Background: The ability to simulate the natural appearance of teeth in dental restorations is one of the most important factors that make treatment successful.
Objectives: The present study evaluated the effects of the substructure thickness, the resin cement color and the finishing procedure on the color and translucency of bilayer zirconia-based ceramic restorations.
Material and methods: Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) CAD/CAM blocks (dimensions of 6.0 × 5.5 × 0.4 mm, 6.0 × 5.5 × 0.8 mm, and 6.0 × 5.5 × 1.6 mm) veneered with the fluorapatite-containing ceramics were used. For polishing, the surfaces of half of the test specimens were adjusted with a blue-belted diamond porcelain bur and a white polishing rubber, and the other half were glazed. The test specimens were then cemented with 2 different colors of the same self-adhesive resin cement to the resin composite. A spectrophotometer was used to measure the L*, a*, and b* color attributes of the specimens. Additionally, the ΔE values were calculated to determine color differences between each group and the control. Data was analyzed using the multifactorial repeated-measures analysis of variance (ANOVA) and subgroup analysis (p < 0.005).
Results: It was found that the highest substructure thickness resulted in the lowest color change (ΔE = 1.24) (p < 0.005). However, a substructure thickness of 0.8 mm showed less color change (ΔE = 1.39) than the 0.4-mm thickness (ΔE = 3.85) in the translucent resin cement/polished subgroup, as measured against a gray background (p = 0.001).
Conclusions: The most significant factor in masking the abutment color in zirconia-based restorations is the thickness of the substructure. The surface finishing procedure or the resin cement color do not have a primary effect on the color change or translucency.
Keywords: color; resin cements; substructure thickness; surface finishing; zirconia.