Written by Stephen D. Poss, DDS Monday, 30 September 2002 19:00
There are a myriad of aesthetic problems that the clinician will face in the dental practice. Everything from rotated teeth to midline shifts can be corrected with orthodontic treatment, or even with porcelain veneers if the clinician has the knowledge of aesthetics.
Even though orthodontic treatment is a viable option, most adults do not want to spend several years and multiple appointments to enhance their smiles. Many articles address porcelain veneers; however, I would like to share the challenge of closing a large diastema with porcelain veneers. Proper planning is important with any case, but it is critical when a large diastema is involved.
|Figure 1. Full-face photo before.||Figure 2. Smile before.|
|Figure 3. Retracted view of upper and lower arch before.|
A 34-year-old male was referred to the office because of a large diastema. The patient presented with sound periodontal conditions and no decay present. The diastema was between the two maxillary central incisors (Figures 1 through 3). To make this case even more of a challenge, the central incisors were axially inclined in the improper direction. With an 8-mm space at the incisal edges of the central incisors, I was hesitant to promise too much until the case could be fully studied.
|Figure 4. Model showing measurements on the best way to obtain ideal height-to-width ratio.|
Study models were taken and a digital image was made to give the patient a rough idea of what his smile would look like after the space was closed. Measurements were made on the study model to determine if the proper height-to-width ratio for the central incisors could be achieved (75% width to height, Figure 4). One aspect that was helpful was the patient’s large papilla between the two central incisors.
Three factors in this case had to be determined. First, could the ideal height-to-width ratio be obtained? If the ideal width was to be 75% of the height, what would I have to do to the two central incisors? To close the space, the central incisors had to be approximately 9 mm wide and 12 mm in length1 (75%). Second, could I increase either the incisal length and/or gingival height? It was determined that an additional 1.5 mm in length was needed. This would be accomplished by adding 0.5 mm in incisal length, with an additional 1 mm in length achieved through gingival contouring. Third, how much tooth structure would I have to remove on the distal aspect of the centrals to maintain a 9-mm wide central incisor? It was measured that roughly one third of the distal portion of the central incisors would have to be removed to provide the 75% width-to-height ratio that would ensure the central incisors would not appear too wide.2
In addition, one factor that is extremely important and that many clinicians overlook is the fact that a large diastema or even a midline shift usually requires involving at least eight, or even 10 teeth. In this case, distributing a space this large would require at least eight teeth. To try to accomplish this with four or six teeth would create a disastrous result. It is imperative that the clinician fully explain to the patient the reasons to prepare more teeth, and not let the patient dictate fewer teeth than necessary to achieve the ideal result.
|Figure 5. Wax-up of prepared model.||Figure 6. Polyvinyl preparation matrix from the wax-up.|
Once this information was obtained, the wax-up was done accordingly. The patient assisted in selecting the shape of the teeth to be in the wax-up (Figure 5). I recommend making a preparation guide from the wax-up. This will greatly assist the clinician while the teeth are prepared. This can be made with any polyvinyl putty (Figure 6). The preparation guide will assure the clinician that adequate tooth structure is removed.
The clinician will have to visualize the process of trying to move the line angles of all eight teeth mesially. This means that the clinician would be removing tooth structure more from the distal of each tooth to be able to close the large space between the central incisors proportionately.
|Figure 7. Preparation matrix in place after the central incisors are prepared to assure adequate reduction.|
The central incisors were prepared first. There was some minor gingival contouring not only to increase length, but to enhance the shape of the large incisive papilla between the two central incisors. As the teeth were prepared, the preparation guide was continually placed to ensure adequate tooth reduction (Figure 7). When all eight teeth were prepared, a hydrophilic polyvinyl impression material (Take One, Kerr) was used to obtain the proper impression. The teeth were then cleaned with chlorhexidine for 15 seconds and air dried. Then a coat of Super Seal (Phoenix Dental) was placed on the teeth to minimize any postoperative sensitivity.
|Figure 8. Provisionals in place. Aesthetics verified.|
From the wax-up a polyvinyl mold was made to help fabricate the provisionals more quickly. From this polyvinyl mold a methacrylic-ester composite material such as Integrity (DENTSPLY Caulk) shade B-1 was injected in the mold and placed in the mouth for 2 minutes. The clinician then carefully removed the mold, making every attempt to leave the Integrity in the mouth. The material was then trimmed and polished (Figure 8). This is very important because the patient now has a preview of the ideal wax-up in his mouth. Both the clinician and the patient can determine if this is what they want the final veneers to look like. The phonetics and aesthetics can be inspected, and changes can be made if needed before the final restorations are made.
|Figures 9 and 10. The two central incisors demonstrating that changing the mesial line angles make the two teeth appear more narrow.|
|Figure 11. Veneers on prepared model.||Figure 12. Veneers on the prepared model showing how the space was closed. Note the difference in appearance between the facial and lingual.|
One other aspect that can be an advantage for the clinician and the patient is the way the two central incisor veneers are made by the laboratory. The line angles on the mesial aspects of the centrals can be closed from the lingual, and slightly stained to give the appearance of a narrower tooth (Figures 9 through 12).
When the patient returned, anesthesia was administered and the provisionals were removed. The veneers were tried in for verification of fit as well as aesthetics. A rubber dam was placed and the cementation process began. The try-in gel was thoroughly rinsed out and the teeth were air dried. Phosphoric acid was placed inside each veneer for at least 30 seconds to acidify the porcelain, and then rinsed. The veneers were then air dried and Silane Primer (Kerr) was placed and brushed thin, and allowed to air dry.
After the rubber dam was placed, the teeth were cleaned with chlorhexidine for 15 seconds and rinsed. The teeth were then etched with 35% phosphoric acid. It is best to not etch more than two or three teeth at a time due to the fact that if the clinician tried to etch all the teeth at one time, the dentin would be over etched, which could lead to sensitivity.3 A wetting agent such as Tubulicid Red (Global Dental Products) was used to dampen the teeth. A single coat of Optibond Solo Plus (Kerr) was placed on the teeth.4 After the excess solvent had evaporated off, the teeth were cured with the Optilux 501 light (Kerr/Demetron) for 10 seconds per tooth. After placing the Nexus II base (Kerr) on veneers Nos. 8 and 9, the two veneers were placed on the teeth. The excess luting cement was cleaned off and the two veneers were tacked into place at the gingival crest. Be sure the light is directed apically so that there is no premature curing interproximally. The same procedure was done with teeth Nos. 10 through 12 and Nos. 5 through 7. After all the veneers were tacked into place, the teeth were carefully flossed and cleaned. All the restorations were then completely cured and cleaned.
|Figure 13. Smile photo after cementation.||Figure 14. Final retracted view (1:2 ratio).|
|Figure 15. Full face of completed case.|
Even difficult aesthetic cases such as the case described can be successfully completed. This requires careful planning and knowledge of preparation and smile design. The diagnostic wax-up and a preparation matrix are predictable ways to consistently obtain the most favorable result for the clinician and the patient. Gathering information and expectations from the patient is important. Taking this information and transferring it to the laboratory is critical. When all of this is combined, it can be a win-win for both the clinician and the patient (Figures 13 through 15).
The author would like to thank Sunrise Dental laboratory and Mike Milne in particular for his excellent work in this case.
1. Dickerson W. Cooperative treatment planning in creating smiles. Signature Magazine. 1996;Summer:2-8.
2. Miller M. Porcelain veneers. Reality. 2000;14:339-400.
3. Jackson R. Postoperative sensitivity to cold. Dental Visions. 1999;8:7.
4. Kanka J. Resin bonding to wet substrate-bonding to dentin. Quintessence Int. 1992;23:39-41.
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