Digital Smile Design Meets the Dento-Facial Analyzer: Optimizing Esthetic While Preserving Tooth Structure (One)

Digital smile design (DSD) is a growing trend in esthetic dentistry.1 This concept is an effective tool to communicate esthetic possibilities to patients prior to treatment initiation, as well as to communicate the desired outcomes to other clinical and laboratory team members. The patient and dentist can view the proposed treatment outcome and modify it as they see fit.The creation of a diagnostic wax­up, silicone index, and surgical stent are all facilitated with the use of DSD.

A 32-year-old man presented with concerns about esthetics associated with missing lateral incisors (Figure 1). He had received orthodontic treatment as a teenager, which had relapsed. His chief concern was his unpleasing smile. He desired a treatment plan that did not involve more orthodontics and that could be completed in a short period of time and would preserve as much tooth structure as possible.

His medical history was noncontributory. A review of his dental history revealed congenitally missing maxillary lateralincisors, as well as mesially tilted teeth Nos. 8 and 11. It was also noted that teeth Nos. 8 and 9 had drifted distally, resulting in excessive spacing between the anterior teeth (Figure 2).

Two treatment plans were presented to the patient. The first required or thodontics to create adequate space to replace the missing teeth Nos. 7 and 10 with implants. This option would offer a highly esthetic and stable result, and would provide ideal space distribution and maxillary anterior tooth proportions The patient was also informed of the long-term success rate for dental implants of 90%.2 This option, however, also required 1 to 1.5 years of treatment and included surgery.

The second treatment plan did not include orthodontics and relied on porcelain veneers to close the anterior spaces. The advantages of this plan were that it fulfilled the patient's desire to have no further orthodontic treatment and could be completed in a shorter period of time. This approach, however, also had some disadvantages. The poor space distribution would not be corrected, and this could result in unesthetic tooth sizes and compromise the esthetic result. Ceramic veneers do, however, have well-documented favorable success rates.3·7

The patient opted for the second treatment plan. Because this approach carried the risk of a compromised esthetic result, 8 DSD was used during the data-gathering phase to determine if the veneers could fulfill the patient's desire for a pleasing smile.

he standard DSD protocol requires the following four extraoral photographs to be taken: retracted view, smile view, lateral view, and 12 o'clock view.1 The retracted and smile views are used to establish the dentalfacial midline, proper incisal edge position, smile curve, and smile design The 12 o'clock view provides a reference for the incisal edge position in relation to the wet-dry border of the lower lip. The lateral view provides a reference for the incisor position and angulation.

The first step in this case was to superimpose the facial midline and 1nterpupillary lines on the photographs of the full-face smile (Figure 3) and then on the retracted close-up smile (Figure 4). In reviewing the treatment plan at this step, it became evident that tooth No. 8 was on the facial mid line, and tooth No. 9 was slightly longer than No. 8.

The interdental ruler was calibrated by measuring the actual size of the central incisor on the stone cast and then used to design the smile according to the facial midline. These steps revealed that the desired esthetic outcome could not be achieved with the teeth in their current

position. To create harmonious tooth widths and keep the dental mid line coincident with the facial midline, aggressive tooth preparation involving endodontics and a post / core restoration would be required. The digital treatment plan allowed the patient to visualize and understand the compromises that a restorative-only approach would induce. He could see that the midline of the fnal restoration would be positioned about 2 mm offset from the facial midline, and he agreed to the placement of the midline slightly to the left of the facial midline in order to avoid orthodontic treatment (Figure 5). 

Smile design begins with determining the upper incisal edge position, as proposed by Spear and Kois. 9-10 Tooth size, tooth proportion, and gingival contours are then designed in sequential in sequential steps once the digital ruler is calibrated (Figure 6 and Figure 7). This digital information is transferred to the master cast with the calibrated digital ruler. The width determined for this patient's central incisor was 9.5 mm, which is within the norm for central incisor dimensions."

    The next step was to determine the upper incisor position in relation to the lower lip, using the lateral smile view and 12 o'clock view (Figure 8) photographs. The upper incisor position is recommended to be at the vermillion border of the lower lip.12 In this case, it was decided that the new incisor edge would be positioned 1.5 mm facially from the preoperative position.