EsTHetics

Increasingly, patients seeking treat-ment present with the primary concernof an esthetic enhancement to their oralcondition. Many articles have beenwritten and courses taught over theyears on concepts of smile design todevelop a treatment plan to get anesthetic outcome for the patient.1-7

Esthetic or cosmetic dentistry hasbecome one of the main areas of dentalpractice emphasis and growth for sever-al years. These terms (ie, esthetic andcosmetic) have almost become syn-onymous in our dental nomenclature.The literal definitions of these terms arevery different. Cosmetic means to do“something superficial to cover a defector deficiency” and secondarily “serving tobeautify the body.” The second part ofthis definition has a very large culturalcomponent to this, ie, beauty is in theeye of the beholder. There is also animplication that something “cosmetic,”while deemed “beautiful,” is obvious tothe observer that a facial or dental char-acteristic has been en-hanced—eg, using make-up to accentu-ate a facial feature. According to theMerriam-Webster dictionary, the defi-nition of esthetics, on the other hand, is“responsive to or appreciative of whatis pleasurable to the senses” or “pleasingin appearance.” Thus, cosmetics andesthetics are somewhat inseparablyintertwined, but esthetics also encom-passes appearances that do not have a“cosmetic appearance.”

Timeless human esthetics implies asense of beauty, a pleasing impulse, natu-ralness, and a youthful appearance relativeto one’s age. The goal for esthetic treat-

ment should be an enhanced but naturalappearance that imparts a vibrant andbelievable appearance to the patient. Thisshould be our goal in dental esthetics: aresult that would be considered “bright,beautiful, but believable.” This may entailthe use of cosmetic procedures as alreadystated but, just as importantly, it blendsthe functional and biologic requirementsof the patient into a durable and long-lasting result. The treatment should be asconservative as possible and allow the pa-tient future options as new technologiesare developed.

This article will focus on historicallyaccepted smile design concepts and pres-ent research of smile parameters that willhelp the reader to design their esthetictreatments. It is very important to notethat smile design concepts have been pre-sented in a very static manner, ie, specif-ic measurements for form, color, and po-sition of esthetic dental elements. This isfine for basic information transfer of smiledesign principles, but it is critical to un-derstand the esthetics is not a finite point;in fact, esthetics can be a broad zone. Welike to refer to this as “the esthetic zone” fora given patient. Thus, we will give from ourevaluations what we believe are zones or“ranges”of esthetic values for smile design.

THE PROCESS OF SMILEDESIGN AND ANALYSISSmile design should involve the evalua-tion of certain elements in a specific se-quence; (1) facial analysis (general facialbalance), (2) dento-facial analysis (maxillo-mandibular relationships to the face, andthe dental midline relationship to the face)(3) dento-labial analysis (the relationship

of the teeth to the lips), (4) dento-gingivalanalysis (the relationship of the teeth tothe gingiva, and (5) dental analysis (theintertooth and intratooth relationships,ie, form and position along with color).Even though there is a specific sequencerecommended it must be understoodthat all of the elements are interrelated;changing one will have an impact on allthe others.

The concept of the evaluation sequenceis based starting with a macro view of thepatient and progressively working downto a micro view, ie, looking at the facefirst and then progressing to evaluate theindividual teeth last. The recommendedsequence does not necessarily imply theorder of importance (even though macroview esthetics is noticed by observers be-fore micro views); it is just a way to sys-tematically evaluate a patient. And thevery last thing planned is what materialshould be used consistent with satisfyingall treatment planning goals. The treat-ment sequence may change and followan entirely different course dependingon these variables. If the treatment planfollows a proper sequence, a restorationwould not be planned for a tooth that ismalpositioned to the point that it wouldrequire mutilation to reposition it restor-atively. The treatment plan would repo-sition it initially so that the tooth is notstructurally compromised with excessivepreparation.

FACIAL AND DENTO-FACIAL ANALYSISThe smile analysis evaluation should be-gin with the observation of the facial ele-ments.1-11 There are guidelines to facial

form and balance that can be affected bydental treatment. Regardless of how at-tractive the teeth appear, if they do notrelate to the facial structures spatially, theresult will be unesthetic. Because of thespace limitations of this article, the top-ics of facial analysis and dento-facial ana-lysis (other than the topic of midline)will not be covered. The reader is referredto many references on facial analysis andits impact on smile design and treat-ment.2-12 Suffice it to say that obviousfacial abnormalities, especially when ob-serving the lower one third of the face,should be referred for orthodontic andorthognathic consultation.

MidlineIdeally, the dental midline should end upcollinear with the facial midline but usu-ally it does not (Figure 1). Fortunately, inour experience of all the esthetic parame-ters, dental midline abnormalities are theleast noticed by patients and dental per-sonnel. In one study by Kokich,13 it wasshown that the public could not tell thatdental midlines were off facial midlinesof up to 4 mm. As long as the midline isparallel with the long axis of the face,midline discrepancies of up to 4 mm willgenerally not be perceived as unesthetic.Slight corrections of midlines can be ac-complished with restorative dentistry aslong as the maxillary centrals are maderelatively symmetric and correct inter-tooth relationships are maintained. If theindividual teeth do not require restora-tion and there is a large midline discrep-ancy, the ideal treatment is orthodontics.

44 INSIDE DENTISTRY—JULY/AUGUST 2009

Smile Analysis and Esthetic Design:“In the Zone” Edward A. McLaren, DDS, MDC; and Phong Tran Cao, DDS

“...it is critical to understand the esthetics is not a finite point; in fact,

esthetics can be a broad zone.”

Figure 1 Image of smile where the facial anddental midline do not line up.

Edward A. McLaren, DDS, MDCFounder and Director

UCLA Center for Esthetic Dentistry Residency Program

Founder and Director

UCLA Master Dental Ceramist Program

Private Practice limited to Prosthodontics and Esthetic Dentistry

insideEsTHetics

Phong Tran Cao, DDSSenior Resident

UCLA Center for Esthetic Dentistry

46 INSIDE DENTISTRY—JULY/AUGUST 2009

DENTO-LABIAL ANALYSISThe next step in the esthetic analysis is toevaluate the relationship of the lips to theteeth, ie, visual tooth display both stati-cally and dynamically, then buccal corri-dor (which is related to arch form).

Incisal Edge PositionPublished reports have shown that theaverage 30-year-old woman displays about3.5 mm of maxillary central incisor toothstructure when the lips are at rest (Fig-ure 2).11,14,15 The prosthodontic litera-ture has generally recommended settingdenture teeth so that 2 mm of tooth struc-ture is displayed at rest.14,16 In the au-thor’s experience, the 2 mm exposed atrest is generally less than desired by es-thetically driven patients. Also, in the au-thors’ experience, for most patients whohave improved esthetics as their primarytreatment goal, between 3 mm and 4 mmdisplayed at rest will be esthetically ideal.Another guide for evaluating the estheticposition of the maxillary anterior incisaledges applies when the patient smiles; inan esthetic composition, the tips of themaxillary anterior teeth come very closeto touch the lower lip up to a maximumof 3 mm away (Figure 3).

The esthetic treatment would be to re-position the incisal edges of the maxillaryanterior teeth within these two dento-labial esthetic zones. The modality of treat-ment would be determined in conjunc-tion with the evaluation of all the othersmile design and treatment goal parame-ters. If patients display less than 4 mm ofthe maxillary central at rest and the teethneed to be lengthened, the length willgenerally be achieved by adding to theincisal edge.

Incisal Display During SmilingTooth size and position, lip length, andlip mobility greatly affect maxillary toothdisplay both statically and dynamically.The average lip length has been measuredat between 20 mm to 24 mm measuredfrom the base of the nose to the edge ofthe upper lip.1,8 Average lip mobility in anormal esthetic smile is 7 mm to 8 mm asmeasured in the UCLA Center for Es-thetic Dentistry (CED) study by showingevaluators images of patients’ lower onethird of their face while smiling. Subjectswho were rated to have a good to excel-

lent smile were measured for an averageof 7 mm to 8 mm of lip movement. Alsoduring smiling, all of the maxillary ante-rior teeth are displayed, from incisal edgeto gingival margin (Figure 2 and Figure3). Most of the maxillary premolars andsometimes the first molar are displayedwhen smiling. In a study by Kokich,13 itwas demonstrated that dental evaluatorsand lay people still considered it estheticif 2 mm of gingiva showed in a full smile.In our opinion, it is still in the “estheticzone” to show up to 3 mm of gingiva in afull smile, especially if there is slightlymore than 8 mm in lip movement duringa smile (Figure 1).

If the incisal display at rest is 3 mm to4 mm, and it is determined that the teethare too short, then surgical crown-length-ening procedures should be considered.Two main considerations for surgicalcrown lengthening are dentin exposureand crown-to-root ratio. The goal is tonever expose root structure (dentin) pure-ly for esthetic reasons, especially if bondedporcelain is the ideal restorative optionfor the patient. If the gingival marginneeds to be apically placed for esthetics,and crown lengthening would expose den-tin, the ideal option would be to ortho-dontically or orthognathically move theteeth with the dento-gingival complexapplicably to satisfy esthetic requirements.The other obvious consideration is crown-to-root ratio. As a guideline, the primaryauthor will not crown length more thanwhat would create a 60:40 crown-to-rootratio. This option is only considered if gin-gival dentin is already exposed and crownlengthening is needed to be done anywayfor biologic and structural reasons.

If there is insufficient tooth display atrest, normal lip mobility, the teeth are thecorrect length, and there is inadequatetooth display during smiling, then this isdiagnostic of vertical maxillary insuffi-ciency. This is not a case that should betreated with esthetic tooth lengthening.This is an orthognathic problem andshould be referred for proper treatment.Conversely, if there is too much tooth dis-play at rest, normal lip mobility, normaltooth length, and an excessive display ofgingival during smiling (more than 3 mm)this is diagnostic of vertical maxillaryexcess.15,17,18 This should not be treatedby restorative dentistry and surgical crown

lengthening alone; this case should bereferred for orthognathic surgical correc-tion. In clinical situations where there isnormal tooth display at rest, correct toothlength, correct relationship of the teeth tothe lower lip when smiling, and excessivegingival display during smiling, this is usu-ally indicative of excessive lip mobility.This is a very difficult situation to treat, asalmost any treatment will leave an estheticcompromise in either a static or dynamiclip position.

Smile LineIn an esthetic smile, the edges of the max-illary anterior teeth follow a convex orgull-wing course matching the curvatureof the lower lip (Figure 4), and are gener-ally radially parallel to the horizon. Froma frontal view, the maxillary arch fromcentral to molar appears to curve upward,but not always. If it does, this apparentcurve may be a result of a slight posteriorcant to the maxilla or the frequent ap-pearance of the Curve of Spee in the in-tact dentition. Slight to moderate devia-

tions to this pattern can be effectivelytreated with esthetic recontouring or con-servative restorative dentistry. In situa-tions where there is ideal tooth form andcolor but there are discrepancies to thesmile line or visual tooth display, restora-tive dentistry is not indicated, as this wouldcause unnecessary mutilation of other-wise healthy tooth structure. In these clin-ical situations, and when there is moder-ate to severe distortion of the smile line,orthodontics would be the more appro-priate treatment.

Buccal CorridorIn an esthetic smile there is what has beentermed negative space, which is a smallspace between the maxillary posterior teethand the inside of the cheek. A broad smilewith a minimal buccal corridor is deemedmost esthetic by lay people;19 however, abroad smile without a buccal corridor couldalso be perceived as fake.20 If the spaceappears excessive (Figure 5) when the pa-tient is smiling, a small amount of thespace can be filled by increasing the buccal

Figure 2 Image of the lower one third showingtooth display at rest. The display was measuredto be between 2.5 to 3 mm.

Figure 3 Lower one third smiling image showingthe relationship of the incisal edge to the lowerlip during smiling.

Figure 4 Image showing the smile line with agull-wing effect.

Figure 5 Image showing excessive (too muchnegative space) buccal corridor problem, whichcan be related to a narrow arch form.

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Figure 6 Image of a smile that was ratedexcellent by several evaluators at the UCLACenter for Esthetic Dentistry.

Figure 7 Image showing the gingival line onthe same patient. Note the lateral and centralapical position of the gingival margin is on astraight line that is completely horizontal.

Figure 8 Image demonstrating the measure-ments of the ideal gingival scallop, with the percentages showing the papilla length relativeto tooth length.

Figure 9 Image showing close to an 80% width-to-length ratio and optical width of the central rel-ative to the lateral and the lateral relative to thecanine. Note that esthetic percentages do not fol-low the golden proportion, especially the canine.

48 INSIDE DENTISTRY—JULY/AUGUST 2009

contours of the maxillary posterior restor-ations—assuming restorations need to beplaced for restorative reasons. If con-servative additive or subtractive (ie, es-thetic contouring) techniques will notwork esthetically, then orthodonticsshould be considered.

DENTO-GINGIVAL ANALYSISThe lips frame the teeth and gingiva. Thegingiva frames the teeth. The ratio of toothstructure to the amount of gingival andlabial tissue should be harmonized toprevent an over-dominance of any oneelement. As such, establishing proper gin-gival relationships relative to the lips hasbeen discussed in the previous section.Gingival margin placement is based onlip dynamics, and to a certain extent de-sired tooth length (which will be dis-cussed in the next section). Other factorsto consider in designing esthetic gingivalrelationships are: gingival line (the rela-tionships of free gingival margins of themaxillary teeth), gingival scalloping andcontour, papillary tip positioning, andgingival color.

Gingival LineThere have been several gingival refer-ence line relationships that exist frommaxillary bicuspid to the contralateralbicuspids that have been discussed as be-ing esthetic.21 Other than the dental mid-line, slight discrepancies in the gingivalline are least noticed by the public or bydental professionals. The key esthetic is-sue is that the gingival line for the anteri-or teeth should be relatively horizontal tothe horizon and relatively symmetric onboth sides of the midline. It may radiateup slightly as it goes posterior. It is notcritical that the lateral incisor gingival linefall incisal to the central as this is not ob-vious when a person is smiling (Figure 6).Positioning the lateral to the central inci-sor within 0.5 mm gingivally and 1 mmincisally is generally perceived as estheticas long as horizontal symmetry is main-tained (Figure 7). The contour of the gin-giva (ie, gingival scallop) to the tip of thepapilla should be between 4 mm or 5 mm(Figure 8), and the tips of the papillaeshould have the same radiating symmetryas the incisal edges and the free gingivalmargins. In an esthetic smile, the volumeof the gingiva from the apical aspect of

the free gingival margin to the tip of thepapilla is about 40% to 50% of the lengthof the maxillary anterior tooth and fullyfills the gingival embrasure (Figure 8).22

In situations where this condition doesnot exist, periodontal and orthodonticprocedures are the treatments of choice tocreate the correct gingival architecture.Orthodontics not only positions the teethbut also can reposition gingiva and bone.Gingival color should appear pink andhealthy or consistent with the healthy col-or of individual race variations.

DENTAL ANALYSIS:INTRATOOTH ANDINTERTOOTH RELATIONSHIPS

Intratooth RelationshipsThe average length for maxillary centralincisors has been measured at between 10mm to 11 mm.11,12,23 In a recent study byMagne,24 the average maxillary length ofa unworn maxillary central to the cemento-enamel junction was slightly over 11 mm.Patients who seek esthetics as a primaryreason for treatment want to have a fullsmile with “above average” looking teeth.From measuring esthetic outcomes onhundreds of personal patients and hun-dreds of resident patients in the UCLACED, the authors have determined theesthetic zone for the central incisor to bebetween 10.5 mm and 12 mm. A goodlength to start the design is 11 mm, as itcan be modified based on the many othertreatment planning parameters. The width-to-length esthetic relationship has beendiscussed in the literature to be between70% to 80%.11,22 In measuring smiles inthe UCLA CED, the optimal width-to-length ratio for the maxillary central zonewas found to be a width of between 75%to 85% of the length. Smiles with thesevalues were most often deemed “estheticto highly esthetic.” The most estheticallypleasing ratio was 80%. (Figure 9). It is ex-tremely important to note that the estheticperception of width-to-length ratios is sig-nificantly affected by the outline form andthe reflective surface of the tooth. The lat-eral incisors are between 1 mm to a maxi-mum of 2.5 mm shorter than the central.For a more petite smile, more toward the 2mm to 2.5 mm length is recommended.The canine is slightly shorter than the cen-tral between 0.5 to 1 mm.

Intertooth RelationshipsWhen a person smiles and the teeth are dis-played, there is an intertooth relationshipthat needs to be maintained for the compo-sition to be considered esthetic. The maxil-lary central incisors should be relatively butnot perfectly symmetrical. They shoulddominate but not overwhelm the smile.11,21

This is obviously very subjective, but re-search has shown that in smiles determinedto be esthetic, there was a clear dominanceof the maxillary central incisor. Many au-thors recommend using the golden propor-tion to define the optical width of the max-illary teeth as they go posteriorly.21,25,26

One study has demonstrated that the actu-al measurements of most people’s anteriorteeth do not in fact follow the golden pro-portion.27 It has not been determined thatif a person’s optical tooth display followedthe golden proportion that this be consid-ered more esthetic than other arrange-ments. In the authors’ experience, the re-lationship of the maxillary lateral to centralincisor comes very close to the golden pro-portion in an esthetic smile, and can beused as a guide in shaping teeth. A goodguide is to make the optical width of the lat-eral incisor about 65% of the central incisor(or a little less than two thirds). The authorshave found that the canine does not followthe golden proportion optically and is gen-erally about 75% to 80% or about threefourths to four fifths of the optical width ofthe lateral incisor in smiles that were con-sidered highly esthetic, with an estheticallyacceptable zone from 70% to 85% (Figure9). Figure 10 through Figure 12 shows pre-operative or preparatory cases and thenpostoperative examples with esthetic para-meters within the zones discussed.

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Figure 10 Preoperative image of a case requiringimproving esthetic proportions.

Figure 11 Preparations of the same case whichshows the significantly pegged lateral that waspresent under the old composite bonding.

Figure 12 Postoperative image of creating idealproportions using bonded porcelain restorations.

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