OBJECTIVES: The aims of this study are to determine the shade correlation between try-in pastes with their corresponding resin cements. Also, to investigate the effect of resin cement shades and various ceramic thicknesses, shades, and translucency in the final color outcome over tooth-shaded backgrounds. MATERIALS AND METHOD: Lithium Disilicate CAD/CAM blocks (IPS e.max CAD) were prepared, in high and low translucency, in two different shades (A1 and A3), and in 2 different thicknesses (0.53 ± 0.02 mm and 0.83 ± 0.02 mm). Four different tooth-shaded backgrounds (ND2, ND5, ND8, and ND9) were prepared from acrylic resin in a standard thickness of 6.610 mm to achieve complete opacity. RelyX veneer cement and its corresponding try-in paste in three different shades, Transparent (TR), White Opaque (WO), and Bleached Opaque (BO), in a thickness of (80 ± 5 μm) were used. For each combination, the color was measured with a spectrophotometer to calculate the color difference (ΔΕ value) in reference to ceramic veneer, and the differences of ΔΕ among the specimens were compared statistically using JMP Pro 13. Analysis was performed for 3 aims, (1) to compare the ability of ceramic to mask the aspect of the abutment in relation to its thickness (0.5 and 0.8) mm, transparency (HT and LT) and shade (A1 and A3), (2) effect of a change in cement color (TR, WO, and BO) on the final color of the ceramic; and (3) to determine the correlation between try-in pastes with their corresponding resin cements. RESULT: A significant difference was found with a p-value of <.0001 for the following factors: Stump Shade, ceramic thickness, cured cement, ceramic shade, cement type and for the interactions of cured cement with cement type, and stump shade with ceramic transparency. Also, a significant difference was found with ceramic transparency with a p-value 0.0476. While cured cement and its corresponding try-in paste showed a significant difference in color masking (p <.0001) shade White Opaque cement and shade White Opaque try-in paste exhibited insignificant color change outcome with a p-value of 0.8051. CONCLUSION: RelyX veneer cements shades (Translucent and Bleached Opaque) have lower masking ability than White Opaque cement. RelyX veneer Try in paste is much less effective in masking than its corresponding resin cement. The only correlation between RelyX veneer cements with their corresponding try-in pastes among the shades tested (White Opaque, Translucent and Bleached Opaque) is with shade White Opaque. This study demonstrated that underlying tooth abutment color, cement color, and ceramic thickness, shade and translucency all influence the resulting optical color of CAD/CAM glass-ceramic lithium disilicate-reinforced restorations. / 2020-10-24T00:00:00Z