paper x10

ORIGINAL ARTICLE

Smile esthetics: Perception and comparison oftreated and untreated smilesErdal Isıksal,a Serpil Hazar,b and Sercan Akyalçınc

Izmir, Turkey

Introduction: Although orthodontic treatment is based primarily on occlusal relationships, greater attentionis now paid to enhancing dentofacial characteristics to produce optimal facial esthetics. The purposes of thisstudy were to compare smile esthetics among extraction and nonextraction patients and a control group,assess certain dentofacial characteristics in those groups, and discuss how these features relate to smileesthetics. Methods: Panels of orthodontists, plastic surgeons, artists, general dentists, dental professionals,and parents used a 5-point scale to rate smiling photographs of 25 extraction, 25 nonextraction, and 25untreated control subjects. Dentofacial characteristics of the 3 groups were obtained from lateral cephalo-metric analyses, direct biometric measurements, and frontal photographs. Smile esthetics and differencesamong the 3 groups were subjected to 1-way analysis of variance (ANOVA), and Pearson correlationcoefficients were calculated to determine the relationship of the variables to the esthetic score. Results: Themean esthetic scores for the extraction, nonextraction, and control groups were 3.15, 3.12, and 3.26,respectively. Visible dentition width relative to the smile width ratio and intercanine distance relative to smilewidth ratio were significantly different among the groups, with extraction patients showing a slightly widerdental arch relative to the soft tissue (P � .05). There was also a significant difference in the U1-SN angleamong the groups (P � .05), and this variable showed a strong correlation with the esthetic score as didmaxillary gingival display (P � .05). However, our study groups could not be differentiated in smile esthetics.
(Am J Orthod Dentofacial Orthop 2006;129:8-16)
Cosmetic dentistry has long been interested inthe esthetics of the smile. Recently, the topichas become important for orthodontists be-

cause more orthodontic patients evaluate the outcomeof treatment by their smiles and the overall enhance-ment in their facial appearance. Although orthodontictreatment is based primarily on occlusal relationships,greater attention is now paid to enhancing dentofacialcharacteristics to produce optimal facial esthetics.

Current knowledge suggests that favorable treat-ment changes are significant to patients, parents, andfriends, and are important aspects of orthodontic ther-apy. Thus, it seems worthwhile to outline the commondenominators of an esthetically pleasing smile, which isoften a primary reason for seeking orthodontic care.The literature contains noteworthy studies1-9 describingthe esthetic elements of the dentition and the surround-ing soft tissues during smiling that can be evaluated on

From the Department of Orthodontics, Faculty of Dentistry, Ege University,Izmir, Turkey.aProfessor and chair.bProfessor.cPostgraduate student.Reprint requests to: Dr Serpil Hazar, Ege Universitesi Dishekimligi Fakultesi, OrtodontiAnabilim Dali 35100 Bornova, Izmir, Turkey; e-mail, [email protected], August 2004; revised and accepted, September 2004.0889-5406/$32.00Copyright © 2006 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2005.07.004
8

a 3-dimensional canvas. Sarver and Ackerman10,11

published instructive data about dynamic smile visual-ization, quantification, and relevant treatment strate-gies. They suggested that the orthodontist should addanother dimension—time—in evaluating smiles (howsmiles change over time because of aging).

In smile esthetics, 2 transverse characteristics—arch form and buccal corridor—have gained greaterinterest recently. It is said that extraction treatmentresults in constriction of the dental arches and hasdeleterious effects on the smile.12 he suspected arch-width reduction by premolar extractions decreases thebuccal corridor ratio and leads to black triangles at thecorners of the mouth during smiling. Johnson andSmith13 concluded that variables related to the buccalcorridor or other measures of the relationship betweenthe widths of the dentition and of the mouth during asmile showed no relationship to extraction esthetics.Furthermore, 2 other studies14,15 support these views bycomparing arch widths after extraction and nonextrac-tion treatment in study casts. However, Spahl16 arguedthat plaster models cannot tell us about human faces orthe lip support they do or do not provide. Similarly,after evaluating the lip-teeth characteristics of the posedsmile in treated and untreated subjects, Ackerman et al9

concluded that not all orthodontically well-treated pa-

American Journal of Orthodontics and Dentofacial OrthopedicsVolume 129, Number 1

Isıksal, Hazar, and Akyalçın 9

tients with exemplary plaster casts have desirableanterior tooth displays while smiling.

Various studies13,17-19 have evaluated the treatedsmiles by judgments of specialists and laypeople, butnone have documented the differences among extrac-tion, nonextraction, and control subjects. A controlgroup can also provide data in addition to the compar-ison of dentofacial characteristics between differenttreatment protocols. Thus, the main purpose of thisstudy was to compare the esthetics of the smile inextraction and nonextraction patients with a controlgroup with ideal occlusion. We also aimed to statisti-cally determine certain dentofacial characteristics of the3 groups and to discuss how these features relate tosmile esthetics.

MATERIAL AND METHODS

Frontal and three-quarter view smiling photo-graphs, direct biometric measurements, and cephalo-metric data were collected from 25 extraction patients,25 nonextraction retention patients, and 25 untreatedparticipants with well-balanced faces and good occlu-sions. The mean ages were 19.08 � 2.40 years in theextraction, 19.04 � 1.97 years in the nonextraction, and20.24 � 2.39 years in the control groups. The sexdistributions for the 3 groups were the same (13women, 12 men).

The control subjects were dental students at thedental school of Ege University, Izmir, Turkey, who

Fig 1. Sample frontal and t

had not had orthodontic therapy. The treatment groups

had Angle Class I malocclusions before treatment.None of the treated subjects had a severe craniofacialanomaly, and all were treated with standard 0.018 x0.022-in edgewise appliances. The treatment objectivesfor both the extraction and the nonextraction groupswere to ideally align the incisors, establish excellentocclusions with teeth interdigitated, and resolve toothsize-arch length discrepancies while maintaining theoriginal arch form. In the extraction group, 4 firstpremolars were extracted. Mean values of crowdingwere 4.15 � 1.76 mm in the maxillary arch and 3.16 �1.41 mm in the mandibular arch for the nonextractiongroup. In the extraction group, crowding was 7.45 �2.12 in the maxillary arch and 5.02 � 2.14 mm in themandibular arch. The average treatment times were27.10 � 14.23 months for the nonextraction group and29.46 � 12.18 months for the extraction group.

Before the study, 198 retention patients and dentalstudents were carefully examined, and those with den-tal features that would have deleterious effects on thesmile, such as diastema, deep bite, open bite, overjet,and rotations, were excluded from the study. The finalsample of 75 subjects had excellent occlusions withAngle Class I molar and canine relationships andwell-balanced faces.

Facial photographs were taken of each participantduring smiling, including frontal and three-quarterviews (Fig 1). All photographs were taken by the sameinvestigator (S.A.) at a constant object-to-lens distance

uarter facial photographs.
hree-q
with a Coolpix digital camera (Nikon Photo Products,

American Journal of Orthodontics and Dentofacial OrthopedicsJanuary 2006

10 Isıksal, Hazar, and Akyalçın

Tokyo, Japan). Several photos were made of eachsubject so that we could choose unforced, naturalsmiles. A frontal view and a three-quarter view of eachsmile were selected for evaluation by the panel mem-bers. These photographs were then transferred to PhotoExpress 3.0 SE image processing software (UleadSystems, Torrance, Calif). The 2 facial photographswere cropped so that only the lower face was shown(Fig 2). The cropped images were converted to blackand white and copied to slides in PowerPoint (Mi-crosoft, Redmond, Wash) for projection.

The panels consisted of 10 orthodontists, 10 plasticsurgeons, 10 dental specialists, 10 general dentists, 10artists, and 10 parents. There were 5 men and 5 womenon each panel to eliminate sex bias. The ages of thepanel members varied from 36 to 56 years, with meanages of 44.3 years for the orthodontists, 41.8 for theplastic surgeons, 46.2 for the dental specialists, 45.3 forthe general dentists, 44.4 for the artists, and 45.7 for theparents. Three of the artists, 1 plastic surgeon, and 1orthodontist had received orthodontic treatment.

The raters were told that they would see 75 slides,each showing 2 views of the same person duringsmiling. They were asked to rate the attractiveness ofthe smiles on a 5-point scale, with 5 as “excellent” and1 as “poor.” The raters were shown the 75 slides inrandom order for 10 seconds. Each rater made his orher evaluation privately with no information about thesubjects. The raters were allowed to view the slidesagain and revise their scores, if they desired.

To further compare the dentofacial characteristicsof the 3 groups, additional data were obtained fromlateral cephalometrics (Fig 3), direct biometric mea-surements, and frontal photographs (Table I). All ra-

Fig 2. Images cropped so that only lower face is visible.

diographs were taken on the same cephalostat with the

subjects standing, Frankfort plane parallel to the hori-zontal, teeth in centric occlusion, and lips relaxed.Direct biometric measurements were made with adigital caliper with the subjects sitting and the Frankfortplane parallel to the horizontal. Frontal photographswere measured by computer with Image Tool forWindows version 3.00 (UTHSCSA, San Antonio, Tex).Spatial measurements were calibrated by drawing a lineof known length (width of the central incisors). Fiveratios (Table I), unaffected by magnification differ-ences, were determined from these measurements. Allmeasurements were repeated 1 month later by the sameinvestigator (S.A.) to ensure accuracy with paired ttests. No differences were found in the remeasurements(P � .05).

Statistical analysis

Reliability of the study was evaluated with theCohen kappa. Kappa statistics are appropriate for test-ing whether agreement exceeds chance levels for binaryand nominal ratings.20 One judge was randomly se-lected from each panel to reevaluate the entire sample2 months later. The second trials of these 6 judges weredetermined to be in the range of good repeatability (P� .05). One-way analysis of variance (ANOVA) wasused to compare smile esthetics and differences amongthe 3 groups. Additionally, multiple comparisons wereperformed with the Bonferroni test. Repeated-measureANOVA was also applied to determine differencesamong the panels. To further determine whether anyvariables related to smile esthetics, Pearson correlationcoefficients were calculated. The level of significancewas established as P � .05 for all statistical tests.

RESULTS

According to the 1-way ANOVA, the 3 groups didnot differ statistically in mean esthetic score, as evalu-ated by the 6 panels (P � .05) (Table II). The subjectswith the highest and the lowest scores were in thenonextraction group. However, according to descrip-tive statistics, there were no significant differences inthe distributions of the highest, lowest, and moderateesthetic scores among the 3 groups (Table III). Thisfinding clearly shows that not only were the meanscores similar, but also the distributions of subjectswith low and high scores were alike in the extraction,nonextraction, and control groups (Fig 4).

Repeated-measure ANOVA showed significant dif-ferences in the mean ratings for the whole sampleamong the 6 panels (Table II). However, according topairwise comparisons, no differences were determinedbetween orthodontists and artists, and between plastics
surgeons and general dentists (P � .05). Other possible

.



pairwise comparisons between panel groups were de-termined significant at the P � .05 level. Parents, onaverage, rated the smiling photographs significantlymore attractive than the other 5 panels. Repeated-measure ANOVA also showed that there was nointeraction between panels and groups; this meant thatthe panels did not rate any group better or worse(P � .05). Additionally, Kendall coefficients of con-cordance were calculated for the 6 panels. The KendallW can be interpreted as a coefficient of agreementamong raters.21 Interrater agreement existed in eachpanel at significant levels (P �.05). Although the meanratings for each panel differed, there was interrateragreement among the 60 raters (P � .05).

Table IV lists descriptive statistics for comparisonof variables among the extraction, nonextraction, andcontrol groups, and Pearson correlation coefficientsbetween the variable and the esthetic score. Additionalmultiple comparisons, determined by Bonferroni test,are given in Table V. According to the statistical data,cephalometric measurements including ANB, SN-MP,SN-PP, and lower lip to H-line did not differ among the3 groups (P � .05), indicating that both jaw orientationand facial harmony were similar.

Fig 3. Cephalometric measurements included in study:1, ANB angle; 2, SN-MP angle; 3, SN-PP angle; 4,U1-SN angle; 5, U1-NA angle; 6, U1-NA distance; 7,IMPA angle; 8, anterior maxillary height; 9, rima oris toocclusal plane distance; 10, lower lip to H-line distance

Visible dentition width relative to smile width ratio

and intercanine distance relative to smile width ratiowere significantly different among the groups, with theextraction patients having slightly wider dental archesrelative to the soft tissues (P � .05). There was also asignificant difference in U1-SN angle among the groups(P � .05). Nonextraction patients had slightly increasedmaxillary incisor inclinations in relation to anteriorcranial base compared with extraction patients; thecontrol subjects had ideal mean values. Although U1 toNA distance, U1-NA angle, and IMPA showed similardifferences among the groups, these differences werenegligible according to the statistical tests. Accordingto Pearson correlation coefficients, no transversecharacteristic of the smile was related to the estheticscore. However, the correlations between estheticscores and measurements including U1-SN angle andmaxillary gingival display were significant at P �.05 levels, indicating the importance of certain sag-ittal and vertical characteristics in an estheticallypleasing smile.

DISCUSSION

Harmony and balance are not fixed concepts. Stan-dards of beauty vary tremendously among persons andracial groups, and according to socioeconomic mores.22

However, the results showed that our study groupswere not differentiated in smile esthetics. The numbersof subjects with high, moderate, and low scores hadsimilar distributions in each group. This is a logicalexpectation because, in any group of subjects, there isindividual variability—shape of the teeth, curl of thelips, and mouth expression—that would lead the smileto be perceived as esthetically pleasing or not.

Hulsey17 stated that the mean rated smile scores oforthodontically treated subjects were significantlypoorer than the mean rated smile scores of the subjectswith normal occlusions. In contrast, according to Mack-ley,18 to conclude that people with ideal occlusions andaccompanying ideal facial proportions who have had noorthodontic treatment have more attractive smiles is anunjust criticism of orthodontic treatment. In our study,neither the treatment groups nor the control group wasseen as having superior smiles. These data corroboratethe findings of Johnston and Smith13 and Gianelly,15

who found no difference in smile esthetic scoresbetween extraction and nonextraction patients. Becausethe art of esthetics lies in the clinicians’ hands and newtechnologies have been developed to better visualizeand treat patients, it is not surprising to find nodifference in smile esthetics among untreated peoplewith ideal occlusions and patients treated either with orwithout extractions.

Many studies3,6,23-25 have evaluated the perceptions

lion

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sor

l

of

y

l

ris

ormed b



of different panels for dentofacial esthetic discrepan-cies. Orthodontists on the average were found to bemore critical of dental esthetics than laypeople indetecting minor discrepancies. In our study, eventhough the mean rating scores were different among thepanels, according to the Kendall coefficients of concor-

Table I. Measurements used to evaluate smile esthetics

Measurements on frontal photographsSmile width (mm) Intercom

durinSmile height (mm) Interlab

smili3-3 distance (mm) Distanc4-4 distance (mm) Distanc

premVisible dentition width (mm) Distanc

durinMaxillary gingival display (mm) Amoun

margSmile index (ratio) Smile w3-3 distance/smile width (ratio) Intercan4-4 distance/smile width (ratio) InterpreVisible dentition width/smile width (ratio) Visible3-3 distance/visible dentition width (ratio) Intercan

Direct biometric measurementsWidth of central incisor (mm) Distanc

crownHeight of central incisor (mm) Distanc

incisoHeight of central incisor during smiling (mm) Distanc

incisoUpper lip length at rest (mm) With m

upperUpper lip length during smiling (mm) DistancSn to incision distance (mm) DistancMaxillary incisor display (ratio %) HeightUpper lip length/Sn to incision (ratio) Lip curt

incisiUpper lip length during smiling/Sn to incision (ratio) Lip curt

subnaUpper lip length during smiling/upper lip length (ratio) Upper l

upperMeasurements made on lateral cephalometricsLinear measurements

Anterior maxillary height (mm) PerpendRima oris to cclusal plane (mm) Relation

to ocLower lip to H-line (mm) DistancU1 to NA line (mm) Linear d

Angular measurementsSNA (°) Angle fSNB (°) Angle fANB (°) DifferenSN-MP (°) Angle fSN-PP (°) Angle fU1-SN (°) Angle fU1-NA (°) Angle fIMPA (°) Angle f

dance, interrater agreement was determined for the 60

raters (P � .05). This finding enhanced the view thatour 3 groups were rated similarly in appearance. Boleyet al26 stated that orthodontic students and generaldentists could not identify the treatment modality whenassessing facial photographs.

Because some orthodontists believe that extraction

e width as measured by distance between left cheilion to right cheigas measured by distance from upper stomion to lower stomion duri

red between most distal points of maxillary caninesred between most distal points of maxillary first premolars (secondextraction group)en most lateral left and right points of visible maxillary dentitiongillary gingival exposure between inferior border of upper lip and

giva of maxillary central incisorsvided by smile heightance divided by intercommissure widthistance divided by intercommisure widthn width divided by smile widthance divided by visible dentition width

red between most distal and mesial points of maxillary central inci

red between marginal gingiva and incisal edges of maxillary centransred between most superior and inferior points on maxillary central

ns during smilingand lips in rest position, distance from subnasale to inferior border

subnasale to inferior border of upper lip during smilingsubnasale to incisal edge of maxillary central incisoral incisor during smiling divided by actual height of central incisorr incisors at rest: upper lip length distance divided by subnasale toncer incisors during smiling: upper lip length during smiling divided bincision distanceaction during smiling: the ratio of upper lip smiling length to actuagth.

istance from ANS projected at right angle to occlusal planeocclusal plane to lip embrasure, measured as distance from rima o

laneer lip to harmony line, tangential to Pog’ and Lsbetween NA line and maxillary incisor.

y intersection of SN and NA linesy intersection of SN and NB lineseen SNA and SNBy intersection of SN line and mandibular plane (Go-Me)y intersection of SN line and palatal plane (ANS-PNS)y intersection of maxillary incisor to anterior cranial basey intersection of maxillary incisor to NAy intersection of mandibular incisor to mandibular plane

missurg smilinial gapnge measue measuolars ine betweg smilint of maxinal ginidth diine distmolar ddentitioine dist

e measus

e measur crow

e measur crow

andiblelip

e frome fromof centrain oveon distaain ovesale toip contrlip len

icular dship of

clusal pe of lowistance

ormed bormed bce betw

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causes arch-width reduction that could lead to a de-

� 0.60

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crease in the buccal corridor ratio, another criticism ofextraction treatment is that it results in poor smileesthetics when compared with nonextraction therapy.However, people with normal occlusions and balancedfaces could also have narrow arch forms related to theirwide lip extensions. In a maxilla of normal width,lingual crown inclinations of posterior teeth might alsoproduce a narrow smile, whereas more upright crowninclinations produce a broader smile. With regard tojaw size, Zachrisson27-29 suggested that the smaller themaxillary apical base, the more labial crown tip shouldbe given to the canines and the premolars for obtainingoptimal esthetics. We intentionally included untreatedsubjects with ideal occlusions with the extraction andnonextraction patients to document the relationships oftransverse variables with treatment modality and es-thetic scores. Surprisingly, the extraction patients ex-hibited slightly wider dental arches relative to the softtissue, but transverse characteristics of the smile ap-peared to be of little significance to an attractive smile.The conclusions of Hulsey,17 Rigsbee et al,30 andGianelly15 agreed with this finding.

According to Utley, cited by Mackley,18 facialesthetics is not static, and its quality is not limited to the

Table II. Comparison of mean esthetic scores among expanels

PanelExtraction

n � 25Nonex

n �

Orthodontists 3.10 � 0.55 3.20Dental specialists 3.28 � 0.52 3.32General dentists 2.90 � 0.53 2.82Parents 3.65 � 0.63 3.64Plastic surgeons 2.71 � 0.45 2.69Artists 3.28 � 0.47 2.98Mean ratings of 6 panels 3.15 � 0.46 3.12

Table III. Distribution of highest, lowest, and moderate

Categories20%

Groups Extraction nWithin groupWithin category

Nonextraction nWithin groupWithin category

Control nWithin groupWithin category

Based on mean ratings of 6 panels, all 75 subjects were categorizedof highest, lowest, and moderate esthetic scores were similar among

measurements of a headfilm or to frontal and lateral

photographs. An orthodontist must have an awarenessof the proper vertical relationship of the denture andsoft tissues. With this in mind, we have included somedirect biometric measurements during a smile and atrest in the vertical plane with other vertical measure-ments made on lateral cephalometrics and frontal pho-tographs. Biometric measurements, used in this study,demonstrate the amount of lip contraction and theamount of vertical lip drape over dentition at rest andduring smiling. However, no vertical measurement wasstatistically significant, and only the maxillary gingivaldisplay measurement appeared to be significant to anattractive smile. A statistically significant correlation(Pearson correlation coefficient, –.410) was determinedbetween the maxillary gingival display and the estheticscore: the greater the maxillary gingival display, thelower the esthetic score. Some authors17,18 concludedthat the upper lip should be at the height of the gingivalmargin of the maxillary central incisors in an attractivesmile. Chiche and Pinault31 stated that the estheticallyideal amount of visible gingiva was about 1 mm,although 2 to 3 mm of gingiva might be estheticallyacceptable. However, this is very much of a function ofage, because children show more teeth at rest and have

n, nonextraction, and control groups as evaluated by 6

Controln � 25 P

Whole samplen � 75

3.16 � 0.61 .85 3.1603.46 � 0.50 .53 3.3562.96 � 0.63 .68 2.8993.90 � 0.42 .22 3.7352.87 � 0.54 .49 2.7613.21 � 0.57 .17 3.1603.26 � 0.44 .55 3.178

s among 3 groups

st scores15

60% moderate scoresn � 45

20% lowest scoresn � 15

14 656% 24%

% 31.1% 40%14 656% 24%

% 31.1% 40%17 368% 12%

% 37.8% 20%

20% highest, 20% lowest, and 60% moderate scores. Distributionsps.

tractio

traction25

� 0.68� 0.69� 0.57� 0.68� 0.68� 0.68

score

highen �

520%33.35

20%33.35

20%33.3

to be in

more gingival display on smile than do adults.11



Of all the factors related to a balanced smile, 1can easily be controlled—maxillary incisor position.These teeth should be angulated and also positionedmost favorably in their anteroposterior and verticalrelationships to all facial structures to ensure maxi-mum facial harmony.32 In this study, the inclinationsof the maxillary central incisors as measured byU1-SN angle were statistically different among the 3

Fig 4. Distribution of es

Table IV. Descriptive statistics for comparison of variabPearson correlation coefficients between variable and e

Variable Pearson corr

Smile index (smile width/smile height) (ratio) .1153-3 distance/smile width (ratio) �.1574-4 distance/smile width (ratio) �.097Visible dentition width/smile width (ratio) .0343-3 distance/visible dentition width (ratio) �.196Maxillary gingival display (mm) �.410*Maxillary incisor display (ratio %) .100Upper lip length/Sn to incision (ratio) �.061Upper lip length (smiling)/Sn to incision (ratio) .043Upper lip length (smiling)/upper lip length (ratio) .111ANB (°) �.004SN-MP (°) �.103SN-PP (°) .141U1-SN (°) �.252*U1-NA (°) �.072U1-NA (mm) �.113IMPA (°) .018Anterior maxillary height (mm) .002Rima oris to occlusal plane (mm) �.198LL to H-line (mm) �.023

*P � .05.†P � .05.

groups. It seems that the maxillary incisors needed

more labial crown torque after retraction in theextraction group. However, the difference did notaffect smile esthetics in the 3 groups. Furthermore,our results showed that increasing the U1-SN anglewould cause smile esthetics to deteriorate (Pearsoncorrelation coefficient, –252). For instance, the useof a high-torque bracket system particularly in non-extraction treatment with anterior crowding and ini-

scores of 75 subjects.

ong extraction, nonextraction, and control groups andic score

Extractionn � 25

Nonextractionn � 25

Controln � 25 P

5.43 � 0.93 5.31 � 0.92 5.60 � 1.08 .6020.72 � 0.030 0.70 � 0.047 0.68 � 0.041 .009†

0.83 � 0.034 0.81 � 0.050 0.80 � 0.040 .5690.9 � 0.040 0.88 � 0.054 0.90 � 0.034 .026†

0.78 � 0.043 0.79 � 0.045 0.76 � 0.041 .0580.06 � 0.22 0.13 � 0.49 0.17 � 0.50 .645

97.58 � 3.69 96.40 � 7.20 95.07 � 6.62 .3420.82 � 0.034 0.81 � 0.053 0.82 � 0.054 .7270.64 � 0.037 0.65 � 0.052 0.64 � 0.049 .3630.78 � 0.045 0.80 � 0.060 0.78 � 0.054 .1993.22 � 1.40 3.24 � 1.60 2.68 � 1.50 .333

33.82 � 2.70 34.34 � 3.04 33.76 � 3.16 .3229.60 � 3.36 8.98 � 3.24 10.88 � 2.88 .103

100.2 � 5.25 104.7 � 6.12 103.3 � 4.83 .013†

21.62 � 5.23 24.52 � 5.50 22.40 � 4.78 .1303.88 � 2.10 5.26 � 2.95 4.45 � 1.77 .117

94.24 � 5.59 97.70 � 7.51 96.32 � 4.93 .13931.32 � 2.90 30.72 � 2.94 30.10 � 2.77 .329

2.91 � 1.61 2.19 � 1.62 2.13 � 1.22 .1270.49 � 1.64 1.18 � 1.39 0.73 � 0.97 .198

thetic

les amsthtet

elation

tial tooth torques that are close to the desired finished



angles would be inappropriate.33 Overexpansion ofthe maxillary dental arch with increased maxillaryincisor torque might flatten the smile arc, which isbest described by the relationship of the curvature ofthe incisal edges of the maxillary incisors and thecanines to the curvature of the lower lip,5,9 and leadto negative esthetic consequences. Proclined maxil-lary incisors might also reduce incisor display. If apatient shows less than 75% of the central incisorcrowns at smile, tooth display is considered inade-quate.7 However, inadequate torque of both themaxillary and mandibular incisors can also result inundesirable effects regardless of the treatment mo-dality.

As a result of our study, no statistically significantdifferences were determined in smile esthetics amongsubjects with ideal occlusions and Class I patientstreated with or without extractions. However, this doesnot mean that extraction of premolars is justified. Jawsize, labial crown angulations, initial incisor torques,initial crowding, and soft tissue extensions should becarefully evaluated before treatment planning. Eachsubject has different problems, and, to create naturaldental esthetics, the entire dentition must be carefullyconsidered.

CONCLUSIONS1. Subjects with ideal occlusions and Class I patients

treated with or without extractions were not differ-

Table V. Multiple comparisons

Variable Extractio

Smile index (smile width/smile height) (ratio)3-3 distance/smile width (ratio)4-4 distance/smile width (ratio)Visible dentition width/smile width (ratio)3-3 distance/visible dentition width (ratio)Maxillary gingival display (mm)Maxillary incisor display (ratio %)Upper lip length/Sn to incision (ratio)Upper lip length (smiling)/Sn to incision (ratio)Upper lip length (smiling)/upper lip length (ratio)ANB (°)SN-MP (°)SN-PP (°)U1-SN (°)U1-NA (°)U1-NA (mm)IMPA (°)Anterior maxillary height (mm)Incision to stomion (mm)LL to H-line (mm)

NS, Not significant.*P � .05.

entiated in smile esthetics by 6 panels of judges

(orthodontists, plastic surgeons, artists, generaldentists, dental professionals, and parents).

2. Transverse characteristics of the smile appeared tobe of little significance to an attractive smile.

3. Maxillary gingival display and the ultimate posi-tions of the anterior teeth have definite effects onsmile esthetics.

4. Treatment modality alone has no predictable effecton the overall esthetic assessment of a smile.

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NS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NSNS NS

n-none

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