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
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
Ponte Vedra Beach, Florida
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.