Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2018-05-16, 11:45:19 | version 1.38.0
SMILE MAKEOVER OF DARK SUBSTRATE WITH VENEERS AND AN ANTERIOR CROWN — using the biologically oriented preparation technique in a digital workflow Dr. Ilan Hecht, Israel works on the cast in order to define the margin and create the crown’s emer- gence profile. Case presentation The patient was a 32-year-old man wish- ing to improve his smile (Fig. 1). He par- ticularly did not like the color and shape of his teeth, especially the crown on the maxillary left central incisor and its dark- er appearance at the gingiva. His maxil- lary left central incisor had an old por- celain-fused-to-metal (PFM) crown (placed more than ten years before) with gingival recession at the cervical area and the metal margins of the crown showing (Fig. 2). After a clinical and radiographic exam- ination, we proceeded to a treatment plan according to the digital smile design (DSD) concept2 in order to create a pre- dictable additive mock-up that would show us the end result prior to com- mencement of treatment (Figs. 3 & 4). Owing to the visual communication (DSD of the case and mock-up), we gained the patient’s acceptance of the treatment plan, which would entail removal of the old PFM crown and preparation of the adjacent teeth for laminate porcelain ve- neers (Fig. 5). The maxillary anterior teeth had vertical and horizontal cracks. This, combined with the initial dark substrate and the patient’s desire for a significantly whiter shade for final restoration, led to a less conservative preparation. Under the PFM, a golden post in good shape was encountered. It was decided that, owing to the differences in substrate color, we would first proceed with the laminate por- celain veneers and, after cementation, move forward with a new monolithic zir- conia crown for tooth #11. Impression taking was done digitally using TRIOS 3 (3Shape) for the laboratory to manufacture the desired restorations. The veneers were manufactured with a CAD/ CAM core of lithium disilicate, allowing for a cutback and layered porcelain. After the veneers had been cemented, I pro- ceeded to refine the old preparation ac- cording to the BOPT, then added com- posite (IPS Empress Direct, Ivoclar Vivadent; A2 dentin shade) to the sub- strate surface in order to achieve a homo- geneous substrate (Figs. 6 & 7). A new digital impression was taken for tooth #11. The laboratory used Zirkonzahn for the CAD restorations and modified the mar- gins of the crown for these to be located in the sulcus for the tissue to have a new emergence profile (Fig. 8). Owing to ac- curate visual communication and shade matching, the laboratory technician was able to manufacture a monolithic zirconia crown for tooth #11 that would mask the dark substrate and match the adjacent restorations (Figs. 9–11). Conclusion The BOPT concept can be of great help for masking dark substrates, in the case of a thin gingival biotype or for a better emer- gence profile. Owing to the digital impres- sion (which is less technique-sensitive than classical impression taking for the BOPT), good visual communication and the ad- vances of CAD/CAM, the laboratory tech- nician can now easily create better emer- gence profiles and thinner and smooth margins that will ensure the longevity of the restorations and better health for the surrounding periodontium. Editorial note: A list of references can be obtained from the publisher. — Dr. Ilan Hecht Introduction This case report demonstrates the possi- bility of combining different materials and approaches in order to achieve a satisfac- tory result when it comes to treating teeth with a dark substrate. The focus is on the biologically oriented preparation technique (BOPT) applied in a digital workflow to achieve maximum predict- ability in the esthetic area. The BOPT entails a vertical preparation or feather edge to achieve satisfactory results in the cervical area, especially in the case of dark substrate or a thin gin- gival biotype that is susceptible to reces- sions in the marginal area. Preparations without finish lines are more conservative and the crown margin is located at the root area.1 For vertical preparations, the laboratory technician positions the mar- gin based on the gingival tissue informa- tion. The problem is that, for digital scan- ners and CAD/CAM restorations, a different protocol is required than for the classical BOPT, where the technician 72 — issue 2018 Meet the Clinical Masters Article