Correlation between periodontal soft tissue and hard tissue surrounding incisors in skeletal Class III patients

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1 Originl Article Correltion between periodontl soft tissue nd hrd tissue surrounding incisors in skeletl Clss III ptients Jeong-Ho Prk ; Ji-Yeon Hong b ; Hyo-Won Ahn c ; Su-Jung Kim d ABSTRACT Objectives: To investigte the ssocition between the periodontl soft tissue, lveolr bone nd dentl prmeters surrounding the incisors t bseline in ptients with skeletl Clss III mlocclusion. Mterils nd Methods: The study smple comprised 154 teeth from 28 ptients with skeletl Clss III mlocclusion (19 men nd 9 women, yers). Periodontl soft tissue exmintion nd hrd tissue mesurements with cone-bem computed tomogrphy (CBCT) were performed. Fctor nlysis ws used to reduce the CBCT vribles, nd correltion nlysis between the hrd tissue fctors nd soft tissue prmeters ws performed. Differences in hrd tissue prmeters between thick nd thin gingivl types were evluted. Results: CBCT mesurements were reduced to three hrd tissue fctors: lingul plte, coronlbuccl plte, nd picl-buccl plte. Kertinized gingiv width nd thickness were positively correlted with the coronl-buccl plte fctor nd negtively correlted with the picl-buccl plte fctor. In the thin gingivl biotype, mndibulr incisors were more proclined, nd the picl prt of the buccl lveolr plte nd the coronl prt of lingul lveolr plte were thicker thn in the thick gingivl biotype. Conclusions: In the nterior teeth in cses of skeletl Clss III mlocclusion, hrd tissue structures on the buccl side cn be grouped bsed on coronl nd picl fctors tht re significntly correlted with kertinized gingivl width nd thickness. Thick nd thin gingivl biotypes exhibited differences in tooth inclintion nd lveolr plte thickness with regrd to the mndibulr incisors. (Angle Orthod. 2018;88:91 99.) KEY WORDS: Periodontl soft tissue; Periodontl hrd tissue; Incisors; Clss III; Fctor nlysis; Correltion INTRODUCTION Postgrdute Student, Deprtment of Orthodontics, Grdute School, Kyung Hee University, Seoul, Kore. b Assistnt Professor, Deprtment of Periodontology, Kyung Hee University School of Dentistry, Seoul, Kore. c Assistnt Professor, Deprtment of Orthodontics, Kyung Hee University School of Dentistry, Seoul, Kore. d Associte Professor, Deprtment of Orthodontics, Kyung Hee University School of Dentistry, Seoul, Kore. Corresponding uthor: Su-Jung Kim, Deprtment of Orthodontics, Kyung Hee University School of Dentistry, 1 Hoegi- Dong, Dongdemoon-Ku, Seoul , Kore (e-mil: ksj113@khu.c.kr) Accepted: September Submitted: June Published Online: October 26, 2017 Ó 2018 by The EH Angle Eduction nd Reserch Foundtion, Inc. The chrcteristics of periodontl tissue surrounding teeth re criticl for periodontl helth during nd fter orthodontic tretment. The ntomic integrity of periodontl tissue includes tht of both soft nd hrd tissue structures. Soft tissue chrcteristics of the periodontium re usully defined by gingivl biotype. 1 When the gingivl biotype is thin, orthodontic tooth movements my be considered unfvorble, incresing the risk of gingivl recession. 2 Melsen nd Allis 3 found significnt correltions between kertinized gingivl width, gingivl biotype, nd the development of or increse in gingivl recession. Alveolr bone is the hrd tissue prt of periodontium, which is mjor remodeling site during orthodontic tooth movement. It hs been suggested tht thin lveolr plte is n ntomic risk fctor for the development of periodontl problem, nd tooth movement beyond the lveolr plte my cuse verticl lveolr bone loss nd subsequent gingivl recession. 4 7 Depending on the verticl nd sgittl skeletl reltionship, there is chrcteristic periodontl DOI: /

2 92 PARK, HONG, AHN, KIM Figure 1. Clinicl periodontl soft tissue mesurements. (A) Probing to determine gingivl biotype. (B) Kertinized gingivl width. (C) Kertinized gingivl thickness. condition tht is closely relted with dentl compenstion. The occurrence of gingivl recession might be more common, especilly in the mndibulr incisors, in ptients with skeletl Clss III mlocclusion nd mndibulr prognthism becuse the teeth re inclined lingully nd then re moved forwrd on the nrrow lveolus during presurgicl orthodontic tretment As three-dimensionl cone-bem computed tomogrphy (CBCT) is widely vilble, comprehensive integrtion of soft nd hrd tissue prmeters of the periodontium is essentil for optimized tretment plnning. Unfortuntely, it is not known which hrd tissue fctors re good predictors of soft tissue chrcteristics nd vice vers. Recently, severl studies hve reported correltions between gingivl biotype nd lbil plte thickness in individul teeth. However they hve focused minly on the buccl plte of mxillry nterior teeth. 2,12 16 To the best of the uthors knowledge, no studies hve investigted the reltionships between soft tissue biotypes nd the buccolingul lveolr structures, prticulrly in ptients with skeletl Clss III mlocclusion. The im of this study ws to investigte ssocitions between the periodontl soft tissue, lveolr bone, nd dentl prmeters surrounding incisors t bseline in ptients with skeletl Clss III mlocclusion. MATERIALS AND METHODS Subjects The subjects consisted of ptients with skeletl Clss III mlocclusion who visited the Deprtment of Orthodontics t Kyung Hee University Dentl Hospitl, Seoul, Kore, between June 2011 nd Mrch Before orthodontic tretment, periodontl exmintion of the mxillry nd mndibulr incisors ws performed. Lterl cephlogrms nd CBCT scns were obtined for dignostic purposes. The study protocol ws pproved by the Institutionl Review Bord of Kyung Hee University Dentl Hospitl (IRB No. KHDRIB ). Initilly, 32 ptients were selected ccording to the following inclusion criteri: (1) ge.18 yers, (2) Angle Clss III molr reltionship, (3) nterior crossbite, nd (4) ANB,08. The following exclusion criteri were then pplied: (1) previous history of orthodontic tretment, (2) severe periodontitis, (3) missing teeth, (4) dentl trum, (5) severe rottions, (6) mrked root resorption, (7) dentl restortion involving the cementoenmel junction (CEJ), nd (8) blurry imging. The finl smple consisted of 28 ptients (19 men nd 9 women, yers), in whom 154 teeth were nlyzed. Periodontl Soft Tissue Exmintion The condition of the mxillry nd mndibulr incisor periodontl soft tissues ws evluted using periodontl probe. Gingivl biotype ws clssified s either thin or thick bsed on the visibility of the underlying periodontl probe through the gingivl tissue (Figure 1). 17 Soft tissue mesurements included gingivl recession, probing pocket depth, kertinized gingivl width nd thickness (Tble 1). CBCT Orienttion nd Periodontl Hrd Tissue Mesurement CBCT scnning ws performed vi n Alphrd Veg instrument (Ashi Roentgen Ind Co, Ltd, Kyoto, Jpn). The following prmeters were used: 80 kv, 5 ma, 0.39-mm voxel resolution, 17.0-second scn time, nd mm field of view. CBCT imges were reconstructed using InVivo-Dentl softwre (version 5.3, Antomge, Sn Jose, Clif). To exmine the morphologic fetures of the lveolr bone, ech CBCT imge ws oriented long the long xis of the root nd the sgittl plne running trnsversely through the midpoint of the incisl edge root pex. The mesurement vribles used re described in Tble 1 nd Figure 2. Root length ws defined s the distnce from the CEJ to the root pex nd ws divided into four sections of equl length (where level 0 ws the CEJ nd level 4 ws t the root pex), nd the thickness of the lveolr plte ws mesured t four loctions (levels 1, 2, 3, nd 4). In ddition, lveolr crest height nd thickness, lveolr plte re, nd tooth inclintion reltive to the bsl bone or lveolr ridge were evluted. Sttisticl Anlysis Power nlysis showed tht, with significnce level of.05, smple size of 154 teeth ws sufficient to provide power bove 80% to detect correltions of 0.5.

3 PERIODONTAL TISSUE RELATIONSHIP IN CLASS III 93 Tble 1. Definitions of Mesurement Mesurement Definition Periodontl Gingivl biotype Visibility of the periodontl probe through the gingivl mrgin soft tissue Gingivl recession Distnce from the CEJ to the free gingivl mrgin Probing pocket depth The distnce between the free gingivl mrgin nd the most picl prt of the pocket bse Kertinized gingiv width The distnce between the free gingivl mrgin to the mucogingivl junction Kertinized gingiv thickness The thickness of gingivl tissue t the gingivl mrgin 1mm picl from the periodontl pocket bse Periodontl hrd tissue Alveolr crest height Verticl distnce from the CEJ to the buccl (or lingul) lveolr crest prllel to the long xis of the tooth Alveolr crest thickness Alveolr plte thickness perpendiculr to the long xis of the tooth t 0.5 mm picl to the buccl (or lingul) lveolr bone crest Alveolr plte thickness Buccl (or lingul) lveolr plte thickness perpendiculr to the long xis of the tooth t ech qurter of root length from CEJ Alveolr plte re Buccl (or lingul) lveolr plte re between lveolr crest nd root pex perpendiculr to the tooth xis Alveolr ridge thickness Buccolingul thickness of lveolr ridge perpendiculr to the long xis of the tooth t ech qurter of root length from CEJ Tooth inclintion to bsl bone Angle between the long xis of incisors nd pltl plne (mndibulr plne) Tooth inclintion to lveolr ridge Angle formed by root pex, CEJ, nd A point (B point) CEJ indictes cementoenmel junction. All mesurements were performed by one orthodontist (Dr Prk). To determine the intrexminer mesurement relibility of the method, 50 rndomly selected smples were remesured t lest 2 weeks fter the initil mesurements by the sme investigtor. A pired t-test compring the first nd second sets of vlues showed no significnt difference between the two sets (P..05), nd the intrclss correltion coefficient of indicted good relibility. The Shpiro-Wilk test ws used to test for normlity nd demonstrted tht not ll vribles were normlly distributed. Therefore, the Mnn-Whitney U test ws used to compre buccl nd lingul lveolr plte mesurements. Fctor nlysis ws used, nd the 20 CBCT vribles were collted into groups of fctors, ech comprising combintion of the originl vribles. These grouped fctors were then used s hrd tissue fctors in subsequent correltion nlysis. Spermn s rnk correltion nlysis ws pplied to identify reltionships between soft tissue prmeters nd hrd tissue fctors. The Mnn-Whitney U test ws used to ssess differences in CBCT vribles between thick nd thin gingivl types. All sttisticl nlyses were performed using SPSS softwre for Windows (version 22.0, IBM Corp, Armonk, NY). The significnce level of ll tests ws estblished t.05. RESULTS Descriptive Dt Assessment The initil cephlometric dt showed skeletl Clss III reltionship (ANB ), norml to hyperdivergent verticl pttern (MPA ), nd dentl compenstions (U1 to FH ; IMPA ). The mens nd stndrd devitions of ll vribles re shown in Tble 2. The difference between buccl nd lingul verticl bone loss ws only sttisticlly significnt in the mxillry incisors (P,.01; Figure 3). The buccl plte of the mxillry incisors ws thinner thn the lingul plte t ll positions except t the lveolr crest level (ll P,.001, except level 1, P,.05). In the mndibulr incisors, the thickness of the buccl plte ws greter thn tht of the lingul plte t the lveolr crest level nd level 1 (P,.01 nd P,.05, respectively), wheres the lingul lveolr plte ws thicker thn the buccl lveolr plte t levels 2, 3, nd 4 (P,.01, P,.001, nd P,.001, respectively). Fctor Anlysis of CBCT Mesurements Using fctor nlysis, three hrd tissue fctors were derived bsed on eigenvlue greter thn one, explining 74.71% of the vrince of the originl 20 vribles (Tble 3). Ech fctor ws combintion of the originl vribles representing the verticl position of the lveolr crest nd the thickness of the lveolr plte on the buccl nd lingul spects. Correltions cn be summrized s follows (Tble 4): Fctor 1 (lingul plte fctor): positively correlted with lingul lveolr plte thickness nd totl lveolr ridge thickness t ll heights nd negtively correlted with verticl bone loss of the lingul plte. Fctor 2 (coronl-buccl plte fctor): positively correlted with buccl lveolr crest thickness nd buccl lveolr plte thickness (levels 1 nd 2) nd

4 94 PARK, HONG, AHN, KIM gingivl width (P,.05) nd kertinized gingivl thickness (P,.001). Lingul plte fctor ws not significntly correlted with ny soft tissue prmeters. Gingivl recession nd probing pocket depth t bseline were not significntly ssocited with ny hrd tissue fctors. Comprisons of Hrd Tissue Prmeters between Thick nd Thin Gingivl Biotypes Differences in hrd tissue prmeters between thick nd thin biotypes re shown in Tble 6. No sttisticlly significnt differences in ny of the vribles in the mxill were detected between the two biotypes. In the mndibulr incisors, the thin biotype ws ssocited with greter thickness of the buccl plte t the pex nd third qurter of the root level, (P,.05 nd P,.01, respectively) nd on the lingul plte t the lveolr crest nd first qurter of the root level (ll P,.05). Mndibulr incisors were more proclined to the lveolr ridge nd bsl bone in the thin biotype (P,.01 nd P,.001, respectively). Figure 2. CBCT mesurements. (A) Alveolr crest height (buccl/ lingul). (B) Alveolr crest thickness (buccl/lingul). (C) Alveolr plte thickness t ech qurter of root length (buccl/lingul). (D) Alveolr plte re (buccl/lingul). (E) Alveolr ridge thickness t ech qurter of root length. (F) Tooth inclintion to the lveolr ridge. (G) Tooth inclintion to bsl bone. tooth inclintion to bsl bone nd negtively correlted with verticl lveolr bone loss t the buccl surfce. Fctor 3 (picl-buccl plte fctor): positively correlted with buccl plte thickness (levels 3 nd 4) nd tooth inclintion to the lveolr ridge. Correltions Between Soft Tissue Prmeters nd Hrd Tissue Fctors Correltions between soft tissue prmeters nd hrd tissue fctors re shown in Tble 5. Coronl buccl plte fctor ws positively correlted with kertinized gingivl width (P,.001) nd kertinized gingivl thickness (P,.01). Conversely, picl buccl plte fctor ws negtively correlted with kertinized DISCUSSION In this study, the correltion between soft tissue chrcteristics nd three hrd tissue fctors extrcted from fctor nlysis of the periodontium in ptients with Clss III mlocclusion ws reported. Becuse of the thin buccl plte overlying the root surfce, the vribles defining totl lveolr ridge thickness nd lingul plte thickness were grouped together s single fctor, referred to s the lingul plte fctor. However, no significnt ssocition ws found between the lingul plte fctor nd buccl soft tissue prmeters. The vribles derived from buccl lveolr plte mesurements were grouped into two collective fctors: coronl-buccl plte fctor nd piclbuccl plte fctor. Coronl-buccl plte fctor ws combintion of verticl nd horizontl dimensions in the coronl prt of the buccl plte of incisors nd tooth inclintion to bsl bone. Apicl-buccl plte fctor included the thickness of the buccl plte in the picl region nd tooth inclintion to the respective lveolr ridge. Tooth inclintion to bsl bone nd to the lveolr ridge ws included in different hrd tissue fctors. Tooth inclintion to bsl bone reflects the chrcteristics of the coronl prt by mesuring the ngle round the root pex, while tooth inclintion to the lveolr ridge reflects the chrcteristics of the picl prt by mesuring the ngle round the CEJ. As expected, gingivl morphology, including kertinized gingivl width nd thickness, ws ssocited with the buccl lveolr plte overlying the incisors in ptients with skeletl Clss III mlocclusion. The

5 PERIODONTAL TISSUE RELATIONSHIP IN CLASS III 95 Tble 2. Descriptive Dt for Mesured Vribles Mxill (n ¼ 59) Mndible (n ¼ 95) Ctegory Mesurement Men SD Men SD Alveolr bone Buccl lveolr crest height Lingul lveolr crest height Buccl plte re Lingul plte re Buccl lveolr crest thickness Buccl plte thickness Buccl plte thickness Buccl plte thickness Buccl plte thickness Lingul lveolr crest thickness Lingul plte thickness Lingul plte thickness Lingul plte thickness Lingul plte thickness Alveolr ridge thickness Alveolr ridge thickness Alveolr ridge thickness Alveolr ridge thickness Dentl Tooth inclintion to bsl bone Tooth inclintion to lveolr ridge Periodontl soft tissue Gingivl recession Probing pocket depth Kertinized gingiv width Kertinized gingiv thickness SD indictes stndrd devition. correltion between soft tissue nd hrd tissue in the mndibulr incisors of ptients with Clss III mlocclusion were opposite in the coronl nd picl prts of the buccl plte. Kertinized gingivl width nd thickness were positively correlted with the coronlbuccl plte fctor but negtively correlted with the picl-buccl plte fctor. It my be dvisble to evlute the periodontl tissue before tretment by dividing the region into the coronl-buccl prt nd the picl-buccl prt in the mndibulr incisors of ptients with skeletl Clss III mlocclusion. On the other hnd, gingivl recession nd probing pocket depth before orthodontic tretment were not significntly ssocited with hrd tissue fctors. In study by Fu et l., 13 there ws no significnt ssocition between gingivl recession nd bone morphology, nd Tble 3. Vrince Explined by the Three Extrcted Fctors Totl Vrince Explined Rottion Sums of Squred Lodings Fctor Totl % Vrince Cumultive % Fctor 1 indictes lingul plte fctor; fctor 2, coronl-buccl plte fctor; fctor 3, picl-buccl plte fctor. the conclusion ws tht, rther thn gingivl recession t bseline being strongly ssocited with tissue biotype or underlying bone thickness, it ws more dependent on multiple fctors, including ge, etiology, nd tooth type. Previous CBCT studies investigting fcil bone thickness in vrious regions of the mxill nd mndible hve found tht thin lveolr bone wll is usully present in both jws. In the current study, t the first qurter of the root level, the thickness of the buccl nd lingul lveolr pltes ws less thn 1 mm in 81.5% nd 87.0% of the lower incisors, respectively. The mount of verticl bone loss ws greter on the buccl side of mxillry incisors nd on the lingul side of mndibulr incisors due to the dentl compenstion in skeletl Clss III mlocclusion. Substntil nteroposterior movement of the mndibulr incisors during orthodontic tretment might be criticl nd could led to progressive bone loss of the buccl nd lingul pltes. In the current study, there were significnt differences in underlying bone structure between thick nd thin biotypes in the mndible but not in the mxill. In the mndibulr incisors, the picl prt of the buccl plte nd the coronl prt of the lingul plte were thicker in the thin biotype. In ddition, more proclintion ws found in mndibulr incisors in the thin gingivl biotype.

6 96 PARK, HONG, AHN, KIM Figure 3. Comprisons between buccl nd lingul lveolr structure mesurements. * P,.05; ** P,.01; *** P,.001.

7 PERIODONTAL TISSUE RELATIONSHIP IN CLASS III 97 Tble 4. Fctors Extrcted Using Vrimx Rottion Rotted Component Mtrix Fctor 1 Fctor 2 Fctor 3 Lingul Plte Fctor Coronl-Buccl Plte Fctor Apicl-Buccl Plte Fctor Lingul lveolr crest height Lingul lveolr crest thickness Lingul plte thickness Lingul plte thickness Lingul plte thickness Lingul plte thickness Lingul plte re Alveolr ridge thickness Alveolr ridge thickness Alveolr ridge thickness Alveolr ridge thickness Buccl lveolr crest height Buccl lveolr crest thickness Buccl plte thickness Buccl plte thickness Tooth inclintion to bsl bone Buccl plte thickness Buccl plte thickness Buccl plte re Tooth inclintion to lveolr ridge In greement with the results of previous studies, 14,23 the more proclined the mndibulr incisor ws, the greter the bone thickness of the lbil lveolr plte t the pex level tended to be. It could be suggested tht tooth inclintion ffects mrginl bone thickness nd gingivl biotype in the mndibulr incisor regions in ptients with skeletl Clss III mlocclusion. Although ptients with Clss III mlocclusion nd thick biotype hve thicker mrginl bone on the buccl side, the mount of decompenstion during presurgicl tretment would lso be greter thn in ptients with thin biotype. Therefore, it cnnot be concluded tht the risk of gingivl recession is low in the thick gingivl biotype during orthodontic tretment in ptients with skeletl Clss III mlocclusion. This study evluted soft tissue nd hrd tissue structures before orthodontic tretment in Koren ptients with Clss III mlocclusion. The 0.39-mm voxel size of the CBCT system my hve limited the bility to ccurtely mesure the thin lveolr plte due to low contrst resolution. Further studies in other popultions nd with vrious skeletl mlocclusions would be necessry to pply the results beyond this smple. In ddition, it would be interesting in future studies to investigte chnges in the prmeters studied over the course of orthodontic tretment. CONCLUSIONS Hrd tissue prmeters of the periodontium were ctegorized s coronl-buccl, picl-buccl, nd lingul plte fctors. Kertinized gingivl width nd thickness were positively correlted with the coronl-buccl plte fctor but negtively correlted with the picl-buccl plte fctor. Morphologic differences in hrd tissue between thick nd thin gingivl biotypes were observed in the lower incisors. In the thin biotype, mndibulr incisors were more proclined, nd the picl prt of the buccl plte nd the coronl prt of lingul plte were thicker. Tble 5. Correltion Anlysis Between Soft Tissue Prmeters nd Hrd Tissue Fctors Gingivl Recession Periodontl Probing Depth Kertinized Gingiv Width Kertinized Gingiv Thickness Coefficient P Vlue Coefficient P Vlue Coefficient P Vlue Coefficient P Vlue Lingul plte fctor Coronl-buccl plte fctor *** ** Apicl-buccl plte fctor * *** Spermn s rnk correltion nlysis ws performed. * P,.05; ** P,.01; *** P,.001.

8 98 PARK, HONG, AHN, KIM Tble 6. Comprisons of Hrd Tissue Prmeters Between Thick nd Thin Gingivl Biotype, Men 6 Stndrd Devition Mxill Mndible Thick Thin P Vlue Thick Thin P Vlue Coronl-buccl plte fctor Buccl lveolr crest height Buccl lveolr crest thickness Buccl plte thickness Buccl plte thickness Tooth inclintion to bsl bone *** Apicl-buccl plte fctor Buccl plte thickness * Buccl plte thickness ** Buccl lveolr plte re Tooth inclintion to lveolr ridge ** Lingul plte fctor Lingul lveolr crest height * Lingul lveolr crest thickness * Lingul plte thickness * Lingul plte thickness Lingul plte thickness Lingul plte thickness Lingul lveolr plte re Alveolr ridge thickness Alveolr ridge thickness Alveolr ridge thickness * Alveolr ridge thickness * Mnn-Whitney U test ws performed. * P,.05; ** P,.01; *** P,.001. REFERENCES 1. Ko RT, Fgn MC, Conte GJ. Thick vs. thin gingivl biotypes: key determinnt in tretment plnning for dentl implnts. J Clif Dent Assoc. 2008;36: Rsperini G, Acunzo R, Cnnlire P, Frronto G. Influence of periodontl biotype on root surfce exposure during orthodontic tretment: preliminry study. Int J Periodontics Restortive Dent. 2015;35: Melsen B, Allis D. Fctors of importnce for the development of dehiscences during lbil movement of mndibulr incisors: retrospective study of dult orthodontic ptients. Am J Orthod Dentofcil Orthop. 2005;127: Slutzkey S, Levin L. Gingivl recession in young dults: occurrence, severity, nd reltionship to pst orthodontic tretment nd orl piercing. Am J Orthod Dentofcil Orthop. 2008;134: Dominik M, Gedrnge T. New perspectives in the dignostic of gingivl recession. Adv Clin Exp Med. 2014;23: Årtun J, Krogstd O. Periodontl sttus of mndibulr incisors following excessive proclintion: study in dults with surgiclly treted mndibulr prognthism. Am J Orthod Dentofcil Orthop. 1987;91: Fuhrmnn R. Three-dimensionl evlution of periodontl remodeling during orthodontic tretment. Semin Orthod. 2002;8: Ygci A, Veli I, Uysl T, Ucr FI, Ozer T, Enhos S. Dehiscence nd fenestrtion in skeletl Clss I, II, nd III mlocclusions ssessed with cone-bem computed tomogrphy. Angle Orthod. 2012;82: Kim Y, Prk JU, Kook YA. Alveolr bone loss round incisors in surgicl skeletl Clss III ptients. Angle Orthod. 2009;79: Kook YA, Kim G, Kim Y. Comprison of lveolr bone loss round incisors in norml occlusion smples nd surgicl skeletl clss III ptients. Angle Orthod. 2012;82: Chung CJ, Jung S, Bik HS. Morphologicl chrcteristics of the symphysel region in dult skeletl Clss III crossbite nd open bite mlocclusions. Angle Orthod. 2008;78: Cook DR, Meley BL, Verrett RG, et l. Reltionship between clinicl periodontl biotype nd lbil plte thickness: n in vivo study. Int J Periodontics Restortive Dent. 2011;31: Fu JH, Yeh CY, Chn HL, Ttrkis N, Leong DJ, Wng HL. Tissue biotype nd its reltion to the underlying bone morpholgy. J Periodontol. 2010;81: Khoury J, Ghosn N, Mokbel N, Nmn N. Buccl bone thickness overlying mxillry nterior teeth: clinicl nd rdiogrphic prospective humn study. Implnt Dent. 2016;25: Ghssemin M, Ljolo C, Semerro V, et l. Reltionship between biotype nd bone morphology in the lower nterior mndible: n observtionl study. J Periodontol. 2016;87: L Rocc AP, Alemny AS, Levi P Jr, Jun MV, Molin JN, Weisgold AS. Anterior mxillry nd mndibulr biotype: reltionship between gingivl thickness nd width with respect to underlying bone thickness. Implnt Dent. 2012;21: Kn JY, Rungchrsseng K, Umezu K, Kois JC. Dimensions of peri-implnt mucos: n evlution of mxillry nterior single implnts in humns. J Periodontol. 2003;74: Nowzri H, Molyem S, Chiu CH, Rich SK. Cone bem computed tomogrphic mesurement of mxillry centrl incisors to determine prevlence of fcil lveolr bone

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