Gender Differences in Class III Malocclusion

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1 Originl Article Gender Differences in Clss III Mlocclusion Tizino Bccetti ; Brin C. Reyes b ; Jmes A. McNmr Jr c Abstrct: This study evluted gender differences in the cephlometric records of lrge-scle cross-sectionl smple of Cucsin subjects with Clss III mlocclusion t different developmentl ges. The purpose lso ws to provide verge ge-relted nd sex-relted dt for crniofcil mesures in untreted Clss III subjects tht re used s reference in the dignostic pprisl of the ptient with Clss III dishrmony. The smple exmined consisted of 1094 pretretment lterl cephlometric records (557 femle subjects nd 537 mle subjects) of Cucsin Clss III individuls. The ge rnge for femle subjects ws between three yers six months nd 57 yers seven months. The mle subject group rnged from three yers three months to 48 yers five months. Twelve ge groups were identified. Skeletl mturity t different ge periods lso ws determined using the stge of cervicl vertebrl mturtion. Gender differences for ll cephlometric vribles were nlyzed using prmetric sttistics. The findings of the study indicted tht Clss III mlocclusion is ssocited with significnt degree of sexul dimorphism in crniofcil prmeters, especilly from the ge of 13 onwrd. subjects with Clss III mlocclusion present with significntly lrger liner dimensions of the mxill, mndible, nd nterior fcil heights when compred with femle subjects during the circumpubertl nd postpubertl periods. (Angle Orthod 2005;75: ) Key Words: Clss III Mlocclusion; Crniofcil growth; Cephlometrics; Sexul dimorphism; Mndibulr growth INTRODUCTION Clss III mlocclusion is the lest prevlent type of Angle s clssifiction of mlocclusion, with number of rcil nd ethnic groups demonstrting greter tendency towrd expression. This occlusl reltionship ppers to be prticulrly common in those of Asin ncestry (the prevlence of Clss III mlocclusion in Assistnt Professor, Deprtment of Orthodontics, University of Florence, Florence, Itly; Thoms M. Grber Visiting Scholr, Deprtment of Orthodontics nd Peditric Dentistry, School of Dentistry, University of Michign, Ann Arbor, Mich. b Orthodontic Grdute Progrm, University of Michign, Ann Arbor, Mich; Privte Prctice of Orthodontics, Rochester Hills, Mich. c Thoms M. nd Doris Grber Endowed Professor of Dentistry, Deprtment of Orthodontics nd Peditric Dentistry, School of Dentistry; Professor of Cell nd Developmentl Biology, School of Medicine; nd Reserch Scientist, Center for Humn Growth nd Development, University of Michign, Ann Arbor, Mich. Corresponding uthor: Tizino Bccetti, DDS, PhD, Università degli Studi di Firenze, Vi del Ponte di Mezzo, 46-48, Florence, Itly (e-mil: tbcc@tiscli.it). Accepted: My Submitted: April by The EH Angle Eduction nd Reserch Foundtion, Inc. Chinese popultion cn be s high s 12% 1,2 ) nd comprtively less prevlent in the Europen (1.5% to 5.3%) nd North Americn Cucsin ( 1 4%) popultions. 3 6 The dentofcil dishrmony ssocited with Clss III mlocclusion is chllenging in both the dignostic nd tretment rens. Dentl professionls nd lypersons identify the clinicl signs of this type of mlocclusion (eg, mesil molr reltionship, nterior crossbite) esily, but the underlying etiology is more difficult to elucidte. Tretment decisions nd their success or filures rely hevily on the future growth potentil in the Clss III individul. Unfortuntely, knowledge of crniofcil growth in Clss III mlocclusion is not well estblished. The lrge-scle longitudinl growth studies providing informtion on so-clled norml growth fil to offer much useful informtion bout Clss III mlocclusion becuse they consist primrily of individuls ctegorized s hving norml occlusion, Clss I mlocclusion, or Clss II mlocclusion. 7,8 In ddition, there is only limited longitudinl investigtion of untreted Clss III individuls in the literture. The cross-sectionl pproch to growth dt requires investigtors to ssemble lrge smples of untreted Clss III individuls t vrious stges of de- 510

2 GENDER DIFFERENCES IN CLASS III velopment nd to drw inferences bout verge growth in Clss III individuls from these dtbses. Miyjim nd ssocites 9 conducted the lrgest crosssectionl Clss III study to dte, but the smple ws limited to Jpnese femle subjects. The literture lcks lrge-scle cross-sectionl study for orthodonticlly untreted Clss III Cucsin mle nd femle subjects. One of the first fundmentl steps in the dignostic evlution of the mlocclusion nd its relted crniofcil components is to estblish whether significnt sexul dimorphism exists. Previous studies of crniofcil growth in untreted subjects hve demonstrted mny gender-relted differences. 8,10,11 For exmple, most of the cephlometric vribles tht were nlyzed in lrge-scle growth studies on Cucsin subjects presenting with vriety of mlocclusions (The Bolton-Brush Growth Study, 7 The University of Michign Elementry nd Secondry School Growth Study 8 ) exhibit significnt differences between mle nd femle subjects. In contrst, previous investigtions tht hve considered individuls with Clss III mlocclusion rrely recognized the issue of sexul dimorphism. Becuse of smll smple sizes, severl studies pooled mle nd femle Clss III subjects together Other investigtors collected smples composed of single sex (usully femle subjects). 9,20,21 Only very few investigtors hve ssembled smples of untreted Clss III subjects belonging to both sexes nd nlyzed the crniofcil mesurements seprtely by sex. 22,23 It is the purpose of this investigtion to estimte gender differences in the cephlometric records of lrge-scle cross-sectionl smple of Cucsin subjects with Clss III mlocclusion throughout the growth period. The im lso ws to provide verge ge-relted nd sex-relted dt for crniofcil mesures in Clss III subjects. This informtion then is very useful s reference in the dignostic evlution of the ptient with Clss III dishrmony. MATERIALS AND METHODS Ptients To study Clss III morphology t consecutive ges, we obtined lrge cross-sectionl smple of lterl cephlogrms. The prent smple consisted of 1549 pretretment lterl cephlometric records of Cucsin Clss III ptients collected from 12 privte orthodontic prctices in Michign nd Ohio nd the University of Michign Grdute Orthodontic Clinic nd the Deprtment of Orthodontics t the University of Florence, Itly. TABLE 1. Smple Selection nd Exclusionry Criteri Smple Selection 511 Ptient smple 1549 Exclusionry criteri 1. Not Cucsin Prior tretment Missing teeth Disqulified due to incisor/molr reltionships Poor qulity rdiogrphs Seril cephlogrms 44 Finl smple 1094 TABLE 2. Chronologic Age Groups Age 6 yr nd younger 7yr 8yr 9yr 10 yr 11 yr 12 yr 13 yr 14 yr 15 yr 16 yr 17 yr nd older Totl To be included in the finl grouping, ptients hd to stisfy ll the following criteri: Europen-Americn ncestry (Cucsin), No orthopedic/orthodontic tretment before cephlogrm, Dignosis of Clss III mlocclusion, Anterior crossbite, Edge-to-edge incisl reltionship, Accentuted mesil step reltionship of the primry second molrs, Permnent first molr reltionship of t lest one-hlf cusp Clss III, No congenitlly missing or extrcted teeth. A finl smple of 1094 subjects with Clss III mlocclusion met the inclusionry criteri (Tble 1). The smple consisted of 557 femle subjects nd 537 mle subjects. The ge rnge for femle subjects ws between three yers six months nd 57 yers seven months. The mle subject group rnged from three yers three months to 48 yers five months. Twelve ge groups were identified nd pplied to the Clss III smple (Tble 2). Cephlometric nlysis Lterl cephlogrms were hnd trced using mtte cette nd shrpened 2H led-drft- n

3 512 BACCETTI, REYES, MCNAMARA FIGURE 1. Digitized cephlometric lndmrks. ing pencil. One of two investigtors trced ech cephlogrm, nd then third investigtor verified lndmrk identifiction. Any disprity ws ddressed by retrcing of the structure. A customized digitiztion regimen of nlysis ws conducted using the Dentofcil Plnner (Dentofcil Softwre, Toronto, Ontrio, Cnd). The descriptive cephlometric nlysis required the digitiztion of 71 lndmrks on ech trcing (Figure 1). A cephlometric nlysis, including mesures dopted from the nlyses of Steiner, 24 Jcobson, 25 Ricketts, 26 nd McNmr, 27 ws performed on ech trcing included in the investigtion. Sttisticl nlysis The initil sttisticl pproch to the collected dt provided descriptive sttistics for the exmined dentofcil prmeters in different gender groups t ll ge stges. The Shpiro-Wilks test reveled norml distribution of the vlues for the cephlometric prmeters in the two groups t the vrious ge stges. Gender differences in the cephlometric vribles were tested initilly by using Hotelling s T 2 test to estimte whether the generl model of differences ws significnt. Becuse significnt differences were identified (F 2; P.01), independent smple t-tests were pplied to individul ge groups to ssess significnt differences between mle nd femle subjects for ech ge group. The dt were nlyzed with commercil socil science sttisticl pckge (SPSS for Windows Version 10.0, SPSS Inc, Chicgo, Ill). Sttisticl significnce ws tested t P.05, nd P.01. Assessment of skeletl mturity The cervicl vertebrl mturtion (CVM) method 28 ws used to ssess individul skeletl mturity of the subjects exmined. The prevlence rte for the stges in CVM t different ge periods ws clculted both in mle nd femle groups. All subjects in the six-yers nd younger group

4 GENDER DIFFERENCES IN CLASS III showed CVMS I (prepubertl). All subjects in the 17- yers nd older group showed CVMS V (dult). RESULTS Tble 3 shows the results long with the sttisticl comprison of mle vs femle groups t ech ge period. Six yers nd younger No significnt differences between the two sexes were identified in this erly ge group. The length of the nterior crnil bse represented the only exception, which ws significntly shorter in femle subjects. Seven yers The results in the seven-yer-old group were similr to the previous ge period, with the ddition of significnt differences in the verticl position of the lower incisors (significntly more extruded in mle subjects), nd in the position of the lower lip in reltion to the esthetic plne (E-plne) (significntly more dvnced position in mle subjects). Eight yers At the ge of eight, the length of the crnil bse gin ws significntly shorter in femle subjects, the lower incisors significntly more extruded in mle subjects, with significntly lrger lower nterior fcil height in mle subjects s well. Nine yers The mle vs femle comprison of crniofcil pttern t the ge of nine yers replicted the differences t the previous ge period. Ten yers The gender comprison of crniofcil pttern t the ge of 10 replicted the differences t the two previous ge periods. Eleven yers No significnt differences existed between the mle nd femle groups for ny of the exmined mesurements t this ge stge. Twelve yers At this stge in chronologic ge, the only significnt difference between mle nd femle subjects ws represented by more retruded position of the lower lip to the E-plne in femle subjects. 513 Thirteen yers The crniofcil mesures t the ge of 13 showed severl significnt differences between mle nd femle subjects. subjects presented with shorter nterior crnil bse, shorter midfcil nd mndibulr lengths, shorter upper nd lower nterior fcil heights, less extruded upper incisors, upper molrs, nd lower incisors. The mxillry incisors were more proclined in femle subjects. Both upper nd lower lips exhibited more retrusive position in reltion to the E-plne in the femle group. Fourteen yers The mle-to-femle comprison t this ge period reveled differences tht were very similr to the previous ge period. The exception ws the lck of sttisticl significnce for the verticl position of the mxillry molrs nd incisors. Fifteen yers The gender comprison t this ge period reveled differences tht were very similr once gin to the 13-yer ge period. The only exception ws the lck of sttisticl significnce for the position of the lower lip reltive to the E-plne. Sixteen yers All prmeters tht were significntly different between mle nd femle subjects t the previous ge period showed significnt difference t this ge period s well, with two exceptions ie, the mxillry molr ws more extruded in mle subjects thn in femle subjects, nd no significnt differences were recorded for the soft tissue mesurements t this ge. Seventeen yers nd older At the young dult ge period, the femle group showed significntly shorter nterior crnil bse, less retrusive position of point A reltive to Nsion perpendiculr, shorter midfcil nd mndibulr lengths, smller mxillomndibulr differentil, shorter upper nd lower nterior fcil heights, less extruded upper molrs nd incisors, nd less extruded lower incisors. DISCUSSION This study nlyzed differences in the cephlometric mesurements of mle nd femle subjects with Clss III mlocclusion t consecutive ge periods during ctive growth, with the im of evluting sexul dimorphism in the crniofcil pttern of the Clss III ptient. All subjects presented with prepubertl growth stge t the initil ge group (six yers nd younger)

5 514 BACCETTI, REYES, MCNAMARA TABLE 3. Descriptive Sttistics nd Between-Gender Comprisons of Cephlometric Mesures t Ech Age Period 6 y nd Younger 7y (n 19) (n 23) (n 30) (n 57) Crnil bse SNFH ( ) S-N (mm) Crnil flexure ( ) Mxillry skeletl SNA ( ) PtA to NPerp (mm) PP-FH ( ) Co-Pt A (mm) Mndibulr skeletl SNB ( ) Pog-N perp (mm) Fcil ngle ( ) Co-Gn (mm) Mxillry/mndibulr FMA ( ) ANB ( ) Wits (mm) Mx-Md diff (mm) Molr reltion (mm) Verticl Nsion to A (mm) A to Me (mm) UFH/LAFH rtio U1-A (mm) U6-PP (mm) L1-Me (mm) Dentolveolr U1-Pt A (V) (mm) U1-SN ( ) IMPA ( ) FMIA ( ) L1-A Pog (mm) Interincisl ngle ( ) Soft tissue UL-E-plne (mm) LL-E-plne (mm) Nsolbil ngle ( ) , not significnt; P.05; P.01. nd with postpubertl, dult growth stge t the finl observtion (17 yers nd older). Most of the dentofcil prmeters did not show significnt sexul dimorphism in Clss III mlocclusion until the ge of 13, even though mle subjects exhibited usully lrger size for most liner mesures when compred with femle subjects. However, very distinctive group composed of few vribles indicted the divergence of the verge Clss III femle subject vs mle subject in the erly developmentl ges. Almost consistently, from the erly ges on, femle subjects with Clss III mlocclusion presented with shorter nterior crnil bse (S-N) when compred with mle subjects. Tollro nd coworkers 29 hve previously described this chrcteristic s feture of the crnil bse in Clss III children four to six yers old in comprison with children with norml occlusion. This study lso reveled tht during the erly stges the distnce from the incisl edge of the lower incisors to the inferior prt of the symphysis (L1-Me) is significntly shorter in femle subjects thn in mle subjects, long with shorter lower nterior fcil height (A-Me).

6 GENDER DIFFERENCES IN CLASS III 515 TABLE 3. Extended 8y 9y 10 y (n 82) (n 73) (n 65) (n 65) (n 42) (n 45) , not significnt; P.05; P.01. At the ge of 11, no significnt differences between mle nd femle subjects could be detected. Interestingly, t this ge none of the mle subjects hd reched the pubertl growth spurt (76% of the mle subjects were t CVMS I, nd 24% t CVMS II), 28 wheres two thirds of the girls (64%) were t CVMS II, nd 24% of them hd undergone the ccelertive portion of the growth spurt lredy (CVMS III). Then, t the ge of 12, only 18% of the mle subjects showed the postpubertl growth stge CVMS III, wheres 82% of the femle subjects were t this stge in skeletl development. These differences in the timing of skeletl mturtion re extremely helpful in the interprettion of the dt tht pertin to sexul dimorphism in Clss III mlocclusion. The lck of significnt differences in the crniofcil prmeters between mle nd femle subjects t 11 nd 12 yers is becuse of the substntilly higher prevlence of femle subjects undergoing their pubertl growth spurt t these ge periods when compred with mle subjects. The onset of the pubertl growth spurt in femle subjects compenstes for the generl

7 516 BACCETTI, REYES, MCNAMARA TABLE 3. Extended 11 y 12 y (n 33) (n 34) (n 43) (n 56) Crnil bse SNFH ( ) S-N (mm) Crnil flexure ( ) Mxillry skeletl SNA ( ) PtA to NPerp (mm) PP-FH ( ) Co-Pt A (mm) Mndibulr skeletl SNB ( ) Pog-N perp (mm) Fcil ngle ( ) Co-Gn (mm) Mxillry/mndibulr FMA ( ) ANB ( ) Wits (mm) Mx-Md diff (mm) Molr reltion (mm) Verticl Nsion to A (mm) A to Me (mm) UFH/LAFH rtio U1-A (mm) U6-PP (mm) L1-Me (mm) Dentolveolr U1-Pt A (V) (mm) U1-SN ( ) IMPA ( ) FMIA ( ) L1-A Pog (mm) Interincisl ngle ( ) Soft tissue UL-E-plne (mm) LL-E-plne (mm) Nsolbil ngle ( ) , not significnt; P.05; P.01. tendency of size deficiency in crniofcil mesurements in femle subjects when compred with mle subjects. At the ge of 13, 94% of the femle subjects hd reched postpubertl stge in skeletl development, but lso 54% of the mle subjects lredy hd gone through the growth spurt. This incresed prevlence rte of boys with growth ccelertion most probbly is fundmentl fctor tht ccounts for the ppernce of lrge set of significnt gender differences t the ge of 13, which will be mintined t lter ge periods. The min fetures concerning sexul dimorphism in Clss III mlocclusion t pubertl nd postpubertl ges (13 yers nd older) re shorter nterior crnil bse, shorter midfcil (Co-PtA) nd mndibulr (Co-Gn) lengths, nd shorter upper nd lower nterior fcil heights in femle subjects when compred with mle subjects (Figures 2 through 4). A reltively lrger mount of retrusion of the upper lip nd milder mount of protrusion of the lower lip pper to be chrcteristics of Clss III femle subjects during the circumpubertl ges. These differ-

8 GENDER DIFFERENCES IN CLASS III 517 TABLE 3. Extended 13 y 14 y 15 y (n 50) (n 52) (n 42) (n 53) (n 32) (n 31) , not significnt; P.05; P.01. ences, however, were not present t lter developmentl phses. Adults with Clss III mlocclusion who did not receive ny tretment of the dishrmony present with considerble mount of sexul dimorphism. In ddition to the differences tht were highlighted during the immedite postpubertl period (13 to 16 yers of ge), dult femle subjects with Clss III mlocclusion exhibited smller mount of mxillomndibulr differentil (becuse of smller midfcil nd mndibulr dimensions) nd smller lveolr heights, both in the mxill nd in the mndible. Liner dimensions for both midfcil nd mndibulr lengths nd for nterior fcil heights pper to be strictly coordinted during postntl growth of the crniofcil region in Clss III mlocclusion. At the moment of enhnced gender differences in crniofcil mesures (from the ge of 13 yers of ge onwrd), ll these prmeters exhibit similr behvior. These findings confirm the observtions by Björk nd Skieller 30 nd Björk nd Helm 31, who described the chronologicl concurrence of the gretest growth increse in the mxillry sutures nd in the mndibulr condyles. According to the results of this study, the existence

9 518 BACCETTI, REYES, MCNAMARA TABLE 3. Extended 16 y 17 y nd over (n 24) (n 14) (n 75) (n 54) Crnil bse SNFH ( ) S-N (mm) Crnil flexure ( ) Mxillry skeletl SNA ( ) PtA to NPerp (mm) PP-FH ( ) Co-Pt A (mm) Mndibulr skeletl SNB ( ) Pog-N perp (mm) Fcil ngle ( ) Co-Gn (mm) Mxillry/mndibulr FMA ( ) ANB ( ) Wits (mm) Mx-Md diff (mm) Molr reltion (mm) Verticl Nsion to A (mm) A to Me (mm) UFH/LAFH rtio U1-A (mm) U6-PP (mm) L1-Me (mm) Dentolveolr U1-Pt A (V) (mm) U1-SN ( ) IMPA ( ) FMIA ( ) L1-A Pog (mm) Interincisl ngle ( ) Soft tissue UL-E-plne (mm) LL-E-plne (mm) Nsolbil ngle ( ) , not significnt; P.05; P.01. of significnt sexul dimorphism in Clss III mlocclusion (especilly fter the ge of 13 yers) provides evidence tht mle nd femle subjects with Clss III mlocclusion during the circumpubertl or postpubertl ges should not be pooled together for investigtive purposes. Children with Clss III mlocclusion t prepubertl ges show much milder mount of sexul dimorphism. These findings re similr to the dt gthered by Ursi nd coworkers 11 on subjects with excellent occlusions from the Bolton-Brush Study. subjects with good occlusion showed lrger nterior crnil bse t ll developmentl ges, wheres effective lengths of the midfce nd mndible becme different in the two sexes from the ge of 14. CONCLUSIO This study showed tht (1) Clss III mlocclusion is ssocited with significnt degree of sexul dimorphism in crniofcil especilly fter the ge of 13 nd (2) femle subjects with Clss III mlocclusion present with significntly smller liner dimensions in the mx-

10 GENDER DIFFERENCES IN CLASS III 519 ACKNOWLEDGMENTS The uthors would like to thnk Dr Alyss S. Levin for her untiring efforts in helping ssemble nd nlyze the cephlogrms used in this investigtion. This study ws supported in prt by funds mde vilble through the Thoms M. nd Doris Grber Endowed Professorship, Deprtment of Orthodontics nd Peditric Dentistry, The University of Michign. REFERENCES FIGURE 2. Digrm of verge vlues for midfcil length (Co-PtA) t subsequent ge periods for mle nd femle subjects with Clss III mlocclusion. FIGURE 3. Digrm of verge vlues for mndibulr length (Co- Gn) t subsequent ge periods for mle nd femle subjects with Clss III mlocclusion. FIGURE 4. Digrm of verge vlues for lower nterior fcil height (A-Me) t subsequent ge periods for mle nd femle subjects with Clss III mlocclusion. ill, mndible, nd nterior fcil heights when compred with mle subjects during the circumpubertl nd postpubertl periods. This study lso provides reference vlues for the cephlometric dignosis of Clss III mle nd femle ptients of Cucsin ncestry. 1. Ishii H, Morit S, Tkeuchi Y, Nkmur S. Tretment effect of combined mxillry protrction nd chincp pplince in severe skeletl Clss III cses. Am J Orthod Dentofcil Orthop. 1987;92: Lew KKK, Foong WC. Horizontl skeletl typing in n ethnic Chinese popultion with true Clss III mlocclusion. Br J Orthod. 1993;20: Foster TD, Dy AJ. A survey of mlocclusion nd the need for orthodontic tretment in Shropshire school popultion. Br J Orthod. 1974;1: Ingervll B, Mohlin B, Thilnder B. Prevlence nd wreness of mlocclusion in Swedish men. Comm Dent Orl Epid. 1979;6: Mills LF. Epidemiologic studies of occlusion IV: the prevlence of mlocclusion in popultion of 1,455 school children. J Dent Res. 1966;45: Proffit WR, Fields HW, Mory LJ. Prevlence of mlocclusion nd orthodontic tretment need in the United Sttes: estimtes from the N-HANES III survey. Int J Adult Orthod Orthognth Surg. 1998;13: Brodbent BH Sr, Brodbent BH Jr, Golden WH. Bolton Stndrds of Dentofcil Developmentl Growth. St. Louis, Mo: CV Mosby; Riolo ML, Moyers RE, McNmr JA Jr, Hunter WS. An Atls of Crniofcil Growth: Cephlometric Stndrds from The University School Growth Study, The University of Michign. Monogrph 2, Crniofcil Growth Series. Ann Arbor, Mich: Center for Humn Growth nd Development, The University of Michign; Miyjim K, McNmr JA Jr, Kimur T, Murt S, Iizuk T. An estimtion of crniofcil growth in the untreted Clss III femle with nterior crossbite. Am J Orthod Dentofcil Orthop. 1997;112: Siriwt PP, Jrbk JR. Mlocclusion nd fcil morphology is there reltionship? An epidemiologic study. Angle Orthod. 1985;55: Ursi WJ, Trotmn CA, McNmr JA Jr, Behrents RG. Sexul dimorphism in norml crniofcil growth. Angle Orthod. 1993;63: Ngn P, Wei SHY, Hägg U, Yiu CKY, Merwin D, Stickel B. Effect of protrction hedger on Clss III mlocclusion. Quintessence Int. 1992;23: Shnker S, Ngn P, Wde D, Beck M, Yiu C, Hägg U, Wei SH. Cephlometric point chnges during nd fter mxillry protrction nd expnsion. Am J Orthod Dentofcil Orthop. 1996;110: Ngn P, Hägg U, Yiu C, Wei H. Tretment response nd long-term dentofcil dpttions to mxillry expnsion nd protrction. Semin Orthod. 1997;3: Ngn P, Yiu C, Hu A, Hägg U, Wei SH, Gunel E. Cephlometric nd occlusl chnges following mxillry expnsion nd protrction. Eur J Orthod. 1998;20: Chong Y, Ive JC, Årtun J. Chnges following the use of protrction hedger for erly correction of Clss III mlocclusion. Angle Orthod. 1996;66:

11 520 BACCETTI, REYES, MCNAMARA 17. Bccetti T, McGill JS, Frnchi L, McNmr JA Jr, Tollro I. Skeletl effects of erly tretment of Clss III mlocclusion with mxillry expnsion nd fce-msk therpy. Am J Orthod Dentofcil Orthop. 1998;113: Bccetti T, Frnchi L, McNmr JA Jr. Tretment nd posttretment crniofcil chnges fter rpid mxillry expnsion nd fcemsk therpy. Am J Orthod Dentofcil Orthop. 2000;118: Westwood PV, McNmr JA Jr, Bccetti T, Frnchi L, Srver DM. Long-term effects of Clss III tretment with RME nd fcil msk therpy followed by fixed pplinces. Am J Orthod Dentofcil Orthop. 2003;123: Mitni H. Prepubertl growth of mndibulr prognthism. Am J Orthod. 1981;80: Mitni H, Sto K, Sugwr J. Growth of mndibulr prognthism fter pubertl growth pek. Am J Orthod Dentofcil Orthop. 1993;104: Guyer EC, Ellis E, McNmr JA Jr, Behrents RG. Components of Clss III mlocclusion in juveniles nd dolescents. Angle Orthod. 1986;56: Bttgel JM. The etiologicl fctors in Clss III mlocclusion. Eur J Orthod. 1993;15: Steiner CC. Cephlometrics for you nd me. Am J Orthod. 1953;39: Jcobson A. The Wits pprisl of jw dishrmony. Am J Orthod. 1975;67: Ricketts RM. Perspectives in the clinicl ppliction of cephlometrics. The first fifty yers. Angle Orthod. 1981;51: McNmr JA Jr. A method of cephlometric evlution. Am J Orthod. 1984;86: Bccetti T, Frnchi L, McNmr JA Jr. An improved version of the cervicl vertebrl mturtion (CVM) method for the ssessment of mndibulr growth. Angle Orthod. 2002; 72: Tollro I, Bccetti T, Bssrelli V, Frnchi L. Clss III mlocclusion in the deciduous dentition: morphologicl nd correltion study. Eur J Orthod. 1994;16: Björk A, Skieller V. Fcil development nd tooth eruption: n implnt study t the ge of puberty. Am J Orthod. 1972; 62: Björk A, Helm S. Prediction of the ge of mximum pubertl growth in body height. Angle Orthod. 1967;37: