Smile analysis digital era


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Smile analysis digital era

  1. 1. Smile Analysis and Designin the Digital EraMARC B. ACKERMAN, DMDJAMES L. ACKERMAN, DDSS mile analysis and smile design have become key elements of orthodontic diagnosis andtreatment planning over the last decade.1-3 Recent lateral borders of the smile, the eye can perceive inner and outer commissures, as delineated by the innermost and outermost confluences,advances in technology now permit the clinician respectively, of the vermillion of the lips at theto measure dynamic lip-tooth relationships and corners of the mouth (Fig. 2). The inner commis-incorporate that information into the orthodonticproblem list and biomechanical plan. Digitalvideography is particularly useful in both smileanalysis and in doctor/patient communication.Smile design is a multifactorial process, withclinical success determined by an understandingof the patient’s soft-tissue treatment limitations Display Zoneand the extent to which orthodontics or multidis-ciplinary treatment can satisfy the patient’s andorthodontist’s esthetic goals.Anatomy of the Smile The upper and lower lips frame the displayzone of the smile. Within this framework, the Gingival Scaffoldcomponents of the smile are the teeth and thegingival scaffold (Fig. 1). The soft-tissue deter- Teeth Lipsminants of the display zone are lip thickness,intercommissure width, interlabial gap, smileindex (width/height), and gingival architecture.Although the commissures of the lips form the Fig. 1 Smile components. Outer CommissureDr. Marc Ackerman Dr. James AckermanDr. Marc Ackerman is a Research Associate in the Department ofOrthodontics, University of North Carolina at Chapel Hill. Both authors Inner Commissureare in the private practice of orthodontics at 931 E. Haverford Road,Suite 2, Bryn Mawr, PA 19010; e-mail: Fig. 2 Anatomy of commissures.VOLUME XXXVI NUMBER 4 © 2002 JCO, Inc. 221
  2. 2. Smile Analysis and Design in the Digital Erasure is formed by the mucosa overlying the buc- Two factors that contribute to the appear-cinator muscle where it inserts with the orbicu- ance of the smile arc are the sagittal cant of thelaris oris muscle fibers at the modiolus. maxillary occlusal plane and the archform (Fig. The extent to which the orthodontist is able 4). Increasing the cant of the maxillary occlusalto differentiate between the anatomy of the inner plane to Frankfort horizontal in natural headand outer commissures is largely dependent on position will increase maxillary anterior toothlighting. When a video is taken with ambient display and improve the consonance of the smilelight only, the buccal corridor often appears arc. The patient’s archform—and particularly themuch more pronounced than when supplemental configuration of the anterior segment—willlight is added (Fig. 3). Thus, what has been greatly influence the degree of curvature of thecalled “negative space”4 is often not space at all, smile arc. The broader the archform, the less cur-but just an illusion. Professional photographers vature of the anterior segment and the greater thetake advantage of this effect by manipulating likelihood of a flat smile to enhance smile characteristics. The vertical aspects of smile anatomy are We have called the curve formed by the the degree of maxillary anterior tooth displayincisal edges of the maxillary anterior teeth the (Morley ratio), upper lip drape, and gingival dis-“smile arc”.5 When there is harmony (paral- play. In a youthful smile, 75-100% of the maxil-lelism) between the smile arc and the curvature lary central incisors should be positioned belowof the lower lip,5-9 the smile arc is described as an imaginary line drawn between the commis-consonant. A flat smile arc is usually less esthet- sures1 (Fig. 5). Both skeletal and dental relation-ic. ships contribute to these smile components. Ambient Light Supplemental Light Fig. 3 Contribution of lighting to illusion of “negative space”.222 JCO/APRIL 2002
  3. 3. Ackerman and Ackerman A BFig. 4 A. Surgical correction of this patient’s Class III malocclusion included maxillary advancement, inferiorrepositioning, and clockwise rotation. Maxillary occlusal plane was steepened; note effect on anterior toothdisplay and smile arc. B. Relationship of archform to smile arc.VOLUME XXXVI NUMBER 4 223
  4. 4. Smile Analysis and Design in the Digital Era tion of the lip elevator muscles, and the teeth and sometimes the gingival scaffold are displayed. The enjoyment smile, elicited by laughter or great pleasure, is involuntary. It results from maximal contraction of the upper and lower lip elevator and depressor muscles, respectively. This causes full expansion of the lips, with max- imum anterior tooth display and gingival show. A Smile style is another soft-tissue determi- nant of the dynamic display zone. There are three styles: the cuspid smile, the complex smile, and the Mona Lisa smile10 (Fig. 7). An individual’s smile style depends on the direction of elevation and depression of the lips and the predominant muscle groups involved. The cuspid or commis- sure smile is characterized by the action of all the B elevators of the upper lip, raising it like a win- dow shade to expose the teeth and gingival scaf-Fig. 5 A. Acceptable Morley ratio. B. Excessive fold. The complex or full-denture smile is char-incisor display below intercommissure line. acterized by the action of the elevators of the upper lip and the depressors of the lower lip act- ing simultaneously, raising the upper lip like aSmile Classification window shade and lowering the lower lip like a There are two basic types of smiles: the window. The Mona Lisa smile is characterizedsocial smile and the enjoyment smile. Each type by the action of the zygomaticus major muscles,involves a different anatomic presentation of the drawing the outer commissures outward andelements of the display zone (Fig. 6). The social upward, followed by a gradual elevation of thesmile, or the smile typically used as a greeting, is upper lip. Patients with complex smiles tend toa voluntary, unstrained, static facial expression.5 display more teeth and gingiva than patients withThe lips part due to moderate muscular contrac- Mona Lisa smiles. Fig. 6 Anterior tooth display in social and enjoyment smiles; note difference in gingival show.224 JCO/APRIL 2002
  5. 5. Ackerman and Ackerman A B C Fig. 7 Three smile styles. A. Cuspid. B. Complex. C. Mona Lisa. Straight Above A BFig. 8 A. Intraoral vs. extraoral photographic technique. B. Differences in smile arc of same patient due tocamera orientation.VOLUME XXXVI NUMBER 4 225
  6. 6. Smile Analysis and Design in the Digital Era 1 2 3 A 4 5 6 1 2 3 B 4 5 6Fig. 9 Photographic repeatability of social smile. Patient A produced six similar social smiles consecutively,but younger sibling (Patient B) was unable to replicate social smile.Smile Capture Method Capturing patient smile images with con-ventional 35mm photography has two majordrawbacks. First, it is exceedingly difficult tostandardize photographs due to differences incamera angles, distances to the patient, headpositions, and discrepancies between intraoraland extraoral photographic techniques. When lipretractors are used for photographing the frontalocclusal view, the lens of the camera is posi-tioned perpendicular to the occlusal plane. When Fig. 10 Digital videography technique for smilethe smile is photographed, the lens of the camera positioned perpendicular to the face in natural226 JCO/APRIL 2002
  7. 7. Ackerman and Ackerman Chelsea Cheese Social Smile Enjoyment SmileFig. 11 Six frames from patient’s video clip. Upper frames show patient moving from repose to speech, high-lighting words “Chelsea” and “cheese”. Lower frames show patient moving from repose to smiling. Note dif-ference in gingival display between social and enjoyment smiles.head position, effectively shooting from above time. The patient is seated in a cephalostat andthe occlusal plane. The result is a difference in placed in natural head position (Fig. 10). Earappearance of the smile arc in those two views rods are used to stabilize the head and avoid(Fig. 8A). Using the simulation method of excess motion. The digital video camera isGunther Blaseio (Quick Ceph Image Pro*), the mounted on a microphone stand and set at a fixedintraoral photograph can be “pasted” into the distance in the records room. The lens is posi-smile display zone taken in natural head position tioned parallel to the true perpendicular of theto demonstrate the discrepancy resulting from face in natural head position, and the camera isthe difference in camera orientation (Fig. 8B). raised to the level of the patient’s lower facialSecond, it is impossible to repeat the social smile third. The patient is asked to say the sentenceexactly during one photography session, much “Chelsea eats cheesecake on the Chesapeake”,less over a longer period of time. When several relax, and then smile (Fig. 11).consecutive smile photographs are taken at the Anterior tooth display is not the same dur-orthodontic records visit, the clinician will often ing speech as in smiling. By taking a video clipnote variations in the smile (Fig. 9). In children, of both, we can evaluate all aspects of anteriorthis phenomenon is most likely due to relatively tooth display. The video camera captures rough-late maturation of the social smile. ly 30 frames per second; this method usually pro- Standardized digital videography allows duces a five-second clip, for a total of 150the clinician to capture a patient’s speech, oraland pharyngeal function, and smile at the same *Apple Computer, Inc., 1 Infinite Loop, Cupertino, CA 95014.VOLUME XXXVI NUMBER 4 227
  8. 8. Smile Analysis and Design in the Digital Era A BFig. 12 A. Entire smile portion of patient’s video clip. B. Comparison of different patient’s pre- and post-treat-ment smiles.228 JCO/APRIL 2002
  9. 9. Ackerman and Ackerman A Fig. 13 A. Patient with immature oral and pharyngeal function during speech. Note tongue position in frames two through six. B. Patient’s smile after esthetic bonding of maxillary central incisors. Bframes. The raw clip is downloaded to Apple ed (Fig. 13). The frame that best represents theFinal Cut Pro** for compression and conversion patient’s social smile is selected, captured with ainto an Apple QuickTime Viewer** file, which is program called Screen Snapz,*** and saved as ausually about 4MB in size. The smile portion of JPEG file.the clip is approximately 12-20 frames, allowing The smile image is then opened in a pro-pre- and post-treatment smiles to be compared gram called SmileMesh,† which measures 15(Fig. 12). attributes of the smile (Fig. 14). This methodolo-Smile Analysis **Quick Ceph, Inc., Orthodontic Processing, 1001 B Ave., Suite 206, Coronado, CA 92118. On first viewing of the QuickTime video ***Ambrosia Software, Inc., P.O. Box 23140, Rochester, NYclip, the clinician should assess tongue posture 14692.and lip function, particularly during speech. †The SmileMesh software was created by TDG Computing (Jon Coopersmith and Greg Cassileth) for Drs. James and Marc Acker-Immature oral and pharyngeal function with man. SmileMesh is a free shareware application available forunfavorable tongue posture can easily be detect- downloading at XXXVI NUMBER 4 229
  10. 10. Smile Analysis and Design in the Digital Era A BFig. 14 A. SmileMesh applied to patient’s social smile, with lines adjusted to appropriate landmarks. B. Smile-Mesh measurements. A B CFig. 15 A. Patient with asymmetrical cant of maxillary anterior transverse occlusal plane. B. Different brack-et height on maxillary left canine vs. maxillary right canine. C. Patient after was first used manually by Hulsey7 and later facial portrait at rest, the three-quarter smilingmodified and computerized by the present view, and the profile view. Consideration shouldauthors.5 Its most significant advantage is that the be given to the vertical and lateral attributes oforthodontist can quantify such aspects of the the smile as well as to the cant of the transversesmile as maxillary incisor display, upper lip occlusal plane. The smile image is a better indi-drape, buccal corridor ratio, maxillary midline cation of transverse dental asymmetry than theoffset, interlabial gap, and intercommissure frontal intraoral view or even an anteroposteriorwidth in the frontal plane. The flaw in tradition- cephalogram (Fig. 15). Next, the cant of the max-al smile analysis has been that many of the ver- illary occlusal plane relative to Frankfort hori-tical and anteroposterior calculations related to zontal should be assessed visually on the lateralanterior tooth display are made from the tracing cephalogram and measured on the tracing.of the lateral cephalogram, which is taken in Vertical and anteroposterior skeletal and dentalrepose.11 As a result, incisor position has been relationships are noted. Panoramic and supple-determined from a static rather than a dynamic mental intraoral radiographs are also analyzed.record. Finally, the plaster study casts are evaluated for The diagnostic part of smile analysis begins static occlusal relationships and tooth-size dis-with the creation of a problem list. The first set of crepancies. The reader should note that thisrecords analyzed is the extraoral photo gallery, sequence of analysis is the exact opposite of theconsisting of the captured social smile, the full method currently taught in most orthodontic res-230 JCO/APRIL 2002
  11. 11. Ackerman and Ackerman A B C D DFig. 16 A. Patient with consonant smile arc, but excessive gingival display. Smile design had to intrude max-illary anterior teeth without flattening smile arc. B. Archwire blank was placed across anterior segment ofstudy casts to indicate positions of maxillary incisor bracket slots needed to preserve smile arc. C. Differencein distances from incisal edges to maxillary central incisor and lateral incisor brackets is more than .5mmcalled for in conventional preadjusted appliance prescriptions. D. Pre- and post-treatment social smilesdemonstrate that smile arc was preserved and gingival display was reduced. Distance from superior borderof lower lip to maxillary incisal edges increased, which was not “ideal”, but best “balance” that could beachieved for this smile.idency programs. inadequate maxillary incisor display, unfavorable The smile component of the orthodontic Morley ratio, excess gingival show, flat orproblem list consists of descriptive terms such as reverse smile arc, asymmetric cant of the maxil-VOLUME XXXVI NUMBER 4 231
  12. 12. Smile Analysis and Design in the Digital EraFig. 17 Continuous leveling can lead to flatteningof smile arc and overintrusion of maxillaryincisors (poor Morley ratio).lary anterior transverse occlusal plane, and oblit-erated buccal corridors, to name a few. The clin-ician should rank these smile attributes in orderof their importance in creating a balanced smile.The final problem list will help the orthodontistto assess the viability of different treatmentoptions and select the appropriate mechanothera-py for optimal smile design.Smile Design Fig. 18 Segmental leveling and use of cantilever It must be understood that there is no uni- springs for high labial ectopic maxillary canines.versal “ideal” smile. The most important estheticgoal in orthodontics is to achieve a “balanced”smile,12 which can best be described as an appro-priate positioning of the teeth and gingival scaf- illary central and lateral incisors and thus flattenfold within the dynamic display zone. As men- the smile arc (Fig. 17). We have found that thetioned above, this includes lateral, vertical, and segmented-arch technique using cantileveranteroposterior aspects, as well as the cant of the springs14 offers better control of leveling and ofmaxillary anterior transverse occlusal plane and the esthetic plane of occlusion (Fig. 18).the sagittal cant of the maxillary occlusal plane.Smile design and mechanotherapy must be built Smile Simulation andaround this esthetic plane of occlusion, which is Interdisciplinary Careoften different from the natural plane of occlu-sion.13 Orthodontists today almost routinely use The first consideration in obtaining a con- video imaging to simulate potential profilesonant smile arc, or preserving an already conso- changes resulting from orthodontics or ortho-nant smile arc, is bracket positioning (Fig. 16). gnathic surgery.15 There is no reason why theSmile design also necessitates changes in overall same technology should not be extended to sim-treatment mechanics. In cases with high labial ulate changes in the components of the dynamicectopic maxillary canines, for instance, leveling display zone in frontal view. Maxillary incisorwith a continuous archwire will intrude the max- shape, size, color, position, and degree of display232 JCO/APRIL 2002
  13. 13. Ackerman and Ackerman A A B BFig. 19 A. Patient with maxillary anterior spacing, Fig. 20 A. Patient with excessive gingival displayexcessive gingival display, and short clinical in social smile, but balanced dentition. B. Com-crowns, after orthodontic space closure and clini- puter simulation of clinical crown crown lengthening. B. Computer simulation ofesthetic bonding of maxillary lateral incisors. approach was recommended instead of orthodon-can all be manipulated, and the gingival architec- tics or restorative dentistry.ture can also be modified. Interdisciplinary care The third patient presented with a Class II,involving periodontics, restorative dentistry, and division 1 malocclusion characterized by maxil-orthodontics can be simulated and presented to lary protrusion (Fig. 21). Her smile showedthe patient for weighing the risks and benefits of acceptable anterior tooth display, a slightly flatall treatment options, as the following cases smile arc (three-quarter view), and lower lipdemonstrate. entrapment. Computer simulation of labiolingual The first patient had maxillary anterior tooth movement using preadjusted mechanicsspacing and excessive gingival display with short and Class II elastics demonstrated an acceptableclinical crowns (Fig. 19). The multidisciplinary profile change. This smile design would increasetreatment plan, simulated for the patient before maxillary incisor display, provide a more conso-commencing therapy, was to redistribute the nant smile arc, and eliminate lower lip entrap-space mesial and distal to the maxillary lateral ment.incisors orthodontically, followed by clinical The next patient had a similar Class II, divi-crown lengthening and esthetic bonding. sion 1 malocclusion, but with mandibular retru- Another patient presented with the chief sion and dental compensation (Fig. 22). Hercomplaint of excessive gingival display during smile demonstrated acceptable anterior tooth dis-the social smile (Fig. 20). Her posterior occlu- play and a consonant smile arc. Two computersion was ideal, and the dental attributes of the simulations were performed to compare the treat-social smile were balanced. After a simulation of ment options of extracting maxillary first premo-clinical crown lengthening was performed, this lars and surgically advancing the mandible. WithVOLUME XXXVI NUMBER 4 233
  14. 14. A B BFig. 21 A. Patient with Class II, division 1 malocclusion and maxillary protrusion. B. Computer simulation oflabiolingual tooth movement and anticipated profile change.234 JCO/APRIL 2002
  15. 15. A BFig. 22 A. Patient with Class II, division 1 malocclusion and mandibular retrusion. B. Computer simulation ofextraction of maxillary first premolars (left) and surgical mandibular advancement (right).extractions, the profile change would be mini- weigh the benefits from an appearance perspec-mal, but subsequent retraction of the maxillary tive. Based on this analysis, no treatment wasanterior teeth would create a less balanced and recommended.less attractive smile. Surgical advancement of the The final patient presented with a Class Imandible appeared to produce a less attractive malocclusion with an anterior deep bite, diminu-profile. Although the patient’s occlusion was not tive maxillary lateral incisors, and excessive gin-optimal, the risks of treatment seemed to out- gival display coupled with short clinical crownsVOLUME XXXVI NUMBER 4 235
  16. 16. Smile Analysis and Design in the Digital Era A B C A BFig. 23 A. Patient with Class I malocclusion, anterior deep bite, diminu-tive maxillary lateral incisors, excessive gingival display, and short clin-ical crowns before treatment. B. After orthodontic treatment. C. Afterclinical crown lengthening and application of laminate veneers. C(Fig. 23). Staged multidisciplinary care was rec- Angle Orthod. 62:91-100, 1992. 3. Mackley, R.J.: “Animated” orthodontic treatment planning, J.ommended for this patient. The first phase, in Clin. Orthod. 27:361-365, 1993.adolescence, consisted of orthodontic treatment 4. Lombardi, R.E.: The principles of visual perception and theirto improve the overbite/overjet relationship. The clinical application to denture esthetics, J. Prosth. Dent. 29:358-382, 1973.second phase, initiated in young adulthood, 5. Ackerman, J.L.; Ackerman, M.B.; Brensinger, C.M.; andinvolved clinical crown lengthening and place- Landis, J.R.: A morphometric analysis of the posed smile, Clin.ment of laminate veneers. Orth. Res. 1:2-11, 1998. 6. Frush, J.O. and Fisher, R.D.: The dynesthetic interpretation of the dentogenic concept, J. Prosth. Dent. 8:558-581, 1958. 7. Hulsey, C.M.: An esthetic evaluation of lip-teeth relationshipsConclusion present in the smile, Am. J. Orthod. 57:132-144, 1970. 8. Zachrisson, B.U.: Esthetic factors involved in anterior tooth Smile analysis and smile design generally display and the smile: Vertical dimension, J. Clin. Orthod.involve a compromise between two factors that 32:432-445, 1998.are often contradictory: the esthetic desires of the 9. Sarver, D.M.: The importance of incisor positioning in the esthetic smile: The smile arc, Am. J. Orthod. 120:98-111, 2001.patient and orthodontist, and the patient’s 10. Rubin, L.R.: The anatomy of a smile: Its importance in theanatomic and physiologic limitations. Using dig- treatment of facial paralysis, Plast. Reconstr. Surg. 53:384-387,ital video and computer technology, the clinician 1974. 11. Subtelny, J.D.: A longitudinal study of soft tissue facial struc-can evaluate the patient’s dynamic anterior tooth tures and their profile characteristics, defined in relation todisplay and incorporate smile analysis into rou- underlying skeletal structures, Am. J. Orthod. 45:481-507,tine treatment planning. Esthetic smile design is 1959. 12. Janzen, E.: A balanced smile: A most important treatmenta multifactorial decision-making process that objective, Am. J. Orthod. 72:359-372, 1977.allows the clinician to treat patients with an indi- 13. Burstone, C.J. and Marcotte, M.R.: The treatment occlusalvidualized, interdisciplinary approach. plane, in Problem Solving in Orthodontics: Goal-Oriented Treatment Strategies, Quintessence Publishing Co., Chicago, 2000, pp. 31-50. REFERENCES 14. Braun, S.: Diagnosis driven vs. appliance driven treatment out- comes, in Orthodontics for the Next Millennium, ed. R.C.L. Sachdeva, Ormco, Glendora, CA, 1997, pp. 32-45.1. Morley, J. and Eubank, J.: Macroesthetic elements of smile 15. Sarver, D.M.; Johnston, M.W.; and Matukas, V.J.: Video imag- design, J. Am. Dent. Assoc. 132:39-45, 2001. ing in orthognathic surgery, J. Oral Maxillofac. Surg. 46:939-2. Peck, S.; Peck, L.; and Kataja, M.: The gingival smile line, 945, 1988.236 JCO/APRIL 2002