixed fixed lingua linguall retainers are probably the most dependable, but still create brushing problems, take up some arch length space with the bands, and in the fixed cuspid L to L cuspid are e"entually considered esthetically undesirable. #n an attempt to incorporate the good features of each to these retainers into one retainer and eliminate some of the bad features at the same time, 1ouglas 3. hilliday de"eloped a remo"able cuspid!to! cuspid retainer. This retainer can be made relati"ely -uickly and by untrained personnel. ,onstruction: 

Two ).)8 wires are bent and placed in the embrasure between the lower cuspids and lateral incisors after separating medium is painted on the cast.

/*& wire bent to shape.

'ires placed between cuspids

and laterals after separating medium is painted on cast

pply a -uick!cure acrylic co"ering the labial surfaces from cuspid to cuspid and the lingual surfaces from first bicuspid to first bicuspid /or second bicuspids if firsts ha"e been extracted2. $hen the acrylic has set, the retainer is remo"ed from the cast, trimmed, pumiced and polished.

'7H

Retention and relapse in orthodontics After acrlic has cured retainer is #nished and polished .

The acrylic acrylic should be cut down on the labial to a"oid being struck by the maxillary maxillary central incisors, but left at the incisal edge on the lingual.

Acrlic e1tends to incisal edges of incisors

on

the lingual, but is trimmed on labial side to avoid interference with ma1illar incisors.

The whole procedure re-uires about fifteen fifteen minutes minutes of working working time and produces produces a smooth smooth,, incons inconspic picuou uous, s, easily easily fitted fitted retain retainer er that that will will do a posit positi"e i"e +ob of contro controlli lling ng corrected lower rotations. #mpression for the remo"able cuspid L to L cuspid retainer is not taken until all lower anterior spaces left at appliance remo"al ha"e closed.'9

=inished

retainer in

place.

) 6emoable  metal 6etainer: 

Retention in the lower arch sometimes presents us with a dilemma. The cemented 6!6 or 9!9 lingual arch a"oids the problems of loss and non!wear. They do ha"e the drawbacks of cement washout, "isibility /of the 6!62, and constantly answering the -uestion, “1octor, when will the braces come off&” The lower lower ;awley ;awley applia appliance nce may a"oid a"oid decalc decalcifi ificat cation ion,, but the plasti plasticc breaks breaks /usu /usual ally ly while while in a pock pocket et2< 2< is bulky bulky /whi /which ch contr contrib ibut utes es to pock pocket etin ing g or, or, wors worsee yet, yet, napkining2< has potential ad"erse gingi"al effects< and is ad+ustable to a limited extent once constructed. n altera alterati" ti"ee which which 1r. 1r. Garl Garl . ;offm ;offman an'H ha"e ha"e foun found d usef useful ul is a meta metall 9!9 9!9 remo"able retainer.

'7>

Retention and relapse in orthodontics ,onstruction: 

2 The lingual lingual arch is formed formed of ).)78 hard hard  wire. wire.

Dingual arch formed of ./&

hard 

wire.

B2 dams clasps clasps are formed formed of ).)> or ).)6  wire. wire. Bend clasp tails tails o"er archwire archwire so that stress is wire!to!wire and not on solder.

Adams clasps formed of ./*(

or ./7* 

wire. 8ote clasp tails bent over

lingual

archwire.

G2 #n soldering, soldering, use ;ydroflame ;ydroflame or electrosolde electrosoldering. ring. ;eat expendable expendable part of clasp tails. tails. Ase solder as heat sink to a"oid o"erheating clasp. 12 dd buccal wires, wires, tubes, tubes, lingual lingual finger finger springs, springs, ball clasps clasps,, distal distal extension extensionss to second molars, or anything else that will do what one desires to be done. +) on C/cr%lic 6emoable 6etainer: 

Remo"able appliances with an acrylic base may cause soft tissue inflammation in patients who tend to accumulate pla-ue or are hypersensiti"e to free monomer, especially when cold curing acrylic is used.  non!acrylic remo"able retainer is a simple, effecti"e alternati"e.  spec specia iall appl applia iance nce was was desi design gned ed by 1r. 1r. #. Brin Brin,, 1r. 1r. Q. ilb ilber erma man, n, and ;. Tennenhaus'> to resol"e the inflammation.

'7(


8on-acrlic removable retainer.

#t was constructed of hea"y wire /).(mm, ).68'”2 adapted to the gingi"opalatal surfaces of the upper teeth. Retention was gained with dams clasps on the first molars and threeL-uarter clasps on the first bicuspids. The inflammation disappeared shortly after this appliance was inserted and the palate was unco"ered.

Case at time of removal of acrlic retainer and lacem lacement ent of non-ac non-acrr lic

Case two wee%s later of removal of acrlic retainer and lacement of non-

-) ,ontinuous ,lear 6etainer: 

$ires that cross from labial to lingual in a standard ;awley retainer tend to hold spaces open, and to interfere with the occlusion and the ability to finish with cuspid or group guidance and with anterior guidance. n allLplastic retainer attempted to sol"e this problem< but tended to interfere with the posterior occlusion, and the plastic would fracture easily when that interference was eliminated. $ith the continuous clear retainer there are no wires crossing from buccal to lingual and no interference with occlusion and settling. #t offers much greater control of the corrected positions due to circumferential retention from the second molar through the central incisor and broad /8!9 mm2 co"erage on the labial side. Because the continuous labial portion is made of cold!cure acrylic and finished to a high shine, it does not stain and tends to be extremely accurate. ,onstruction: 

The wires are outlined on a stone working model and bent out of ).)6)” stainless steel wire. The two loops should be in the same hori%ontal plane, with no "ertical component that could unseat the appliance when it is acti"ated. #n patients with de"eloping second molars, it is important to car"e the gingi"a to permit the most posterior circumferential wire

'8)

Retention and relapse in orthodontics to settle into the de"eloping gingi"al embrasure, and this must be ad+usted in the mouth. The spur between the first molar and second bicuspid should fit snugly. The model is coated with l!Gote and the wires are stickyLwaxed into place.

'ires bent and stic%-wa1ed in place.

 strip of soft white wax is pressed on the occlusal surfaces as a barrier between the inner and outer portions of the appliance.

'a1 barrier between inner and outer elements.

The acrylic portions of the appliance are then fabricated using a cold!cure acrylic. a crylic.

'8'


Acrlic Acrlic portions completed.

The appliance is then finished and polished. The palate is relie"ed in a A!shaped to a"oid interference with taste and temperature perception, and to a"oid gagging and speech impediments. n ).))” rubber ligature is used to connect the two wire loops, and the appliance is ready for insertion.

Appliance #nished and polished.

Minor finishing finishing corrections corrections can be achie"ed by resetting resetting teeth in wax, similar similar to the positioner, or by relie"ing the acrylic on the buccal or lingual side to permit an ad+usting action. Gonstruction time of the continuous clear retainer is approximately ')!'8 minutes longer than for a standard retainer but the results achie"ed are effecti"e of this retainer. The continu continuous ous clear clear retain retainer er permit permitss normal normal "erti "ertical cal settli settling ng of the teeth teeth without without +iggli +iggling. ng. Results ha"e been rewarding for esthetics and for settling into a good functional occlusion.'( .) 6etainer >plint: 

The purpose of this retainer is, primarily, to replace the lower fixed cuspid L to L cuspid retainer. #t is easy to construct and rarely breaks. The usual usual constr construct uction ion employ employss an. ).)69 ).)69  wire wire around around the six anterior anterior teeth teeth embedded in acrylic.

'8

Retention and relapse in orthodontics Construction of retainer splint !6oriEontal and 4ertical section".

lthough it is basically a cuspid L to L cuspid appliance, it can be carried posteriorly to hold hold bucca buccall expan expansi sion. on. #t can can also also be used used effe effect cti" i"el ely y to acco accomp mpli lish sh minor minor toot tooth h mo"ements.  tooth may be cut off the cast, o"er!rotated, set in plaster and the retainer made to the new position. The appliance can also be used to maintain space.

etainer splints showing the use of an upper splint to maintain space for small, malformed lateral incisors

#t is only worn at night. #t has been used as a nightly check on stability, only being worn if needed. #t has also been used o"er a period of years in less stable circumstances.'6) 18) 6emoable Plastic Herbst 6etainer: 

 "arie "ariety ty of fixe fixed d and remo remo"a "abl blee singl single! e!ar arch ch reta retain iner erss ha"e ha"e been been usef useful ul in maintaining alignment, space closure, and rotation correction. ;owe"er, single!arch retainers are not effecti"e for pre"enting anteroposterior relapse, which can result in the reappearance of a Glass ## bite relationship. 5rankel L and bionator L type appliances ha"e been used, as dual L arch retainers to pre"ent anteroposterior relapse, but these are less predictable than single!arch retainers in maintaining intra!arch stability. #n an effort to combine the useful properties of both single L and dual L arch retainers, Raymond C. ;owe'6' ha"e begun using a Remo"able Clastic ;erbst /RC;2 retainer.

'86


emovable 5lastic 6erbst retainer, with upper and lower occlusal splints connected b the herbst mechanism.

#ts full upper and lower plastic splints function as con"entional singleLarch retainers. t the same time, the remo"able splints are connected on each side by the telescoping ;erbst mechanism, which acts as a dual L arch anteroposterior retainer.

esign:  The The desi design gn of the the Remo Remo"a "able ble Clas Clasti ticc ;erb ;erbst st reta retain iner er is simi simila larr to that that of the the Remo"able Clastic ;erbst treatment appliance. Apper and lower plastic splints are fabricated o"er a supporting wire framework and connected by the ;erbst mechanism. The principal difference difference between the retainer retainer and the treatment treatment appliance appliance is that the retainer has full occlusal co"erage on all teeth, including the upper incisors. This maintains tooth positions and pre"ents passi"e eruption. /lternatie uses:  1)
 patient*s compliance with Glass ## elastics, headgear, diet, or hygiene occasionally becomes unsatisfactory near the end of treatment. #n such a case, in may be possible to remo remo"e "e fixe fixed d appl applia iance ncess and and use use a Remo" Remo"ab able le Clas Clasti ticc ;erb ;erbst st reta retain iner er as a fini finish shin ing g appliance. #f the patient*s hygiene does not impro"e, at least the potential for decalcification and decay can be reduced with the remo"al of fixed appliances. 2) 6etreatment /ppliance: 

#t is commonly assumed that if a proper cusp!fossa relationship is established, a correc corrected ted class class ## maloccl malocclusi usion on will will remain remain in a proper proper antero anteropos poster terior ior archLt archLtoLar oLarch ch relationship. Regardless of the treatment mode ! extraction, class ## elastics, headgear, or orthopedic methods L certain cases ha"e a tendency toward anteroposterior relapse. These patients can benefit from retreatment with a Remo"able Clastic ;erbst retainer. retainer. 3) Post >urgical 6etainer: 

'87

Retention and relapse in orthodontics The Remo"able Clastic ;erbst retainer may ha"e an application as a post!surgical retainer in pre"enting skeletal relapse. This use is speculati"e and should be confirmed with research and limited clinical trials before general application.

'88


4) /id for =bstructie >leep /pnea: 

0arly clinical trials suggest that the Remo"able Clastic ;erbst appliance may be useful in protruding the lower +aw to maintain an airway in patients who suffer from episodes of obstructi"e sleep apnea. &) /nterior 6epositioning >plint: 

 form of the Remo"able Clastic ;erbst appliance has been used as an anterior repositioning splint for treatment of temporomandibular +oint disorders. Creliminary results seem fa"orable, but this is still an area of acti"e in-uiry.'6' 11) "ssi7 6etainers: 

Orthodontists* concept of retention is mo"ing toward the idea that teeth will mo"e unless retained indefinitely. ;owe"er, permanent retention implies permanent super"ision, and that is where wh ere reality clashes with stability. $hen permanent retention is emphasi%ed, the e-uilibrium is upset. The cornerstone of 0ssix permanent retention is the complete delegation of responsibility to the patient. 0ssix retainers'6 ha"e nothing to ad+ust< the only thing that could be done on a recall "isit would be to check the patient*s compliance and listen to any comments. 0ssix thermoplastic copolyester retainers change the rules of permanent retention. They are a thinner, but stronger, cuspid!to!cuspid "ersion of full!arch, "acuum Lformed de"ices.

5atient before and after placement of 3ssi1 retainers.

'89


'8H


/dantages include:  

The ability to super"ise without office "isits.



bsolute stability of the anterior teeth.



1urability and ease of cleaning.



:ow cost and ease of fabrication.



Minimal bulk and thickness /).)'8”2



The brilliant appearance of the teeth caused by light reflection.

0ssix 0ssix retainers retainers can be placed the same day fixed appliances appliances are remo"ed. remo"ed.  single!arch single!arch 0ssix retainer should be worn 7 hours a day /except for cleaning2 for two weeks, and then at night only. #f both upper and lower retainers are placed, the patient should wear the lower during the day and the upper at night for four weeks, then both at night only. The material is so thin that accommodation to speaking and eating is not a problem. 0ssix retainers are nearly imper"ious to fracture or distortion.

Dabial contour of upper and lower

3ssi1

retainers.

0ssix retainers ha"e pro"en -uite "ersatile. Their flexibility and positioner effect make them an alternati"e to spring retainers in correcting minor tooth mo"ements. They can be used to reduce occlusal forces from the opposing arch when mo"ing posterior teeth with air! rotor stripping mechanics. They can ser"e as a temporary bridge for a missing anterior tooth, when thermoformed thermoformed o"er a pontic placed placed in the edentulous edentulous space on the cast. They can also act as night guards for bruxism and as bite planes to relie"e bracket impingement until the bite can be opened.'6

5alatal 5alatal contour of upper 3ssi1 retainer

pace cut at distogingival margin of cuspid

'8>

Retention and relapse in orthodontics 12) / e# Thermoplastic 6etainer: 

Glear Glear thermo thermopla plasti sticc applia appliances nces ha"e been been recomm recommende ended d for use as transi transiti tional onal retainers, finishing appliances, '2 and e"en permanent retainers. 2 They are easy to fabricate, inexpensi"e, esthetic, and comfortable, and thus ha"e a high le"el of patient acceptance. 62 The ma+or drawbacks are their tendency to open the bite and their low durability. durability.

;hermoplastic ;hermoplastic retainer retainer

Most thermoplastic retainers'66 are made from 'mm splint material. '2 The 0ssix retainer, howe"er, is fabricated from ).H8 mm /).)6)”2 copolyester, which is thermoformed to a thickness of ).)'8”. This appliance is thinner and stronger than other designs, but since it co"ers only the six anterior teeth, it still has a slight tendency to open the bite. 2 The low modul modulus us of elas elasti tici city ty of poly polyme meri ricc mate materi rial alss is a ma+o ma+orr cons consid ider erat atio ion n in stru struct ctur ural al applications of plastics. 62 To afford maximum stiffness, plastics must be designed for the most efficient use of the material. 72 Gorrugated and dimpled sheet surfaces are widely used to enhance stiffness, as are shapes with specific and non!repetiti"e geometries, such as a cylindrically cur"ed plate. The resistance to deformation is related to the amount of cur"ature of the plate.

A. Corrugated sheet. B. Clindricall curved plate .

This new clear thermoplastic retainer is both thin and strong. Catient cooperation and clinical results are excellent. The enhanced flanges facilitate the remo"al and increase the stiffness of the appliance.'66

'8(


13) Positioners as 6etainers: 

 tooth positioner ' also can be used as a remo"able retainer, either fabricated for this purpose alone, or more commonly, continued as a retainer after ser"ing initially initially as a finishing de"ice. Cositioners are excellent finishing de"ices and under special circumstances can be used to an ad"antage as retainers. 5or routine use, howe"er, a positioner does not make a good retainer. The ma+or problems are4 '2 The pattern of wear of a positioner does not match the pattern usually desired for retainers. Because of its bulk, patients often ha"e difficulty wearing a positioner full!time or nearly so. #n fact, positioners tend to be worn less than the recommended 7 hours per day after the first few weeks, although they are reasonably well tolerated by most patients during sleep. 2 Cositioners do not retain incisor irregularities and rotations as well as standard retainers. This problem follows directly from the first one4 a retainer is needed nearly full!time initially to control intra!arch alignment. lso, o"erbite tends to increase while a positioner is being worn, and this effect as well probably relates in large part to the fact that it is worn only a small percentage of the time.  posi positi tion oner er does does ha"e ha"e one one ma+o ma+orr ad"a ad"ant ntag agee o"er o"er a stan standa dard rd remo remo"a "abl blee or wraparound wraparound retainer< retainer< howe"er ! it maintains maintains the occlusal occlusal relations relationships hips as well as intra!arch intra!arch tooth positions. 5or a patient with a tendency toward class ### relapse, a positioner made with the +aws rotated somewhat downward and backward may be useful. lthough a positioner with the teeth set in a slightly exaggerated “supernormal” from the original malocclusion can be used for patients with a skeletal Glass ## or open bite growth pattern, it is less effecti"e in controlling growth than part time headgear or a functional appliance.

Fesling>s tooth positioner

'9)

Retention and relapse in orthodontics #n fabricating a positioner, it is necessary to separate the teeth by  to 7 mm. Cositioners ideally are worn for as close to 7 hours per day as possible for the first  days after appliances are remo"ed and then for 7 hours per day plus sleeping. 5or 7 hours per day during the first two days then during the 7 working hours of wear, the patient is re-uested to bite and clench into the appliance for ) seconds, release for ) seconds and repeat. #f the patient follows this schedule, sched ule, after the first  to 6 weeks, all mo"ement that might occur will ha"e done so and the appliance becomes a true “passi"e” retainer rather than an acti"e appliance. Catients wearing a positioner, as a retainer should be checked carefully to see that there is no separation of the posterior teeth when the incisors are in contact as it is the usual sign of a positioner made to an incorrect hinge axis. #n addition to tooth positioning and enhancing the setting or “fine tuning” of the dentition, these appliances act to stimulate and massage the gingi"a during the exercise aspects of their use. II) Fixed Appliances Appliances as Retainers: Retainers: -

5ixed 5ixed orthod orthodont ontic ic retain retainers ers' are are norma normall lly y used used in situ situat atio ions ns wher wheree intr intra! a!ar arch ch instability is anticipated and prolonged retention is planned. 1irect or indirect bonded or band based orthodontic appliances can be used in one or more applications in"ol"ing space and J or rotation control. Their most important use is in the control of arch circumference and alignment of mandibular anterior teeth. Other applications are holding space for pontics or maintaining the closure of diastema, usually at the maxillary midline. The appliance usually runs from canine!to!canine or premolar!to!premolar following contour of the lingual surfaces of the in"ol"ed teeth and resting on the incisors or, in some cases, all four incisors are in"ol"ed. O"er the years acid!etch techni-ue and "arious adhesi"e materials in combination with stainless steel or wire mesh and e"en the fiber glass retainers ha"e been used for orthodontic retention purposes. Two different types of bonded retainer are used routinely to pre"ent "ertical anterior relapse and secondary crowding of the lower incisors, and a ).)6!inch wire from canine!to! canine is used as a 6!6 retainer. $ith the round ).)6 inch multistranded wire, it is no longer necessary to bend loops at the ends because the twists in the spiral wire gi"e undercuts for

'9'

Retention and relapse in orthodontics retention retention /0arly bonded bonded retainers retainers were made with plain round or rectangular rectangular wires2. The other type of retainers is used to pre"ent space reopening and rotational relapse< it is made of thin, flexible spiral wire of ).)'H8 or ).)'8 inch and is bonded to each tooth of the anterior segment.  "ariety of methods ha"e been suggested for fabrication and bonding of fixed retainers to the lingual surface of anterior teeth. The importance of a passi"e and precise positioning has been stressed because tension in the wire results in a failure of retention. 5ailures 5ailures that occurred occurred were due to some degree of distortio distortion n during during setting setting of adhesi"e, adhesi"e, the use of too little adhesi"e, or direct trauma to the retainer. Bonding thin, flexible spiral wires lingually to each tooth in a segment has been proposed as an effecti"e way to retain anterior teeth in difficult difficult situations, situations, such as holding holding central central incisors incisors together after median median diastema diastema closur closure, e, pre"ent pre"enting ing space space opening opening after after closur closure, e, and holdin holding g teeth teeth that that are extens extensi"e i"ely ly tor-ued. They are flexible enough to permit physiologic tooth mo"ements, which are not possible by tooth contact splinting, and the twist in the wire pro"ides mechanical retention to a composite resin. Knierim /'(H62

'67

published the first report of a techni-ue of making the lower

cuspid!to!cuspid retainer without bands. The basis of the techni-ue was to acid etch the lingual lingual surface surface of the lower cuspids.  self!cur self!curing ing resin is then applied to the lingual of the cuspids to hold a wire against the lingual of lower incisors /).)>” round stainless steel wire2. fter application the patient is instructed to check retention of the wire e"ery two weeks. #nstructions are gi"en to apply pressure with a toothbrush handle on the resin mass on the lingual of the cuspids to be sure it is not loose. The wire can be extended around the second bicuspids in extraction cases to keep the extraction site closed.

=inished retainer with resin on lingual on cuspids

'9

Retention and relapse in orthodontics $olfson /'(H72 '68 ga"e a step!by!st step!by!step ep procedure of Bandless Bandless but fixed retention retention by placing the direct!banded mandibular lingual canine!to!canine retainer. The retainer has all ad"antages of a fixed soldered canine!to!canine retainer. #n addition, it does not re-uire bands, which in themsel"es, besides re-uiring space, compromise upon esthetics. #t allows for normal teeth contacts mesial and distal to canines and can be fabricated at the chair in one appointment of approximately 6) minutes.

Reinhardt /'(H(2 presented another techni-ue for retention ! a cast metal framework attached attached with the acid etch techni-ue techni-ue and composite composite resins. resins. The method method is not indicated indicated for all situations but is an option with the practitioner. #t consists of flattened retenti"e portions with numerous poles, which are smoothly connected to stabili%ing wires. The components need not be greater than ).8!' mm in thickness. Ase of this techni-ue offers ad"antages of patient comfort since the metal can be highly polished and well adapted outside the mouth for a precision fit. mooth controls are possible because there is not bulky wire. trength of the material pre"ents drifting or rotation. @o preparation of teeth is necessary. Thus, the procedure is easily re"ersible. 0sthetics is readily acceptable, since the appliances are easily hidden from a labial "iew.'69 1iamond 1iamond /'(>H2 '6H de"eloped a direct techni-ue that uses glass fibers from wo"en fiberglass fabric /sold in boating supply stores2 or 5iberbond. These fibers are separated into 9” strips, sterili%ed with dry heat, and kept in in"entory. fter remo"ing the brackets and any material adhering to the teeth, prepare the mouth with cheek retractors, a sali"a e+ector, and a tongue retractor or mouth mirror. Cumice, etch, wash, dry, and seal the lingual surfaces of the teeth to be bonded to the retainer.  piece of fiberglass thread is measured from the distal aspects of the canines, contacting the lingual surfaces of the incisors and soaked in light! cured bonding resin.  second mixture of resin and restorati"e paste to the consistency of hea"y cream is incorporated into the fiberglass thread to increase its strength. The resin!

'96

Retention and relapse in orthodontics soaked fibers are applied to the teeth and positioned with an explorer, plastic instruments, or ligature director. Then a "isible!light curing unit is used to cure the retainer to the tooth surfaces. This system has following ad"antages4 The resin fiberglass retainer is rigid and imper"ious. Catients appreciate the tooth!colored material and the comfort that is pro"ided by smoothing the margins with rubber abrasi"e points or wheels. Retainer sections can easily be recontoured, remo"ed, or repaired in the mouth. Because no metal wires are used, additional material can be applied to the teeth or the fiberglass or both.

=inished resin #berglass retainer. retainer.

There are four ma+or indications for fixed orthodontic retainers'4 ! 1) $aintenance $aintenance of lo#er incisor position during late gro#th: gro#th: 

The ma+or cause of lower incisor crowding in the late teen years, in both patients who ha"e had orthodontic treatment and those who ha"e not, is late growth of the mandible in the normal growth pattern. 0specially if the lower incisors ha"e pre"iously been irregular, e"en a smal smalll amou amount nt of diff differ erent entia iall mand mandib ibul ular ar grow growth th betw between een ages ages '9 and and ) can caus causee recrowding of these teeth. Relapse into crowding is almost always accompanied by lingual tipping tipping of the central central and lateral incisors incisors in response to the pattern of growth. growth. n excellent retainer to hold these teeth in alignment is a fixed lingual bar, attached only to the canines /or to canines and first premolars2 and resting against the flat lingual surface of the lower incisors abo"e the cingulum.

Banded and bonded canine-to-canine canine-to-canine #1ed lingual retainer

'97

Retention and relapse in orthodontics This pre"ents the incisors from mo"ing lingually and is also reasonably effecti"e in maintaining correction of rotations in the incisor segment.  fixed lingual canine!to!cani canine!to!canine ne retainer retainer can be fabricated fabricated with bands on the canines or can be bonded to the lingual surface.  bonded canine!to!canine retainer is preferred for two reason reasons4 s4 /'2 unless unless bands were used used during during the acti"e acti"e treatm treatment ent,, band space can be a problem< and /2 the labial part of a band tends to trap pla-ue against the cer"ical part of the labial surface, predisposing this area to decalcification, and is also unsightly. ince their introduction in '(HH, direct!bonded lingual canine!to!canine retainers ha"e been used to impro"e the long!term stability of orthodontic treatment results. Because of technological impro"ements, the design of the retainer bar has changed o"er the years. The fixed fixed bonded bonded canine canine!to !to!ca !canin ninee retain retainer er is attache attached d only to the canines canines,, resti resting ng passi"ely against the central cen tral and lateral incisors. #f the retainer wire is fitted to a cast of the lower arch, a silicone carrier of the type used for indirect bonding of brackets can be made to assist in placing the retainer. n alternati"e approach is to tie the retainer wire in place with wire ligatures or dental floss around the contacts, to h old it so that it can be bonded.

teps in the fabrication of canine-to-canine retainer

5ixed 5ixed canine! canine!to! to!cani canine ne retain retainers ers must must be made made from from a wire wire hea"y hea"y enough enough to resist resist distortion o"er the rather long span between these teeth. Asually 6)!mil steel is used for this purpose, with the end of the wire sandblasted to impro"e retention when wh en it is bonded to the canines.

'98


A

bonded

canine-to-c o-canine

retainer

can

advantageousl be made from a twist wire, which improves retention of the bonded wire. *( mil wire

is

recommended if onl the canines are to be bonded.

If

the incisors also are bonded, a lighter wire should be used.

#t is also possible to bond a fixed lingual retainer to one or more of the incisor teeth. The ma+or indication for this "ariation is a tooth that had been se"erely rotated. $hate"er the type of retainer, howe"er, it is desirable that teeth not be held rigidly during retention. 5or this reason, if the span of the retainer wire is reduced by bonding an intermediate tooth or teeth, a more flexible wire should be used.  good choice for a fixed retainer with ad+acent teeth bonded is a braided steel arch wire of 'H.8!mil diameter. diameter.

Mandibular incisor retainer, with wire lightl bonded to the canines, before before the incisors are bonded

Completed ma1illar retainer, with all four incisors bonded

2) iastema maintenance: 

 second indication for a fixed retainer is a situation where teeth must be permanently or semipermanently bonded together to maintain the closure of a space between them. This is encountered most commonly when a diastema between maxillary central incisors has been closed. 0"en if a frenectomy has been carried out, there is a tendency for a small space to open up between the upper central incisors. ince this is unsightly, prolonged or permanent retention usually is needed. The best retainer for this purpose is a bonded section of flexible wire. The wire should be contoured so that it lies near the cingulum to keep it out of occlusal contact. The

'99

Retention and relapse in orthodontics ob+ect of the retainer is to hold the teeth together while allowing them some ability to mo"e independently during function, hence the importance of a flexible wire.

Bonded lingual retainer for maintenance of a ma1illar central diastema

 remo"able remo"able retainer retainer is not a good choice choice for prolonge prolonged d retent retention ion of a central central diastema. #n troublesome cases, the diastema is closed when the retainer is remo"ed but opens opens up -uickly -uickly.. The tooth tooth mo"eme mo"ement nt that that accomp accompani anies es this this back!an back!and!f d!fort orth h closur closuree is potentially damaging o"er a long period. 3) $aintenance of pontic or implant space: 

 fixed retainer is also the best choice to maintain a space where a bridge pontic or implant e"entually will be placed. Asing a fixed retainer for a few months reduces mobility of the teeth and often makes it easier to place the fixed bridge that will ser"e, among other functions, as a permanent orthodontic retainer. #f further periodontal therapy is needed after the teeth ha"e been positioned, se"eral months or e"en years can pass before a bridge is placed, and a fixed retainer is definitely re-uired. #mplants should be placed as soon as possible after the orthodontics is completed, so that integration of the implant can occur simultaneously with the initial stages of o f retention. The preferred orthodontic retainer for maintaining space for posterior restorations is a hea"y intra!coronal wire, bonded in shallow preparations in the future abutment teeth.

=i1ed retainer to maintain space for a missing second premolar. A shallow preparation has been made in the

'9H

Retention and relapse in orthodontics enamel of the marginal ridges adjacent to the e1traction site, and a section of *+G*& wire is bonded as a retainer.

Ob"iously, the longer the span, the hea"ier the wire should be. Bringing the wire down out of occlusion decreases the chance that it will be displaced by occlusal forces. nterior spaces need a replacement tooth, which can be attached to a remo"able retainer. This approach guarantees nearly full!time wear and is satisfactory for short periods. Often a better alternati"e is a fixed retainer in the form of a simple acid!etch bridge, such as a replacement tooth held by twist wires bonded to ad+acent teeth. #f a healing implant is in the area, or if a permanent bridge will be delayed for a long time, a temporary bonded bridge decreases the chance of soft tissue inflammation and pro"ides better stability.

Acid-etch bridge using segments of braided orthodontic wire to attach the pontic to the abutment tooth

4) ?eeping e7traction spaces closed in adults: 

 fixed retainer is both more reliable and better tolerated than a full!time remo"able retainer, and spaces reopen unless a retainer is worn consistently. #t may be better in adults to bond a fixed retainer on the facial surface of posterior teeth when spaces ha"e been closed.

'9>

Retention and relapse in orthodontics A bonded bonded retaine retainerr maintain maintaining ing the space closure closure in an adult adult with missing missing ma1illar ma1illar  latera laterall incis incisors ors in whom whom the space space was close closed d and and the canine canines s substi substitut tuted ed for the laterals.

'9(

Retention and relapse in orthodontics >ome other t%pes of fi7ed orthodontic retainers:  1) irectbonded labial retainers: 

1irect!bonded retainers'69 are usually placed lingually, since one of the chief ad"antages of such retainers is their in"isibility. ;owe"er, certain problems experienced with direct! bonded lingual retainers were4 ! a2 hort!or hort!or long!term long!term inability inability to pre"ent pre"ent some reopening reopening of premolar premolar extraction extraction sites sites in adults. b2  tendency for some lingual crown relapse of canines that had been palatally impacted. c2 1ifficult 1ifficulty y in holding holding premola premolars rs that had been se"erel se"erely y rotated. rotated. d2 Iarious rious types of space reopenin reopening g in cases where where posteri posterior or teeth had been mo"ed mesially, in young or adult patients with pre"iously excessi"e spacing. Gommon to these situations was the desirability of adding some support to the premolar areas for one or two years after treatment. #t appeared preferable to bond the retainer wires labially, labially, based on earlier experience expe rience with bond failures at the enamel!adhesi"e interface when bonding to the lingual surfaces of premolars. nother alternati"e would be to bond the retainer in the occlusal fissure, which is usually successful if there is no contact with antagonists. #n most cases, howe"er, a groo"e has to be prepared with a bur to a"oid such contact. This amount of enamel remo"al would not be acceptable in routine situations.

Dong direct-bonded labial retainer

hort direct-bonded labial retainer

Bonding success rates and patient acceptance appear to be excellent for labial retainers bonded to two ad+acent teeth. uch retainers may therefore be recommended for impro"ed stabil stabili%a i%atio tion n of extrac extractio tion n sites sites in adults, adults, and for added added retent retention ion of palata palatally lly impact impacted ed canines.

'H)

Retention and relapse in orthodontics On the other hand, the results obtained with three!or four!unit bonded labial retainers were unsatisfactory, unsatisfactory, particularly in the mandibular arches of young patients. 5urther technical impro"ements will be re-uired before these retainers can be routinely used on long buccal spans. 2) 44 ,ro(at retainer:  '6> $hen a basic Gro%at appliance'6> is used as retainer, a tooth will sometimes rotate

away from the lingual wires, and crowding will return in spite of the appliance.

Basic CroEat appliance

dding a closed labial wire with pins pro"ides p ro"ides ade-uate retention, but the appliance is bulky and unsightly as a retainer. The spring retainer and modified ;awley!spring retainer afford labial and lingual control, but these appliances do not seat securely on the teeth. tability problems of these appliances lead to the fabrication of a bicuspid!to!bicuspid Gro%at appliance with a labial frame as a retainer.  7!7 Gro%at appliance has cribs on the first bicuspids, recur"ed double!lapping lingual finger springs, and a labial bow.

Mandibular - CroEat retainer

#t combines many of the ad"antages of other types of retainers and has been well recei"ed by patients. #ts ad"antages include4 ! 2 5irm retention, because of the Gro%at clasping mechanism. B2 :abiolingual control of anterior teeth /although rotational control of the canines is limited2 to maintain or restore arch form in the lower or upper arch.

'H'


Ma1illar - CroEat retainer

G2 5lexibility, 5lexibility, because it is all wire. #t can be left out for months and still fit. 12 Maintenance of ade-uate oral hygiene, because it is remo"able. 02 0sthetics, because only a single labial wire shows. The The ma+o ma+orr draw drawba backs cks of the the appl applia iance nce are are that that it must must be fabr fabric icat ated ed at a -uali -uality ty laboratory, which may cost more< and it is breakable, although breakage has been minimal. #t is poss possib ible le to treat treat both both arch arches es simu simult ltan aneo eous usly ly with with 7!7 7!7 Gro% Gro%at at reta retain iner ers. s. Occl Occlus usal al interferences from the crib wires are rare and do not pose a problem. Once the teeth are aligned, full!time wear should be continued for at least three months, after which nighttime wear is sufficient to maintain the corrected alignment. The 7!7 Gro%at retainer retainer is flexible flexible in design design potential, potential, and it is capable capable of indi"idual tooth mo"ements that may be difficult e"en with fixed appliances. #t can mo"e teeth rapidly ! usually re-uiring only three to four months ! to correct mandibular and maxillary anterior relapse and in special cases in"ol"ing Crosthodontics. ;owe"er, the 7!7 Gro%at is mainly a retention appliance, especially for cases in which the incisors are resistant to ideal alignment. #t is not a treatment appliance, nor should it be used to maintain faulty treatment results.

Dower Dower anter anterior ior relapse corrected in three-months with a -

ppe pperr ante anteri rior or relapse corrected in four-months with a -

'H


Case Case in which which - CroEa CroEatt retai retainer ner was was used over a partial denture to improve the alignment of anterior teeth prior to

3) Prefabricated Bonded mandibular retainer: 

Cre"ious report ha"e presented techni-ues for direct bonded mandibular retainers whose principal drawbacks included lengthy fabrication time, accumulation of pla-ue on the bonded attachment areas, and potential irritation to the lingual soft tissues due to the 6( bulkiness of the attachment areas. The Crefabricated :ower Retainer /C:R2 ' 6( minimi%es

these deficiencies. /ppliance construction: 

The Crefabricated :ower Retainer is prefabricated of two mesh!backed attachment bases, +oined by a lingual bar with interbase lengths in four si%es ! ), , 7 and 9 mm.

;he 5D

The attachment bases constructed constructed of a stainless stainless steel shield on a welded welded wire mesh, are +oined to the lingual bar with sil"er solder. The lingual bar may be constructed of gold, brass, or stainless steel, with a diameter range of ).)8 to ).)69. mall gauge wire is preferable. The only drawback to using brass wire is that it may tarnish in patients with poor hygiene. The only drawback to stainless steel is that it takes more time and is more difficult to ad+ust. Both were used successfully on patients in this study. =old wire is probably the ideal wire for the Crefabricated :ower Retainer, since it is strong, tarnish resistant, easy to

'H6

Retention and relapse in orthodontics ad+ust, and a smaller, more comfortable wire can be used. #t was found that ).)6!brass wire can resist 7) ounces of pulling force without distortion, distortion, while ).)> gold wire can resist resist 8 ounces. #n normal circumstances, 7) ounces should be strong enough to retain mandibular incisors and resist the force of mastication.

Buccolingual section of base

and mesh

Prefabricated ;o#er 6etainer >i(e >election and Placement: 

 measuring template is used, either on the model or directly in the mouth, to determine the proper Crefabricated :ower Retainer si%e. The measurement is made ).8 L ' mm distal to the mesial marginal ridge of the canines, +ust lingually, with the arrows of the gauge resting on the incisal edge of the mandibular incisors.

sing measurement gauge. In this

case, siEe *

is correct.

The Crefabricated :ower Retainer is fabricated with ideal arch form and a well! treated case re-uires only minimal ad+ustment. The best time to place the Crefabricated :ower Retainer is right after band remo"al, unless ob"ious band spaces are present between the teeth. #n patients with bonded brackets, the Crefabricated :ower Retainer can be placed before appliance remo"al. ny acceptable techni-ue techni-ue and materials materials for direct bonding may be employed for the attachment of Crefabricated :ower Retainer to the “abutment” teeth.

'H7


Bonded 5D

The author author Richard Richard . Ghen Ghen prefer preferss cotton cotton pliers pliers for carry carrying ing and holding holding the Crefabricated :ower Retainer while the bonding resin is setting.  scaler is used to press the bases firmly to the enamel surfaces and to remo"e excess resin. The optimum placement p lacement of the stainless steel base is the center of the lingual surface of the cuspid below the prominent cusp of the crown. This will minimi%e detachment due to mastication. The patient can floss the mandibular anterior teeth with Crefabricated :ower Retainer in place, oral hygiene can be maintained. #t is possible that Crefabricated :ower Retainer can be used as a permanent retainer when checked periodically. Crefabricated :ower Retainer can be reused after reconditioning by burning out with low temperature, ultrasonic cleaning, and sterili%ation. The Crefabricated :ower Retainer is designed to sa"e orthodontist*s chair time and to obtain the best result for mandibular incisor retention esthetically and functionally. III) /ctie 6etainers: 

“cti"e “cti"e retainer” retainer”' is a contrad contradict iction ion in terms terms,, since since a de"ice de"ice cannot be acti"e acti"ely ly mo"ing teeth and ser"ing as a retainer at the same time. #t does happen, howe"er, that relapse or growth changes after orthodontic treatment will lead to a need for some tooth mo"ement during retention. This usually is accomplished with a remo"able appliance that continues as a retainer after it has repositioned the teeth, hence the name.  typical ;awley retainer, if used initially to close a small amount of band space, can be considered an acti"e retainer, but the term usually is reser"ed for two specific situations4 realignment of irregular incisors, and functional appliances to manage class ## or class ### relapse tendencies.'

'H8

Retention and relapse in orthodontics 1) 6ealignment of irregular incisors:  1 Spring retainers retainers : -

Recrowding of lower incisors is the ma+or indication for an acti"e retainer to correct inci inciso sorr posi positi tion on.. #f late late crow crowdi ding ng has de"e de"elo lope ped, d, it ofte often n is nece necess ssary ary to reduc reducee the the interproximal width of lower incisors before realigning them, so that the crowns do not tip labially into an ob"iously unstable position. The cause of the problem in these cases usually is late mandibular growth, which has uprighted the incisors, and they must be realigned in their more upright position. @ot only does stripping of contacts reduce the mesiodistal width of the incisors, decreasing the amount of space re-uired for their alignment, it also flattens the contact areas, increasing the inherent stability of the arch in this region. s with any procedure in"ol"ing the modification of teeth, howe"er, stripping must be done cautiously and +udiciously. #t is not indicated as a routine procedure. #nterproximal enamel can be remo"ed with either abrasi"e strips or thin discs in a handpiece.

tripping

of

lower

reduce

mesio-distal

Ob"iously, enamel reduction should not

incisors to width

be

o"erdone,

but if necessary, the width of o f each lower incisor can c an be reduced up to ).8 mm on each side without going through the interproximal enamel. #f an additional mm of space can be gained, reducing each incisor ).8 mm per side, it is usually possible to realign typically crowded incisors. #f the irregularity is modest and if the teeth are to be realigned without mo"ing facially, a canine!to!canine clip!on is usually the acti"e retainer used to realign crowded incisors. The steps in making such an acti"e retainer are4 '2 Reduce the interpr interproximal oximal width width of the incisor incisorss and apply topical topical fluorid fluoridee to the newly exposed enamel surfaces<

'H9

Retention and relapse in orthodontics 2 Crepare Crepare a laboratory laboratory model, model, on which which the teeth teeth can be reset into alignmen alignment< t< and 62 5abricate 5abricate a canine!to!c canine!to!canine anine clip!on clip!on applian appliance. ce.

teps in the fabrication fabrication of a canine-to-canine clip-on appliance to realign lower incisors

#f there is more than a modest degree of relapse, howe"er, placing a fixed appliance for comprehensi"e retreatment must be considered. $ith bonded brackets on the lower arch from premolar to premolar, superelastic @iTi wires can be used to bring the incisors back into alignment -uite efficiently. #f the incisors are ad"anced toward the lip when this is done, a bonded lingual retainer should be placed before the brackets are remo"ed. Cermanent retention will be re-uired after the realignment.

'HH

Retention and relapse in orthodontics 2) ,orrection of =cclusal iscrepancies:  + Modiied F!nctional F!nctional Appliances Appliances as Acti"e Acti"e Retainers Retainers : -

#t is possible to describe an cti"ator as consisting of maxillary and mandibular retainers +oined by an interocclusal bite block.  typical use for an acti"ator as an acti"e retainer would be a male adolescent who had slipped back  to 6 mm toward a class ## relationship after early correction. #f he still is experiencing some "ertical growth /and almost all adolescents fall into this category, e"en at age 'H or '>2, it may be possible to reco"er the proper occlusal position of the teeth. 1ifferential anteroposterior growth is not necessary to correct a small occlusal discrepancy ! tooth mo"ement is ade-uate L but some "ertical growth is re-uired to pre"ent downward and backward rotation of the mandible. 5or all practical purposes, this means that a functional appliance as an acti"e retainer can be used in teenagers but is of no "alue in adults. timulating skeletal growth with a de"ice of this type simply does not happen in adults, at least to a clinically useful extent.

;he Andresen-tpe Andresen-tpe activator activator

The use of an acti"ator as an acti"e retainer differs somewhat from its use to guide skeletal growth during the mixed dentition or when it is used as a pure retainer. #n the latter circumstances, the ob+ect is to control growth, and tooth mo"ement is largely an undesirable side effect. #n contrast, an cti"ator as an acti"e retainer is expected primarily to mo"e teeth L no significant skeletal change is expected.

n acti"ator as an acti"e retainer is not

indicated if more than 6mm of occlusal correction is sought, and o"er this distance, tooth mo"ement as a means of correction is a possibility. The correction is achie"ed by restraining the erupti eruption on of maxill maxillary ary teeth teeth poster posterior iorly ly and direct directing ing the erupti erupting ng mandi mandibula bularr teeth teeth anteriorly.

'H>

Retention and relapse in orthodontics ny of the family of modified cti"ators designed to produce tooth mo"ement is most useful in this acti"e L retention mode, not in early mixed dentition treatment where tooth mo"ement for the most part is undesirable. On the other hand, the more flexible a remo"able appliance becomes, the less suited it is for the retention part of acti"e retention and the more likely it would be to re-uire replacement with another type of retainer when the occlusa occlusall relati relations onship hip had been been reesta reestabli blishe shed. d. n cti cti"at "ator or or Bionat Bionator or with with an acryl acrylic ic framework that contacts most teeth therefore is usually the best compromise when this type of acti"e retention is needed. The appliance is made like any other functional appliance, with a slight slight ad"ancement of the mandible into the correct correct occlusal relationship. relationship. #n contrast contrast to a functional appliance that would be placed as a retainer immediately upon completion of acti"e treatment, some freedom eruption for posterior teeth normally would be pro"ided.

'H(


/d'uncts to 6etention t times deli"ering only a retenti"e appliance may not be sufficient to pre"ent post treatment relapse in all the cases. These special cases may re-uire ad+uncts to be maintained in stabili%ed condition post treatment.  number of ad+uncts ha"e been proposed that aid in retention. These include4 ! '2 Gircumferential upracrestal 5iberotomy 2 Reproximation 62 5renectomy and associated procedures 72 eptotomy 82 Gorticotomy 92 #mmediate torsion H2 Crosthetic retainers

,ircumferential >upracrestal
'7' '7'

described a surgical procedure to eliminate rotational relapse in

clinical orthodontic patients. This surgical procedure, now referred to as Gircumferential upracrestal 5iberotomy /G52, has become well documented. Girc Gircum umfe fere rent ntia iall upra upracr cres esta tall 5ibe 5ibero roto tomy my is indi indica cate ted d for for any any case case where where the the supragingi"al fibers ha"e been markedly displaced. 0xamples are found in moderately to se"erely rotated teeth, markedly crowded or bunched teeth, displaced impacted teeth, and se"erely tipped teeth. The procedure is contraindicated in the presence of bacterial pla-ue, chronic gingi"itis, chronic periodontitis and should a"oid areas with little or no attached gingi"a. Gircumferential upracrestal 5iberotomy is not necessary or recommended in cases, which exhibit mild to moderate displacement of incisors in a buccolingual direction. Catients with systemic medical problems can be treated but should be co"ered with the appropriate therapeutic agent.

'>)

Retention and relapse in orthodontics Many Many arti articl cles es ha"e ha"e appe appear ared ed conc concer erni ning ng the the effi effica cacy cy of the the Girc Gircum umfe fere rent ntia iall upracr upracrest estal al 5ibero 5iberotom tomy y in pre"ent pre"enting ing or minim minimi%i i%ing ng tooth tooth rotati rotational onal relaps relapse. e. To date, date, howe"er, there ha"e been no reports in the literature concerning the long!term effecti"eness of Gircumferential upracrestal 5iberotomy and few assessments ha"e been made of the possible periodontal se-uelae, which might result from these procedures. Timing transection of the displaced supraal"eolar fibers can best be accomplished afte afterr band band remo remo"al "al sinc sincee ther theree is usua usuall lly y a decr decreas easee in ging gingi" i"al al infl inflam amma mati tion on and, and, subse-uently, a marked impro"ement in tissue tone following debanding. #n the case of closure of an extraction site although it is debatable to what extent the transseptal fibers reorgani%e and adapt to a normal anatomic configuration it is important that these fibers be surgically eliminated after closure of the space and also after closure of a diastema. The orthodontic closure of an extraction site and the closure of a diastema affect the transs transsept eptal al ligam ligament ent differ different ently ly.. #t has been been obser" obser"ed ed that that upon upon final final closur closuree of an extraction site and the approximation /paralleling2 of the root structure of the ad+acent teeth, the more apical transseptal fiber appears relati"ely normal in histologic sections. #t is also not sufficient merely to transact the transseptal ligament, as is done in eliminating a rotational relapse potential in the supracrestal fibers, since the total interruption of the transseptal ligament is re-uired before a new and functionally adapted ligament can be formed. formed. #n fact the disruption disruption of the transseptal transseptal fibers would be the sole surgical procedure procedure indicated indicated in the case of a diastema diastema with no associated associated aberrant aberrant frenum. ome researcher researcherss ha"e obser"ed that only a 6)!day period is sufficient sufficient for the formation formation of a completely new transseptal ligament after dissection. 5ollowing Gircumferential upracrestal 5iberotomy the most striking feature is an increase in mobility of the surgeri%ed teeth.>, ( This increased mobility is due to the cutting of transseptal fibers which splint tooth to tooth. ;owe"er, mobility gradually diminishes within a two!four week period. #f mobility does persist for more than four weeks, factors other than Gircumferent Gircumferential ial upracresta upracrestall 5iberotomy 5iberotomy should be considered< considered< for example, example, the occlusal prematurities which are due to prominent marginal ridges on the maxillary central or lateral incisors. nother obser"able feature is slight degree of spacing between the surgeri%ed teeth. This spacing is transitory in nature and may be attributed to postsurgical edema, which

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Retention and relapse in orthodontics can can occur occur with within in the the peri period odont ontal al space space as a resu result lt of Girc Gircum umfe fere rent ntia iall upra upracr cres esta tall 5ibero 5iberotom tomy y. Costop Costopera erati ti"e "e bleedi bleeding ng has not been a proble problem m and patien patientt discom discomfor fortt is minimal. $hen e"aluating post!surgical relapse of Gircumferential upracrestal 5iberotomy, one must reali%e that the primary purpose of this procedure is to eliminate rotational relapse. #n most cases, Gircumferential upracrestal 5iberotomy alone cannot stabili%e the entire lowe lowerr ante anteri rior or segm segmen ent. t. The The main main fact factor or in rela relaps psee of surg surger eri% i%ed ed rota rotate ted d teet teeth h is an insuff insuffici icient ent period period of axial axial stabil stabili%a i%ati tion on immedi immediatel ately y follow following ing rotati rotationa onall correc correctio tion, n, assuming that surgery has been properly performed. nother significant factor in relapse is failure to completely correct the rotation prior to Gircumferential upracrestal 5iberotomy. #f normal contact point relationships cannot be produced before surgery, surgery, a degree of relapse is ine"itable. The clinician should attempt to produce a slight o"ercorrection of a rotated tooth prior to band remo"al. Relapse following Gircumferen Gircumferential tial upracrestal upracrestal 5iberotomy has been obser"ed in those cases where lower incisors ha"e originally been bodily!displaced labiolingually and subse-uently aligned with insufficient root tor-ue. #n addition, a small amount of relapse can be attributed to occlusal prematurities that result from prominent lingual ! marginal ridges on maxillary central and lateral incisors. Boese>,

(

in"est in"estiga igated ted the long!t long!term erm effect effectss of Gircum Gircumfer ferenti ential al upracr upracrest estal al

5iberotomy and Reproximation on the periodontal tissues in mandibular anterior region. Glinical examination with a periodontal probe re"ealed gingi"al tissue with minimum pocket depth, which appeared to be well within normal limits. The tissues had good morphology, normal color and normal stippling. There was no e"idence of gingi"al recession on any mandibular incisors. Reproximation did not cause interdental bone loss in the lower incisor area. ;is study demonstrated marked stability of the mandibular anterior segment 7 to ( years post retention, which did not result from a refinement of orthodontic mechanics, but rather de"eloped from better understanding the b iology of that area. @ow the clinician can readily accept the concept of Gircumferential upracrestal 5iberotomy which se"ers displaced connecti"e tissue fibers and can employ Reproximation

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Retention and relapse in orthodontics which pro"ides space and broad!contact point areas, thereby placing the mandibular anterior segment more in harmony with the original arch form.

6epro7imation:   sub+ect of renewed interest is the “reproximation” or “stripping” of lower anterior teeth and its purposed ability to reduce lower incisor re!crowding. This reduction of lower incisor width is often the last resort at holding tooth alignment and is usually employed after all con"entional measures ha"e failed. #ts application has been empirical and its long!term effecti"eness -uestionable. The procedure often e"okes the concern of many practitioners who mention the possibility of associated periodontal destruction plus an increased caries susceptibility in the mandibular anterior area. ;owe"er, in '(H Ceck and Ceck 77 reported that well!aligned mandibular incisors possess distincti"e dimensional characteristics< these teeth are significantly smaller mesiodistally and significantly larger faciolingually, when compared with a"erage population tooth tooth dimens dimension ions. s. Their Their report report showed showed that that a substa substanti ntial al relati relations onship hip exists exists betwee between n mandibular incisor shape and the presence and J or absence of mandibular incisor crowding. #t also described a mesiodistal /M1J5:2 faciolingual index as a numerical expression of mandi mandibul bular ar inci inciso sorr crow crown n shap shapee when when "iew "iewed ed inci incisa sall lly y. ccor ccordi ding ng to the the stan standa dard rdss recommended recommended by Ceck and Ceck, ideally shaped lower centrals centrals ha"e a M1J5: index of >>L ( percent, while the lower laterals recommended range is ()!(8. They concluded that wellL aligned mandibular incisors usually ha"e M1J5: indices significantly lower than those of crowde crowded d inciso incisors rs and recomm recommende ended d reprox reproxima imatio tion n as a mechani mechanical cal method method of reduci reducing ng unfa"orable incisor shapes. Based on these finding, finding, clinical clinical application application of reproximation reproximation has become much less empirical and more predictable. Reproximation is indicated in all cases with crowded lower incisors, which exhibit poor M1J5: ratios and on teeth with unfa"orably shaped contact points. erial reproximation can also be employed to compensate for the natural loss of arch length, which appears to occur in many patients especially during periods of marked hori%ontal mandibular growth.

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Retention and relapse in orthodontics The significance of reproximation resides in two main benefits. #t pro"ides broader contact contact point point areas areas and thereb thereby y furnis furnishes hes greate greaterr contac contactt stabil stability ity,, plus plus reprox reproxima imati tion on increases the amount of a"ailable space in the mandibular anterior area. The process of pro"iding space is extremely useful when working within a biologic framework that usually limits our ability to increase arch length or drastically change basic mandibular arch form. #n spite of the benefits of the procedure, e"ery conscientious orthodontist must be fully aware of the inherent dangers. Reproximation ob"iously is not a re"ersible process< once the enamel is remo"ed and the shape of a tooth altered, the result is permanent. To being with, reproximation should be employed only after the lower incisors ha"e been completely aligned because it is impossible to be both conser"ati"e and precise in establishing broad new contact areas if the teeth are still malposed. 0"ery effort must be made to a"oid excessi"e stripping. The remo"al of more than oneLhalf the enamel cap could be excessi"e since this may lead to dental caries plus increased sensiti"ity to thermal changes and sweets. nd of course, clinicians should consider the positi"e correlation that exists between an increase in anterior o"erbite with an increase in the amount of lower incisor stripping. 5inally, excessi"e reproximati reproximation on could theoretically theoretically reduce the amount of transseptal transseptal bone between between the lower incisors which might predispose those areas to periodontal disease. The timing of reproximation appears to fall in three distinct phases, based on the clinical clinical experiences experiences gained from treating treating many crowded lower arches without without use of lower retention.>, ( Most reproximation is done as soon as alignment o f the mandibular anteriors has been accomplished. This will pro"ide good lower incisor shape early in treatment and allow for ideal o"erbite correction, correction, which can be maintained maintained following band remo"al. remo"al. Ob"iously Ob"iously,, the maxillary anterior tooth si%e relationships are affected by lower incisor stripping. 5ortunately, most cases with unfa"orably large lower incisor M1J5: ratios usually possess lower anterior tooth si%e excess. The second phase of reproximation, if no lower retention is used, takes place shortly after band or bond remo"al. #f the intercanine width has been expanded or basic arch form significantly altered, a periodic check of the mandibular anterior segment with dental floss will often re"eal an increase in contact point pressure. This is obser"ed in both extraction and

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Retention and relapse in orthodontics nonextraction cases. ome degree of reproximation is usually performed serially o"er a four! six month period following band remo"al< at each maxillary retention "isit the contact points of the lower incisors are e"aluated. #f some mo"ement appears to be taking place or contact points become extremely tight, reproximation is performed. The timing and degree of third phase reproximation is related to any significant change in lower anterior arch form and to the amount and direction of mandibular growth. Asually little reproximation is necessary after the first six months< howe"er, iatokowski, 1ekock, and chudy recogni%e that uprighting of lower incisors is fre-uently seen during the terminal phase of growth, especially in counterclockwise growers. The uprighting of these teeth is responsible for secondary crowding, which often occurs following treatment. Crior to beginning the third phase of reproximation, one must exercise sound clinical +udgment and consider the degree of stripping already performed, the amount of enamel remaining, shape of the lower inciso incisor, r, degree degree of o"erbit o"erbite, e, and the anticipat anticipated ed amount amount and direct direction ion of mandibular growth. #f the concep conceptt of Gircum Gircumfer ferent ential ial upracr upracrest estal al 5ibero 5iberotom tomy y and reprox reproxim imati ation on is routinely employed on crowded mandibular arches, the choice of net utili%ing mandibular retention is most logical and less frightening. 5ina 5inall lly y, we cann cannot ot look look upon upon Girc Gircum umfe fere rent ntia iall upra upracr cres esta tall 5iber 5iberot otomy omy and reproximation as a panacea for all our retention problems, but rather as an embellishment of soun sound d orth orthod odont ontic ic trea treatm tment ent prin princi cipl ples es and and good good orth orthod odon onti ticc ther therapy apy.. The The use use of Gircumferential upracrestal 5iberotomy and reproximation should not be accepted as a guarantee for permanent ideal lower anterior teeth alignment, but percei"ed as a useful process, which appears to work within a framework of natural changes that ine"itably will occur.

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Retention and relapse in orthodontics the the orth orthod odon onti ticc and pedo pedodon donti ticc lite litera ratu ture re that that rare rarely ly shoul should d any port portio ion n of e"en e"en an “abnormal” frenum be remo"ed prior to eruption of the maxillary lateral incisors and the canines, since it has been obser"ed that most diastemas close autonomously with the final eruption of the remaining anterior teeth. Moreo"er 1owel has stated that early “pre"enti"e” frenectomies without prior orthodontic closure in diastema situations may result in scar formation, which itself might tend to pre"ent normal mesial mo"ement o f the incisors.

Dabial frenectom

=ibbs found an intermingling of the frenal tissue with the transseptal fibers and therefore, did not ad"ocate early frenectomy for fear that the excision of the frenum would also se"er the transseptal fibers and reduce the natural forces acting to bring the central incisors together. Most oral anatomists, howe"er, would ha"e difficult agreeing with such an argument, since the fibers of the transseptal group ha"e ne"er been shown to possess elastic properties. Baum in addition indicated that the transseptal fibers did not e"en span the distance across a midline diastema but inserted into a relapse o"erlying the midline suture of the maxilla. @otwithstanding the fact that there exists little but empiric and arbitrary agreement that the maxillary frenum plays an important role in causing the re!opening of diastemas after orthodontic closure, a number of surgical techni-ues ha"e been de"ised to eliminate this undesirable relapse phenomenon. The terms frenectomy and frenotomy represent procedures that differ in degree. 5renectomy is complete remo"al of the frenum, including its attachment to underlying bone. 5renotomy is the partial remo"al of frenum, and is used extensi"ely for periodontal purposes to relocate the frenum, and is used to create an increased %one of attached gingi"al between the gingi"al margin and the frenum.

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Retention and relapse in orthodontics #n his textbook rcher depicts the classic frenectomy techni-ue in which the frenum, interdental tissues and palatine papillae are completely excised, lea"ing bone or periosteum exposed.  number of modifications of the basic frenectomy operations ha"e been described including the addition of hori%ontal relaxing incisors at the mucogingi"al +unction, and the lateral undermining of the labial attached gingi"al ad +acent to the excision area. Bell'7 has ad"ocated the immediate closure of diastemas by interdental and subapical oste osteot otom omie ies. s. ltho lthough ugh one one of Bell Bell**s +ust +ustif ific icat atio ions ns for for this this surg surgic ical al appr approa oach ch is the the indisp indispect ectable able unpred unpredict ictabi abilit lity y of retain retaining ing closed closed diaste diastemas mas,, most most orthodo orthodonti ntist st would would seriously -uestion his second +ustification that the con"entional approach to the closure of diastemas is “lengthy” treatment difficult. #n addition, Bell*s con"iction that the resistance to acti"e orthodontic mo"ement of teeth and their final stability is al"eolar bone, and not the gingi" gingi"al al and frenal frenal tissu tissues es is in contra contradic dictio tion n to recent recent oral oral anatom anatomic ic and physio physiolog logic ic research. #f such osteotomies should alle"iate relapse in diastema problem, it would more plausibly be due to the surgical interference with the supra al"eolar soft tissues and not the direct manipulation of al"eolar bone. nother procedure to eliminate the alleged relapse potential of the maxillary midline frenum is the two!plasty techni-ue, which does not remo"e the frenum but is intended to relax the pull of the frenum on the interdental soft tissues. 0wen and Castermak were encouraged by the use of re"erseLbe"el /in"erted2 gingi"ectomy procedure on the labial and palatal tissues of all six maxillary teeth. lthough their experimental group in"ol"ed only six patients and the researchers were not primarily interested in relapse caused by midline frenum, frenum, their surgical surgical inter"ention inter"ention did appear to alle"iate alle"iate the tendency tendency for the diastemas diastemas to reopen. Gampbel Gampbell, l, Moore Moore and Mathew Mathewss'76 ha"e ha"e atte attemp mpte ted d to incr increa ease se the the stab stabil ilit ity y of orthodontically closed diastema as by combining the standard excision type of frenectomy and its remo"al of interincisal soft tissue with either! '2 the re"erse re"erse be"el gingi"ec gingi"ectomy tomy labial labial and palatal palatal to the the six anterior anterior teeth teeth or 2 the G5 G5 techni techni-ue -ue de"el de"elope oped d by 0dward 0dwards. s.

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Retention and relapse in orthodontics Thei Theirr

prel prelim imin inar ary y

find findin ings gs

fa"o fa"ore red d

the the

comb combin inat atio ion n

of fren frenec ecto tomi mies es

and and

Gircumferential upracrestal 5iberotomy procedures.  techni techni-ue -ue ad"ocat ad"ocated ed by some some period periodont ontist istss combin combinee and frenect frenectomy omy with with no excision of the marginal papillae and the labial “curtain type” of gingi"ectomy of the palatal tissue behind the four incisor teeth as described by 5risch, 3ones and Baskar. Ceriodontal literature has stated that it makes little difference in the therapeutic result whether the frenectomy incisions are made to bone in order to denude the al"eolar plate or whether the incisions partly penetrates the al"eolar mucosa so that the bone remains co"ered. #t has been stressed that the therapeutic result is not dependent on whether bone is denuded, but rather, on the lack of mobility of granulation tissue that co"ers co "ers the wound. @e"ertheless, in performance of a frenectomy for the alle"iation of relapse of orthodontically closed diastemas, the remo"al of periosteum under the excised portion of the frenum is ad"ocated in an attempt to remo"e the elastic fibers of the frenum which ha"e been shown to penetrate the periosteum. uch elastic fibers ha"e not been demonstrated to ad"ersely affect the increase in attached gingi"a following a frenectomy nor ha"e they been shown to ad"ersely affect the alle"iation of relapse of diastema cases. ;owe"er, if the purpose of the surgical procedure is to eliminate the undesirable frenal tissue and to establish a normal interdental soft tissue anatomy, it is important to remo"e the elastic fibers impregnating the periosteum underlying the frenum, since, nowhere in the human periodontium there is an elastic tissue in"ol"ed with attached gingi"a.

>eptotom%:  0xcessi"e reproximation could theoretically reduce the amount of transseptal bone and predispose to periodontal disease. kogsberg /'(92 >,( de"ised the rather radical surgical techni-ues of septotomy to lessen the fre-uen fre-uency cy of relaps relapsee in rotate rotated d teeth. teeth. This This method, method, which which employ employss "erti "ertical cal secti sections ons through the entire al"eolar process mesial and distal to the rotated tooth from a le"el parallel with the apex of the root to the al"eolar crest, is too poorly documented for credibility. These

'>>

Retention and relapse in orthodontics septotomies were performed not with an idea of neutrali%ing forces within the soft tissue but with the intention of elimination of the tensions remaining in the bone after tooth rotation.

Immediate Torsion:  ;allett /'(892, belie"ed that chances for relapse are greatly reduced if the misaligned tooth is rotated forcibly with surgical forceps. 0"idently this “immediate torsion” treatment is intended to destroy completely all!fibrous attachment to the tooth and allow new attachment after rotation. rotation. Anfortunately Anfortunately this method method does not appear to lesser lesser relapse significantly significantly and has been pro"ed to result in fre-uent pulpal degeneration /;arriet, '(92. >,(

,orticotom%: ,orticotom%:  Kole /'(8(2

'77

remo"ed the buccal and lingual cortical plates before orthodontic

mo"ements in an effort to eliminate the relapse phenomenon. Bra"er and Tsopel /'(9H2 found that transecting transecting the supracrestal supracrestal fibers with "ertical incisions incisions mesial and distal distal to the rotated tooth may reduce the danger of relapse. ;e was unable to pre"ent relapse by this procedure. Reitan /'(9(2 8, among others, has ad"ocated the use of early rotation to lessen relapse. ;e feels that such early treatment will ensure stability, since there will be formation of new and stronger ligamentous fibers as the apical portion of the root as it complete its growth after the tooth has already been rotated to its proper position. uch a postulation is surprising, since Reitan himself was the first to report that alternations in the fibers and bone attached to the tooth rapidly reorgani%e and adapt to the new positions of a rotated tooth. pparently there exists little e"idence that the periodontal ligament and its al"eolar tissue play any significant part in rotation relapse after  to 6 months of mechanical retention. retention. Thompson /'(8>2 '( and Boese /'(892 >,( remo"ed all of the attached gingi"al fibers lea"ing only the mucosa surrounding the rotated teeth in experimental animals and reported a significant reduction in relapse after an initial retention of 7 to > weeks. They concluded that two phases of orthodontic rotational relapse can be identified /2 1uring the first 7 weeks

'>(

Retention and relapse in orthodontics following orthodontic rotation of a tooth< a significant proportion of relapse is caused by the stretched principal fibers. This phase terminates before > weeks, when remodeling o f al"eolar bone pro"ides new attachment for the principal fibers. /B2 fter first > weeks, the relapse is caused caused by the supraa supraal"e l"eola olarr fibers fibers.. This This phase phase continu continues es until until almost almost total total relaps relapsee has occurre occurred, d, since since the cement cemental al attachm attachment ent of the transs transsept eptal al fibers fibers remain remain unchange unchanged. d. =ingi"ectomy followed by a minimum of > weeks of retention significantly reduced relapse to one tenth its normal.  retention of only 7 weeks marks the effecti"eness of gingi"ectomy, because the first phase of relapse is still in progress. The number of oxytalan fibers and the amount of collagen in the supra!al"eolar tissue appear increased by orthodontic rotation. This proliferate response, combined with stable attachments of transseptal fibers, seems responsibl responsiblee for the second phase of orthodontic orthodontic relapse. relapse. They concluded that procedures of o"errotation and prolonged retention would b e ineffecti"e for pre"enting rotational relapse.

Prosthetic 6etention Procedures:  #f one or more teeth are missing, the usual solution is to replace them with bridges, which are designed according to the si%e and location of edentulous areas. ometimes, prosthodontic inter"ention may be re-uired to impro"e the position of abutment teeth for fixed prosthesis, e.g. in cases of mesially tilted molars, displaced teeth and in cases of partial anodontia etc. Crecautions should be taken to deli"er the fixed partial denture as early as possible after crown preparation so as to a"oid inad"ertent tooth shifting during the waiting period. o, tempora temporary ry restor restorati ation on should should be deli"e deli"ered red to the patien patientt immedi immediate ately ly after after crown crown preparation.'78

'()

Retention and relapse in orthodontics occlusion, Ronald Roth. Cremature contacts and plunger cusps could be detrimental to the stability and health of the stomatognathic system.

$%ofunctional therap%:  The proponents of the myofunctional therapy ad"ocate the management of tongue thrust thrust and open open bite bite cases cases with with well!p well!pres rescri cribed bed tongue tongue exerci exercises ses for stable stable result results. s. :ip exercises and other muscle exercises like the masseter exercise, temporalis muscle exercise and others others ha"e been been ad"ocat ad"ocated ed since since the time immemo immemoria riall for stable stable result results. s. :ip seal seal exercises are strongly ad"ocated by 5rankel for open bite cases and he firmly belie"es that when lip seal has not been established the correction of open bite cannot be stable.

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iscussion Time Time was when when the Orthod Orthodont ontist ist regard regarded ed treatm treatment ent of maloccl malocclusi usion on as a stati staticc mechanical procedure. 1iagnosis restricted itself to the description of the malocclusion and treatm treatment ent to the correc correctio tion n of irregul irregulari aritie tiess found found in indi"i indi"idual dual patien patients ts mouth, mouth, without without regard regarding ing the multif multifact actori orial al etiolo etiologic gical al factor factors, s, resist resistanc ancee offeri offering ng biolog biologica icall tissue tissues, s, functioning orofacial musculature and a proper dynamic functional occlusion. d"ancements in biotechni-ues, physical diagnosis, surgical orthodontics, computer case analysis, socio! biology and use of o f sophisticated armamentarium, though has helped the ongoing research in the orthodontic practice, eliminating of relapse of treated malocclusions presents a persisting annoying problem to the practicing orthodontist. The stomatognathic system is "ulnerable to "arious etiological factors and each of the components of the dentofacial complex follows its own independent course of de"elopment. ;ence, the etiology of dentofacial abnormality does not lend itself readily to a cause and effect diagnosis, excepting cases with specific etiologies like trauma, congenital and genetic malformations and pressure habits. The positional changes of teeth affected alteration of maxillo!mandibular relation and position of the mandible with the teeth in occlusion, a changed configuration of the %one of tongue mo"ement, when interfered with, disturbs the kinesthetics of the patient*s functional pattern and the patient experiences dyskinesia. d yskinesia.  changing kinesthetic functioning dynamics is well tolerated by young children than by adults in which cases it is an in"itation for relapse. #n order for the teeth to retain their position at rest and in function, the denture should ha"e a sound static occlusion, minimal interference from the periodontal tissues, efficient masticatory system without "iolating the arch form and the soft tissue en"ironment, a coinciding centric occlusion and centric relation with all three tissue systems namely skeletal, dental and neuromuscular in harmony with each other. The state of orthodontics does not at present contain information on the extent and limits of the area of tolerance, where the mo"ed teeth will experience immediate functional balance in the in"esting tissues. Retaining appliances are necessary as an aid in stabili%ing the mo"ed teeth. t present, how long retention should be, is something the orthodontist learns by trial and error.

'(

Retention and relapse in orthodontics The problem of “retention and relapse” is likely to continue to tense the Orthodontist because of the complexities of the etiological factors and one has to be thorough with all the implicating concepts. The choice of the type of retention, duration of retention, has a great bearing on successful post retention cases. ny "iolation of the biologic limit, which trespasses the low of optimality, optimality, will end in miserable failure.

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>ummar% Orthodontic history tells us that esthetics was the primary concern of treatment in its beginning in the first century and from then onwards it has spawned contro"ersy. contro"ersy. 0stabl 0stablish ishmen mentt of proper proper static static functi functional onal occlus occlusion ion,, mainta maintaini ining ng arch arch form form and intercanine width, correct positioning of lower incisors, permitting reorgani%ation of the periodontal tissues, eliminating etiological factors, o"er!correction, establishing balance in threeLtissue system and proper understanding of growth and de"elopment are cardinal points in establishing an esthetically harmonious, functionally efficient and structurally balanced dental arches in the area of functional tolerance. Iiolation Iiolation of the law of optimality is likely to re+ect the alteration imposed on an existing orofacial en"ironment. The summary of "arious theoretical models of stability and relapse are well tabulated b y 0nlow. $hile it is essential to stri"e for an ideal result, orthodontics as an art and science harbors sub+ecti"e goals that are constantly changing. There can be no guarantee of results< only probabilities expressed and these should be communicated realistically to the patient. #n analy%i analy%ing ng some some of the proble problem m areas, areas, we recogn recogni%e i%e insuff insuffici icient ent case case analy analysis sis prior prior to treatment as the first step towards failure.  careful examination of the original records will gi"e "aluable guidance concerning the duration and type of retention indicated for each case. Retention is considered to be one of the most fascinating and on the other hand it is considered the most important aspect of orthodontic treatment as far as treatment results and stability from the patient and from the operator*s point of "iew. :ong back it had been called as the stepchild of orthodontics since no attention was paid towards this aspect. 0"en today debate still continues regarding post treatment stability and the role!played by retainers in pro"iding this stability. 0"en after so much of ad"ancement, great deal of studies< research is still re-uired on this sub+ect. Our results will impro"e as we stri"e for perfection and realistically balance the scale with more planning for retention.  thorough thorough knowledge of retention is necessary for those of us with bruised egos and a desire to impro"e.

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6eferences '2 Croff Croffit it $R, 5ields 5ields ;$, ;$, ckerm ckerman an 3:, Bailey Bailey :3, Tulloc Tulloch h 35. 35. Gontempor Gontemporary ary Orthodontics. 6rd ed. t. :ouis4 Mosby< ))). 2 hapiro hapiro C, C, Kokich Kokich I=. The rationa rationale le for "ariou "ariouss modes modes of retent retention ion.. ymp ymp Orthod 1ent Glinics @orth merica '(>'< 8/'24'HH!'(6. 62 Moye Moyers rs R0. ;andboo ;andbook k of Orthod Orthodon onti tics cs.. 7th ed. Ghicago4 Qear Book Medical Cublishers< '(>>. 72 =raber TM, TM, wain B5. Gurrent Gurrent Orthodonti Orthodonticc Crinciples Crinciples and Techni-ue Techni-ues. s. t. :ouis4 Mosby< ))). 82 Reitan Reitan K. Crinci Crinciple pless of retentio retention n and a"oidance a"oidance of posttr posttreat eatmen mentt relaps relapse. e. m 3 Orthod 1entofacial Orthop '(9(< 884 6)!77. 92 Kaplan Kaplan ;. The logic of modern modern retenti retention on procedure procedures. s. m 3 Orthod Orthod 1entofa 1entofacia ciall Orthop '(>>< (6/72468!67). H2 =raber TM, TM, Ianarsd Ianarsdall all R:. Orthodontics Orthodontics Gurrent Gurrent Crinciples Crinciples and Techni-u Techni-ues. es. 6rd ed. t. :ouis4 Mosby< ))). >2 Riedel Riedel R.  re"iew re"iew of the retent retention ion problem problem.. ngle ngle Orthod Orthod '(9)< 6)/724 6)/724 'H(! '((. (2 Klon Klontt% ;, Ialden den 3:, 3:, 1ale 1ale 3=. Tweed eed Merr errifi ifield eld 0dgew dgewiise appl appliiance ance philosophy, diagnosis diagnosis and treatment planning. nd ed. ')2 @anda R, Burstone Burstone G3. Retention Retention and tability tability in Orthodonti Orthodontics. cs. Chiladelphia4 Chiladelphia4 $.B. aunders Gompany. ''2 ''2 B+or B+ork k , kie kiell ller er I. 5acia 5aciall de"el de"elopm opment ent and toot tooth h erup erupti tion on.. m 3 Orth Orthod od 1entofacial Orthop '(H< 9/72466(!6>6. '2 B+ork B+ork , Odont Odont 1r. 1r. Credic Credictio tion n of mandib mandibular ular growth growth rotati rotation. on. m 3 Orthod Orthod 1entofacial Orthop '(9(< 88/924 8>8!8((. '62 tockli tockli C$ C$,, Teuscher Teuscher AM. Gombined Gombined acti"ator acti"ator headgear orthopedics. orthopedics. #n =raber =raber TM, wain B5 /eds.24 Gurrent Orthodontic Crinciples Crinciples and Techni-ues. Techni-ues. t. :ouis4 Mosby. '(>8, pp. 7)8!7>6. '72 Ahde M1, andowsky G, Be=ole 0. :ong!term stability of dental relationships after orthodontic treatment. ngle Orthod '(>6< 86/624 7)!8.

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Retention and relapse in orthodontics '82 olow B. The dentoal"eolar dentoal"eolar compensatory compensatory mechanism4 Background Background and clinical clinical implications. Brit 3 Orthod '(>H< H4 '78!'9'. '92 @anda @anda R, @anda @anda K. Gonsi Gonsider derati ations ons of dernto derntofac facial ial growth growth in long!t long!term erm retent retention ion and stabil stability ity44 #s acti"e acti"e retent retention ion needed& needed& m 3 Orthod Orthod 1entof 1entofaci acial al Orthop '((< ')'/724 (H!6). 'H2 @anda @anda K. Catter Catterns ns of "ertic "ertical al growth growth in the face. m 3 Orthod Orthod 1entof 1entofaci acial al Orthop '(>>< (6/24 ')6!''9. '>2 @anda @anda K. Gircum Gircumpube pubert rtal al growth growth spurt spurt relate related d to "erti "ertical cal dyspla dysplasia sia.. ngle ngle Orthod '(>(< 8(/24 ''6!'. '(2 lexander lexander R=. The Iari!i Iari!implex mplex 1iscipline 1iscipline Cart 7 Gountdown Gountdown to Retention. Retention. 3 Glin Orthod '(>6< 'H/(24 9'(!98. )2 Mc:aughlin RC, Bennett3G. 5inishing and detailing with a pread+usted appliance system. 3 Glin Orthod '(('< 8/724 8'!97. '2 Muchnic ;I. Retention or continuing treatment. m 3 Orthod 1entofacial Orthop '(8H< 8H/'24 6!67. 2 ;orowit% ;orowit% :, ;ixon 0;. Chysiologic Chysiologic reco"ery reco"ery following orthodontic orthodontic treatment. treatment. m 3 Orthod 1entofacial Orthop '(9(< 884 '!7. ' !7. 62 King 0$. Relapse of orthodontic treatment. ngle ngle Orthod '(H7< 77/724 6))!6'8. 72 Richardson Richardson M0. The etiology of late lower arch crowding alternati"e alternati"e to mesially mesially directed forces4  re"iew. m 3 Orthod 1entofacial Orthop '((7< ')8/924 8(! 8(H. 82 ;ouston ;ouston $3B, tephens tephens G1, Tulley Tulley $3, 5oster 5oster M0, Mars Mars M, Coswil Coswillo lo 1.  textbook of Orthodontics. nd ed. Oxford4 $right< '(>9. 92 Blake Blake M, Bibby Bibby K. Retent Retention ion and stabil stability ity44  re"iew re"iew of the literatu literature. re. m 3 Orthod 1entofacial Orthop '((>< ''7/624 ((!6)9. H2 =ilmor =ilmoree G, :ittl :ittlee RM. Mandibula Mandibularr inciso incisorr dimens dimension ionss and crowdi crowding. ng. m 3 Orthod 1entofacial Orthop '(>7< >9/924 7(6!8). >2 Boese :R. 5iberotomy 5iberotomy and reproximat reproximation ion without lower retention, retention, nine years in retrospect4 Cart #. ngle Orthod '(>)< 8)/24 >>!(H. (2 Boese :R. 5iberotomy 5iberotomy and reproximat reproximation ion without lower retention, retention, nine years in retrospect4 Cart ##. ngle Orthod '(>)< 8)/624 ' 9(!'H>.

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Retention and relapse in orthodontics 6)2 :ittle :ittle RM, $allen allen TR, Riedel Riedel R. tability tability and relapse of mandibular mandibular anterior anterior alignm alignment ent L first first premola premolarr extrac extractio tion n cases cases treat treated ed by tradit tradition ional al edgewi edgewise se orthodontics. m 3 Orthod 1entofacial Orthop '(>'< >)/724 67(!698 6'2 ;aas 3. 3. :ong!term posttreatment posttreatment e"aluation of rapid rapid palatal expansion. ngle Orthod '(>)< 8)/624 '>(!'H. 62 andstr andstrom om R, Klapper Klapper :, Capacons Capaconstan tanti tinou nou . 0xpansi 0xpansion on of the lower arch arch concurr concurrent ent with with rapid rapid maxill maxillary ary expans expansion ion.. m 3 Orthod Orthod 1entofa 1entofacia ciall Orthop Orthop '(>>< (7/724 (9!6). 662 Moussa R, O*Reilly MT, MT, Glose 3M. :ong!term stability stability of rapid palatal expander treatment and edgewise mechanotherapy. m 3 Orthod 1entofacial Orthop '((8< ')>/824 7H>!7>>. 672 1e :a Gru% , ampson C, :ittle RM, rtun rtun 3, hapiro C. :ong!term changes in arch form after orthodontic treatment and retention. m 3 Orthod 1entofacial Orthop '((8< ')H/824 8'>!86). 682 Reitan Reitan K. Tissue Tissue rearrangement rearrangement during retention retention of orthodontic orthodontically ally rotated teeth. ngle Orthod '(8(< (/24 ')8!''6. 692 0dwards 3=.  study of the periodontium during orthodontic rotation of teeth. m 3 Orthod 1entofacial Orthop '(9>< 87/924 77'!79'. 6H2 Redlic Redlich h M, Rahami Rahamim m 0, =aft =aft , hosha hoshan n . The response response of supraa supraal"e l"eola olar r gingi" gingi"al al collag collagen en to orthodo orthodonti nticc rotati rotation on mo"eme mo"ement nt in dogs. dogs. m 3 Orthod Orthod 1entofacial Orthop '((9< '')/624 7H!88. 6>2 trang trang R;$. R;$. The fallacy of denture denture expansion expansion as a treatment treatment procedure. procedure. ngle Orthod '(7(< '(/'24 '!. 6(2 $oodside $oodside 1=. Round table4 extra oral force. 3 Glin Orthod '(H)< '7/')24 '7/')24 887! 8HH. 7)2 Broadbent Broadbent B;. Ontogenic Ontogenic de"elopment de"elopment of occlusion. ngle ngle Orthod '(7'< ''4 6!7'. 7'2 Kaplan R=. Mandibular third molars and postretenti postretention on crowding. crowding. m 3 Orthod Orthod 1entofacial Orthop '(H7< 99/724 7''!76). 72 ndrews :5. The six keys to normal occlusion. m 3 Orthod 1entofacial Orthop '(H< (9!6)(.

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Retention and relapse in orthodontics 762 Bolton $. $. 1isharmony 1isharmony in tooth si%e and its relation to the analysis and treatment of malocclusion. ngle Orthod '(8>< >/624 ''6!'6). 772 Ceck ;, Ceck . n index for assessing assessing tooth shape de"iations de"iations as applied applied to the mandibular incisors. m 3 Orthod 1entofacial Orthop '(H< 9'/724 6>7!7)'. 782 Kuftinec Kuftinec M. 0ffect 0ffect of edgewise edgewise treatment and retention on mandibular incisors. incisors. m 3 Orthod 1entofacial Orthop '(H8< 9>4 6'9!6. 6 '9!6. 792 illmann 3;. 1imensional changes of dental arches longitudinal study from birth birth to 8 years. m 3 Orthod 1entofacial Orthop '(97< 8). 7H2 McGaul McGauley ey 1R. The cuspid cuspid and its function function in retent retention ion.. m 3 Orthod Orthod Oral Oral urgery '(6>< 7. 7>2 trang trang R;$. R;$. 5actors 5actors of influence influence in producing a stable stable result result in treatment treatment of malocclusions. m 3 Orthod '(79< 6. 7(2 @anc @ancee ;. 5act 5actor orss of infl influe uenc ncee in produ produci cing ng a stabl stablee resu result lt in trea treatm tment ent of malocclusions. m 3 Orthod '(79< 6. 8)2 $a $alter lterss 1G. Gomparati"e Gomparati"e changes in mandibular mandibular canine and first first molar widths. widths. ngle Orthod '(9< 6/724 6!7'. 8'2 hapi hapiro ro C. Mand Mandib ibul ular ar dent dental al arch arch form form and dime dimens nsio ion. n. Trea Treatm tmen entt and and postretention changes. m 3 Orthod 1entofacial Orthop '(H7< 99/'24 8>!H). 82 =ardner =ardner 1, Ghaconas 3. Costtreat Costtreatment ment and postreten postretention tion changes following following orthodontic treatment. ngle Orthod '(8>< 79/24 '8'!'9'. 862 trang trang R;$. R;$.  textbook textbook of Orthodonti Orthodontists. sts. 'st ed. Chiladelphia4 :ea and 5ibiger< '(8). 872 imons imons M0, 3oondeph 1R. Ghange in o"erbite4 o"erbite4  ten!year ten!year postretenti postretention on study. study. m 3 Orthod 1entofacial Orthop '(H6< 97/'24 67(!69H. 882 hields hields T0, :ittle :ittle RM, Ghapko MK. tability tability and relapse relapse of mandibular mandibular anterior anterior alignment4  cephalometric appraisal of first!premolar!extraction cases treated by traditional edgewise orthodontics. m 3 Orthod 1entofacial Orthop '(>8< >H/'24 H!6>. 892 inclair CM, :ittle RM. Maturation Maturation of untreated normal occlusions. m 3 Orthod 1entofacial Orthop '(>6< >6/24 ''7!'6.

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Retention and relapse in orthodontics 8H2 wans wanson on $1, $1, Riede Riedell R, R, 1*n 1*nna na 3. 3. Cost Costre rete tent ntio ion n study study44 #nci #ncide denc ncee and stability of rotated teeth in humans. ngle Orthod '(H8< 78/624 '(>!)6. 8>2 :ittle :ittle R. The irregul irregulari arity ty index4 index4  -uanti -uantitat tati"e i"e score score of mandib mandibula ularr anteri anterior or alignment. m 3 Orthod 1entofacial Orthop '(H8< 9>4 887!896. 8(2 :ittle :ittle R, Riedel R. Costretention Costretention e"aluation of stability stability and relapse!ma relapse!mandibul ndibular ar arches with generali%ed spacing. m 3 Orthod 1entofacial Orthop '(>(< (8/'24 6H!7'. 9)2 adowsk adowsky y G, akols akols 0#. :ong!t :ong!term erm assess assessmen mentt of orthodo orthodonti nticc relaps relapse. e. m 3 Orthod 1entofacial Orthop '(>< >/924 789!796. 9'2 =lenn =lenn =, incla inclair ir CM, lexa lexande nderr R=. @onext @onextrac ractio tion n orthod orthodont ontic ic therapy therapy44 Costtreatment dental and skeletal stability. m 3 Orthod 1entofacial Orthop '(>H< (/724 6'!6>. 92 Riedel R.  postretention e"aluation. ngle Orthod '(H7< 77/624 '(7!'. 962 chwart% ;. The case against biomechanics. ngle ngle Orthod '(99< 6H/'24 8!8>. 972 Ricketts Ricketts RM, Bench R$, R$, =ugino G5, ;ilgers ;ilgers 33, chulhof chulhof R3. Bioprogressi"e Bioprogressi"e therapy. nd ed. Rocky Mountain< '(>). 982 Mc@ama Mc@amara ra 3. The de"elo de"elopme pment nt of occlus occlusion ion and facial facial balance, balance, centre centre for growth and de"elopment. ymposium. 992 Croff Croffit it $R. $R. 0-uili 0-uilibri brium um theory theory re"isi re"isited ted44 5actors 5actors influe influenci ncing ng posit position ion of the teeth. ngle Orthod '(H>< 7>/624 'H8!'>9. 9H2 Bishara Bishara 0. Third Third molars4 molars4 dilemmaX dilemmaX Or is it& m 3 Orthod 1entofacial 1entofacial Orthop '(((< ''8/924 9>!966. 9>2 Iego Iego :.  longitudinal study of mandibular arch perimeter. ngle Orthod '(9< 6/624 '>H!'(. 9(2 :ind-"i :ind-"ist st B, Thilan Thilander der B. 0xtrac 0xtractio tion n of third third molars molars in cases cases of antici anticipat pated ed crowding in the lower +aw. m 3 Orthod 1entofacial Orthop '(>< >'/24 '6)! '6(. H)2 des des =, =, 3oonde 3oondeph ph 1R, :ittle :ittle RM, Ghapko MK.  long!te long!term rm study study of the relationship of third molars to changes in the mandibular arch. m 3 Orthod 1entofacial Orthop '(()< (H/724 66!668.

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Retention and relapse in orthodontics H'2 Kahl!@ieke Kahl!@ieke B, 5ischbach 5ischbach ;, chwar%e chwar%e G$. G$. Cost retention retention crowding crowding and incisor incisor irregularity4  long term follow up e"aluation of stability and relapse. Brit 3 Orthod '((8< 4 7(!8H. H2 outhar outhard d T0, outha outhard rd K, $eeda :$. Mesial Mesial force force from from unerupt unerupted ed third third molars. m 3 Orthod 1entofacial Orthop '(('< ((/624 )!8. H62 Cirtti Cirttinie niemi mi CM, Oikarine Oikarinen n K, Raustia Raustia M. The effect effect of remo"a remo"all of all third molars on the dental arches in the third decade of life. Granio '((9< '4 6!H. H72 ;aas 3. Calatal Calatal expansion4 3ust the beginning beginning of dentofacial dentofacial orthopedics. orthopedics. m 3 Orthod 1entofacial Orthop '(H)< '(!88. H82 Mew Mew 3. Rela Relaps psee foll followi owing ng maxi maxill llar ary y expa expans nsio ion4 n4  stud study y of twen twenty ty!f !fi" i"ee consecuti"e cases. m 3 Orthod 1entofacial Orthop '(>6< >6/'24 89!9'. H92 rndt $I. $I. @ickel titanium titanium palatal expander. 3 Glin Orthod '((6< H/624 '(!'6H. HH2 $it%ig $it%ig 3$, pahl T3. The clinical management of basic maxillofacial orthopedic appliances. Iolume Iolume # mechanics. 'st ed. t. :ouis4 Mosby< '(('. H>2 Coulton Coulton 1R, $are $;. $;. urgi urgical cal!or !ortho thodont dontic ic treatm treatment ent of se"ere se"ere mandib mandibula ular r retrusion /Cart#2. m m 3 Orthod 1entofacial Orthop '(H'< 8(4 77!98. H(2 Coulton Coulton 1R, $are $;. $;. urgi urgical cal!or !ortho thodont dontic ic treatm treatment ent of se"ere se"ere mandib mandibula ular r retrusion /Cart##2. m 3 Orthod 1entofacial Orthop '(H6< 96 /624 6H!88. >)2 Mc@eill Mc@eill R$, R$, ;ooley 3R, undberg R3. keletal keletal relapse relapse during intermaxill intermaxillary ary fixation. 3 Oral urg '(H6< 6'4 '!H. >'2 chende chendell , 0pker 0pker B@. Result Resultss after after mandib mandibula ularr ad"anc ad"anceme ement nt surger surgery4 y4 n analysis of >H cases. 3 Oral urg '(>)< 6>4 98!>. >2 :ake :, Mc@eill R$, R$, :ittle RM, $est $est R. urgical mandibular ad"ancement4 a d"ancement4  cephalometric analysis of treatment response. m 3 Orthod 1entofacial Orthop '(>'< >)/724 6H9!6(7. >62 chendel chendel , 0isenfeld 0isenfeld 3;, Bell $;, 0pker B@. uperior uperior repositioning repositioning of the maxilla4 tability and soft tissue osseous relations. m 3 Orthod 1entofacial Orthop '(H9< H)/924 996!9H7. >72 >72 Bram Bramme merr 3, 5inn 5inn R, Bell Bell $;, inn inn 1, Reis Reisch ch 3, 1ana 1ana K. tab tabil ilit ity y afte after r bimaxillary surgery to correct "ertical maxillary excess and mandibular deficiency. 3 Oral urg '(H6< 6>4 997!9H).

))

Retention and relapse in orthodontics >82 $orms $orms 5$, peidel TM, Be"is RR, $aite $aite 10. Costtreatment stability esthetics of orthognathic surgery. ngle Orthod '(>)< 8)/724 8'!H6. 8'!H6 . >92 0llis 0llis 0 ###, Garlson Garlson 1. tability tability two years after mandibular mandibular ad"ancement with and without suprahyoid myotomy4 n experimental study. 3 Oral Maxillofacial urg '(>6< 7'4 79!76H. >H2 Booth 15. Gontrol Gontrol of the proximal fragment by lower border wiring in the sagittal split osteotomy. 3 Maxillofacial urg '(>'< (4 '9!'>. >>2 Bennet Bennettt M, $olf $olford ord :M. The maxill maxillary ary step step osteot osteotomy omy and teinm teinmann ann pin stabili%ation. 3 Oral Maxillofacial urg '(>8< 764 6)H!6''. >(2 >(2 Gham Ghampy py M, :odd :oddee 3C, 3C, chm chmiitt R, 3aege aegerr 3;, Must Muster er 1. Mand Mandiibula bular r osteosynthesis by miniature screwed plates "ia a buccal approach. 3 Maxillofacial urg '(H>< 94 '7!'. ()2 0llis 0, =allow $3. $3. Relapse following mandibular mandibular ad"ancement with dental plus skeletal fixation. 3 Oral Maxillofacial urg '(>9< 774 8)(!8'6. ('2 :uyk @;, $ard!Boot ard!Booth h RC. RC. The stability stability of :e5ort :e5ort # ad"ancement ad"ancement osteotomie osteotomiess using bone plates without bone grafts. 3 Maxillofacial urg '(>8< '64 8)!86. (2 andor =K, toelinga R3, Tideman Tideman ;. The role of intraosseo intraosseous us osteosynthesis osteosynthesis wire wire in sagi sagitt ttal al spli splitt oste osteot otom omie iess for for mand mandib ibul ular ar ad"a ad"anc ncem emen ent. t. 3 Oral Oral Maxillofacial urg '(>7< 64 6'. (62 $a $atske tske #M, Tur"ey Tur"ey T, T, Chillips Chillips G, Croffit Croffit $R. tability tability of mandibular mandibular after sagitt sagittal al osteot osteotomy omy with with screw screw or wire wire fixati fixation4 on4  comparat comparati"e i"e study study.. 3 Oral Oral Maxillofacial urg '(()< 7>4 ')>!''. (72 Gaskey RT, RT, Turpin Turpin 1:, Bloom-uist 1. tability of mandibular lengthening using bicortical screw fixation. m m 3 Orthod 1entofacial Orthop '(>(< (9/724 6)!69. (82 Bare Barerr C=, C=, $allen llen TR, TR, Mc@e Mc@eil illl R$, Reit Reit%i %ik k M. tab tabil ilit ity y of mandi mandibul bular ar ad"ancement osteotomy using rigid internal fixation. m 3 Orthod 1entofacial Orthop '(>H< (/824 7)6!7''. (92 Ian Ian ickels 30, :arsen 3, Thrash $3. $3. Relapse after rigid fixation of mandibular ad"ancement. 3 Oral Maxillofacial urg '(>9< 774 9(>!H) .

)'

Retention and relapse in orthodontics (H2 Kobayashi Kobayashi T, $at $atanabe anabe #, Aede K. tability tability of the mandible after sagittal sagittal ramus osteotomy for the correction of prognathism. 3 Oral Maxillofacial urg '(>9< 774 9(6!9(H. (>2 Rosen-uist Rosen-uist B, Rune B, el"ik el"ik =. 1isplacemen 1isplacementt of the mandible mandible after remo"al of the the inte interm rmax axil illa lary ry fixa fixati tion on foll follow owin ing g obli obli-u -uee slid slidin ing g oste osteot otom omy y. 3 Oral Oral Maxillofacial urg '(>9< '74 8'!8(. ((2 5ranco 30, Ian Ian ickels ickels 30, Thrash $3. 5actors contributing contributing to relapse relapse in rigidly rigidly fixed mandibular setbacks. 3 Oral Maxillofacial urg '(>(< 7H4 78'!789. '))2

Croffit Croffit $R, Chilli Chillips ps G, Tur"ey Tur"ey T.. tability tability follow following ing superior superior repositioni repositioning ng

of the maxilla by :e5ort # osteotomy. m 3 Orthod 1entofacial Orthop '(>H< (/24 '8'!'9'. ')'2

Bishara Bishara 0, Ghu =$, =$, 3akobsen 3akobsen 3. tability tability of the :e5ort :e5ort # one!piece one!piece maxill maxillary ary

osteotomy. osteotomy. m 3 Orthod 1entofacial Orthop '(>>< '(>> < (7/624 '>7!)). ')2 ')2

Tur" Tur"ey ey T, Chil Chilli lips ps G, ayt aytoun oun ;, Crof Croffi fitt $R. $R. imu imult ltan aneou eouss supe superi rior or

repo reposi siti tion onin ing g of the the maxi maxill llaa and mandi mandibul bular ar ad"an ad"ance ceme ment nt.. m 3 Orth Orthod od 1entofacial Orthop '(>>< (7/824 6H!6>6. ')62

atrom atrom K1, incl inclair air CM, CM, $olfo $olford rd :M. The The stabil stability ity of double double +aw +aw surgery surgery44 

comparison of rigid "ersus wire fixation. m 3 Orthod 1entofacial Orthop '(('< ((/924 88)!896. ')72

Teusc Teuscher her A, ailer ailer ;5. ;5. The The stabilit stability y of :e5ort :e5ort # osteot osteotomy omy in Glass Glass ### cases cases

with repositioned maxillae. 3 Maxillofacial urg '(>< ')4 >)!>6. ')82 ')82

$eiss iss M3, M3, Catt Catty y , Chil Chilli lips ps G. 1ent 1ental al and and skel skelet etal al stab stabil ilit ity y foll follow owin ing g

maxillary ad"ancement. 3 1ent Res '(>(< 9>4 8( /abstr. 982. ')92

$ardro ardrop p R$, R$, $olfo $olford rd :M. Maxill Maxillary ary stabil stability ity followi following ng downgraft downgraft andJor andJor

ad"ancement procedures with stabili%ation using rigid fixation and porayblock hydroxylapetite implants. 3 Oral Maxillofacial urg '(>(< 7H4 669!67. ')H2

;edemark ;edemark , 5reihofer 5reihofer ;C. ;C. The beha"io beha"iorr of the maxill maxillaa in "ertical "ertical mo"emen mo"ements ts

after the :e5ort # osteotomy. 3 Oral Maxillofacial urg '(H>< 94 77. ')>2 ')>2

Bell Bell $;, che cheid idem eman an =B. =B. Gorr Gorrec ecti tion on of "ert "ertic ical al maxi maxill llar ary y defi defici cien ency cy44

tability and soft tissue changes. 3 Oral Maxillofacial urg '(>'< 6(4 999!9H).

)

Retention and relapse in orthodontics ')(2 ')(2

Cer Cersson sson =, ;el ;ellem , @ord @ord C=. C=. Bone Bone plat plates es for stabi tabili li%i %ing ng :e5o :e5ort rt #

osteotomies. 3 Oral Maxillofacial urg '(>9< '74 9(!H6. '')2 '')2

chaer chaerer er C, tall tallard ard R0, ander ander ;. Occlusa Occlusall interfer interference encess and masticat mastication ion44

n electromyographic study. 3 Crosthet 1ent '(9H< 'H4 76>!77(. '''2 '''2

:askin :askin 1 et al. The The Creside Cresident* nt*ss Gonfer Gonference ence on the the examina examinatio tion, n, diagnos diagnosis is and

management of temporomandibular disorders. m 1ent ssoc ssoc '(>6, pp.'!>7. ''2 ''2

meric merican an cademy cademy of Cediatr Cediatric ic 1entistr 1entistry y. Treatm Treatment ent of tempor temporoma omandi ndibul bular ar

disorders in children4 ummary statements and recommendations. 3 m 1ent ssoc '(()< ')4 98!9(. ''62 ''62

Roth Roth R;. Tempo Temporom romandi andibul bular ar pain!dys pain!dysfun functi ction on and occlus occlusal al relation relationshi ships. ps.

ngle Orthod '(H6< 76/24 '69!'86. ''72 ''72

ado adows wsky ky G, Be=o Be=ole le 0. 0. :ong :ong!t !ter erm m stat status us of temp tempor orom oman andi dibu bula larr +oin +ointt

functi function on and function functional al occlus occlusion ion after after orthodo orthodonti nticc treatm treatment ent..

m 3 Orthod Orthod

1entofacial Orthop '(>)< H>/24 )'!'. ''82 ''82

ado adows wsky ky G, Cols Colson on M. Temporo poroma mand ndib ibul ular ar diso disord rder erss and and func functi tion onal al

occlusion after orthodontic treatment4 Results of two long!term studies. m 3 Orthod 1entofacial Orthop '(>7< >9/824 6>9!6(). ''92 ''92

Oppe Oppenhe nheim im . . #nt 3 Orthod Orthod '(67< '(67< 94 Vuote Vuoted d from Reid Reidel el R4  re"i re"iew ew of

retention problem. ngle Orthod '(9)< 6)/724 'H(!'((. ''H2

$illia $illiams ms R. 0liminati 0liminating ng lower lower retenti retention. on. 3 Glin Orthod Orthod '(>8< '(>8< '(/824 '(/824 67!67(. 67!67(.

''>2

Carker =R. Trans Transsepta septall fibers fibers and and relapse relapse follow following ing bodily bodily retraction retraction of teeth4 teeth4

 histologic study. study. m 3 Orthod 1entofacial Orthop '(H< 9'/724 9 '/724 66'!677. ''(2 ''(2

Thomps Thompson on ;0. Orthodo Orthodonti nticc relapse relapsess analy%e analy%ed d in a study study of connect connecti"e i"e tissu tissuee

fibers. m m 3 Orthod 1entofacial Orthop '(8(< 78/24 78 /24 (6!')(. ')2

5ried 5ried K;. 0moti 0motional onal stres stresss during during retent retention ion and its its effect effect on tooth tooth positi position. on.

ngle Orthod '(H9< 79/'24 HH!>8. ''2 ''2

Bhal Bhala+ a+hi hi #. #. Ortho Orthodo dont ntic icss 4 The The art art and scie scienc nce. e. 6rd ed. @ew 1elhi4 rya

/Medi2 Cublishing ;ouse< ))6. '2 '2

=rab =raber er TM. Orth Orthodo odont ntic ics4 s4 Crinci Crincipl ples es and Cract Cractic ice. e. 6rd ed. Chiladelphia4 $.B.

aunders Gompany< '((.

)6

Retention and relapse in orthodontics '62 '62

Bahr Bahrem eman an . Modifi Modified ed ;awley ;awley applia applianc ncee for for bette betterr rete retent ntio ion n of cuspid cuspids. s. 3

Glin Orthod '(HH< ''/')24 9>(. '72

3errold 3errold :.  Toothbor Toothborne ne ;awley ;awley type type retainer retainer.. 3 Glin Glin Orthod Orthod '(>7< '>/724 >!

>6. '82

:e"it :e"ittt ;:. ;igh ;igh :abia :abiall Retain Retainer er.. 3 Glin Glin Ortho Orthod d '(H< '(H< 9/'24 9/'24 68!6( 68!6(..

'92

hilli hilliday day 13.  Remo"ab Remo"able le Guspid! Guspid!to! to!Gus Guspid pid Retain Retainer er.. 3 Glin Glin Orthod Orthod '(H6<

H/24 ''>!'). 'H2

;offman ;offman G5. G5. Remo"able Remo"able 9!9 9!9 Metal Metal Retaine Retainer. r. 3 Glin Glin Orthod Orthod '(H6< '(H6< H/624 '().

'>2

Brin Brin #, ilber ilberman man Q, Q, Ten Tennen nenhaus haus ;. @on!cr @on!cryl ylic ic Remo"abl Remo"ablee Retain Retainer er.. 3 Glin Glin

Orthod '(>7< '>/(24 97'. '(2

lpern lpern MG, MG, ;yden ;yden :. Gontinu Gontinuous ous Glear Glear Retai Retainer ner.. 3 Glin Glin Orthod Orthod '(>7< '(>7< '>/H24 '>/H24

7(7!7(9. '6)2

1eal 1eal C:. Retain Retainer er plin plint. t. 3 Gli Glin n Orthod Orthod '(9H< '(9H< '/''2 '/''244 '7. '7.

'6'2

;owe RC RC. Remo"able Remo"able Clastic Clastic ;erbst ;erbst Retainer Retainer.. 3 Glin Orthod Orthod '(>H< '/>24 866!

86H. '62 '62

her heriidan dan 33, 33, :edo :edoux ux $, Mcm Mcminn R. 0ssi ssix Reta Retaiiner4 ner4 5abr 5abric icat atio ion n and and

super"ision for permanent retention. 3 Glin Orthod '((6< H/'24 6H!78. '662

$ang 5. 5.  @ew Therm Thermoplast oplastic ic Retainer Retainer.. 3 Glin Glin Orthod Orthod '((H< '((H< 6'/''24 6'/''24 H87!H8H. H87!H8H.

'672

Knieri Knierim m R$. R$. #n"isib #n"isible le lower lower Guspid Guspid to Guspid Guspid Retain Retainer er.. ngle ngle Orthod Orthod '(H6< '(H6<

76/24 '>!). '682

$olfson olfson 3, 3, er"oss er"oss 3M. 3M. Bandless Bandless but fixed fixed retenti retention. on. m m 3 Orthod Orthod 1entofacial 1entofacial

Orthop '(H7< 99/724 76'!767. '692

xelss xelsson on , achris achrisson son BA. Glini Glinical cal experi experienc encee with 1irect 1irect!Bo !Bonded nded :abia :abiall

Retainers. 3 Glin Orthod '((< 9/>24 7>)!7(). '6H2

1iamon 1iamond d M. Resin Resin 5ibergl 5iberglass ass Bonde Bonded d Retainer Retainer.. 3 Glin Glin Orthod Orthod '(>H< '(>H< '/624 '/624

'>!'>6. '6>2

Owen Owen ;. ;. 7!7 Gro% Gro%at at Retain Retainer er.. 3 Glin Glin Orthod Orthod '(>8< '(>8< '(/62 '(/6244 '(7!'(H. '(7!'(H.

'6(2 '6(2

Ghen Ghen R. R. Cref Crefab abri rica cate ted d Bonde Bonded d Mand Mandib ibul ular ar Reta Retain iner er.. 3 Glin Glin Orthod Orthod '(H>< '(H><

'/''24 H>>!H>(. '7)2

0dwards 0dwards 3=. The diastem diastema, a, the frenum, frenum, the the frenectomy frenectomy44  clinical clinical study study.. m m 3

Orthod 1entofacial Orthop '(HH.

)7

Retention and relapse in orthodontics '7'2 '7'2

0dwa 0dward rdss 3=. 3=.  long long!t !ter erm m pros prospe pect cti" i"ee e"al e"alua uati tion on of the the circ circum umfe fere rent ntia iall

supr suprac acre rest stal al fibe fibero roto tomy my in alle alle"i "iat atin ing g orth orthodo odont ntic ic rela relaps pse. e. m 3 Orth Orthod od 1entofacial Orthop '(>>< (6/824 6>)!6>H. '72 '72

Bell Bell $;. urgi urgica call orth orthodo odont ntic ic trea treatm tmen entt of inte interi rinc ncis isal al dias diaste tema mas. s. m 3

Orthod 1entofacial Orthop '(H)< 8H. '762 '762

Gamp Gampbel belll CM, CM, Moor Mooree 3M, 3M, Math Mathew ewss 3:. 3:. Orth Orthodo odont ntic ical ally ly corre correct cted ed midl midlin inee

diastemas. m 3 Orthod 1entofacial Orthop '(H8< 9H. '772

Reitan Reitan K. Glini Glinical cal and and histolo histologic gic obser" obser"ati ations ons on tooth tooth mo"em mo"ement ent during during and and

after orthodontic treatment. m 3 Orthod 1entofacial Orthop '(9H< 86/')24 H'! H78. '782 '782

eid eidee :3. :3. dult dult Ortho Orthodon donti tics cs.. m 3 Orth Orthod od 1entof 1entofac acia iall Orth Orthop op '(98< '(98< 8'4

67'!68.

)8

Ld retention and relapse

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