Long-Term Profile Changes Associated with Successfully Treated Extraction and Nonextraction Class II Division 1 Malocclusions

Transcription

1 Originl Article Long-Term Profile Chnges Associted with Successfully Treted Extrction nd Nonextrction Clss II Division 1 Mlocclusions Eileen C. Zierhut, DDS, M ; Donld R. Joondeph, DDS, MS b ; Jon Artun, DDS, Dr Odont c ; Robert M. Little, DDS, M, PhD d Abstrct: This study ws undertken to compre the post-tretment nd long-term soft tissue profiles of successfully mnged nd stble Clss II, division 1 mlocclusions treted with either 4 first premolr extrctions or nonextrction therpy. It ws hypothesized tht, if sound extrction decisions were mde ccording to ccepted tretment objectives nd successful tretment outcomes were chieved, there should be no differences between groups in soft tissue profiles post-tretment nd long-term post-retention. The smple consisted of 63 Cucsin dolescents (23 extrction, 40 nonextrction). Correction of the mlocclusion ws chieved using combintion of cervicl hedger concurrent with mndibulr growth nd mxillry incisor retrction. Pretretment, post-tretment, nd long-term post-retention lterl cephlometric rdiogrphs were evluted. The soft tissue fcil profiles of the extrction nd nonextrction smples were the sme following ctive tretment nd long-term post-retention. Progressive flttening of the fcil profile ws observed in both smples. This flttening ws ttributed to the mturtionl chnges ssocited with continued mndibulr growth nd nsl development nd ws not influenced by whether or not teeth were removed. Long-term lip positions were more retrusive thn the idels suggested by Ricketts nd Steiner, but close to the vlues reported for norml, untreted dults of similr ges. The pretretment position nd thickness of the lower lip s well s the initil mxillomndibulr skeletl reltionship my be predictors of post-tretment or long-term lower lip position. (Angle Orthod 2000;70: ) Key Words: Soft tissue profile; Extrction; Nonextrction, Post-tretment; Post-retention INTRODUCTION Orthodontists continue to debte the issue of extrcting permnent teeth to improve dentoskeletl reltionships. Much of the negtive commentry on extrction hs centered on the clim tht the extrction of 4 premolrs produces n unesthetic soft tissue profile by flttening or dishing-in of the lips reltive to chin nd nose. This supposition ppers to be bsed in lrge prt on opinion nd necdotl cse reports nd lcks well-documented support Deprtment of Orthodontics, University of Wshington, Settle. b Associte Professor, Deprtment of Orthodontics, University of Wshington, Settle. c Associte Professor, Deprtment of Orthodontics, University of Wshington, Settle. d Professor, Deprtment of Orthodontics, University of Wshington, Settle. This study ws submitted in prtil fulfillment of the requirements for the degree of Mster of Science in Dentistry. Corresponding uthor: Eileen Zierhut, 7345 Medicl Center Driver, #330, West Hills, CA (e-mil: ezierhut@ol.com) Accepted: August Submitted: Jnury by The EH Angle Eduction nd Reserch Foundtion, Inc. in the refereed literture. Furthermore, inherent to this conclusion re the unproven ssumptions tht chnges in the hrd tissue directly nd eqully ffect the overlying soft tissue profile, nd tht norml mturtion does not ply significnt role in post-tretment nd long-term profile outcomes. As Liebermnn 1 reminds us,... our role in the long rnge fcil chnges tht tke plce over the life of our ptient my be less significnt thn we think. Studies tht hve compred tretment effects on the soft tissue profile in extrction nd nonextrction smples re few in number, but re of some vlue in the resolution of this debte. Finnoy et l 2 found tht there were very few soft tissue profile differences in 2 groups of subjects with Clss II division 1 mlocclusion treted with nd without extrction therpy 3 to 5 yers post-tretment. However, significnt differences in the soft tissue profiles existed before tretment between the extrction nd nonextrction smples. Looi nd Mills 3 lso evluted lip nd incisor chnges in extrction nd nonextrction groups of subjects with Clss II division 1 mlocclusions. Although they found greter retrction of both the incisors nd the lower lip in the extrction group, vlid comprison between 208

2 PROFILE CHANGES ASSOCIATED WITH MALOCCLUSIO groups ws difficult due to the substntil differences in the mechnotherpy used to tret ech group. In ddition, lip chnges were mesured from midcrnil skeletl reference lines, with no quntifiction of lip chnge reltive to soft tissue chin nd nose. Pquette, Betty, nd Johnston 4 compred the effects of extrction nd nonextrction therpy on the profile in Clss II division 1 mlocclusions with borderline rch length deficiencies. They found tht the denture ws significntly more protrusive in the nonextrction smple t the completion of tretment, s well s t recll more thn 10 yers lter. However, despite sttisticlly significnt retrusive denture, the extrction subjects were just s likely to view their outcome s n improvement s were their nonextrction counterprts. Finlly, 2 compnion studies by Dobrocky nd Smith 5 nd Young nd Smith 6 found tht, in spite of significntly more men lip retrction in their extrction group, the individul vritions in fcil chnge, s determined by the stndrd devitions, were similr between groups. Most importnt, they found tht the frequency of undesirble fcil chnges, s mesured by comprison with idel nsolbil nd lbiomentl ngles nd lip position reltive to fcil reference lines, ws similr for the extrction nd nonextrction smples. The concept tht extrction therpy flttens the profile ssumes tht greter mount of incisor retrction tkes plce secondry to tooth removl nd tht the soft tissues ct s pssive drpe following the underlying dentl chnges by corresponding nd predictble mount. The literture, however, does not support this ssumption. Studies quntifying the response of soft tissue reltive to chnges in hrd tissue re numerous, with equivocl results. Most studies hve described reltionship between incisor nd lip retrction, but the strength of this reltionship vries gretly between studies. 3,7 14 It is generlly concluded tht the reltionship between hrd nd soft tissue chnge is subject to lrge individul vrition, nd the presumption tht this individul vribility differs between extrction nd nonextrction groups ppers unjustified. Long-term ssessment of the soft tissue profile must lso consider the norml mturtionl chnges tht occur nd the considerble individul vrition. Growth of the nose nd chin in untreted dolescents hs been shown to fr exceed concomitnt chnge in the lips This norml mturtion chnge tended to continue postdolescence, resulting in further reltive retrction of the lips Nose nd chin growth hve lso been shown to exceed the lip chnges observed in dolescents undergoing ctive tretment. 11,12,20 The purpose of this study ws to compre the post-tretment nd long-term soft tissue profiles of successfully mnged nd stble Clss II division 1 mlocclusions treted with either 4 first premolr extrction or nonextrction tretments. TABLE 1. Men Smple Chrcteristics Men ge T1 Men ge T2 Men ge T3 Men tretment time Men postretention time 209 Vrible Extrction Nonextrction MATERIALS AND METHODS Smple The smple consisted of 63 Americn Cucsin ptients (33 femles, 30 mles) treted by fculty or grdute students of the Deprtment of Orthodontics t the University of Wshington. The smple ws prt of lrger smple evluted in previous study by Fidler et l 21 of the longterm Clss II stbility of successfully treted Clss II division 1 mlocclusions. Subjects were included if they presented with pretretment Clss II division 1 mlocclusion showing molr reltionship of t lest end-on, minimum overjet of 5 mm, nd successful tretment result s determined by model evlution. Three experienced fculty members t the University of Wshington Deprtment of Orthodontics determined the cceptbility of subjects by subjective evlution of intercusption, tooth lignment, nd incisor reltionship. Cephlometric chrcteristics nd long-term post-tretment occlusl reltionships were not considered in the smple selection. Specific criteri for inclusion in this study included the vilbility of high-qulity pretretment (T1), post-tretment (T2), nd long-term post-retention (T3) lterl cephlometric rdiogrphs tht clerly showed the soft tissue profile. The extrction group ws limited to subjects treted with 4 first premolr extrctions only, with ll other permnent teeth present from first permnent molr to contrlterl first permnent molr. The nonextrction group hd ll permnent teeth present from first permnent molr to contrlterl first permnent molr. The smple included 23 subjects (11 mles, 12 femles) treted with extrction nd 40 (19 mles, 21 femles) treted with nonextrction therpy. The men ges for the extrction nd nonextrction groups t T1, T2, nd T3, nd the men ctive tretment nd men post-retention durtions re shown in Tble 1. Fifteen subjects from the study conducted by Fidler et l 21 were excluded becuse the extrction combintion did not meet these smple criteri or becuse the rdiogrphs did not dequtely revel the soft tissue profile. All subjects were treted during dolescence with fixed edgewise mechnotherpy. Clss II correction ws chieved primrily using extrorl force in the form of cervicl hedger to redirect or inhibit mxillry growth with concurrent fcil growth nd mxillry incisor retrction. No ptients in this smple were treted with either functionl pplinces or orthognthic surgery.

3 210 ZIERHUT, JOONDEPH, ARTUN, LITTLE Cephlometric nlysis FIGURE 1. Cephlometric lndmrks. Lterl cephlometric rdiogrphs used in this study were mde using stndrdized Brodbent cephlometric technique. The pretretment (T1), post-tretment (T2), nd long-term post-retention (T3) lterl cephlometric rdiogrphs were trced nd superimposed by the sme investigtor. Lndmrks used on ech rdiogrph re shown in Figure 1. The liner nd ngulr vribles mesured for ech rdiogrph re given in Tbles 2 through 8. Chnges in these vribles were clculted between T1 nd T2 nd between T2 nd T3. An increse in vrible ws recorded s positive nd decrese ws recorded s negtive. Overll, mxillry, nd mndibulr superimpositions were mnully performed for ech subject from T1 to T2 nd from T2 to T3. A liner distnce representing chnge over time between lndmrks ws mesured on the superimpositions using the Fowler Ultr-Cl II digitl cliper (Fred V. Fowler Co, Inc, Newton, Mss). These mesurements were lso mde from T1 to T2 nd from T2 to T3. A forwrd chnge ws recorded s positive nd bckwrd chnge s negtive. All liner mesurements were mde to the nerest 0.01 mm nd the ngulr mesurements were mde to the nerest 0.5 degree. Overll superimposition ws done to evlute reltive TABLE 2. Profile Mesurements, Extrction Vs Nonextrction Groups t T1 Vrible LI to APg LI to NB, mm LI to NB, degrees LI to MP UI to NA, mm UI to NA, degrees Overjet NAPg N A Pg ANB A N B Pg to NB UL to E LL to E UL to S LL to S H ngle A to H B to H UL curve N thickness A thickness UL thickness LL thickness B thickness Pg thickness Men Extrction indictes stndrd devition;, not significnt. P.05. Significnt with the Bonferroni correction (P.002). Nonextrction Men Difference P Vlue Significnce

4 PROFILE CHANGES ASSOCIATED WITH MALOCCLUSIO 211 TABLE 3. Profile Mesurements, Extrction Vs Nonextrction Groups t T2 Vrible LI to APg LI to NB, mm LI to NB, degrees LI to MP UI to NA, mm UI to NA, degrees NAPg N A Pg ANB A N B Pg to NB UL to E LL to E UL to S LL to S H ngle A to H B to H UL curve N thickness A thickness UL thickness LL thickness B thickness Pg thickness Men Extrction indictes stndrd devition;, not significnt. P.05. Significnt with the Bonferroni correction (P.002). Nonextrction Men Difference P Vlue Significnce chnges in the soft tissue profile resulting from both growth nd tretment response between ll 3 times. Overll superimpositions were mde using the best fit of the ethmoid trid, specificlly the greter wings of the sphenoid, pltinum sphenoidum (sphenoethmoidl plne), nd the surrounding detiled ntomy 22 (Figure 2). Chnges evluted using this superimposition technique were mesured long line prllel to the verge occlusl plne for the 3 times. This verge occlusl plne ws determined by verging the ngle of the 3 occlusl plnes to line common to ech of the superimposed trcings. It ws then trnsferred to the T1 trcing. To evlute incisor nd lip chnges in mxill nd mndible, while eliminting the effects of growth, mxillry nd mndibulr superimpositions were performed. Mxillry superimpositions were mde on the nterior nd posterior borders of the zygomtic process, llowing the floor of the orbit to rise in rtio of 1.5:1 mm in reltion to the lowering of the pltl plne 23 (Figure 3). Mndibulr superimpositions were mde using the best fit of the internl ntomy of the symphysis, using the mndibulr cnl nd inferior border of the third molr crypt s guides 24 (Figure 4). Mesurements mde from the mxillry nd mndibulr superimpositions were lso mde prllel to the verge occlusl plne. Pretretment overjet ws mesured from dignostic models tken t T1. Lower incisor to mndibulr plne ngle ws tken from mesurements mde on this sme smple by Fidler et l. 2l Method error study All rdiogrphs were retrced nd ll vribles remesured for 10 cses selected t rndom to determine intrexminer error in trcing, superimposition technique, nd mesurements. These duplictions were performed minimum of 2 weeks prt. The error of the method ws clculted using Dhlberg s formul. 25 SUM D 2 Sx sq root of 2n where D is the difference between double mesurements nd N is the number of duplicted mesurements. The men error for liner mesures ws between 0.1 mm nd 1.2 mm nd for ngulr mesures ws between 0.4 nd 1.6. Anlysis of dt Mens of the vribles mesured from the lterl cephlometric rdiogrphs t T1, T2, nd T3 were clculted. To compre profile sttus t T1, T2, nd T3, between-group differences were ssessed using 2-smple t-tests for unpired dt (independent smples). Mens were lso clculted for the chnges in the liner nd ngulr profile mesures nd for chnges mesured

5 212 ZIERHUT, JOONDEPH, ARTUN, LITTLE TABLE 4. Profile Mesurements, Extrction Vs Nonextrction Groups t T3 Vrible LI to APg LI to NB, mm LI to NB, degrees LI to MP UI to NA, mm UI to NA, degrees NAPg N A Pg ANB A N B Pg to NB UL to E LL to E UL to S LL to S H ngle A to H B to H UL curve N thickness A thickness UL thickness LL thickness B thickness Pg thickness Men Extrction indictes stndrd devition;, not significnt. P.05. Significnt with the Bonferroni correction (P.002). Nonextrction Men Difference P Vlue Significnce from the superimpositions for T1 to T2 nd T2 to T3. To determine if these chnges were significntly different between extrction nd nonextrction groups, 2-smple t-tests for unpired dt were used. A lrge number of t-tests were crried out between groups. In order to reduce the possibility of some t-tests chieving significnce due to chnce lone, Bonferroni corrections were crried out seprtely for t-tests between groups for ech time period nd between time periods between groups. Only those t-tests with P-vlues less thn the corresponding Bonferroni correction were considered significnt. The significnce level for this correction ws.002 for the mesurements mde from ech seprte rdiogrph t T1, T2, nd T3 nd.001 for the chnges between time periods. To determine if there ws ny ssocition between lip position t T2 or T3 nd the profile sttus t T1, or the chnges in profile during tretment, stepwise bckwrd elimintion regression procedure ws employed. Regression models were built for the upper s well s the lower lip, looking seprtely t the ssocitions with pretretment vribles nd with tretment chnges in these vribles. A correltion coefficient equl to or greter thn 0.70 ws considered cliniclly significnt. RESULTS Results for the comprison of the extrction nd nonextrction groups re presented in Tbles 2 through 4. t-tests with P-vlues less thn.05 re indicted to note tht, without the Bonferroni correction, these would be considered significnt. Considerble individul vrition ws observed in both the profile mesures nd chnges between time periods. All subjects grew during the study period, s evidenced by men chnge in the position of rticulre of 6.84 mm from T1 to T2 nd 4.62 mm from T2 to T3. Pretretment Pretretment men hrd nd soft tissue profile mesurements for the extrction nd nonextrction groups re presented in Tble 2. No significnt differences between groups were found except in the position of the lower incisor nd the mount of chin prominence. In the extrction group, the lower incisor ws significntly further forwrd reltive to APg nd NB lines nd significntly more proclined reltive to the NB line. Hrd tissue chin prominence, s mesured by Pg reltive to the NB line, ws significntly greter in the nonextrction group.

6 PROFILE CHANGES ASSOCIATED WITH MALOCCLUSIO 213 TABLE 5. Significnt Chnges, Extrction Vs Nonextrction, T1 T2 Vrible LI to APg LI to NB, mm LI to NB, degrees LI to MP UI to NA, mm UI to NA, degrees NAPg N A Pg ANB A N B Pg to NB UL to E LL to E UL to S LL to S H ngle A to H B to H UL curve N thickness A thickness UL thickness LL thickness B thickness Pg thickness Men Extrction indictes stndrd devition;, not significnt. P.05. Significnt with the Bonferroni correction (P.002). Nonextrction Men Difference P Vlue Significnce Post-tretment Post-tretment men hrd nd soft tissue profile mesurements for the extrction nd nonextrction groups re presented in Tble 3. No sttisticlly significnt differences between the extrction nd nonextrction groups were found. Long-term post-retention Long-term post-retention hrd nd soft tissue profile men mesurements for the extrction nd nonextrction groups re presented in Tble 4. No sttisticlly significnt differences between the extrction nd nonextrction groups were found for the hrd nd soft tissue profile mesurements long-term post-retention. Tretment chnges (T1 to T2) A comprison of the tretment chnges for the extrction nd nonextrction groups is shown in Tbles 5 nd 6. Significnt differences between groups were found for the chnges in lower lip nd lower incisor only. Significntly greter retrction of the lower lip reltive to the esthetic nd S plnes ws observed in the extrction group. Mndibulr superimpositions lso reveled tht the extrction group exhibited significntly more retrction of the lower lip nd lower incisor during the tretment period. No other intergroup differences were found for tretment chnges. Retrction of the upper lip reltive to esthetic plne lso occurred, with no significnt difference between groups. No significnt differences were observed between groups in the mount of mndibulr growth s mesured by chnge t rticulre. Nsl development nd forwrd movement of soft tissue chin s mesured on the overll superimpositions were lso not significntly different between groups during tretment. Long-term post-tretment chnges (T2 to T3) Long-term post-retention chnges for the extrction nd nonextrction groups re presented in Tbles 7 nd 8. Significnt chnges did occur from post-tretment to long-term (men 14 yers), but these chnges were not significntly different between the extrction nd nonextrction groups. The upper nd lower lips becme more retrusive reltive to esthetic nd S plnes. Overll superimpositions reveled tht this chnge ws due to significnt nsl development nd forwrd movement of the soft tissue chin. No significnt differences were observed between groups in the mount of long-term nsl development, forwrd soft tissue chin movement, or mndibulr growth s mesured by chnge t rticulre.

7 214 ZIERHUT, JOONDEPH, ARTUN, LITTLE TABLE 6. Significnt Chnges From Superimpositions, Extrction Vs Nonextrction Groups, T1 T2 Vrible Men Overll superimposition N 1.87 Nose tip 4.41 A 0.16 UL 1.03 LL 0.06 B 1.98 Pg 3.72 N 1.45 A 0.3 B 1.54 Pg 3.08 UI 4.93 LI 0.28 Mxillry superimposition A UL UI Mndibulr superimposition LL B LI Articulre Extrction indictes stndrd devition;, not significnt. P.05. Significnt with the Bonferroni correction (P.0011). Nonextrction Men Difference P Vlue Significnce Chnges pretretment (T1) to long-term post-tretment (T3) No significnt differences between groups were found in the chnges from T2 to T3. Consequently, the differences between groups found from T1 to T3 reflect those found from T1 to T2. Therefore, seprte considertion of the composite chnges tht occurred from T1 to T3, ws not necessry. Regressions Bckwrds stepwise regression nlyses were run to determine if the pretretment sttus of ny of the profile vribles or if ny of the tretment chnges could be used s predictors of lip position reltive to the esthetic plne posttretment or long-term. Associtions with correltions of.70 or greter were found for the post-tretment nd longterm positions of the lower lip only. Lower lip position reltive to esthetic plne t T2 Positive ssocitions were found between the position of the lower lip reltive to the esthetic plne t T2 nd the position of the lower lip reltive to esthetic plne t T2 nd the size of the ANB ngle t T1. The correltion coefficients were 0.84 nd 0.74, respectively. Lower lip position reltive to esthetic plne t T3 A positive correltion coefficient of 0.74 ws found between the position of the lower lip reltive to esthetic plne t T3 nd the position of the lower lip reltive to the esthetic plne t T1. A negtive ssocition ws found between the position of the lower lip reltive to the esthetic plne t T3 nd the thickness of the lower lip t T1. The correltion coefficient ws DISCUSSION Prior to tretment, the 2 groups of Clss II division 1 mlocclusions presented with lmost identicl hrd nd soft tissue profile chrcteristics with only 2 significnt differences. In the extrction group, the lower incisor ws positioned further forwrd nd ws more proclined reltive to skeletl lndmrks. The position nd inclintion of the upper incisor ws the sme in ech group. Despite this difference in lower incisor position, the 2 groups did not differ in men pretretment overjet, which ws 8.3 mm in the extrction group nd 8.5 mm in the nonextrction group. The second difference ws tht the nonextrction group presented with lrger hrd tissue chin button, which ws not reflected, however, in significnt differences between groups in hrd nd soft tissue convexity mesurements or

8 PROFILE CHANGES ASSOCIATED WITH MALOCCLUSIO 215 TABLE 7. Significnt Chnges, Extrction Vs Nonextrction Groups, T2 T3 Vrible LI to APg LI to NB, mm LI to NB, degrees LI to MP UI to MA, mm UI to NA, degrees NAPg N A Pg ANB A N B Pg to NB UL to E LL to E UL to S LL to S H ngle A to H B to H UL curve N thickness A thickness UL thickness LL thickness B thickness Pg thickness Men Extrction indictes stndrd devition;, not significnt. P.05. Significnt with the Bonferroni correction (P.0011). Nonextrction Men Difference P Vlue Significnce S in lip position reltive to the nose nd chin. The initil soft tissue profiles of ech group were the sme. Correction of the Clss II mlocclusions ws ccomplished primrily with cervicl hedger to redirect or inhibit mxillry nterior development with concurrent mndibulr growth nd mxillry incisor retrction. After successful completion of tretment, comprison of the extrction nd nonextrction groups reveled no differences in ny mesures of hrd or soft tissue profile between the extrction nd nonextrction groups. Following n verge post-retention period of 14 yers, group comprisons lso reveled no differences in ny profile mesures. In short, the fcil profiles of the extrction nd nonextrction groups were the sme following tretment nd long-term post-retention. These findings re comprble to those reported by Finnoy et l, 2 who found strikingly similr morphology of the hrd nd soft tissue profiles in their comprison of extrction nd nonextrction groups 3 to 5 yers post-retention. They found very few differences in soft tissue profile nd no differences in incisor nd lip position. As in the present study, their pretretment extrction group exhibited lower incisor tht ws more procumbent nd proclined reltive to the NB line. Pquette, Bettie, nd Johnston 4 lso strted with very similr profiles in their borderline extrction smple. They found tht following tretment, lip retrusion reltive to esthetic plne ws greter in their extrction group, while the incisors were more proclined nd procumbent reltive to skeletl reference lines in their nonextrction group. It is interesting to note tht this difference in incisor position between groups ws still evident fter n verge of 14.5 yers post-retention, while the posttretment difference in lower lip position reltive to esthetic plne ws no longer significnt. In the present study, mndibulr superimpositions reveled tht during tretment the lower incisor in the extrction group ws retrcted, while no chnge occurred in the nonextrction group. This dissimilr incisor chnge during tretment offset the pretretment differences between groups in lower incisor position so tht following tretment, incisor position ws the sme in ech group. The lower lip ws lso retrcted more reltive to the nose nd chin in the extrction group, but this difference in lip chnge ws not reflected in ny differences in fcil profile between groups following tretment. Finnoy et l 2 lso found greter retrction of the lower incisor in their extrction group during tretment, with negligible chnge in the nonextrction group. They did not find ny intergroup differences in the mount of retrction of the lips reltive to the esthetic plne. Pquette et l 4 observed tht following tretment the lower incisors were significntly more proclined in the nonextrction group, while

9 216 ZIERHUT, JOONDEPH, ARTUN, LITTLE TABLE 8. Significnt Chnges From Superimpositions, Extrction Vs Nonextrction Groups, T2 T3 Vrible Overll superimposition N Nose tip A UL LL B Pg N A B Pg UI LI Mxillry superimposition A UL UI Mndibulr superimposition LL B LI Articulre Men Extrction indictes stndrd devition;, not significnt. P.05. Significnt with the Bonferroni correction (P.0011). Nonextrction Men Difference P Vlue Significnce FIGURE 3. Mxillry superimposition. FIGURE 2. Overll superimposition. slight retrction ws noted in the extrction group. A possible explntion for this difference in findings is tht the smple studied by Pquette et l 4 strted tretment with no differences between groups in initil incisor position, which would be in ccord with their selection of borderline extrction smple. It is resonble to ssume tht the difference in extrction nd nonextrction mechnics nd spce closure would be reflected in the corresponding differences seen in their post-tretment lower incisor position. In the present study, pretretment smple chrcteristics showed more protrusive nd procumbent lower incisor position in the extrction group initilly. Accordingly, the sme tretment chnges described by Pquette et l, 4 nd lso found in this study, resulted in the incisor position being the sme in ech group following ctive tretment. In greement with the present investigtion, Pquette et l 4

10 PROFILE CHANGES ASSOCIATED WITH MALOCCLUSIO FIGURE 4. Mndibulr superimposition. FIGURE 5. Rickett s E plne nd Steiner s S plne. lso noted more lower lip retrction reltive to esthetic plne in their extrction smple. Although the lips were more retrusive reltive to esthetic plne in both groups following tretment, the mount of this chnge ws the sme for ech group. This decrese in fcil profile convexity secondry to orthodontic tretment hs lso been reported by numerous other investigtors. 2,9,14 Crnil bse superimpositions reveled tht the chin nd nose moved forwrd reltive to the lips by similr mounts in both groups, nd it ppered tht this mndibulr growth nd nsl development contributed more to the flttening of the profile thn did ctul lip retrction. The mount of mndibulr growth nd nsl development tht occurred during tretment ws not sttisticlly different between extrction nd nonextrction groups. During the men post-retention period of 14 yers, significnt flttening of the profile continued to occur, but these chnges were lso the sme in ech group. Consequently, the long-term fcil profiles were the sme, independent of whether or not premolr extrction ws per- 217 formed. This continued decrese in fcil convexity ws lso observed during 3- to 5-yer post-retention intervl by Finnoy et l, 2 who observed tht this soft tissue chnge ws the sme in spite of differences in long-term incisor position. In the present study, the significnt nd similr mounts of mndibulr growth nd nsl development observed during the post-retention intervl surpssed the slight forwrd movement of the lips nd resulted in further long-term retrusion of the lips reltive to the nose nd chin. A thinning of the upper lip occurred during this period s well. As there were no differences between groups in these post-retention chnges, it ppers tht the flttening of the profile tht occurred with time ws primrily due to mturtionl chnges ssocited with continued mndibulr growth nd nsl development nd is not influenced by tooth removl. Progressive flttening of the fcil profile hs been well documented in numerous untreted smples 16,19 s well s in long-term post-tretment studies. 2,4 These long-term post-tretment studies lso found, incidentlly, tht there were no differences in long-term lip position when compring extrction nd nonextrction smples. Prior to tretment, lip position in both groups ws protrusive reltive to the nose nd chin bsed upon the esthetic idels proposed by Ricketts 26 4 mm for the upper lip nd 2 mm for the lower lip. Lip position reltive to the S line ws lso more protrusive thn Steiner s idel of the lips lying tngent to this plne. 27 Although the initil profiles were lso more protrusive thn the vlues reported by Forsberg nd Odenrick 28 for untreted normls of this ge group, they were very similr to vlues reported by others. 18,19,29 Following ctive tretment, lip position reltive to the nose nd chin ws the sme in ech group, with both groups exhibiting modertely more lip retrusion thn Ricketts idels nd the vlues reported for untreted normls of this ge group by Bishr et l, 29 Beget, 18 nd Nnd et l. 19 The lips were considerbly more retrusive, however, when compred with Steiner s idel. Long-term lip retrusion ws considerbly greter thn the idels suggested by both Ricketts nd Steiner, but ws only slightly more retrusive thn the vlues reported for norml untreted dults of similr ge by Beget, 18 nd of slightly lower ge group reported by others. 28,30 In greement with previous studies, 2,12,17,18,29 soft tissue convexity decresed during tretment nd this decrese progressed with time, independent of extrction. The soft tissue ANB nd NAPG ngles s well s the H ngle decresed similrly throughout the study period in both groups. It is of interest to note tht t the end of tretment s well s long-term post-retention, the soft tissue ANB nd H ngles were very similr to the vlues reported for untreted normls of the sme verge ge. 18 The H ngle did not rech the idel vlues proposed by Holdwy 31 until long-term post-retention. A better understnding of wht contributes to the ob-

11 218 ZIERHUT, JOONDEPH, ARTUN, LITTLE served profile chnges would certinly ssist the clinicin in tretment plnning by llowing nticiption of the soft tissue response to chnges of the underlying skeleton nd dentition nd with norml mturtion. Few pretretment hrd or soft tissue chrcteristics or chnges concurrent with ctive tretment were strong predictors of profile outcomes either fter tretment or long-term. Predictors were found for the position of the lower lip post-tretment nd long-term post-retention. The more retruded the lower lip ws to esthetic plne pretretment, the more likely it ws to be retruded fter tretment nd long-term. In ddition, the less severe the pretretment skeletl Clss II mlocclusion, s defined by the skeletl ANB ngle, the more likely the lower lip ws to be retrusive reltive to esthetic plne post-tretment. Finlly, the greter the lower lip thickness pretretment, the more retrusive the lower lip long-term. This finl ssocition my be due to the presence of initil lower lip eversion secondry to excess overjet. Consistent with other studies, 2 9,11 15,20,28 30 lrge individul vrition ws found in the hrd nd soft tissue profile mesurements both during nd fter tretment. This ws especilly true for lip position reltive to the esthetic plne. Studies evluting the soft tissue profile nd lip thickness must lso consider the effect of lip strin on the ccurcy of mesurements of sttic lip position nd response. Lip tension will vry between individuls nd between time periods for ny one individul. Inbility to control or quntify this vrible remins shortcoming of retrospective soft tissue cephlometric studies. The use of Ricketts esthetic plne 26 nd other mesures to ssess the profile in this study comes with the subtle impliction tht these stndrds my be good indictors of whether or not fce is esthetic. The perception of n esthetic fce is much more thn the sum of these sgittl mesurements. The view of the entire fce (not necessrily in sttic position), the blnce nd hrmony of the prts, nd the 3-dimensionl chrcter ll ply roles in ech individul s perception of wht constitutes plesing fcil ppernce. This study demonstrted tht in successfully treted cses where teeth were extrcted for combintion of resons (nd the cses therefore differed initilly in lower incisor position nd hrd tissue chin prominence from nonextrction cses) the sme soft nd hrd tissue profile endpoints were reched post-tretment nd long-term. The results cnnot be extrpolted to extrction nd nonextrction cses tht re perfectly mtched pretretment. It would be interesting to evlute mtched extrction nd nonextrction cses with significnt pretretment rch length deficiencies, protrusion, or both, or with miniml pretretment rch length deficiencies nd protrusion. Further studies re needed to provide informtion regrding the soft tissue responses in these types of mtched smples. CONCLUSIO The soft tissue fcil profiles of ptients with Clss II division 1 mlocclusion who were successfully treted with extrction nd nonextrction tretment were the sme following ctive tretment nd long-term post-retention. The fcil profile continued to fltten both during tretment nd long-term. This progressive decrese in soft tissue convexity ws primrily due to the mturtionl chnges ssocited with continued mndibulr growth nd nsl development, nd ws not influenced by whether or not teeth were removed. Long-term lip position ws more retrusive thn the idels suggested by Ricketts nd Steiner, but were close to the vlues reported for norml, untreted dults of similr ge. The pretretment position nd thickness of the lower lip s well s the initil mxillomndibulr skeletl reltionship my be predictors for post-tretment or long-term lower lip position. ACKNOWLEDGEMENTS The Wshington Dentl Service Foundtion nd the University of Wshington Orthodontic Alumni Assocition supported this study. REFERENCES 1. Liebermn MA, Gzit E. Fcil profile s ffected by extrction or non-extrction decisions. Quintessence Int. 1982;13: Finnoy JP, Wisth PJ, Boe OE. Chnges in soft tissue profile during nd fter orthodontic tretment. Eur J Orthod. 1987;9: Looi LK, Mills JR. The effect of two contrsting forms of orthodontic tretment on the fcil profile. Am J Orthod. 1986;89: Pquette DE, Bettie JR, Johnston LE Jr. A long-term comprison of nonextrction nd premolr extrction edgewise therpy in borderline Clss II ptients. Am J Orthod Dentofcil Orthop. 1992;102: Drobocky OB, Smith RJ. Chnges in fcil profile during orthodontic tretment with extrction of four first premolrs. Am J Orthod Dentofcil Orthop. 1989;95: Young TM, Smith RJ. Effects of orthodontics on the fcil profile: comprison of chnges during nonextrction nd four premolr extrction tretment. Am J Orthod Dentofcil Orthop. 1993;103: Bloom LA. Periorl profile chnges in orthodontic tretment. Am J Orthod. 1961;47: Rudee DA. Proportionl profile chnges concurrent with orthodontic therpy. Am J Orthod. 1964;50: Hershey HG. Incisor tooth retrction nd subsequent profile chnge in postdolescent femle ptients. Am J Orthod. 1972;61: Wisth PJ. Soft tissue response to upper incisor retrction in boys. Br J Orthod. 1973;1: Anderson JP, Joondeph DR, Turpin DL. A cephlometric study of profile chnges in orthodonticlly treted cses ten yers out of retention. Angle Orthod. 1973;43: Angelle PL. A cephlometric study of the soft tissue chnges during nd fter orthodontic tretment. Trns Eur Orthod Soc. 1973; Roos N. Soft-tissue profile chnges in clss II tretment. Am J Orthod. 1977;72: Tlss MF, Tlss L, Bker RC. Soft-tissue profile chnges re-

12 PROFILE CHANGES ASSOCIATED WITH MALOCCLUSIO sulting from retrction of mxillry incisors. Am J Orthod Dentofcil Orthop. 1987;91: Pelton WJ, Elssser WS. Studies of dentofcil morphology, IV. Profile chnges mong 6,829 white individuls ccording to ge nd sex. Angle Orthod. 1955;25: Subtelny JD. A longitudinl study of soft tissue fcil structures nd their profile chrcteristics, defined in reltion to underlying skeletl structures. Am J Orthod. 1959;45: Beget BC. A Cephlometric Study of Profile Chnges to Age 32 in Orthodontic normls [thesis]. Settle, Wsh: University of Wshington; Nnd RS, Meng H, Kpil S, Goorhuis J. Growth chnges in the soft tissue fcil profile. Angle Orthod. 1990;60: Wisth PJ. Chnges of the soft tissue profile during growth. Trns Eur Orthod Soc. 1972; Koch R, Gonzles A, Witt E. Profile nd soft tissue chnges during nd fter orthodontic tretment. Eur J Orthod. 1979;1: Fidler BC, Årtun J, Joondeph DR, Little RM. Long-term stbility of Angle Clss II, division 1 mlocclusions with successful occlusl results t end of ctive tretment. Am J Orthod Dentofcil Orthop. 1995;107: Elmjin KE. A Seril Study of Fcil Growth s Relted to 219 Crnil Bse Morphology [thesis]. Settle, Wsh: University of Wshington; Doppel DM, Dmon WM, Joondeph DR, Little RM. An investigtion of mxillry superimposition techniques using metllic implnts. Am J Orthod Dentofcil Orthop. 1994;105: Bjork A. Vritions in the growth pttern of the humn mndible: longitudinl rdiogrphic study by the implnt method. J Dent Res. 1963;42(suppl 1): Dhlberg G. Sttisticl Methods for Medicl nd Biologicl Students. New York, NY: Interscience Publictions; Ricketts RM. Plnning tretment on the bsis of the fcil pttern nd n estimte of its growth. Angle Orthod. 1957;27: Hmbleton RS. The soft-tissue covering of the skeletl fce s relted to orthodontic problems. Am J Orthod. 1964;50: Forsberg CM, Odenrick L. Chnges in the reltionship between the lips nd the esthetic line from eight yers of ge to dulthood. Eur J Orthod. 1979;1: Bishr SE, Hession TJ, Peterson LC. Longitudinl soft-tissue profile chnges: study of three nlyses. Am J Orthod. 1985; 88: Srnäs KV, Solow B. Erly dult chnges in the skeletl nd softtissue profile. Eur J Orthod. 1980;2: Holdwy RA. A soft-tissue cephlometric nlysis nd its use in orthodontic tretment plnning, Prt 1. Am J Orthod. 1983;84: 1 28.