A Comparative Study of Two Methods of Quantifying the Soft Tissue Profile

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1 Originl Article A Comprtive Study of Two Methods of Quntifying the Soft Tissue Profile Hyeon-Shik Hwng, DDS, M, PhD ; Wng-Sik Kim, DDS, M b ; Jmes A. McNmr, Jr, DDS, PhD c Abstrct: One of the most importnt components of orthodontic dignosis is the evlution of the ptient s soft tissue profile. There hve been mny ttempts to quntify the soft tissue profile bsed on the lterl cephlogrm. Yet, the methodology used to evlute the profile vries widely mong studies, nd there hs been no consistency in the wy stright lines re constructed in the nlysis of the soft tissue contours. The purpose of the current study ws to compre the vlues obtined by 2 drwing methods (tngent line nd ntomic points) of constructing ngles, nd to ssess the introbserver nd interobserver reproducibility for both methods. There were sttisticlly significnt differences between the 2 methods for 9 of the 10 mesurements evluted. In the comprison of reproducibility ssessed by Person correltion nlysis, both methods showed sttisticlly significnt correltions between repeted mesurements. The ntomic point method, however, showed greter reproducibility by mens of pired t-test. In the nlysis of introbserver reproducibility, 2 mesurements showed significnt differences with the ntomic point method nd 4 mesurements demonstrted significnt differences when the tngent line method ws used. In the nlysis of interobserver reproducibility, 5 mesurements showed significnt differences in the ntomic point method, while 6 mesurements represented significnt differences in the tngent line method. Our results indicte tht precise description of the methodology used in the nlysis of the soft tissue must be provided becuse of the differences between methods. In the nlysis of soft tissue contours, the construction of lines with the ntomic point method is more reproducible thn the tngent line method. (Angle Orthod 2000;70: ) Key Words: Soft tissue profile; Drwing method; Reproducibility; Cephlometry INTRODUCTION One of the most importnt components of orthodontic dignosis nd tretment plnning is the evlution of the Associte Professor nd Chirmn, Deprtment of Orthodontics, College of Dentistry, Chonnm Ntionl University, Kwngju, Kore. b Wng-Sik Kim, Grdute Student, Deprtment of Orthodontics, College of Dentistry, Chonnm Ntionl University, Kwngju, Kore. 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, The University of Michign, Ann Arbor, Michign. Privte prctice of orthodontics, Ann Arbor, Michign. Corresponding uthors: Hyeon-Shik Hwng, DDS, M, PhD, Associte Professor nd Chirmn, Deprtment of Orthodontics, College of Dentistry, Chonnm Ntionl University, Chonnm Ntionl University, Kwngju , Kore(e-mil: hhwng@chonnm.c.kr) nd Jmes A. McNmr Jr, DDS, PhD, Deprtment of Orthodontics nd Peditric Dentistry, The University of Michign, Ann Arbor, MI (e-mil: mcnmr@umich.edu). Accepted: Jnury Submitted: August by The EH Angle Eduction nd Reserch Foundtion, Inc. ptient s soft tissue. 1,2 Subtelny, 3 Burstone, 4 nd Bowker et l 5 hve recommended tht the nlysis of the soft tissue should be tken into considertion for the proper evlution of n underlying skeletl discrepncy becuse of individul differences in soft tissue thickness. Investigtors 6 9 hve developed numerous nlyses to interpret the dignostic informtion tht the lterl cephlogrm provides. The nlysis of the hrd tissue structures of the fce, s seen in the lterl cephlogrm, is reltively strightforwrd. Lndmrks re identified to represent vrious skeletl nd dentl structures; distnces, ngles, nd rtios re clculted ccording to the requirements of the specific cephlometric nlysis selected by the clinicin. To quntify the profile, however, curved surfces of the soft tissue lso must be reduced to distnces, ngles, nd rtios procedure tht is much less precise thn simply connecting hrd tissue lndmrks. For the mesurement of n ngle in the nlysis of soft tissue contour, the construction of 2 stright lines is needed. Those lines cn be drwn in severl wys, including the connecting of lndmrks identified long the soft tissue contour (ntomic point method), constructing stright lines 200

2 QUANTIFYING THE SOFT TISSUE PROFILE 201 TABLE 1. Definition of Nsolbil Angle According to the Authors Author Definition Men Vlue (degrees) Lustermn 10 Angulr reltionship of the extremity of the upper lip to the inferior No dt on white ptients border of the nose Scheidemn et l 11 Columell tngent nd upper lip tngent (M), (F) Legn nd Burstone 12 Cm-Sn-Ls 102 Prk nd Burstone 13 Pn-Sn-Ls Genecov et l 14 Not mentioned (M), (F) Nnd et l 15 Cm-Sn-Ls (M), (F) Fitzgerld et l 16 Anteroinferior ngle formed by the intersection of PCm tngent nd (M), (F) the PCm-Ls line Zylinski et l 17 Tngent to columell of nose-sn-ls McNmr et l 2 Intersection of the tngent to the inferior spect of the nose to the (M), (F) upper lip Formby et l 18 Cm-Sn-Ls (M), (F) Mrgolis 19 Angle formed by line tngent to the columell of the nose nd nother line tngent to the philtrum of the upper lip Approximtely 100 tngent to the curved surfces (tngent line method), or combintion of the 2 techniques. The quntifiction of specific soft-tissue contour my vry ccording to the method used in the nlysis. A review of the literture demonstrtes tht there hs been no consistency in the construction of lines for the nlysis of soft tissue contours. The nsolbil ngle, for exmple, is one of the most importnt soft tissue mesurements. 2,10 19 For the mesurement of this ngle, the construction of 2 lines long the inferior contour of nose nd upper lip is needed. There is much vrition, however, in the definition nd drwing method of the nsolbil ngle, with some uthors 12,13,15,18 using ntomic lndmrks, some 2,11,19 using tngent lines, nd others 16,17 using both (Tble 1). The vlues of the nsolbil ngle reported vry mong studies, in prt becuse of the specific mesurement technique used. The purpose of the present study is to compre the mesurements obtined from 2 methods of soft tissue nlysis: one bsed on the use of ntomic points nd the other on the use of tngent lines in the construction of ngles. We ssess the introbserver nd interobserver reproducibility for both methods. MATERIALS AND METHODS Forty norml occlusion individuls were used s subjects in this study. These individuls possessed idel fcil esthetics nd Clss I occlusl reltionships. None of these individuls hd history of orthodontic tretment. The verge ge of the 20 mles in this study ws 18 yers nd 9 months; the verge ge of the 20 femles ws 18 yers nd 8 months. The lterl cephlogrms were trced by 1 investigtor (Dr Kim) on cette pper using pencil with 0.3 mm dimeter led. Ech trcing ws photocopied twice; once for the ntomic point method nd the other for the tngent line method. Ten vribles were selected to quntify the TABLE 2. Definition of 10 Angulr Mesurements nd Drwing Method in Ech Group Vrible Antomic Point Group Tngent Line Group FHA NP-OG NP forehed tngent FNA O-G -N Forehed tngent subglbellr tngent NDA G -N -Prn Subglbellr tngent nose dorsum tngent D-NP N Prn-NP Nose dorsum tngent NP NTA N -Prn-Sn Nose dorsum tngent inferior contour tngent of nose NLA Cm-Sn-Ls Inferior contour tngent of nose upper lip tngent UL-NP SnLs-NP Upper lip tngent NP LL-NP LiSm-NP Lower lip tngent-np MLA Li-Sm-Pog Inferior contour tngent of lower lip- Anterior contour tngent of chin SmPog ThMe Anterior contour tngent of chin-inferior contour tngent of chin FHA indictes forehed ngle; FNA, frontonsl ngle; NDA, nsl depth ngle; D-NP, dorsum-nsion perpendiculr; NTA, nsl tip ngle; NLA, nsolbil ngle; UL-NP, upper lip-nsion perpendiculr; LL-NP, lower lip-nsion perpendiculr; MLA, mentolbil ngle;, pogonion-menton ngle. contour of the fcil region ccording to the method described previously by McNmr et l. 2 The following regions were nlyzed: forehed ngle (FHA), frontonsl ngle (FNA), nsl depth ngle (NDA), dorsum-nsion perpendiculr (dorsum-np), nsl tip ngle (NTA), nsolbil ngle (NLA), upper lip-nsion perpendiculr (UL-NP), lower lip-nsion perpendiculr (LL-NP), mentolbil ngle (MLA), nd pogonion-menton ngle (). To construct the bove ngles using the ntomic point method, the following lndmrks were selected, nd ech ngle ws drwn ccording to the definition in Tble 2 (Figure 1). O: Intersection of the nsion perpendiculr 2 with the forehed

3 202 HWANG, KIM, MCNAMARA FIGURE 1. Construction of ngles using ntomic points. G (soft tissue glbell): The most prominent point in the midsgittl plne of the forehed N (soft tissue nsion): The most concve point in the tissue overlying the re of the frontonsl suture Prn (pronsle): The most prominent point of the nose Cm (columell): The most nterior soft tissue point on the columell (nsl septum) of the nose Sn (subnsle): The point t which the columell merges with the upper lip in the midsgittl plne Ls (lbrle superius): The most nterior point on the upper lip Li (lbrle inferius): The most nterior point on the lower lip Sm (suprmentle): The point of gretest concvity in the midline of the lower lip between lbrle inferius nd soft tissue pogonion Pog (soft tissue pogonion): The most nterior point on the soft tissue chin Me (soft tissue menton): The most inferior point on the soft tissue chin Th (throt): The intersection between the submentl re nd the tngent line of the neck. To construct the sme 10 ngles using the tngent line method, tngentil lines were drwn to the soft tissue contour in ech region ccording to the method of McNmr et l 2 s follows (Tble 2; Figure 2). Forehed tngent Subglbellr tngent Nose dorsum tngent Inferior contour tngent of nose Upper lip tngent Lower lip tngent Anterior contour tngent of chin Inferior contour tngent of chin Ech trcing ws digitized using computer progrm FIGURE 2. Construction of ngles using tngent lines. Quick Ceph Imge Pro (Orthodontic Processing, Corondo, CA) nd 10 ngulr mesurements were computed in ech trcing. To ssess the introbserver reproducibility, the drwings were executed second time by 1 exminer. The corresponding drwing ws executed fter 2-week intervl. To ssess interobserver reproducibility, immeditely following the initil procedure, second exminer independently constructed ech drwing using either the ntomic point or the tngent line method. The repeted mesurements by the primry exminer were used to ssess introbserver reproducibility. The mens of the difference between the first nd second mesurements were clculted for both methods, nd pired t-test nd Person correltion were used to ssess introbserver reproducibility. The mesurements obtined by 2 exminers were used to ssess interobserver reproducibility. Mens of difference between both mesurements were clculted for both methods, nd pired t-test nd Person correltion were computed. RESULTS Comprison of the mesurements between methods The mens nd stndrd devitions for the 2 methods re listed in Tble 3. All vribles except for the forehed ngle showed significnt differences between the 2 drwing methods. There were mjor differences for the nsl tip nd nsolbil ngles, 31.5 nd 31.2 respectively. The difference for upper lip-np nd mentolbil ngle lso showed differences of over 20 (Tble 3). All vribles hd sttisticlly significnt correltion coefficients (Tble 4). Introbserver reproducibility The results of pired t-test showed sttisticlly significnt differences (P.01) between the first nd second me-

4 QUANTIFYING THE SOFT TISSUE PROFILE TABLE 3. Comprison of Mesurements According to the Drwing Method Between Antomic Point nd Tngent Line Groups Vrible FHA FNA NDA D-NP NTA NLA UL-NP LL-NP MLA Antomic Point Men Tngent Line Men Significnce * FHA indictes forehed ngle; FNA, frontonsl ngle; NDA, nsl depth ngle; D-NP, dorsum-nsion perpendiculr; NTA, nsl tip ngle; NLA, nsolbil ngle; UL-NP, upper lip-nsion perpendiculr; LL-NP, lower lip-nsion perpendiculr; MLA, mentolbil ngle;, pogonion-menton ngle; men, men of mesurements in ech group;, stndrd devition; nd, not significnt. * P.05. P.001. TABLE 4. Person Correltion Coefficients Between Antomic Point nd Tngent Line Groups Vrible r Significnce FHA FNA NDA D-NP NTA NLA UL-NP LL-NP MLA FHA indictes forehed ngle; FNA, frontonsl ngle; NDA, nsl depth ngle; D-NP, dorsum-nsion perpendiculr; NTA, nsl tip ngle; NLA, nsolbil ngle; UL-NP, upper lip-nsion perpendiculr; LL-NP, lower lip-nsion perpendiculr; MLA, mentolbil ngle; nd, pogonion-menton ngle. P.001. surements in 2 vribles (dorsum-np nd pogonion-menton ngles) when the ntomic point method ws used. When the tngent line method ws used, 4 vribles (dorsum-np, nsolbil, upper lip-np, nd pogonion-menton ngles) showed significnt differences (P.05) (Tble 5). Significnt correltions were found between the first nd second mesurements for both methods. Their vlues rnged from to 0.99 in the ntomic point method, nd from 0.85 to in the tngent line method (Tble 6). Interobserver reproducibility 203 Tble 5 lso gives the results of the t-test between the 2 types of mesurements mde by the 2 exminers. Five of the 10 vribles demonstrted sttisticlly significnt differences (P.05) with the ntomic point method, wheres 6 vribles showed significnt differences (P.01) with the tngent line method (Tble 5). Significnt correltions were found between the 2 types of mesurements mde by the 2 exminers. Their vlues rnged from to 0.99 with the ntomic point method nd from 0.84 to with the tngent line method. The ntomic point method, generlly, hd higher degree of greement between replictes thn did the tngent line method (Tble 6). DISCUSSION Producing chnge in the soft tissue profile through tretment often is one of the primry concerns of the orthodontic ptient. While the perception of beuty vries widely mong individuls nd mong rcil nd ethnic groups, mny investigtors 7,9,11,20 hve sought to quntify objectively their clinicl impressions of the soft tissue profile. Yet, the quntifiction of the soft tissue profile is not simple mtter becuse the profile, s observed in the lterl hedfilm, consists of mny curved lines. The curved lines usully re converted to stright lines to quntify the soft tissue contours nd then these stright lines re compred to so-clled norml vlues. Questions my be rised s to whether the converted stright lines ccurtely depict the originl curvture nd if the construction of the stright line is consistent. The construction of the lines should be reproducible over time nd should be independent of the specific person performing the nlysis. When compring the ccurcy of the mesurements obtined by using the 2 methods, the dt in this study showed tht 9 of the 10 vribles generted by the 2 methods differed significntly from one nother. Specificlly, the nsl tip ngle nd the nsolbil ngle presented difference of more thn 30, nd the upper lip-np nd mentolbil ngles showed the difference of greter thn 20. The results of the present study strongly indicte tht precise description of the definition of the methodology used is impertive when evluting soft tissue vrible. On the other hnd, the forehed ngle did not demonstrte significnt difference between the 2 drwing methods. The lck of difference in this mesure pprently is relted to the proximity of soft tissue glbell to the tngent drwn long the forehed. When evluting introbserver reproducibility, 2 vribles in the ntomic point method nd 4 of 10 vribles in the tngent line method presented significnt differences between the first nd second mesurements. Thus, the use of the ntomic point method resulted in greter introbserver reproducibility thn did the use of the tngent line method. Wheres the dorsum-np ngle nd the pogonionmenton ngle showed low reproducibility when the ntomic point method ws used, this lck of reproducibility my be relted to errors in lndmrk identifiction. Figure 3A shows scttergrms illustrting introbserver reproducibili-

5 204 HWANG, KIM, MCNAMARA TABLE 5. Comprison nd Differences Between First nd Second Drwing in Ech Group (Introbserver Reproducibility) nd Between 2 Drwers (Interobserver Reproducibility) Vrible FHA FNA NDA D-NP NTA NLA UL-NP LL-NP MLA Difference b Antomic Point Introbserver Reproducibility Significnce Difference b Tngent line * Significnce Difference c Antomic Point Interobserver Reproducibility * * Significnce Difference c Tngent Line Significnce FHA indictes forehed ngle; FNA, frontonsl ngle; NDA, nsl depth ngle; D-NP, dorsum-nsion perpendiculr; NTA, nsl tip ngle; NLA, nsolbil ngle; UL-NP, upper lip-nsion perpendiculr; LL-NP, lower lip-nsion perpendiculr; MLA, mentolbil ngle;, pogonionmenton ngle;, stndrd devition; nd, not significnt. b Men of bsolute vlue of differences between first nd second mesurements. c Men of bsolute vlue of difference between drwers. * P.05. P.01. P.001. TABLE 6. Person Correltion Coefficients Between First nd Second Drwing in Ech Group (Introbserver Reproducibility) nd Between 2 Drwers (Interobserver Reproducibility) Vrible FHA FNA NDA D-NP NTA NLA UL-NP LL-NP MLA Introbserver Reproducibility Antomic Point Tngent Line Interobserver Reproducibility Antomic Point Tngent Line FHA indictes forehed ngle; FNA, frontonsl ngle; NDA, nsl depth ngle; D-NP, dorsum-nsion perpenpiculr; NTA, nsl tip ngle; NLA, nsolbil ngle; UL-NP, upper lip-nsion perpendiculr; LL-NP, lower lip-nsion perpendiculr; MLA, mentolbil ngle;, pogonion-menton ngle. All mesurements showed sttisticlly significnt correltion t P.001 except FHA. P.01. ty of the ntomic points. Inconsistency in locting pronsle, prticulrly in the verticl dimension, cn ccount for the low reproducibility of the dorsum-np ngle, nd the vribility of the throt point seems to be relted to the low reproducibility of the pogonion-menton ngle. As mentioned, the tngent line method presented significnt differences in 4 of 10 vribles (dorsum-np, nsolbil, upper lip-np, nd pogonion-menton ngles). Wheres there ws no significnt difference in the ntomic point method, the nsolbil ngle showed low reproducibility when the tngent line method ws used. The shpe of inferior spect of nose cn ccount for such difference. When the inferior spect of nose hs n S shpe, there often cn be n inconsistency in the construction of tngentil line. Similrly, the vribility in drwing line tngent to the upper lip lso contributes to low reproducibility of nsolbil ngle when the tngent line method is used. In ddition to the nsolbil ngle, the pogonion-menton ngle is n importnt vrible in the dignosis of the sgittl reltionship of the chin. This ngle lso showed significnt difference between the first nd second mesurements by mens of the tngent line method, but not with the ntomic method. It is likely tht the shpe of the inferior contour of the chin, prticulrly n S shpe, contributes to inconsistency of pogonion-menton ngle. Figure 4A shows the difference between the 2 mesurements for ech tngent line used to construct ngles in this study. This figure should be helpful in understnding the source of error for ech ngulr mesurement. In the comprison of introbserver reproducibility by wy of the Person correltion nlysis, both methods showed high correltions between the first nd second mesurements. In generl, however, the ntomic point method showed higher degree of greement thn did the tngent line method. One of the bsic steps in dignosis is to obtin series of cephlometric mesurements of ptient nd compre these mesures with published verge or norml vlues. For the proper comprison, the lines used to obtin me-

6 QUANTIFYING THE SOFT TISSUE PROFILE 205 FIGURE 3. Scttergrms illustrting the reproducibility of ech ntomic point. (A) Difference between the first nd second mesurements or introbserver difference, (B) Difference between 2 mesurements mde by 2 opertors or interobserver difference. Ech dot indictes the difference between 2 mesurements. This figure illustrtes which lndmrk contributes to n inconsistency of n ngulr mesurement when the ntomic point method is used. surement should be drwn exctly the sme wy, regrdless of the opertor or the time intervl between trcings. According to the results of the interobserver study, 5 of the 10 vribles in the ntomic point method nd 6 of the 10 vribles in the tngent line method showed sttisticlly significnt differences. These findings indicte tht there ppers to be no mjor difference in interobserver reproducibility between the 2 methods. It should be noted, however, tht the vlues of the differences with the tngent line method were greter thn were those with the ntomic point method. All vribles obtined with the tngent line method presented differences of more thn 1, wheres few vribles showed the difference greter thn 1 with the ntomic point method. Considering tht discrepncy of less thn 1, in generl, would not result in different clinicl decision, it cn be stted tht mesuring with the ntomic point method hs greter interobserver reproducibility thn does the tngent line method. Unlike in the introbserver study, the nsolbil ngle constructed by ntomic point method demonstrted significnt difference between exminers. It is likely tht this finding is ssocited with the difference between exminers in columell point identifiction (Figure 3B). As mentioned, the tngent line method showed significnt differences between exminers in 6 of 10 vribles. The reson the vribles with the tngent line method showed differences between exminers is similr to tht seen in introbserver study. Prticulrly, the dorsum-np ngle is ssocited with the shpe of the nsl dorsum. Some of subjects hve n S or hump of cmel shpe, nd this dorsl hump my contribute to diversity in construction of tngent line to the dorsl spect of the nose. The diversity in the nsolbil ngle my be ssocited with the shpe of inferior spect of the nose. It is likely tht the construction of tngent line on lower lip is much more inconsistent thn on the upper lip. This vrition contributes to the difference between drwings of lower lip-np nd mentolbil ngles (Figure 4B). Also, in the comprison of interobserver reproducibility through Person correltion nlysis, the ntomic point method hd slightly higher greement thn did the tngent line method. While this study found tht the ntomic point method hs superior reproducibility thn the tngent line method, this does not men tht soft tissue mesurements should be obtined only by the ntomic point method. Another importnt issue in soft tissue nlysis is whether the converted stright lines ccurtely depict the originl curvture becuse most of these lines re used s components of ngles to express the degree of convexity or concvity. Such n issue is beyond the scope of the present study. CONCLUSIO The present study showed significnt differences between the mesurements with the ntomic point method nd

7 206 HWANG, KIM, MCNAMARA FIGURE 4. Grphic presenttion of reproducibility of ech tngent line. (A) Difference between the first nd second mesurements or introbserver difference, (B) Difference between 2 mesurements mde by 2 opertors or interobserver difference. An ngle ws constructed between the nsion perpendiculr nd ech tngent line. The direction of ech rrow represents the men of 2 mesurements. The width of the rrow nd the vlue in the figure indicte the men of difference between the 2 mesurements. This figure illustrtes which tngent line contributes to n inconsistency of n ngulr mesurement when the tngent line method is used. A, Forehed tngent; B, Subglbellr tngent; C, Nose dorsum tngent; D, Inferior contour tngent of nose; E, Upper lip tngent; F, Lower lip tngent; G, Anterior contour tngent of chin; H, Inferior contour tngent of chin. those with the tngent line method. These findings indicte tht the vlue of soft tissue mesurement my be different depending on the method used. It is evident tht precise description of the methodology used in the nlysis of the soft tissue must be provided becuse of the differences between drwing methods. On the other hnd, the present study compred the reproducibility between 2 drwing methods: the ntomic point method nd the tngent line method. This study found tht ntomic point method hs greter reproducibility in either introbserver or interobserver comprison thn the tngent line method. REFERENCES 1. Tweed CH. Indictions for the extrction of teeth in orthodontic procedure. Am J Orthod. 1944;30: McNmr JA Jr, Brust EW, Riolo ML. Soft tissue evlution of individuls with n idel occlusion nd well-blnced fce. In: McNmr JA Jr, ed. Esthetics nd the Tretment of Fcil Form. Crniofcil Growth Series. Ann Arbor, Mich: Center for Humn Growth nd Development, The University of Michign; 1992: Subtelny JD. A longitudinl study of soft tissue fcil structures nd their profile chrcteristics, defined in reltion to underlying skeletl structures. Am J Orthod. 1958;45: Burstone CJ. Integumentl contour nd extension ptterns. Angle Orthod. 1959;29: Bowker WD, Meredith HV. A metric nlysis of the fcil profile. Angle Orthod. 1959;29: Merrifield LL. The profile line s n id in criticlly evluting fcil esthetics. Am J Orthod. 1966;52: Ricketts RM. Esthetics, environment, nd the lw of lip reltion. Am J Orthod. 1968;54: Burstone CJ, Jmes RB, Legn H, Murphy GA, Norton LA. Cephlometrics for orthognthic surgery. J Orl Surg. 1978;36: Holdwy RA. A soft tissue cephlometric nlysis nd its use in orthodontic tretment plnning. Prt I. Am J Orthod. 1983;84: Lustermn EA. The esthetics of the occidentl fce: study of dentofcil morphology bsed upon nthropologic criteri. Am J Orthod. 1963;49: Scheidemn GB, Bell WH, Legn HL, Finn RA, Reisch JS. Cephlometric nlysis of dentofcil normls. Am J Orthod. 1980;78: Legn HL, Burstone CJ. Soft tissue cephlometric nlysis for orthognthic surgery. J Orl Surg. 1980;38: Prk YC, Burstone CJ. Soft tissue profile-fllcies of hrd-tissue stndrds in tretment plnning. Am J Orthod Dentofc Orthop. 1986;90: Genecov JS, Sinclir PM, Dechow PC. Development of the nose nd soft tissue profile. Angle Orthod. 1990;60:

8 QUANTIFYING THE SOFT TISSUE PROFILE 15. Nnd RS, Meng H, Kpil S, Goorhuis J. Growth chnges in the soft tissue fcil profile. Angle Orthod. 1990;60: Fitzgerld JP, Nnd RS, Currier GF. An evlution of the nsolbil ngle nd the reltive inclintions of the nose nd upper lip. Am J Orthod Dentofcil Orthop. 1992;102: Zylinski CG, Nnd RS, Kpil S. Anlysis of soft tissue fcil profile in white mles. Am J Orthod Dentofcil Orthop. 1992; 101: Formby WA, Nnd RS, Currier GF. Longitudinl chnges in the dult fcil profile. Am J Orthod Dentofcil Orthop. 1994;105: Mrgolis MJ. Esthetic considertions in orthodontic tretment of dults. Dent Clin North Am. 1997;41: Steiner CC. The use of cephlometrics s n id to plnning nd ssessing orthodontic tretment. Am J Orthod. 1960;46: