Post-cementation colorimetric evaluation of the interaction between the thickness of ceramic veneers and the shade of resin cement.

PURPOSE: To evaluate the color parameters (CIELab*) after the cementation of ceramic disks of different thicknesses onto a resin substrate using four different shades of resin cements, and determine the color difference (ΔE) between the adhesively cemented disks and a 10 mm-thick A1 shade ceramic control (target color).

METHODS: Ceramic disks, simulating laminate veneers, with thicknesses of 0.5, 0.7 and 1.0 mm (shade A1, IPS Classic) were fabricated (n = 40) and cemented with a dual-cured resin cement (Variolink II, shades A1, bleach, opaque and transparent) onto 120 2 mm-thick resin composite substrates (shade A3.5, Adoro). Each ceramic disk was photocured for 80 seconds. The determination of the CIELab* parameters of each ceramic-cement-substrate set was performed with a spectrophotometer. A 10 mm-thick A1 ceramic disk was used as a control. The results for the color difference (ΔE) obtained from L*, a* and b* parameters were analyzed using ANOVA and Tukey's test (α = 0.05).

RESULTS: The ΔE values ranged from 2.46 (1.0 mm, opaque cement) to 12.11 (0.5 mm, A1 cement). The opaque cement showed the lower ΔE values, followed by the bleach, transparent and A1 cements. With respect to the thickness of the ceramic, color differences between the target color and the group with 1.0 mm ceramic disks were smaller for all cement shades tested. Only the combination of 1.0 mm ceramic disks cemented with the opaque cement was able to mask the background color (ΔE < 3.7). The color differences between the control and the specimens cemented with opaque resin cement were smaller in comparison with the bleach, transparent and A1 cements.