DENTAL TEAM: Kazunobu Yamada, RDT, Cusp Dental Supply Co., Ltd., Nagoya, Japan and Dr. Yoshihiko Mutobe, Mutobe Dental Clinic, Osaka, Japan
RESTORATIVE PROBLEM: The patient had a full cast crown on tooth #30 but wanted a more esthetic appearance.
TREATMENT PLAN: The dental team opted for a full contour zirconia restoration using the new Katana Zirconia ML, a gradational multilayered zirconia disc with four layers of color--35% enamel, 15% of the first gradation layer, 15% of the second gradation layer and 35% dentin--that offers the look of layered porcelain.
The pre-colored multilayered shades provide esthetic results without manual dipping or staining and eliminate additional material costs. KATANA Zirconia ML discs are available in three shades: A-Light, A-Dark and B-Light (KATANA HT--a high translucent mono-colored zirconia--is also available in three shades: HT10, HT12 and HT13).
FABRICATION PROCESS: Since KATANA ML is a brand new material, the technician chose to fabricate two restorations in two different shades to study the process and get the best possible results. The case was scanned using the 3Shape D700 scanner and milled on the DWX-50N by Roland DG.
After milling, Yamada evaluated the shade of the two different restorations. The A-Light crown was lighter than the prescribed shade of A3, so he adjusted the chroma using CERABIEN ZR (CZR) LF in shade A+; the stain further enhanced the lifelike appearance with minimal intervention. The A-Dark restoration matched the A3 shade tab nicely, so it was only polished using Noritake's Pearl Surface Z Diamond Paste for a mirror finish.
At the try-in, the cervical shade of both restorations matched surrounding dentition but, on the occlusal, the enamel layer of the A-Light restoration was lighter than A3 in value. The A-Dark restoration was selected for the final prosthesis due to the natural look of the pre-colored enamel gradation and translucency.