the importance of incisor positioning in the esthetic ... · a characteristic of the esthetic smile...

98

The subject of the smile and facial animation asthey relate to communication and expression ofemotion is, and should be, of great interest to

orthodontists. Although the English language is repletewith words that conjure up images of specific types ofsmiles—insipid, wry, sardonic, ironic, inscrutable,infectious, warm, and enigmatic—these descriptionsare entirely subjective. An attractive smile helps winelections, and a beautiful smile sells products for com-panies whose subliminal message in advertising is“look better, feel younger.” But even a well-treatedorthodontic case in which the plaster casts meet everycriterion of the American Board of Orthodontics forsuccessful treatment may not produce an estheticsmile.

Few objective criteria exist for assessing attributesof the smile, establishing lip-teeth relationships asobjectives of treatment, or measuring the soft tissueoutcomes of treatment. It would be nice to have somesort of a tool to quantitatively assess beauty but, cur-rently, one does not exist—and it probably never will.As a result, an eye for beauty is an important attributefor an orthodontist.

When a patient looks in the mirror, the smile he orshe sees is framed by what Lavater,1 more than 200years ago, called the lip curtain and what is currentlycalled the soft tissue drape. Smiles can be either posedor spontaneous. Peck and Peck2 classified smiles as

stages I and II, and Ackerman et al3 designated thestage I smile as the posed smile and stage II as theunposed (spontaneous) smile. The posed smile (Fig 1,A) is voluntary and need not be elicited or accompaniedby emotion. A posed smile is static in the sense that itcan be sustained. The lip animation is fairly repro-ducible, similar to the smile that may be rehearsed forphotographs or school pictures.4,5

The unposed smile (Fig 1, B) is involuntary and isinduced by joy or mirth. It is dynamic in the sense thatit bursts forth but is not sustained. An unposed smile isnatural in that it expresses authentic human emotion.Lip elevation in the unposed smile is often more ani-mated, as seen in the laughing smile, for example.

In orthodontic smile analysis, we usually evaluatethe posed smile on the basis of 2 major characteristics:the amount of incisor and gingival display and thetransverse dimension of the smile.

Most orthodontists and dentists prefer that the ele-vation of the lip for the posed smile stop at the gingivalmargins of the maxillary incisors, as depicted in Figure1, A. Some amount of gingival display is certainlyacceptable and, in many cases, is even esthetic andyouthful appearing (Fig 2). Conversely, a completelack of gingival display (defined in terms of the per-centage of incisor show on smile) is not as attractive ascomplete tooth display or even some gingival dis-play.6,7 Males, as a group, show less of the maxillaryincisors and more of the mandibular incisors at rest andon smile than do females.8 It is a characteristic of agingto show less of the maxillary incisors at rest and onsmile, so that, to a degree, more tooth display is con-sidered a more youthful smile.

The transverse dimension of the smile was firstintroduced in the prosthodontic literature by Frush and

Adjunct Professor, University of North Carolina, Department of Orthodontics,and in Private Practice, Vestavia Hills, Alabama.Reprint requests to: David M. Sarver, 1705 Vestavia Parkway, Vestavia Hills,AL 35216; e-mail, [email protected], November 2000; revised and accepted, January 2001.Copyright © 2001 by the American Association of Orthodontists.0889-5406/2001/$35.00 + 0 8/1/114301doi:10.1067/mod.2001.114301

SPECIAL ARTICLE

The importance of incisor positioning in theesthetic smile: The smile arcDavid M. Sarver, DMD, MSBirmingham, Ala

The smile arc is defined as the relationship of the curvature of the incisal edges of the maxillary incisors and caninesto the curvature of the lower lip in the posed smile. The ideal smile arc has the maxillary incisal edge curvatureparallel to the curvature of the lower lip. Evaluation of anterior smile esthetics must include both static and dynamicevaluations of profile, frontal, and 45° views to optimize both dental and facial appearance in orthodontic planningand treatment. This article presents the concept of the smile arc and how it relates to orthodontics—from therecognition of its importance, to its impact on orthodontic treatment planning, to how procedures and mechanics areadapted to optimize the appearance of the smile. Three cases are used to illustrate how treatment is directed,emphasizing how facial and smile goal setting go hand in hand. (Am J Orthod Dentofacial Orthop 2001;120:98-111)

American Journal of Orthodontics and Dentofacial Orthopedics Sarver 99Volume 120, Number 2

Fisher.9 This smile characteristic is referred to in termsof broadness to the smile and the presence and theamount of buccal corridors (more commonly referredto by orthodontists as negative space). It is well docu-mented in the prosthodontic literature that one charac-teristic of an unrealistic or contrived smile—a “denturesmile”—is the lack of buccal corridors. Anything canbe overdone. Again, the orthodontist’s eye for beauty isan important factor in creating appropriately sized buc-cal corridors. This smile feature has been thought ofprimarily in terms of maxillary width, but there is evi-dence that the buccal corridors are also heavily influ-enced by the anteroposterior position of the maxilla rel-ative to the lip drape.10,11

A characteristic of the esthetic smile that has notbeen as well recognized is the relationship of the cur-vature of the maxillary anterior teeth (smile arc) in theesthetic smile. The term smile arc has a number of def-initions depending on whether one is reading literaturefrom prosthodontics, orthodontics, or cosmetic den-tistry. In his cosmetic dentistry text, Goldstein12

describes the “older smile,” in which the incisal edges

appear straight across the smile, and contrasts it withthe “youthful smile” in which the front teeth are longerand create a line that comes slightly downward in themiddle of the smile, traveling superiorly to the corners.Frush and Fisher9 proposed that there should be har-mony between the curvature of the incisal edges of themaxillary anterior teeth and the curvature of the upperborder of the lower lip; this is referred to as the smilearc.

Definition of the smile arc

The smile arc should be defined as the relationshipof the curvature of the incisal edges of the maxillaryincisors and canines to the curvature of the lower lip inthe posed smile. The ideal smile arc has the maxillaryincisal edge curvature parallel to the curvature of thelower lip upon smile; the term consonant is used todescribe this parallel relationship (Fig 3, A). A noncon-sonant, or flat, smile arc is characterized by the maxil-lary incisal curvature being flatter than the curvature ofthe lower lip on smile, as shown in Figure 3, B.

Conceptual evolution

The importance of the smile arc, as an esthetic con-cept, has probably not been fully appreciated by ortho-

Fig 2. Some gingival display on smile is estheticallyappealing because of the youthfulness of incisor show.

Fig 1. A, Posed smile is voluntary and may producefairly reproducible lip animation; B, unposed smile isinvoluntary and spontaneous, often characterized bymore lip elevation than in posed smile.

A

B

100 Sarver American Journal of Orthodontics and Dentofacial OrthopedicsAugust 2001

dontists. Hulsey4 assessed standardized photographs of40 subjects, 20 treated orthodontically and 20 consid-ered to have normal occlusion. He noted that the cur-vature of the incisal edges of the maxillary anteriorteeth was flatter in those who were treated orthodonti-cally. A panel judged the smiles with flatter arcs asbeing less attractive, confirming the hypothesis ofFrush and Fisher.9 Zachrisson13 has made similarobservations that some treated smiles are less esthetic.

In a recent study, Ackerman et al3 evaluated thesmile arc in both treated and untreated patients in theirown practice. Almost 40% of the treated patientsshowed a discernible change in the smile arc; flatteningof the smile arc occurred in 32%. In the untreatedgroup, 13% had a change in the smile arc, and flatten-ing of the arc occurred in only 5%. They noted no gen-der differences in the smile characteristics when thetreated and untreated groups were compared.3

Smile arc flattening during orthodontic treatmentcan occur in several ways. Normal orthodontic align-ment of the maxillary and mandibular arches mayresult in a loss of the curvature of the maxillary incisorsrelative to the lower lip curvature. In case evaluation, itis important to assess and visualize the incisor-smilearc relationships and place brackets so as to extrude themaxillary incisors in flat smiles and to maintain the

smile arc where it is appropriate. A set formula forbracket placement based on tooth measurements, as isoften taught in orthodontic courses and programs, isnot appropriate for maximum esthetics. For example, ifall patients routinely have their maxillary centralincisors placed 4.5 mm above the incisal edge, their lat-eral incisors at 4 mm, and their canines at 5 mm, with-out the clinician taking into account the relationship ofthe incisal edges to the lower lip curvature in each indi-vidual case, the positioning may or may not fit theesthetic criteria required. Just as patients get individu-alized treatment plans, they also should have individu-alized designs for appliance placement.

Bracket placement may unwittingly lead to supe-rior repositioning of the incisal edges relative to theposterior buccal segment heights. For example, withour emphasis on the goal of attaining canine guidance,it is possible that we are creating relative intrusion ofthe maxillary incisors while extruding the maxillarycanines. The 14-year-old patient in Figure 4, A, has anonconsonant smile arc with 80% of the maxillaryincisors displayed on smile. While canine guidance hasbeen emphasized in this case, it may be at the expenseof the appearance of the smile. Another possibilityarises when lower bracket placement in the samepatient is evaluated (Fig 4, B). Note that the mandibu-

Fig 3. A, Ideal smile arc is characterized by consonant relationship of arc formed by maxillary teethand lower lip on smile; B, nonconsonant, or flat, smile arc is characterized by maxillary incisal arcline that is flatter than curvature of lower lip on smile.

A B


lar incisor brackets were placed very close to the gingi-val margins, probably in an effort to avoid occlusalinterferences that might cause unwanted bracket loss.Unfortunately, this resulted in extrusion of themandibular incisors, and the maxillary incisors had tobe compensated vertically to open the bite, which alsocontributed to flattening of the smile arc.

In patients in whom excessive gingival display onsmile is noted, and for whom one of the treatmentobjectives is to reduce the gumminess of the smile,maxillary incisor intrusion may improve the gingivaldisplay on smile. However, if the smile arc relationshiphas not been noted and evaluated, unwanted flatteningof the smile arc may result. Maxillary intrusion archesor maxillary archwires with accentuated curve couldresult in a flattening of the smile arc.

The subject’s inherent growth pattern may also beat fault. The studies of smile arc flattening have shownthat, while treated patients did have a higher rate ofsmile arc flattening, 5% of the untreated populationalso experienced smile arc flattening. More verticalgrowth in the posterior maxilla than in the anteriormaxilla could result in a changed relationship betweenthe occlusal plane and the curvature of the lower lipupon smile. In this type of patient, high-pull headgearkeeps the maxillary posterior teeth superior to theincisors and is therefore an aid in maintaining orimproving the smile arc.

It is also possible that growth in the brachyfacialpattern (low mandibular plane angle and a tendency forparallelism of the sella-nasion line, palatal plane, andocclusal plane) may lead to a flat smile arc. Patientswith this skeletal pattern might, theoretically, have atendency for the anterior maxilla to lack the clockwisetilt needed for an ideal smile arc; in some cases it mighteven exhibit a counterclockwise tilt that results in a flatsmile arc. Whether this is fact, however, is yet to beproven.

Habits may also be an etiologic factor. The reduc-tion in anterior vertical dentoalveolar development sec-ondary to thumb sucking is the most obvious example.

CASE ILLUSTRATIONSCase 1

Treatment planning for this patient was a challengebecause of discordant esthetic and functional goals.This demonstrates how problem-oriented treatmentplanning helps us identify a path to the attainment ofour desired treatment goals. In this patient, the smilearc was an important consideration in planning treat-ment.

At age 11, the patient’s chief complaint was thediastema between the maxillary incisors. The parents,

however, were concerned about the mandibular defi-ciency and its effect on her facial appearance and werecommitted to a treatment plan directed at facialimprovement in addition to occlusal correction (Fig 5,A-C).

Data from systematic analysis of the patient, begin-ning appropriately with an examination of facial pro-portions, was summarized.6,14

Profile. Relative to the upper face, the maxillaappeared to be moderately procumbent, but the mostremarkable aspects of the patient’s profile included anobtuse chin-neck angle, a short lower facial height withshort chin height, and a deep labiomental sulcus witheversion of the lower lip (Fig 5, A).

Frontal at rest. The lower facial height was short,with the upper lip and chin height ratio approximating50:50, versus the ideal 33:66 ratio. The lower facialheight presented a problem in reaching occlusal goals,

Fig 4. A, Bracket placement to emphasize canine guid-ance may be at the expense of appearance of the smileby relatively intruding maxillary incisors, resulting in flatsmile arc; B, maxillary incisor intrusion is required toopen the bite, resulting in flattening of smile arc.

A

B


as will be seen later in this analysis, because the patienthad an open bite. She also had an everted lower lip anda deep labiomental sulcus (Fig 5, B).

Frontal on smile. Only 80% of the maxillary incisorwas exposed on smile, and with further maturation andaging, this amount was expected to decrease.8 There-fore, the lack of incisor show was considered both aninitial esthetic problem and a long-term problembecause it was expected to worsen with further growthand maturation. Also present was the large maxillarymidline diastema (Fig 5, C).

Dental relationships. The patient had an anterioropen bite with bilateral Class II molar relationships(Fig 6). The maxillary incisors were flared and a largemaxillary midline diastema present. Spacing ofapproximately 5 mm was also present in the mandibu-lar arch.

The treatment goals for this patient were to correctboth the esthetic problems and the Class II open bitemalocclusion. The esthetic problems in this case, assummarized from the facial characteristics and theincisor-smile relationship, were:

1. Marked mandibular deficiency noted on profile,with concomitant obtuse chin-neck angle;

Fig 5. A, This patient’s profile was characterized by deficient mandibular height, in both horizontalprojection and vertical height; B, patient had short lower facial height with everted lower lip; C,approximately 80% of maxillary incisor showed on smile; with further maturation and aging, thisamount of tooth show is expected to decrease.

A B C

Fig 6. Anterior open bite was present, an occlusal relation-ship not frequently associated with short-faced patients.

Fig 7. Growth modification through use of cervicalheadgear was chosen. Outer bow was shortened andplaced inferiorly in an effort to have desirable effects ofcervical headgear (maxillary retardation, downwardvector to increase lower facial height) in addition to pro-ducing rotational effect on palatal plane to continueincrease in incisor show and continue bite closure.


2. Short lower facial height, a problem for both pro-file and frontal relationships;

3. Maxillary anterior dental spacing;4. Lack of incisor show at rest and on smile;5. Flat smile arc.

The major treatment challenge in this case was thatseveral changes to correct the open bite and the ClassII relationships would also tend to exacerbate estheticproblems. We very rarely see an anterior open bite in ashort-faced patient, and the orthopedic forces used to

Fig 8. A, Final profile reflected vast improvement of lower facial projection and increase in facial height;B, final frontal picture demonstrates significant increase in lower facial height; C, on smile, all maxillaryteeth show, with beautiful smile vertically, as well as ideal smile arc relationship; D, 45° view clearlyshows excellent smile arc relationship as well as improved submental and submandibular soft tissue.

A B

C D


reduce vertical growth and close the open bite wouldwork against the goal of increasing lower face height.

Extrusion of the maxillary anterior teeth to increasethe amount of tooth exposure on smile was both desir-able and possible because the teeth were markedlyflared and space was present. Space closure by upright-

ing the incisors through retraction on round wire (toallow the crown to rotate inferiorly) would elongate thecrowns of the teeth, which would accomplish the func-tional goal of closing the bite and increasing theamount of tooth show at rest and on smile.6 Extrusionof the maxillary incisors also offered the advantage ofsteepening the smile arc to be more consonant with thelower lip. Extrusion of the maxillary incisors wouldallow more tooth to show on smile and would close thebite but would not increase lower facial height.

Growth modification also required careful choices.The goal was to bring the mandible relatively forwardand increase the lower facial height to improve overallvertical facial proportionality and the deep labiomentalsulcus. The everted lower lip was due to a combinationof soft tissue redundancy created by the decreased ver-tical dimension of the face and excessive overjet. How-ever, an increase in the lower facial height would workagainst closing the bite. Thus, growth modificationwith cervical headgear was selected to place force onthe maxilla; however, the outer bow was shortened andplaced inferiorly (Fig 7). The use of cervical headgearin a patient with an open bite is unusual, but full appli-ance engagement of the entire maxillary arch wouldtheoretically result in clockwise rotation of the palatalplane, which would also close the bite and extrude theanterior segment to increase incisor show.

Fig 9. Final frontal dental pictures reflect successful biteclosure.

Fig 10. Superimposition on palatal plane demonstratesuprighting of maxillary anterior teeth resulting in retrac-tion and lengthening of maxillary incisors relative toupper lip. This movement improved smile by increasingtooth display. Mandibular superimposition demonstratesuprighting and retraction of mandibular incisors, result-ing in bite deepening and increased overjet.

Fig 11. Overall superimposition reflects that rotation ofpalatal plane was favorably clockwise and amount ofmandibular growth was significant, resulting in remark-able improvement in skeletal relationships.


Treatment was initiated during the prepubertalgrowth phase at age 11 with a maxillary fixed appli-ance and cervical headgear; additional appliances wereplaced as the remaining permanent teeth erupted. Once.016-in archwires were attained (in a .018-in appli-ance), elastic chain was used to close the maxillarydiastema, and the remainder of treatment was directedtoward managing the maxillary rotation and bite clo-sure. After approximately 30 months of treatment, thepatient’s profile (Fig 8, A) was dramatically improvedwith improved mandibular projection, an increase inthe lower facial height, and a significant change in thechin-neck angle. An improvement in the cervicomentalangle should be expected with increased mandibularprojection, but the soft tissue changes with the growthspurt were also a great addition.15 The resting frontalrelationship (Fig 8, B) was characterized by an increasein the lower facial height. The smile was greatlyimproved with much more incisor show on smile (Fig8, C) and a consonant smile arc. The 45° view (Fig 8,D) shows the smile and the lower facial changesattained. The final dental relationships were greatlyimproved (Fig 9), with some mild unilateral Class IIasymmetry remaining.

The cephalometric superimpositions reflect thechanges accomplished with the total orthodontic andorthopedic treatment. Superimposition on the palatalplane (Fig 10) demonstrates the uprighting of the max-illary anterior teeth with the rotational effect thatresulted in retraction and lengthening of the maxillaryincisors relative to the upper lip. This movementimproved the smile by increasing tooth display. Themandibular superimposition demonstrates the upright-ing and retraction of mandibular incisors, which con-tributed to closure of the open bite. The overall super-imposition (Fig 11) documents that the rotation of thepalatal plane was favorably clockwise, and the amountof mandibular growth was significant, resulting in aremarkable improvement in the skeletal relationships.

This case illustrates nicely the principle of the faceas determinant of treatment choice because the growthmodification and orthodontic mechanics were all cho-sen, not just to correct the malocclusion, but to improvefacial esthetics as well.

Case 2

This 35-year-old woman came for treatment with achief complaint of dental crowding. Her frontal facialproportions at rest were normal, and an evaluation ofher smile line revealed an ideal incisor curvature to thelower lip line (Fig 12). Her dental relationships (Fig13) were distinguished by crowded maxillary andmandibular incisors and a 100% deep bite.

Treatment choices in regard to both orthodonticproblems have esthetic ramifications that must be con-sidered. Options for treatment of crowding includeexpansion of the arches or extraction of first or secondpremolars. The criteria would include the amount ofcrowding, the vertical skeletal pattern, periodontal con-dition and attachment, and profile considerations. In

Fig 12. This 35-year-old female had a chief complaint ofdental crowding. Frontal facial proportions at rest werenormal, and smile line was characterized by ideal incisorcurvature to lower lip line.

Fig 13. Dental relationships were distinguished bycrowded maxillary and mandibular incisors and 100%deep bite.


this case, the amount of gingival attachment on themandibular incisors was adequate and the amount ofcrowding was moderate. Nonextraction treatmentwould produce more lip fullness to counteract the nor-mal thinning of the lips that occurs with aging.16 It wasdecided to treat the crowding problem without extrac-tion by flaring the mandibular incisors forward. Thismovement would moderately increase lip protrusion.

Several options were considered for correction ofthe deep overbite. Alignment and leveling with normalbracket positions and conventional accentuated or

reverse curve archwires was one option. This treatmentmight result in some undesirable leveling of the maxil-lary arch. Because the smile arc would be affected bythis maxillary leveling, it was important to maintain the

Fig 15. Final dental result was good functionally andesthetically, with alignment and bite opening achieved.

Fig 16. Overall cephalometric superimposition reflectsflaring of mandibular incisors resulting in bite opening(advancement of mandibular incisor crown with its rota-tion point at root apex; this resulted in a more inferiorposition of incisal tip) and increased lower lip fullness.

Fig 14. A, Frontal view shows beautiful smile with excellent incisor display; B, 45° view shows con-sonance of maxillary anterior dental curvature with curvature of lower lip.

A B


maxillary incisor position rather than to intrude themaxillary incisors during any phase of leveling.

Extrusion of the posterior teeth would also help tocorrect the deep overbite. This option offered theadvantage of not changing the smile arc while having atendency to increase the lower facial height. However,there is evidence that posterior dental extrusion is diffi-cult in adult patients.17

Another option was intrusion of the mandibularincisors. This would permit us to leave the maxillaryincisors vertically where they were, so that the smilearc would be protected. Inferior positioning of themandibular incisor crowns can occur through 2 mecha-nisms: intrusion arch mechanics (like a utility arch orauxiliary intrusion arch) or inferior positioning of thecrowns with anterior tipping of the teeth through level-ing with reverse curve lower archwires. Reverse curvearchwires place an intrusive force on the bracket ante-rior to the center of resistance, resulting in labial flareand a decrease in crown height.

Bite opening was to be achieved with bracket place-ment on the maxillary incisors to maintain the presentmaxillary incisor vertical position, and placement ofthe mandibular incisor brackets nearer to the incisal

edge than to the center of the tooth. Bracket placementis very important to protect the maxillary smile arc andto avoid the complications noted in Figure 4, A and B.Reverse curve lower archwires, with flat upper arch-wires, were also used to achieve bite opening.

Total treatment time was 14 months. The frontalview shows a beautiful smile with excellent incisor dis-play (Fig 14, A). The 45° view shows the consonance

Fig 17. A, Profile exhibited strong lower face, with lower lip more prominent than upper lip; B, lowerfacial height was long with disproportionately long chin; upper lip comprised only 25% of lower facialvertical third, and lower lip and chin comprised 75%; C, on smile, there was slightly more gingivaldisplay in posterior aspect of smile than in anterior display. Posterior maxilla was tilted with moder-ate posterior cant that contributed to flat smile arc relative to curvature of lower lip.

A B C

Fig 18. Occlusal relationships were quite good; however,some slight dental compensation (uprightness ofmandibular incisors) was still present.


of the maxillary anterior dental curvature with the cur-vature of the lower lip (Fig 14, B). The final dentalresult was good, both functionally and esthetically,with alignment and bite opening achieved (Fig 15). Theoverall cephalometric superimposition shows that themaxillary incisors and molars remained virtuallyunchanged vertically, whereas the mandibular incisorswere tipped facially (Fig 16). This produced morelower lip fullness and resulted in a more inferior posi-tion of the incisal tip. This was not true intrusion but itdid have the effect of opening the bite.

Obviously, this patient could have been treated in anumber of ways and maintained her attractive appear-ance. But attention to maintaining her existing incisor-to-lip relationship, so that the orthodontic mechanics didnot alter the smile arc, enhanced the esthetic outcome.

Case 3

This 28-year-old patient had a history that includedorthodontic treatment as an adolescent with 4 premolarextractions, followed by an unfortunate period of ClassIII growth. She underwent orthodontic retreatment with

mandibular reduction at age 24. She was seeking fur-ther treatment because she felt she had not attained theesthetic benefit of treatment that she desired. A sys-tematic evaluation included the profile, frontal at rest,frontal on smile, and dental relationships.

Profile. The profile problem list was characterizedby a nasal tip that was slightly over-projected andlocated more inferiorly than was desirable (Fig 17, A).The nasolabial angle was slightly acute because of lownasal tip placement. The upper lip was not as procum-bent as the lower lip, and the mandible was slightlyahead of the maxilla.

Frontal at rest. The lower facial height was longwith a disproportionately long chin (Fig 17, B). Theupper lip comprised only 25% of the lower facial ver-tical third, while the lower lip and chin comprised 75%of the lower facial height (a 1:2 ratio is more esthetic).Nasal width was slightly narrower than the intercanthalwidth, and the vermilion show of the upper lip wasslightly less than that of the lower lip.

Frontal on smile. On smile, the transverse smilerelationships were quite good, and the amount of gin-

Fig 19. A, After maxillomandibular surgery and clockwise occlusal plane rotation with rhinoplastyand vertical genioplasty, profile was improved in facial height, nasal form, and lip balance; B, 45°view reflects contribution of advancement of maxilla and change in upper lip projection relative tolower lip, along with refinement of midface by means of rhinoplasty.

BA


gival display in the upper central area was excellent(Fig 17, C). However, there was slightly more gingivaldisplay in the posterior aspect of the smile than theanterior display. The posterior maxilla was tilted with amoderate posterior cant that contributed to a flat smilearc relative to the curvature of the lower lip.

Dental relationships. The occlusal relationshipswere excellent. However, some dental compensation(uprightness of the mandibular incisors) was still pres-ent (Fig 18).

The observations outlined above can be brokendown into treatment options, starting from superior toinferior:

1. Nasal overprojection. Consider rhinoplasty forreduction of tip projection, as well as rotation ofthe tip more superiorly to improve the nasolabialangle.

2. Retrusive upper lip relative to lower lip. Althoughmovement of the lower lip back is an option, thiswould tend to flatten the profile, and 2 mandibularpremolars had already been removed. Maxillaryadvancement might be considered, but was con-traindicated because of the existing Class I occlusion.

3. Maxillary lip augmentation with rhinoplasty. Thisis an option but is unpredictable.

The frontal facial relationships and the treatment ofthe smile line virtually dictated the rest of the ortho-dontic and orthognathic treatment plan. Because of theposterior gingival display and the flatness of the smilearc, posterior maxillary impaction was recommendedto reduce posterior gingival display and tip the occlusalplane clockwise. This movement would improve theposterior smile line and, at the same time, tip the max-illa so that the incisal alignment is more consonantwith the lower lip, resulting in a better smile arc.

The profile would be favorably affected by theclockwise occlusal plane rotation. Because of the tip tothe maxilla, the anterior nasal spine would travel for-ward when the anterior tip of the maxilla is performedsurgically, and some maxillary advancement could alsobe performed. Then the mandible would necessarily berepositioned surgically to rotate it in a clockwise fash-ion to compensate for the changed palatal plane. This,in essence, would rotate the mandible back, while themaxilla travels forward.18,19 The posterior maxillaryimpaction would also upright the flared maxillaryincisors relative to the upper face. Vertical chin reduc-tion was also recommended as part of the treatmentplan. Recall that the vertical proportions of the lowerface were less than ideal, with the upper lip represent-

Fig 20. A, Final frontal picture characterized by slightly wider nose; vertical facial proportionalityimproved significantly by shortening of chin height; B, smile relationship was changed with elimina-tion of posterior gingival display. Consonance of occlusal plane and lip line improved dramatically bymeans of surgically tilting palatal plane.


ing 25% of the facial height and the lower lip and chin75%, as compared with the one third–to–two thirdsideal. Therefore, a wedge genioplasty was planned toshorten the lower facial height.

The surgical plan summary was as follows:1. Maxillomandibular surgery to rotate the occlusal

plane and lower face in a clockwise fashion waschosen. The point of rotation was planned to be atthe incisal edge, with the posterior maxilla goingup approximately 3 mm (the amount of gingivaldisplay measured on smile) and no anteriorimpaction because the incisor-to-lip relationshipswere ideal. Rotation around the incisal edge tobring the upper part of the maxilla forward wasdesigned to improve lip projection and widen theslightly narrow nose. The mandibular procedurewould rotate the mandible in a clockwise fashionand thus reduce mandibular projection and bal-ance the lower lip with the upper lip.

2. Adjunctive and simultaneous rhinoplasty wouldbe performed to elevate the nasal tip and reduceprojection. No effort was made to control nasalwidth because a wider nose was desired.

3. Vertical genioplasty with wedge reduction toreduce the chin height and normalize facialheights was planned.

Figure 19, A, represents the finished profile. Theelevation of the nasal tip and the elegance provided bythe rhinoplasty dramatically improved the appearanceof the midface. Also note the improved relationship ofthe upper lip to the lower lip, and the increased vermil-ion show in the upper lip. The reduction in chin heightimproved the vertical facial proportionality, but alsodeepened the labiomental sulcus, which was flatter inthe preoperative picture. It is important to look at thepatient at a 45° angle (Fig 19, B) and note the contri-

bution of the advancement of the maxilla and thechange in upper lip projection relative to the lower lipand, again, the refinement of the midface with rhino-plasty.

The final frontal picture (Fig 20, A) is characterizedby a slightly wider nose, and the vertical facial propor-tionality improved significantly by the shortening ofthe chin height. Finally, Figure 20, B, represents thechange in the smile relationships, with the posteriorgingival display eliminated. The consonance of theocclusal plane and the lip line was improved dramati-cally.

The limiting constraint in this case was the contourof the lower lip in relation to the smile arc. For thispatient, surgery was the only option that could changethese relationships. The final occlusal relationship isshown in Figure 21.

The cephalometric superimposition (Fig 22)reflects the clockwise rotation of the occlusal plane bymeans of posterior maxillary impaction and saggitalsplit osteotomy. Note that the maxillary incisor posi-tion was maintained vertically and horizontally whilethe palatal plane rotated around the incisal edge, whichresulted in advancement of the superior portion of themaxilla and more upper lip and midfacial fullness. Theclockwise rotation of the mandible resulted in less

Fig 21. Final occlusal photographs reflect good finalrelationships.

Fig 22. Cephalometric superimposition reflects clock-wise rotation of occlusal plane by means of posteriormaxillary impaction and saggital split osteotomy.


emphasis in mandibular projection as well, all of which(with vertical chin reduction) resulted in a superiorfacial result as well as superior smile esthetics.

CONCLUSIONS

The concept of the smile arc is not a new one, as theliterature review has shown. Clearly, its impact on thefinal facial and smile appearance can be quite dramatic.This demands that we rethink some of our orthodonticmechanics and concepts of treatment to consistentlybuild this factor into our diagnostic, treatment plan-ning, and treatment regimens.

I would like to acknowledge the contribution of DrJim Ackerman of Bryn Mawr, Pa, in the developmentof this article.

REFERENCES

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