Conservative Midline Correction
Minimal tooth reduction to correct a midline cant
Courtney Lavigne, DMD, FAGD
Today, cosmetic dentistry requires conservative approaches and thinking beyond traditional porcelain veneer preparations to achieve patients’ esthetic goals in a responsible manner.
A midline cant is a prominent esthetic concern, even to the layperson. While a midline shift is not recognizable to dental professionals or the layperson until it is quite significant, even the slightest midline cant is easily detectable.
A midline cant correction often requires restorations on multiple teeth. When one or both of the teeth affected by the cant are in otherwise healthy condition without additional esthetic concerns, more conservative approaches than traditional porcelain veneers should be considered. Esthetic composite bonding is one option. When porcelain is the material of choice, a non-prep or minimal-prep “chip” veneer is a valid option and should be considered.
A 34-year-old woman presented to our office in good dental health, having seen a dentist for routine cleanings and examinations every 6 months throughout her life. She came to our office with a chief complaint of poor esthetics of teeth Nos. 8 and 9. The patient didn’t like the poor esthetics of the composite, the canted midline, or the tooth size discrepancy between the two teeth (Figure 1). Her goals were to have symmetrical, natural-looking front teeth that matched the rest of her smile. She wanted to fix the midline, the shade, and the shape. The patient was frustrated with how many times she had replaced the bonding on tooth No. 8 without improved results, and desired porcelain veneers based on her own research.
Diagnosis and Treatment Plan
The patient desired a porcelain veneer to fix the unesthetic bonding on tooth No. 8. We discussed possible treatment options, including redoing the composite bonding on tooth No. 8, as well as composite bonding on tooth No. 9 to address the cant. We also discussed porcelain options; because of the patient’s history with composite replacement on tooth No. 8, she wanted to move forward with porcelain veneers. While porcelain could achieve the cosmetic result she was looking for, tooth No. 9 was a non-restored tooth in very good condition. A veneer preparation seemed aggressive, and because the patient was comfortable with porcelain moving forward, a chip non-prep veneer on tooth No. 9 and a porcelain veneer on tooth No. 8 were proposed. After showing the patient several before and after photo examples of similar treatment, we were both comfortable moving forward with a porcelain veneer to replace the composite bonding on tooth No. 8, and a porcelain non-prep chip veneer to correct the canted midline (Figure 2).
Treatment Description Prior to preparation
The patient’s initial appointment involved intra- and extraoral photographs and diagnostic alginate impressions. From these impressions, we made two sets of models. One set was used for a diagnostic wax-up to establish the proposed shape and size of the teeth for the final restorations. The second set of models was used to create a preparation guide. From the diagnostic wax-up, three putty matrices were established. One matrix was used for temporization, one was used for an incisal edge guide, and one was used as a reduction guide. Prior to the patient’s preparation appointment, she completed 3 weeks of at-home whitening with KöR Whitening (www.korwhitening.com) custom trays. The patient was satisfied with the results prior to in-office whitening and opted to move forward with treatment. After 3 weeks of shade stabilization, we had the patient return for shade analysis. The shade was taken using shade guides and photography.
The preparation appointment began with administration of one cartridge of 2% Xylocaine (DENTSPLY Pharmaceutical, www.dentsply.com) 1:100,000 epinephrine. An OptraGate (Ivoclar Vivadent, www.ivoclarvivadent.com) was used during preparation with a plastic tongue retractor. Tooth No. 8 was prepared with Brasseler (https://brasselerusa.com) medium-coarseness diamonds, followed by fine diamonds. The preparation was finished with greenies. Tooth No. 9 was not prepared, but a series of medium to fine coarseness interproximal finishing strips were used to reduce any surface abnormalities and smooth the incisal edge while eliminating the sharp corner. Tooth No. 9 was finished with white stones. The matrices were used to confirm the incisal edge position of the preparation and that sufficient reduction had been achieved.