Masking ability of CAD/CAM monolithic ceramics: effect of ceramic type and thickness, and try-in paste shade

Objective: This in vitro study evaluated the color differences when discolored tooth substrates were restored with CAD/CAM monolithic ceramics depending on ceramic type and thickness, and the try-in paste shade. Method and materials: Six ceramic types were tested: high-translucent lithium disilicate (LD-HT); feldspathic ceramic (FC); and BL1 low-translucent lithium disilicate, stained to A1 shade (LD-BL1-LT). The ceramics were tested in disk-shaped specimens with 0.5-, 1.0-, and 1.5-mm thickness (n = 10; N = 180; shade A1). The try-in pastes were tested to simulate luting materials and corresponded to colors A1 and Opaque White. Six substrates were used: A1 (reference), B2, B3, A3, C2, and C3. Color differences ( increment E00) and translucency parameter (TP00) were assessed with the CIEDE2000 formula. The results were compared with acceptability (1.77) and perceptibility (0.81) thresholds. Results: Ceramic type, thick- ness, and the try-in paste shade influenced the color differ- ences. LD-LT and LC-LT ceramics and Opaque White try-in paste provided, in general, lower increment E00 values. The most adequate ceramic thickness varied according to the substrate discolor- ation. With 1.0 mm of ceramic thickness, it was possible to ob- tain increment E00 lower than the perceptibility threshold for substrates C2 and A3, and increment E00 lower than the acceptability threshold for C3 and B3. increment E00 lower than the acceptability threshold were obtained with 0.5 mm of ceramic thickness for B2, A3, and C2. Conclusion: The use of low-translucent glass-ceramics and Opaque White try-in paste are useful to reduce color differ- ences. The most adequate ceramic thickness depends on the substrate discoloration. (Quintessence Int 2023;54: 442-450; doi:10.3290/j.qi.b3964073)