Masking ability of CAD-CAM resin-matrix ceramics with different translucencies and thicknesses combined with four cement shades against varying background colors when facing veneer restorations.

Background: To evaluate the comprehensive effect of translucency, thickness, cement shades, and background color on the masking ability of resin-matrix ceramic veneer restorations. Methods: Resin-matrix ceramic specimens with 2 translucencies (LT, HT) and 3 thicknesses (0.5, 1.0, and 1.5 mm) were made of Upcera Hyramic (A2 shade). Cement specimens were made of Variolink N in 4 shades (yellow, white, transparent, and bleach XL). Five background specimens were made of IPS Natural Die Material in 5 shades (ND1, ND2, ND3, ND4, and ND5). Color coordinates of 120 subgroups (n = 5) of combined specimens composed of different ceramic, cement, and background specimens were obtained using a spectroradiometer. Color difference (ΔE₀₀) compared with a 4-mm thick specimen of LT and HT ceramics was calculated and four-way ANOVA was used for statistical analysis (α = 0.05). Results: Translucency, thickness, cement shade, background color, and their interaction had significant effects on ΔE₀₀ (p < 0.001). ΔE₀₀ values of HT groups were always higher than that of LT groups and were greater than 1.8 against all background colors. ΔE₀₀ values of LT groups could be achieved to be less than 1.8 with appropriate thickness and cement shade. ΔE₀₀ value decreased with increasing ceramic thickness. The effect of cement shade on ΔE₀₀ had no obvious regularity, but ΔE₀₀ values of bleach XL cement shade group were always lower than other cement shade groups under ND3 and ND5 background color. Conclusions: The masking ability of CAD-CAM resin-matrix ceramics can be simultaneously affected by translucency, thickness, cement shade, and background color. Resin-matrix ceramics with low translucency has a better masking ability than that with high translucency. The masking ability of CAD-CAM resin-matrix ceramics increase with increasing thickness. Cement shade has less impact on the final color of resin-matrix ceramic restorations. [ABSTRACT FROM AUTHOR]