Effect of the thickness and translucency of the lithium disilicate veneer ceramic on the optical properties of bilayered zirconia

Abstract

Aim: This study evaluates the effect of lithium disilicate veneer ceramics on the color difference (∆Eab and ∆E00), translucency parameters (TPab and TP00), and opalescence parameter (OP) of different thicknesses and translucencies. Methodology: Ten 0.5 mm thick zirconia core specimens were prepared, and sixty veneer ceramics in A2 shade were prepared from high translucence (HT) and low-translucence (LT) lithium disilicate glass ceramics (IPS e.max CAD) in three different thicknesses (0.5 mm, 0.7 mm, and 1 mm). The specimens were evaluated as bilayered structures, and group names were assigned based on the thickness of the core–veneer combinations (n = 10): E1 = (0.5 + 0.5), E2 = (0.5 + 0.7), and E3 = (0.5 + 1). A spectrophotometer (Vita EasyShade V) was used to measure the Commission Internationale de l'Elcairage (CIE) color coordinates L*, a*, and b*, and the ∆Eab, ∆E00, TPab, TP00, and OP values were calculated. A two way analysis of variance (ANOVA) and Tukey HSD tests (α = 0.05) and Pearson correlation tests (α = 0.01) were applied for statistical analysis. Results: The optical properties (∆E76, ∆E00, TP76, TP00, and OP) of the bilayered zirconia-based ceramics were significantly affected by the thickness and translucency of the lithium disilicate veneer ceramics (p