Effect of Indirect Resin Composite Color on Early Microhardness of Resin Cement
Purpose: To determine the influence of the color of resin composite restorative materials on the early microhardness of the resin cement used to lute indirect resin composite restorations.
Materials and methods: Four composite discs (2 mm thick and 8 mm in diameter) were prepared from four different colors of indirect resin composites (Adoro®) : Group 1, Transpa clear 1 (TS1) shade; Group 2, A1 shade; Group 3, A4 shade; and Group 4, D4 shade. Six specimens of Multilink® N resin cement were prepared in brass molds (0.5 mm thick and 6 mm in diameter) for each of the four experimental groups. All specimens in each group were light-cured through different composite discs for 20 seconds. Nine minutes after the curing process the resin cement surfaces were tested with a Knoop microhardness testing machine. The means of the microhardness tests of all groups were analyzed using One - Way ANOVA and the Tukey multiple comparison test. Results: The Knoop microhardness of the resin cement was significantly influenced by the color of the indirect resin composites (p<0.05). Cured resin cement underneath the TS1 shade indirect resin composite disc exhibited the highest mean microhardness, followed by the A1, D4 and A4 shades, respectively. Conclusions: The color of an indirect resin composite has an effect on the microhardness of the underlying resin cement.
Keywords: indirect resin composite, Knoop microhardness, resin cement