Microhardness of light- and dual-cured resin cements after light curing through various translucencies of translucent monolithic zirconia

Abstract

Purpose: This study aims to investigate the microhardness of light- and dual-cured resin cements under various translucencies of monolithic zirconia specimen; translucent (T), super translucent (ST), high translucent (HT), and extra translucent (XT). Materials and Methods: Four different translucencies of zirconia specimen were prepared in the square shape, size 10×10×1 mm. The light-cured resin cement (Variolink® N LC) and the dual-cured (RelyX™ U200) resin cement were mixed and loaded in a 2-mm height and 5-mm diameter of space in a customized mold and cured through the zirconia specimens and 1-mm thick glass slide in a control group, using the light curing unit for 20 seconds (n=5). All samples were stored dry in a dark room at 37°C for 24 h. The microhardness test was performed on the top of the cement layer with a Vickers hardness tester with a 300-g load. The results of mean and standard deviation of Vickers hardness number (VHN) were recorded and statistically analyzed with two-way ANOVA and post hoc analysis (α=0.05). Results: The mean VHN values of both cements were significantly lower when cured under T group compared to the XT, HT, and ST groups. RelyX™ U200 resin cement showed higher VHN value than Variolink® N LC in all groups. Conclusion: The VHN of both light- and dual-cured resin cement was influenced by different translucencies of zirconia. For both light- and dual-cured resin cements under the lowest translucency of T zirconia showed significantly lower than the other groups.