Effect of resin cement and ceramic thickness on final color of laminate veneers: an in vitro study.

STATEMENT OF PROBLEM: Different shades of resin cements may adversely affect the final color of translucent restorations, especially thin laminates.

PURPOSE: The purpose of this study was to determine the effect of different types and shades of resin cement and different thicknesses and shades of IPS Empress Esthetic ceramics on the final color of laminate restorations.

MATERIAL AND METHODS: A total of 392 disks were made with A1, A3, EO, and ET shades of IPS Empress Esthetic with 0.5-mm and 1-mm thicknesses. Two dual-polymerizable and 2 light-polymerizable resin cement systems from different manufacturers (a total of 13 shades) were selected for cementation (n=7). Similarly, with porcelain ingot shades A1 and A3, opaque and translucent shades were selected from the Rely X Veneer and Maxcem Elite cement systems. For the opaque and translucent shades of the Variolink II resin cement system, the highest and lowest (+3 and -3) and medium (0) shades of Variolink Veneer cement were included in the study. Color changes in the porcelain substructures after cementation were examined with a colorimeter, and color differences (ΔE) were calculated. The results were analyzed with Wilcoxon signed-ranks and Kruskal-Wallis tests (α=.05).

RESULTS: The results indicated that the color of porcelain disks changed significantly after cementation (P<.001). Most of the color changes appeared after cementation with Variolink-3 Veneer in all porcelain shades. The smallest color change was obtained from Variolink II Tr in the EO shade of porcelain. The colors of the same shades of different resin cement systems were found at different coordinates in the CIE L*a*b* system. The final color difference (ΔE) of cemented veneers decreased when ceramic thickness increased.

CONCLUSIONS: The type and shade of resin cement and the thickness and shade of the ceramic all influenced the resulting optical color of laminate restorations.