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Creating Smile Symmetry: Applying Classical Esthetic Principles While Using Digital Technology

Joyce Bassett, DDS

April 2020 RN - Expires Thursday, December 31st, 2020

Inside Dental Technology


Having a thorough understanding of classical esthetic principles, including basic tooth shape and form rules, is crucial for clinicians to achieve successful esthetic outcomes, even when implementing digital technologies in their dental offices. The use of advanced, cutting-edge digital tools does not negate the need to adhere to the timeless fundamentals of esthetic dentistry. This article reviews key esthetic principles and describes their application in treating a challenging cosmetic case. Showcasing the use of smile design software, the case illustrates the diagnosis, planning, and clinical execution used to mask a congenitally missing lateral incisor while preserving the natural dentition on the contralateral side. The principles of symmetry and harmony are employed to create a smile in which the restorative dentistry would be imperceptible and the remaining dentition protected from structural compromise.

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Fig 1. The outline form of a square tooth shows an incisal edge that is straight or slightly curved.

Figure 1

Fig 2. In an ovoid tooth form, the incisal edge is relatively narrow and occasionally rounded.

Figure 2

Fig 3. The outline form of a triangular tooth displays a wide incisal edge that is slightly curved.

Figure 3

Fig 4. Interincisal angles: A narrow inverted “V” forms between the two central incisors; asymmetrical inverted “V”s form between the central and lateral incisors; and wide inverted “V”s form between the
lateral incisors and canines.

Figure 4

Fig 5. From an incisal perspective, a concave
facial contour causes the tooth to appear
thinner, while a convex facial contour causes
the tooth to appear wider.

Figure 5

Fig 6. Preoperative smile; note that the maxillary left canine is in the lateral incisor space, and Cupid’s bow is over the center of the right central incisor.

Figure 6

Fig 7. Preoperative occlusal view; note the left
second premolar is rotated 90°, and the lateral incisors had a significant size disparity.

Figure 7

Fig 8. Outlining the preoperative tooth forms enables visualization of inconsistencies.

Figure 8

Fig 9. Using the principle of continuous proportion, the preoperative outline form of the right side of the dentition is mirrored and placed over the
teeth on the left side.

Figure 9

Fig 10. The right-to-left space discrepancy is equalized by moving the midline to the patient’s left.

Figure 10

Fig 11. The digital template is then shifted onto the teeth on the left side at the gingival margins.

Figure 11

Fig 12. Both lateral incisors are lengthened, and the illusion of increased width on tooth No. 7 is created by closing the mesioincisal and distoincisal embrasures. To create the illusion of a narrower left canine, the
distoincisal embrasure is opened and the distal aspect is rounded.

Figure 12

Fig 13. The smile design is synced with the preoperative photograph by overlaying the blue landmarks.

Figure 13

Fig 14. The design overlay facilitates the
analysis of the digital design proposal, including gingival fit (encircled).

Figure 14

Fig 15. Two-dimensional images are entered as overlays in the 3D design (gingival fit encircled).

Figure 15

Fig 16. The 3D design proposal is finalized.

Figure 16

Fig 17. The digital prototypes are placed in face for a virtual try-in.

Figure 17

Fig 18. The contact of tooth No. 7 mesial and tooth No. 8 distal is opened to widen No. 7 and slenderize No. 8, and then the contact between Nos.
8 and 9 is opened to allow the desired tooth width changes to enable the
midline shift to the patient’s left.

Figure 18

Fig 19. Lithium-disilicate restorations;
note the distinct shade transitions and use of horizontal and vertical
tertiary surface texture on the porcelain to create an illusion of symmetry.

Figure 19

Fig 20. The final prosthetics are displayed, mounted on a model.

Figure 20

Fig 21. The final prosthetics are displayed, mounted on a model.

Figure 21

Fig 22. The final prosthetics are displayed, mounted on a model.

Figure 22

Fig 23. The final prosthetics are displayed, mounted on a model.

Figure 23

Fig 24. Postoperative view of HT BL2 lithium-disilicate restorations; a natural-looking harmonious smile is created using 3D prosthetic planning.

Figure 24

COST: $0
SOURCE: Inside Dental Technology | April 2020

Learning Objectives:


The author reports no conflicts of interest associated with this work.

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