Porcelain Veneer Density on Varied Zirconia Thickness and Firing Cycles

Objectives: Evaluate the effect of various firing cycles and zirconia thickness on the density of two veneering porcelains.
Methods: Vita YZ zirconia blocks (Vita Zahnfabrik, Germany) were sectioned and sintered to provide slabs of 0.5, 1.0, and 5.0 mm thickness. Vita VM9 and E.max Ceram porcelain (Ivoclar, Liechtenstein) were mixed with deionized water, condensed in a mold, and sintered: (1) According to the manufacturer’s instructions; (2) Two cycles at peak temperature above the recommended value for each veneer material. A layer of carbon paint was applied to the zirconia to allow removal of the porcelain discs. Density was measured using this equation :(ρ=m⁄v) where ρ is the density, m is the mass and v is the volume.The data were analyzed statistically by the one-way ANOVA test and Tukey analysis at a significance level of 0.05 .
Results: Density of E.max Ceram and VM9 at various cycles and zirconia thickness are described in tables 1 and 2.
Conclusions: Firing cycle and zirconia thickness have a significant affect on the density of both materials.