Originl Article Dynmic smile evlution in different skeletl ptterns Noshi Siddiqui ; Prdeep Tndon b ; Alk Singh c ; Jitesh Hryni ABSTRACT Objective: To evlute dynmic smile in different skeletl ptterns nd to correlte verticl smile prmeters with the underlying custive fctors. Mterils nd Methods: A totl of 150 prticipnts rnging in ge from 16 25 yers were selected nd divided into one of three groups horizontl, verge, nd verticl skeletl pttern using the following three cephlometric prmeters: SN-MP, FMA, nd Jrbk rtio. Videogrphic records of smile were obtined, nd mesurements were recorded nd nlyzed t rest, including upper lip length, nd during smile, including mxillry incisl disply, interlbil gp, intercommisurl width, chnge in upper lip length, nd smile rc. Differences mong the three groups were subjected to twowy nlysis of vrince nd post hoc nd chi-squre tests for smile rc. Correltions between verticl smile vribles nd verticl skeletl (N-ANS, N-Me) nd dentl cephlometric mesurements (U1 to pltl plne) were lso investigted. Results: Verticl prmeters were significntly incresed in the verticl pttern when compred with the horizontl pttern, ie, upper lip length (P,.01), mxillry incisl disply (P,.001), interlbil gp (P,.001), nd chnge in upper lip length (P,.001), wheres intercommisurl width ws significntly decresed in verticl pttern when compred with the horizontl pttern (P,.001). Flt smile rc ws seen more frequently in the horizontl pttern. Positive correltions were found between the N-Me, U1-PP, nd chnge in upper lip length with verticl smile prmeters. Conclusions: Different skeletl ptterns exhibit their chrcteristic smile fetures. Upper lip length is not responsible for incresed incisl disply during smile. Incresed incisl disply during smile is more closely ssocited with upper lip elevtion thn verticl skeletl nd dentl fctors. (Angle Orthod. 2016;86:1019 1025) KEY WORDS: Dynmic smile; Skeletl pttern; Verticl dimension INTRODUCTION Resident, Deprtment of Orthodontics nd Dentofcil Orthopedics, Fculty of Dentl Sciences, King George s Medicl University, Lucknow, Uttr Prdesh, Indi. b Professor nd Hed, Deprtment of Orthodontics nd Dentofcil Orthopedics, Fculty of Dentl Sciences, King George s Medicl University, Lucknow, Uttr Prdesh, Indi. c Associte Professor, Deprtment of Orthodontics nd Dentofcil Orthopedics, Fculty of Dentl Sciences, King George s Medicl University, Lucknow, Uttr Prdesh, Indi. Corresponding uthor: Dr Noshi Siddiqui, Junior Resident, Deprtment of Orthodontics, Fculty of Dentl Sciences, King George s Medicl University, Lucknow 226003, Indi (e-mil: noshisid@gmil.com) Accepted: April 2016. Submitted: Jnury 2016. Published Online: My 16, 2016 Ó 2016 by The EH Angle Eduction nd Reserch Foundtion, Inc. Fcil esthetics hs been n objective of orthodontic tretment plnning since the beginning of this specilty. For decdes, the period of cephlometric dominnce continued in which esthetics ws defined primrily in terms of the profile s mesured on lterl cephlogrm, nd clinicl exmintion ws secondry. By the end of the 20th century, the soft tissue prdigm continued to expnd nd resulted in prdigm shift in the field of orthodontics, plcing greter emphsis on the clinicl exmintion of soft tissue function nd esthetics. 1 Physicl ttrctiveness is n importnt socil issue in our culture, nd the fce is one of its key fetures. An ttrctive smile in modern society is often considered n sset in interviews, work settings, socil interctions, nd even the quest to ttrct mte. 2 Improvement in fcil esthetics is lso powerful motivtion for seeking tretment 3 ; therefore, orthodontic tretment should crefully consider ptient s fcil ppernce nd prticulrly his or her smile. Smile chrcteristics re determined by the interply of sttic nd dynmic reltionships between the dentoskeletl nd soft tissue components of the fce. DOI: 10.2319/012616-69.1 1019
1020 SIDDIQUI, TANDON, SINGH, HARYANI A perusl of the literture revels tht vrious verticl skeletl ptterns present with their chrcteristic dentoskeletl nd soft tissue fetures, but this is only the sttic spect. No study hs inquired bout the dynmic spect of the hrd nd soft tissue reltionship, nd whether different verticl fcil ptterns present with chrcteristic ptterns of the smile. A few studies reported tht smile chrcteristics chnge with chnged verticl skeletl dimensions. 4 7 Peck et l. 4 observed tht incresed verticl mxillry height is fctor in cusing gingivl disply. The present study ws conducted to investigte whether smile chrcteristics differ in different skeletl ptterns nd to inquire bout the contributing fctors tht govern the verticl smile prmeters. The informtion thus obtined will help in directing the tretment towrd the min contributing fctors. MATERIALS AND METHODS This study ws conducted with 150 prticipnts selected mong students, residents, nd ptients visiting the Deprtment of Orthodontics. The prticipnt selection criteri re described in Tble 1. The study ws pproved by the Institutionl Ethicl Committee, nd informed consent ws obtined from ll prticipnts. Stndrdized lterl hed cephlogrms were tken first to ctegorize the prticipnts into different skeletl ptterns using three cephlometric prmeters: SN- MP, FMA, nd Jrbk rtio (Tble 2, Figure 1). This smple selection ws in ccordnce with Bishr nd Augspurger 8 nd Zher et l., 9 who stted tht single cephlometric prmeter is not sufficient to ccurtely identify given fcil type. Therefore, the division of prticipnts into the groups ws done on the bsis of stisfying t lest two of the three previously mentioned prmeters. The groups were further divided into two subgroups ccording to sex, tht is, mles nd Tble 1. Prticipnt Selection Criteri Inclusion Criteri Exclusion Criteri North Indin prticipnts ged Gross fcil symmetry between 16 25 yers Prticipnts with well-ligned Visible periodontl disese, rches cries, excessive dentl ttrition Overjet of 1 5 mm History of trum to the dentofcil region No previous orthodontic tretment Any missing or supernumerry teeth visible on smiling or prosthodontic or restortive work on ny teeth visible on smiling Lip irregulrities or history of lip surgery Tble 2. Distribution of Prticipnts According to Fcil Pttern nd Sex (N ¼ 150). Fcil Pttern nd Sex Horizontl Skeletl Pttern (n ¼ 60) Averge Skeletl Pttern (n ¼ 50) Verticl Skeletl Pttern (n ¼ 40) SN-MP,318 318 348.348 FMA,228 228 288.288 Jrbk rtio.63% 59% 63%,59% Mle 30 25 20 Femle 30 25 20 Jrbk rtio ¼ S-Go c /N-Me 3 100 (Go c, constructed gonion). femles (Tble 2) to study smiles seprtely in mles nd femles. The videogrphic equipment nd method for recording dynmic smiles were bsed on the guidelines estblished in previous studies. 10,11 The digitl cmcorder (Nikon D7100 DSLR cmer with 18 105 mm lens; Nikon, Tokyo, Jpn) ws stbilized on tripod stnd nd plced t the sme distnce of 3 feet from the prticipnt (this ensured equl mgnifiction for ll prticipnts). Two rulers with millimeter mrkings secured t right ngles to ech other on stnd were Figure 1. Prmeters used to clssify fcil ptterns, ie, SN-MP, FMA, nd the Jrbk rtio (S-Goc/N-Me 3 100; where Goc is the constructed gonion nd N-Me is the verticl skeletl height of the fce) in the following cephlometric vribles used in the study: (1) verticl height of nterior mxill, (2) U1 to pltl plne, (3) verticl skeletl height of fce.
SMILE EVALUATION IN DIFFERENT SKELETAL PATTERNS 1021 kept longside the fce of the prticipnt, llowing direct mesurement t life size. The nturl hed position ws cliniclly chieved by sking ech prticipnt to look eye level into mirror hung on the wll in front of the prticipnt. The cmer lens ws djusted t the level of pprent occlusl plne. The relxed lip position ws chieved by sking the prticipnt to lick the lips nd then swllow. The prticipnts were then instructed to sy Subject number my nme is cheese followed by smile. Recording begn 1 second before the prticipnt strted speking nd ended fter the smile. All video clips were tken by the first uthor. The digitl video clips were imported into commercilly vilble video editing softwre (Adobe Premiere Pro CC version 7.0.0; Adobe Systems Inc., Sn Jose, Clif), which provided individul frmes tht could be viewed (30 imges per second). Ech frme ws then nlyzed, nd two frmes were selected for ech prticipnt nd sved in JPEG file formt: the first frme represented ech prticipnt s lip t rest, nd the second frme represented ech prticipnt s widest posed smile. The chosen frmes of ech prticipnt were imported into Adobe Photoshop (Adobe Premiere Pro CC version 7.0.0) nd cropped, leving only rectngulr proportionte re of 6 3 4 inches tht contined the periorl region, nd scle nd mesurements were tken. For liner mesurements in ech photogrph, the mesurement scle ws preset s follows nd customized: Choose Imge. Anlysis. Set Mesurement Scle. Custom (the ruler tool is utomticlly selected while setting the mesurement scle). Drg the tool to drw 10-mm line on the metllic scle visible in the photo nd enter the logicl length s 10 nd logicl units s millimeters (Figure 2). Click OK in the Mesurement Scle dilog box to set the mesurement scle on the document. Now the ruler tool is customized nd will give rel lifesize mesurements between ny two selected points in millimeters. Mesurements were tken by drwing line with the ruler tool, nd mesurements were recorded from the Mesurement Log pnel tht ppered in the window. One mesurement of upper lip length (ULL) ws tken on ech rest position photogrph, nd the following four mesurements were tken on ech smiling photogrph: mxillry incisl disply (MID), interlbil gp (ILG), chnge in upper lip length (DULL), outer intercomissurl width (ICW; Tble 3, Figure 3,b). Smile rc ws recorded s the one qulittive prmeter, smile rc ws lso recorded (Tble 3). The following three cephlometric mesurements were lso noted: verticl height of nterior mxill (N- ANS), verticl skeletl fcil height (N-Me), nd verticl dentl height of the mxill, (U1-PP; Tble 3, Figure 1). Sttistics Dt were summrized s men (stndrd devition). Groups were compred by two-fctor nlysis of vrince, nd the significnce of men difference within (intr) nd between (inter) groups ws done by Tukey s post hoc test fter scertining normlity by the Shpiro-Wilk test nd homogeneity of vrince between groups by the Levene test. Ctegoricl groups were compred by chi-squre test. Correltions between the verticl smile vribles nd N-ANS, N-Me, U1 to PP, nd DULL were lso clculted. A two-tiled P vlue less thn.05 (P,.05) ws considered sttisticlly significnt. All nlyses were performed on SPSS softwre (Windows version 17.0; SPSS Inc., Chicgo, Ill). RESULTS Intrexminer relibility coefficients rnged from 0.965 to 0.983. In terms of root men squre vlues, the rndom errors of estimtion were less thn 0.42 mm. No vribles were significntly different between the test nd retest mesurements. Comprisons between mles nd femles re summrized in Tble 4. Significnt sexul dimorphism ws observed in ULL, with mles hving longer lips thn femles. Comprisons between the three groups within ech gender reveled n incresing trend of vlues from horizontl to verge to verticl pttern (Tble 5). Post hoc tests revel significntly higher vlues in the verticl pttern when compred with the horizontl pttern for verticl smile prmeters, tht is, ULL (P,.01), MID (P,.001), ILG (P,.001), nd DULL (P,.001). The trnsverse smile mesurement, tht is, ICW, ws significntly decresed in the verticl pttern when compred with the horizontl pttern (P,.001). Person correltion nlysis (Tble 6) revels wek positive correltion between verticl skeletl prmeters N-Me nd U1 to PP nd the verticl prmeters of smile. Correltion coefficients re given in Tble 6. ULL ws lso positively correlted (r ¼ 0.3) with N-ANS, wheres other smile prmeters were not correlted with N-ANS. DULL ws positively correlted with ULL, MID, nd ILG, with moderte strength of ssocition with MID (r ¼ 0.59). A significnt difference ws found in the frequency distribution of smile rc mong the three groups in both genders (Tble 7). In the horizontl pttern, the flt smile rc ws the most frequent observtion (mles 66.7%, femles 60%).
1022 SIDDIQUI, TANDON, SINGH, HARYANI Figure 2. Anlysis of smile using Adobe softwre (Adobe Systems Inc., Sn Jose, Clif). DISCUSSION Smile is representtion of the dynmic reltionship of periorl soft tissue with underlying skeletl nd dentl components. Mny studies hve reported gerelted vritions 14,15 s well s sexul dimorphism 16 in smile chrcteristics. To eliminte the effect of these fctors, we evluted the smile dynmics of individuls ged 16 25 yers nd seprtely s mles nd femles. An unequl smple size ws ccepted becuse of the decresed prevlence of verticl skeletl ptterns. All of the verticl smile prmeters (ie, MID, ILG, DULL) were significntly higher in the verticl pttern when compred with the horizontl pttern. The trnsverse smile mesurement, (ie, ICW) showed the opposite trend. ICW ws significntly higher in the horizontl pttern when compred with the verticl pttern. Therefore, it cn be speculted tht smile dynmics lso vry ccording to the skeletl pttern of the fce, with verticl pttern hving n incresed verticl dimension of smile, incisl disply, nd ILG nd decresed trnsverse smile dimension, nd vice vers with the horizontl pttern. Similr observtions were mde by Grover et l. 5 In the present study, it ws lso reveled tht the verticl pttern exhibits significntly higher upper lip elevtion during smile. It is lredy well estblished tht different skeletl ptterns hve chrcteristic dentoskeletl fetures, nd the results of the present study revel tht different skeletl ptterns present with different ptterns of smile s well. The second spect of this study delt with the serch for the ssocited fctors contributing to the differing ptterns of smile. Upper lip length t rest (ULL) ws highest in the verticl pttern nd lest in the horizontl pttern. Significnt differences in ULL were found between the verticl nd the horizontl ptterns. In the present study, ULL ws found to be positively correlted Tble 3. Mesurements Used in the Study Mesurements on rest position photogrph (Figure 3) 1. Upper lip length t rest (ULL) 12 : distnce mesured between subnsle nd stomion superius Mesurements on smile photogrph (Figure 3b) 1. Mxillry incisl disply (MID) 12 : distnce mesured from stomion superius to mxillry incisor edge 2. Interlbil gp (ILG) 12 : distnce mesured from stomion superius to stomion inferius 3. Outer intercommissurl width (ICW) 12 : distnce mesured between right nd left outer commisures 4. Chnge in upper lip length from rest to smile (DULL) 12 : difference in upper lip length during rest nd during smile tken s percentge rtio of upper lip length t rest. It represents the lip elevtion during smile. 5. Smile rc 13 :. Flt (mxillry incisl edges, cnine nd premolr cusp tips hd no curvture reltive the lower lip line) b. Prllel (mxillry incisl edges, cnine nd premolr cusp tips, from mesil to distl, followed the curvture of the lower lip) c. Reverse (incisl edges, cnine nd premolr cusp tips hd reverse curve reltive the lower lip line). Cephlometric mesurements (Figure 1) 1. N-ANS: skeletl height of nterior mxill 2. N-Me: verticl skeletl height of fce 3. U1 to pltl plne (U1-PP): perpendiculr distnce from mxillry incisl edge to pltl plne
SMILE EVALUATION IN DIFFERENT SKELETAL PATTERNS 1023 Tble 4. Mens nd Stndrd Devitions (SD) of Vribles nd Comprisons of Mens Between Mles nd Femles (P Vlue) Within the Three Groups by Tukey s Post Hoc Test Mesurement Group Mle, Men (SD) Femle, Men (SD) P Vlue ULL Horizontl 21.10 (2.35) 18.26 (1.95),.001*** Averge 22.00 (2.00) 19.27 (2.25),.001*** Verticl 23.36 (2.23) 20.44 (1.96),.001*** MID Horizontl 7.93 (1.98) 8.01 (1.62).87 Averge 9.32 (1.51) 9.49 (1.11).999 Verticl 11.45 (1.90) 11.03 (1.48).966 ILG Horizontl 9.67 (2.22) 9.96 (1.99).992 Averge 11.76 (2.24) 10.74 (1.76).454 Verticl 14.15 (1.49) 12.81 (1.89).263 DULL Horizontl 22.21 (6.01) 24.26 (7.08).912 Averge 34.74 (9.46) 29.30 (8.71).135 Verticl 42.31 (6.56) 42.51 (8.83) 1 ICW Horizontl 60.12 (3.53) 59.63 (4.86).997 Averge 58.43 (3.66) 56.38 (3.99).444 Verticl 55.14 (3.96) 51.10 (3.25).015* ULL, upper lip length; MID, mxillry incisl disply; ILG, interlbil gp; DULL, chnge in upper lip length; ICW, outer intercomissurl width. * P,.05, just significnt; *** P,.001, highly significnt. Figure 3. () Mesurement tken t rest: upper lip length t rest. (b) Mesurements tken t smile photogrph: (1) mxillry incisl disply, (2) interlbil gp, (3) outer intercommissurl width. with verticl skeletl nd dentl height. The results of our study were comprble with the findings of Blnchette et l. 17, Li et l. 18, nd Feres et l., 19 who reported in their cephlometric studies tht dolichofcil individuls hve longer lips, wheres brchyfcils hve shorter lips. They stted tht in dolichofcil individuls, soft tissue follows the underlying skeletl development nd tries to compenste for lip sel difficulties becuse these individuls re more prone thn others to develop lip incompetence. ULL is one of the importnt fctors tht determine the mount of mxillry incisor nd gingivl exposure during speech nd smiling. 20,21 Short ULL hs been considered suspect in producing gingivl smile line, nd controversil dt exist in the literture regrding this. Although Peck et l. 4 found no difference in ULL between the gingivl smile group nd reference groups, Miron et l. 22 observed short ULL in prticipnts with high smile line. In the present study, it ws reveled tht ULL t rest ws not responsible for incresed incisl exposure during smile. Mxillry incisor disply during smile is ffected by hrd tissue fctors, such s verticl mxillry height nd dentl height, nd soft tissue fctors, such s lip length nd lip elevtion. 22 In the present study, ULL t rest ws recorded to be more evident in individuls with verticl skeletl pttern thn in the short or verge fce groups. A wek positive correltion ws found between MID during smile nd N-Me nd U1 to PP, wheres moderte positive correltion ws found with DULL. Therefore, it cn be implied tht incresed incisl disply during smile is result of combintion of incresed skeletl s well s incresed mxillry dentl height but more closely ssocited with the incresed elevtion of the upper lip in individuls with verticl skeletl pttern, nd vice vers for individuls with horizontl skeletl pttern. However, McNmr et l. 7 reported tht the verticl disply on smile of the mxillry right centrl incisor could not be correlted with the skeletl verticl dimension, s mesured from N-Me nd ANS-Me. The ILG on smiling is one of the determinnts tht ffects the smile index, 23 nd it depicts the verticl limit of the smile zone. A positive correltion ws observed with N-Me, U1 to PP, nd DULL, so it ws inferred tht the ILG is governed by contributions from both skeletl nd dentl height s well s soft tissue fctors, such s ULL elevtion. Chnge in ULL (%) ws mximl for the verticl pttern followed by verge nd minimum for the horizontl pttern. Chnge in ULL is primrily function of ctivity of upper lip musculture. It ppers tht individuls with verticl skeletl pttern hve more musculr cpcity to rise the upper lip thn do individuls with horizontl or verge ptterns. A positive correltion ws found between ULL t rest
1024 SIDDIQUI, TANDON, SINGH, HARYANI Tble 5. Comprisons Between the Three Groups Within Mles nd Femles (P Vlue) by Tukey s Post Hoc Test Mesurement Horizontl Pttern vs Averge Pttern Comprison P Vlue Horizontl Pttern vs Verticl Pttern Averge Pttern vs Verticl Pttern ULL Mle.389.003**.471 Femle.493.005**.450 MID Mle.001**,.001***,.001*** Femle.010*,.001***.021* ILG Mle.001**,.001***.001** Femle.692,.001***.007** DULL Mle,.001***,.001***.015* Femle.161,.001***,.001*** ICW Mle.371,.001***.096 Femle.896,.001***.016* ULL, upper lip length; MID, mxillry incisl disply; ILG, interlbil gp; DULL, chnge in upper lip length; ICW, outer intercomissurl width; ns, not significnt. ** P,.01, modertely significnt; *** P,.001, highly significnt. Tble 7. Frequency Distribution of the Smile Arc Horizontl Pttern, %(n¼ 30) Averge Pttern, %(n¼ 25) Smile Arc Mles Flt 66.7 48.0 20.0 Prllel 33.3 44.0 80.0 Reverse 0.0 8.0 0.0 Femles Verticl Pttern, %(n¼ 20) v 2 Vlue P Vlue 14.96.005** Flt 60.0 28.0 30.0 11.82.019* Prllel 33.3 72.0 70.0 Reverse 6.7 0.0 0.0 * P,.05, just significnt; ** P,.01, modertely significnt. nd DULL, which implies tht the longer the upper lip, the more it elevtes during smile. The sme observtion ws lso mde by Miron et l., 22 who found positive correltion between the lip length nd lip elevtion. Determintion of the smile rc is highly dependent on the hed posture s the hed moves nd the converstionl distnce. 13 Every effort ws mde to keep ech prticipnt s pprent occlusl plne prllel with the cmer. A sttisticlly significnt difference ws found between the frequency distribution of the smile rc of the three groups in both mles nd femles. A flt smile rc ws more frequently observed in the horizontl pttern with mles (66.7%) nd femles (60%; Tble 7). Previous studies hve reported flt smile rcs s less cceptble or hving lower esthetic scores when compred with consonnt smile rcs. 24,25 In the present study, the observed high frequency of flt smile rcs in the horizontl skeletl pttern group my be ttributed to inherent brchyfcil growth ptterns tht my led to flt smile rcs. Ptients with this skeletl pttern might theoreticlly hve tendency for the nterior mxill to lck the clockwise tilt needed for n idel smile rc. 25 Ackermn nd Ackermn 26 stted tht two fctors tht contribute to the ppernce of the smile rc re the rchform nd sgittl cnt of the mxillry occlusl plne. An individul s rchform nd prticulrly the configurtion of the nterior segment will gretly influence the degree of curvture of the smile rc. The broder the rchform, the less the curvture will be of the nterior segment nd the greter the likelihood of flt smile rc, which my explin the greter frequency of flt smile rcs seen in our study. Incresing the cnt of the mxillry occlusl plne to Frnkfort horizontl in the nturl hed position will increse the mxillry nterior tooth disply nd improve the consonnce of the smile rc. Studies hve reported greter frequency of smile rc flttening in orthodonticlly treted ptients. 23 Therefore, the tretment plns for different fcil types should be different, with specil precutions tken during incisor intrusion in the horizontl skeletl pttern becuse these ptients re prone to smile rc flttening. Adequte mesures should be employed for creting prllel smile rcs, such s creful plnning of incisor intrusion, individulized brcket positioning, nd controlling the cnt of the occlusl plne by the pproprite use of extrorl forces. Tble 6. Correltions Between the Verticl Smile Vribles nd the Cephlometric Vribles Correltion Coefficient (r) Mesurement Men (SD) ULL MID ILG DULL N-ANS 53.4 mm (3.40) 0.301244 0.076243 0.121277 0.098292 N-Me 119.59 mm (6.06) 0.403499 0.290157 0.316439 0.226048 U1-PP 27.64 mm (3.05) 0.28164 0.289385 0.284528 0.263954 DULL 31.32% (11.0) 0.269461 0.599493 0.485744 1 N-ANS, verticl height of nterior mxill; N-Me, verticl skeletl fcil height; U1-PP, U1 to pltl plne; DULL, chnge in upper lip length; SD, stndrd devition. Wek correltion level (6 0.1 r,60.5); moderte correltion level (6 0.5 r,60.8); strong correltion level (6 0.8 r,61).
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