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Inside Dentistry
September 2015
Volume 11, Issue 9
Peer-Reviewed

Seven Worst Violations of Smile Design

Achieve better esthetics by understanding common mistakes

Jason Olitsky, DMD, AAACD

Students and practitioners of esthetic dentistry study smile design principles to quantify and demonstrate potential esthetic changes to patients and dental team members, including laboratory technicians. These principles encompass facial esthetics, labiodental dynamics, gingival and dental architecture, and phonetics.1-3 To best educate patients and their colleagues alike, many lecturers do a fantastic job of illustrating smile design principles using examples of the ideal, and/or what falls within an ideal range, based on individual patient anatomical and physiologic characteristics.

Although this type of instruction is beneficial, it is equally helpful to recognize the worst violations of these principles. Instructive approaches incorporating proper evaluation and management of deviations from smile design principles are essential. This article examines the seven worst smile design principle violations and how to appropriately evaluate and restore them to ideal form.

1. A Crooked Smile

A smile that appears crooked on the face is immediately obvious to laypersons and dentists,4,5 similar to noticing a crooked wall-hanging. When smiles are restored, often little attention is paid to the inter-incisal line, resulting in a smile that appears tipped in the face (Figure 1 and Figure 2). Straightening the smile requires a pretreatment plan work-up that facilitates evaluation of facial esthetic principles. Among the aspects to be evaluated are horizontal and vertical facial parameters, including the commissural and inter-pupillary lines. A vertical line drawn through the middle of the face should focus attention to the glabellar area, tip of the nose, and middle of the chin. It is also important to ensure that inter-incisal contact areas between the central incisors are perpendicular to the horizon.6

Beginning with facial esthetics when treatment planning a smile may be overlooked if the scope of evaluation quickly becomes narrowed by analyzing only models of teeth on work benches.7,8 Instead, beginning with excellent pretreatment photography enables thorough facial esthetic analysis. Be aware of the patient’s natural horizontal head position when examining facial planes, and choose a horizontal reference line that represents the horizontal plane to be the basis for designing the smile. This is usually the true horizontal plane, which can be influenced by facial asymmetries commonly found among individuals. Perceiving the face as a whole, rather than focusing on one or two references to the horizon, is helpful. The restorative horizontal plane then can be ideally shared with the laboratory technician involved with mounting and waxing the case via a face-bow or digital smile design method (Figure 3 and Figure 4).9

2. The Reverse Smile

A radiating smile requires symmetry among incisal edges of maxillary anterior teeth that follow the lower lip border (ie, labiodental dynamic principle).10 Formed from the incisal edges, this shape creates a convex line blending into the posterior teeth. Posterior teeth would typically follow an occlusal plane or Campers Plane from the nose to the ear tragus. Curvature depends on patient gender, age, lower lip shape, and smile preferences.11,12 Straighter smile curves typically favor a more masculine or older smile characteristic, while more convex curves are characteristic of youth and femininity. A reverse smile or concave curve creates an unesthetic incisal line or an “unhappy”-looking smile (Figure 5).13

Ensuring a “happy”-looking smile involves analyzing tooth lengths and their relationship with lip dynamics. A reference point for incisal edge position is important for determining whether to shorten the canines or lengthen the incisors to correct a concave smile. Although the literature provides guidance for choosing canine incisal edge position from a patient’s lip position at rest, typically just at the lip border, central incisor tooth display varies greatly among patients depending on lip length and shape, tooth length, and lip mobility.6,8,10

Final incisal edge position is communicated to the laboratory before waxing when correcting concave smile lines by analyzing images of the smile and identifying length changes using digital smile design techniques or direct mock-ups on the patients’ teeth (Figure 6 through Figure 8). A precisely taken face-bow also alerts the technician to a concave smile line when the case is properly mounted on an articulator, but addressing labiodental dynamics also requires photographic images or video communication.9,14

3. The Social Six

Esthetically altering anterior teeth, including color and shape, is difficult without creating contrast with the posterior teeth, which produces a fake-looking smile. The dentolabial dynamic relationship of smile width demonstrates that smiles usually include 10 to 12 maxillary teeth, so restorative corrections also must account for more than just the six anterior teeth (Figure 9 through Figure 11). When taking pretreatment photographs, evaluating front and lateral smile views determines how the patient is viewed from the sides and front.

Another dentolabial dynamics principle (eg, buccal corridor or buccal width) dictates that posterior teeth not leave too much or too little space between the buccal aspects of the teeth and cheek. Too much space creates a narrow-looking smile, and treating only the six anterior teeth usually accentuates a narrow smile. Additionally, an artificial look results from emphasizing only the treated teeth, which detracts from the natural smile progression from anterior to posterior teeth.1 Conversely, restoratively brightening and accentuating the buccal aspects of posterior teeth can overfill this space and produce a denture-like look in the new smile.15

Finding the right balance is key. Examine patient smile photographs to assess whether they present a narrow smile and evaluate the color and contour of existing posterior teeth.16 Also consider the occlusal plane and its relationship to the incisal plane. Provide options to correct esthetic shortcomings in the posterior teeth in the smile. Consider offering case fees to improve the entire smile, rather than itemizing individual restorations, to educate patients about the importance of correcting the whole smile and not just the anterior.

4. Ignoring Central Incisor Proportions

Central incisors are naturally dominant in smiles, and central dominance, like radiating symmetry, is paramount to achieving a beautifully restored smile. The Golden Proportion was traditionally the standard applied when creating ideal smiles, but today artistic smile designers lean toward less regimented and proportion-based designs.

The width-to-height ratio is normally around 80% in unworn central incisors, so efforts must be made to maintain a similar ratio to prevent the centrals from appearing too long and narrow or too wide and fat.2,7,8 When planning esthetic length or width changes, or correcting incisor crowding, narrow teeth can easily result from over-lengthening or -narrowing compared to the actual width. A loss of central dominance results, with the two anterior teeth appearing to have the same width as the laterals, creating an unesthetic and artificial appearance.

If space is limited, ensure central dominance is maintained by narrowing or even slightly rotating the laterals to create room for the centrals (Figure 12 and Figure 13). A good guideline is proportioning the laterals to be about 65% of the central width, and the canines to be 75% of the lateral width. Using lines with constrained proportions in Keynote or PowerPoint overlaid on images of a patient’s teeth—or measuring the tooth widths and heights to determine their percentages—facilitates visualizing these proportions, sharing them with the laboratory during preplanning, and ensuring central dominance.6

5. Over-Contoured Teeth

There are three fundamental categories of tooth forms observed in patients: basically tapering, basically square, or basically ovoid. All teeth exhibit reflective and deflective zones separated by transition line angles. Manipulating these line angles impacts whether teeth appear shorter and fatter, longer and narrower, or more rectangular or curved.

Mesiofacial and distofacial line angles are usually found on facial aspects of teeth close to the contact areas. Moving line angles outward toward contact areas creates wider looking teeth. Moving them toward the center creates narrower looking teeth. Without distinction between deflective and reflective zones, teeth can appear over-contoured (Figure 14 and Figure 15).17,18

Because ceramists work under the confines of preparation designs, under-reduced transitional line angles for porcelain veneers force them to obscure the reflective and deflective zones when building up porcelain. When preparing for porcelain veneers, ensure that depth cuts of appropriate thicknesses are made through a properly designed mock-up of the final restorations overlaid on the teeth. The depth cut should extend across the facial and through the mesiofacial and distofacial line angles in three facial planes, providing sufficient space for recreating this area in porcelain without thickening the entire tooth.

6. Ignoring Negative Space

Space around a tooth establishes its boundaries and balances smile composition. When designing a smile, it is important to provide adequate room for incisal embrasures or inter-incisal angles between anterior teeth at the incisal edge.19

Tooth width and depth is determined by interdental contact areas, and for central incisors, these typically extend up to the incisal edges, reducing the incisal angle created. In common dental compositions, contact points move apically from central incisors to canines, which increases inter-incisal angles.2 With worn tooth edges in a smile, the inter-incisal angles are reduced or completely disappear, producing a flat smile line and aged appearance.11

When treating a smile, clinicians must recreate the natural inter-incisal angle progression, which restores morphology, appropriate tooth lengths, and convex incisal curve. Incisal angles are properly addressed in preparation design by providing ceramists with room to recreate negative space. These areas can be further accentuated post-cementation using proper instrumentation (Figure 16 through Figure 19).

7. Gingival Asymmetry

Overlooking gingival margin positions is another major smile design violation. Gingival esthetics should be properly evaluated to create a treatment plan that idealizes the gingival margins and accounts for symmetry versus harmony.1-3 More emphasis should be placed on harmony (ie, a recurring theme, such as centrals or laterals of the same lengths) versus symmetry (ie, the mirror image of parts or components on the y axis).

Restoring tooth length to create symmetry can disrupt smile harmony by detracting from balance and beauty, especially when gingival margins and tissue heights are not evaluated during treatment planning. Gingival margin position is significant in people with medium-to-high smile lines. The smile line, a labiodental dynamics principle, is the lip location when the person smiles (eg, 69% of people show 75% to 100% of their central incisors, along with interproximal papilla).

Canines and central incisor gingival margins should be symmetric and positioned more apically compared to the lateral incisors. The gingival margins should gradually move incisally toward the posterior teeth. A good rule is keeping maxillary canines and central incisors on the same plane and the laterals slightly incisal to that line. However, the gingival margins of the laterals should fall short of the line drawn from the gingival apex of the centrals to the canines (Figure 20).

Because gingival margins should always be evaluated using photography or a model properly oriented to resemble the patient’s horizontal position, excellent pretreatment images are necessary Plan gingival changes prior to gingival contouring or hard tissue crown lengthening utilizing diagnostic information (eg, sounding bone at various sites on each tooth). Canted gingival margins or undesirable tissue heights inadvertently result when surgical procedures are not properly planned, so consider using surgical guides or templates for the teeth to control gingival changes during surgery.

Evaluate images of the teeth and smile with patients before performing restorative treatments, which helps them visualize unideal gingival areas that will compromise esthetics. Routinely educating patients about these compromises before commencing treatment helps ensure that the results reflect their expectations.20

Conclusion

Proper evaluation and management of cases with deviations from smile design principles are essential for appropriately and predictably restoring teeth and smiles to their ideal form. While many principles of smile design are worth studying, understanding these seven common violations and how to avoid them is equally beneficial to achieving successful outcomes.

About the Author

Jason Olitsky, DMD, AAACD
Director of Aesthetics andPhotography, Clinical Mastery Series
clinicalmastery.com
Private Practice
Ponte Vedra Beach, Florida

References

1. Fradeani M. Esthetic analysis: a systematic approach to prosthetic treatment. In: Esthetic Rehabilitation in Fixed Prosthodontics, Vol. 1. Chicago, IL: Quintessence Publishing; 2004.

2. Tarnow TP, Chu SJ, Kim J. Aesthetic Restorative Dentistry: Principles and Practice. Montage Media Corporation; 2008.

3. Chiche GJ, Pinault A. Artistic and scientific principles applied to esthetic dentistry. In: Chiche GJ, Pinault A, eds. Esthetics of Anterior Fixed Prosthodontics. Chicago, IL: Quintessence Publishing; 1994:13-32.

4. Behrend DA, Harcourt JK, Adams GG. Choosing the esthetic angle of the face: experiments with laypersons and prosthodontists. J Prosth Dent. 2011;106(2):103-108.

5. Witt M, Flores-Mir C. Laypeople’s preferences regarding frontal dentofacial esthetics: tooth-related factors. J Am Dent Assoc. 2011;142(6):635-645.

6. Alsulaimani FF, Batwa W. Incisors’ proportions in smile esthetics. J Orthod Sci. 2013;2(3):109-112.

7. Rufenacht CR. Fundamentals of Esthetics. Chicago, IL: Quintessence Publishing; 1990:67-134.

8. Morley J, Eubank J. Macroesthetic elements of smile design. J Am Dent Assoc. 2001;132(1):38-45.

9. Coachman C, Calamita M. Digital smile design: a tool for treatment planning communication in esthetic dentistry. In: Sillas Jr D, ed. Quintessence of Dental Technology. Chicago, IL: Quintessence Publishing; 2012.

10. Misch CE. Guidelines for maxillary incisal edge position-a pilot study: the key is the canine. J Prosthodont. 2008;17(2):130-134.

11. Morley J. Smile design workshop. 6. The role of age in smile design. Dent Today. 1991;10(9):42-43.

12. Morley J. Smile designer’s workshop. 5. The role of gender in smile design. Dent Today. 1991;10(5):46-47.

13. Duchenne GB. The Mechanism of Human Facial Expression. New York, NY: Cambridge University Press; 1990.

14. Goldstein RE. Masters of esthetic dentistry. Considerations for smile-generated long-range treatment planning: thoughts and opinion of a master of esthetic dentistry. J Esthet Restor Dent. 1999;11(1):49-53.

15. Lombardi RE. The principles of visual perception and their clinical application to denture esthetics. J Prosth Dent. 1973;29(4):358-382.

16. Fradeani M, Barducci G. Establishing communication with patients. In: Fradeani M, Barducci G, eds. Esthetic Rehabilitation in Fixed Prosthodontics, Vol. 2. Chicago, IL: Quintessence Publishing; 2008:29-115.

17. LeSage B. Revisiting the design of minimal and no-preparation veneers: a step-by-step technique. J Calif Dent Assoc. 2010;38(8):561-569.

18. LeSage B. Finishing and polishing criteria for minimally invasive composite restorations. Gen Dent. 2011;59(6):422-428.

19. LeSage BP. Minimally invasive dentistry: paradigm shifts in preparation design. Pract Proced Aesthet Dent. 2009;21(2):97-101.

20. Kokich VO Jr, Kiyak HA, Shapiro PA. Comparing the perception of dentists and lay people to altered dental esthetics. J Esthet Dent. 1990;11(6):311-324.

Recognizing a pre-existing cant in work-ups is important for initiating treatment to correct the violation. Analyzing teeth without the face is accomplished by first ensuring that the inter-incisal angle is accurately represented, not understated orinadvertently corrected with photographic techniques, which facilitates laboratory communication for correcting the canted smile. Smile design restorations fabricated with IPS e.max® and IPS® Empress (Ivoclar Vivadent, www.ivoclarvivadent.com).

Figure 1

Recognizing a pre-existing cant in work-ups is important for initiating treatment to correct the violation. Analyzing teeth without the face is accomplished by first ensuring that the inter-incisal angle is accurately represented, not understated orinadvertently corrected with photographic techniques, which facilitates laboratory communication for correcting the canted smile. Smile design restorations fabricated with IPS e.max® and IPS® Empress (Ivoclar Vivadent, www.ivoclarvivadent.com).

Figure 2

A properly obtained face-bow and a mock-up enhance laboratory communication about necessary incisal edge position changes and non-perpendicular inter-incisal line correction, making controlling the outcome more predictable.

Figure 3

A properly obtained face-bow and a mock-up enhance laboratory communication about necessary incisal edge position changes and non-perpendicular inter-incisal line correction, making controlling the outcome more predictable.

Figure 4

In a reverse or concave smile, the incisal edge outline is not congruent with the outline of the lower lip border. Correcting the incisal line to a more convex form creates radiating symmetry with the lower lip for a more esthetic smile.

Figure 5

Before initiating treatment, it is important to establish final incisal edge positions based on any possible gingival margin changes and future width-to-height tooth proportions. Overly lengthening teeth can create narrow central incisors. Using digital techniques (eg, proportion boxes with defined width-to-height percentages) to pretreatment plan final incisal edge length prior to undertaking any gingival height changes is beneficial. The final incisor length can be previewed in a mock-up before preforming gingival lifts and ordering wax-ups to minimize chairtime for contouring provisional restorations. Concave smile restored to a more convex appearance with IPS Empress restorations.

Figure 6

Before initiating treatment, it is important to establish final incisal edge positions based on any possible gingival margin changes and future width-to-height tooth proportions. Overly lengthening teeth can create narrow central incisors. Using digital techniques (eg, proportion boxes with defined width-to-height percentages) to pretreatment plan final incisal edge length prior to undertaking any gingival height changes is beneficial. The final incisor length can be previewed in a mock-up before preforming gingival lifts and ordering wax-ups to minimize chairtime for contouring provisional restorations. Concave smile restored to a more convex appearance with IPS Empress restorations.

Figure 7

Before initiating treatment, it is important to establish final incisal edge positions based on any possible gingival margin changes and future width-to-height tooth proportions. Overly lengthening teeth can create narrow central incisors. Using digital techniques (eg, proportion boxes with defined width-to-height percentages) to pretreatment plan final incisal edge length prior to undertaking any gingival height changes is beneficial. The final incisor length can be previewed in a mock-up before preforming gingival lifts and ordering wax-ups to minimize chairtime for contouring provisional restorations. Concave smile restored to a more convex appearance with IPS Empress restorations.

Figure 8

Patients with excessive buccal space could benefit from smile improvements extending beyond the anterior teeth. In attempts to correct anterior tooth violations, the buccal corridor deficiency could be inadvertently emphasized, creating an artificial looking smile. Extending the smile from the anterior IPS e.max restorations to the directly restored bicuspids established a more ideal buccal width.

Figure 9

Patients with excessive buccal space could benefit from smile improvements extending beyond the anterior teeth. In attempts to correct anterior tooth violations, the buccal corridor deficiency could be inadvertently emphasized, creating an artificial looking smile. Extending the smile from the anterior IPS e.max restorations to the directly restored bicuspids established a more ideal buccal width.

Figure 10

Patients with excessive buccal space could benefit from smile improvements extending beyond the anterior teeth. In attempts to correct anterior tooth violations, the buccal corridor deficiency could be inadvertently emphasized, creating an artificial looking smile. Extending the smile from the anterior IPS e.max restorations to the directly restored bicuspids established a more ideal buccal width.

Figure 11

Loss of central dominance often occurs in cases with crowding and restorations will straighten the teeth. Uprighting the teeth to correct the anterior lingual tipping created restorative space for the restorations and established ideal central-to-lateral proportions. IPS e.max and IPS Empress restorations idealized the arch form and established central dominance.

Figure 12

Loss of central dominance often occurs in cases with crowding and restorations will straighten the teeth. Uprighting the teeth to correct the anterior lingual tipping created restorative space for the restorations and established ideal central-to-lateral proportions. IPS e.max and IPS Empress restorations idealized the arch form and established central dominance.

Figure 13

Teeth lacking definitive line angles may appear over-contoured because the height of contour moves toward the vertical center of the facial aspect. This results from preparation design. Preparing into a mock-up enables completion of the ideal preparation design for the ceramist. Pre-planning with an ideal wax-up facilitates control of the case when proper steps are followed from preparation to cementation. Existing ceramic restorations on teeth No. 4 through No. 13 replaced with IPS e.max restorations; teeth No. 20 through No. 29 also restored.

Figure 14

Teeth lacking definitive line angles may appear over-contoured because the height of contour moves toward the vertical center of the facial aspect. This results from preparation design. Preparing into a mock-up enables completion of the ideal preparation design for the ceramist. Pre-planning with an ideal wax-up facilitates control of the case when proper steps are followed from preparation to cementation. Existing ceramic restorations on teeth No. 4 through No. 13 replaced with IPS e.max restorations; teeth No. 20 through No. 29 also restored.

Figure 15

Incisal embrasure loss creates an aged smile appearance. Preoperatively, a 38-year-old patient with attrition effects of bruxism exhibited evident incisal embrasure loss, which aged the smile. Pretreatment planning incorporated mock-ups and proportion guides to establish ideal length, and IPS e.max restorations were placed to recreate the incisal embrasures and maintain a masculine look; optimize strength, function, and esthetics; and create a youthful appearance.

Figure 16

Incisal embrasure loss creates an aged smile appearance. Preoperatively, a 38-year-old patient with attrition effects of bruxism exhibited evident incisal embrasure loss, which aged the smile. Pretreatment planning incorporated mock-ups and proportion guides to establish ideal length, and IPS e.max restorations were placed to recreate the incisal embrasures and maintain a masculine look; optimize strength, function, and esthetics; and create a youthful appearance.

Figure 17

Incisal embrasure loss creates an aged smile appearance. Preoperatively, a 38-year-old patient with attrition effects of bruxism exhibited evident incisal embrasure loss, which aged the smile. Pretreatment planning incorporated mock-ups and proportion guides to establish ideal length, and IPS e.max restorations were placed to recreate the incisal embrasures and maintain a masculine look; optimize strength, function, and esthetics; and create a youthful appearance.

Figure 18

Incisal embrasure loss creates an aged smile appearance. Preoperatively, a 38-year-old patient with attrition effects of bruxism exhibited evident incisal embrasure loss, which aged the smile. Pretreatment planning incorporated mock-ups and proportion guides to establish ideal length, and IPS e.max restorations were placed to recreate the incisal embrasures and maintain a masculine look; optimize strength, function, and esthetics; and create a youthful appearance.

Figure 19

Gingival esthetics is crucial in smile design, and understanding ideal gingival position parameters facilitates planning appropriate treatments, and/or reveals important considerations warranting patient discussion before beginning treatments. For ideal symmetry, centrals fall on the same horizontal plane as the canines. Another perception of beauty allows the lateral incisors to fall gingivally and incisally between a line drawn from the apex of the gingival margins of the canines and centrals and their incisal edges.

Figure 20

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