Abstract
Purpose: Monolithic zirconia crowns, which are made entirely with zirconia, are becoming commonly used for an occlusal surface owing to improvements in zirconia translucency. Because they are translucent, however, there is concern regarding their influence on esthetics when the abutment is metal, but the degree of influence is not apparent. The purpose of this study was to investigate the influence on the color of the transparency of the cement adhered to the metal abutment and the thickness of the zirconia.
Methods: Dsc specimens 10 mm in diameter and 0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm in thickness were cut from pre-sintered, highly translucent zirconia blocks. After the final sintering, the zirconia plates were intervened with cement onto stainless steel to simulate a metal abutment. Two kinds of cement, translucent and opaque, were used in this study. Zirconia plates intervened with translucent cement on the resin abutment were used as the control group. L*, a*, and b* values were determined with a spectrophotometer. The color differences (⊿E) were derived from the differences between the control group and the metal abutment group.
Results: ⊿E values of opaque cement were less than 1.6 only for thicknesses of 2.0 mm and 1.5 mm. A significant difference was seen between the translucent cement and the opaque cement for each thickness except 1.5 mm.
Conclusions: A color difference with the resin abutment is seen when opaque cement is used for highly translucent zirconia of thickness less than 1.5 mm for metal abutments.
