Effect of monolithic CAD-CAM ceramic thickness on resin cement polymerization: An in-vitro study

To evaluate the effect of different thicknesses of CAD-CAM ceramic sections on the polymerization of two different resin cements.Three CAD-CAM all-ceramic restorative materials were sectioned with four different thicknesses. A total of 240 resin cement specimens were prepared from light cured and dual cure resin cements and absorption peaks were recorded. 10 samples of each resin cement were examined before and after polymerization and served as the control group. Data were analyzed using one-way ANOVA, independent t- and Tukey HSD tests (P0.05).Control group showed the highest DOC values while samples cured under Vita Enamic section with a thickness of 2 mm presented the lowest values (P0.05). Polymerization performed under sections of 0.5 and 1 mm thicknesses provided statistically higher values. Dual cured resin cement samples showed higher DOC values compared to light cured resin cement samples. IPS Empress CAD sections with 0.5 and 1 mm thickness exhibited statistically higher values than other ceramics of the same thickness for light cured resin cement samples. A significant difference was observed between IPS Empress CAD and Vita Enamic while comparing ceramic sections of the same thickness (P0.05). There was no difference for sections of 1.5 and 2 mm (P0.05).Thickness of the restorative material for an indirect restoration is a key element to determine the type of resin cement.