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 (∆E_ab and ∆E₀₀), translucency parameters (TP_ab 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 ∆E_ab, ∆E₀₀, TP_ab, 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<0.001). However, the interaction between the thickness and translucency of the veneer ceramic was significant only for OP (p<0.05). For each thickness, the TP₇₆ and TP₀₀ values were significantly higher for the HT groups than for the LT groups. The HT groups demonstrated higher OP values than the LT groups, and there were strong correlations between ∆E₇₆ and ∆E₀₀ and TP₇₆ and TP₀₀. Furthermore, there were significant correlations between the TP₇₆ and TP₀₀ values and the OP parameter.

Conclusion: The optical properties of the bilayered structures were significantly affected by the thickness and translucency of the veneer ceramics. Therefore, the thickness and translucency of the veneer ceramic must be taken into account to achieve a restoration with the desired shade and appearance.

How to cite this article:

Yılmaz Savaş T, Savaş A. Effect of the thickness and translucency of the lithium disilicate veneer ceramic on the optical properties of bilayered zirconia. Int Dent Res 2022;12(1):1-8. https://doi.org/10.5577/intdentres.2022.vol12.no1.1

Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.