Effects of CAD/CAM restorative materials and thickness on the depth of cure of various light-cured resin composite materials

The study assessed the depth of cure (DOC) of different resin composites light-cured through different types of CAD/CAM materials of variable thickness. Three CAD/CAM materials (multilayer zirconia, lithium disilicate glass ceramic, composite) of three thicknesses (2-, 3-, and 4-mm) were prepared and their translucency parameter (TP) were measured. A light-curable and a dual-curable resin cement (Variolink Esthetic LC and DC) and a bulk-fill resin composite with a higher Ivocerin concentration (Tetric PowerFill) were used to mimic luting agents. DOC was assessed via Vickers microhardness testing. Increased thickness of CAD/CAM specimen was associated with decreased DOC. The chemical composition of the resin composites affected their curing performance depending on the light curing mode. Tetric PowerFill presented the greater DOC among the other resin composites. Receiver operating characteristic models of curing status appeared to provide better insight in predicting the DOC of luting agent according to TP than linear regression.