Effect of glazing on translucency, color, and surface roughness of monolithic zirconia materials

Objectives To assess the effect of material, thickness and glazing upon the color, translucency, and roughness of monolithic zirconia. Materials and methods Sixty discs (0.8, 1.5, and 2 mm thickness) were fabricated from A1 translucent zirconia (IPS e.max ZirCAD/MT, Katana/HT, Vita YZ/HT, Cercon/HT) and glazed. Roughness (Ra) was assessed with a profilometer and color coordinates were measured with a spectrophotometer on a black, white, and tooth-shaded background before and after glazing. Relative translucency parameter (RTP), color differences (CIEDE2000) and differences in translucencies between materials, before and after glazing were calculated. RTP, Ra, color differences were statistically analyzed using ANOVA. Any significant interaction between factors was further analyzed using Tukey's HSD. Results RTP values were significantly different between materials (P < .001) and thicknesses (P < .001), with the interaction effect between material type and thickness, also significant (P < .001). However, glazing did not have a significant effect on RTP values (P = .782). Color differences resulted after glazing were significantly different between materials (P < .001), and thicknesses (P < .001) with the interaction effect also significant (P < .001). Glazing influenced roughness, Ra decreasing for all materials (P < .001). Conclusions As a result of glazing, only color changes were statistically significant. Translucency varied among brands of precolored monolithic zirconia; the differences increased for greater thicknesses. Clinical significance Glazing is an important step in the technological process of ceramic restorations; however, it can influence the final optical appearance of the restoration as color changes could be expected after the application of the glaze.