Impact of adhesive curing mode and dentin sealing on bond strength of CAD/CAM resin composite

The aim of this study was to investigate influence of curing mode of universal adhesives and dentin sealing approach on microtensile bond strength (MTBS) of CAD/CAM composite to dentin. Occlusal surfaces of 36 human molars were ground to expose flat dentin and randomly assigned to 6 groups according to: (1) Adhesive curing mode [light-cured/LC (One coat 7 Universal, COLTENE); dual-cure/DC (One coat 7 Universal/Dual-cure Activator, COLTENE); and self-cure/SC (Palfique Universal Bond, Tokuyama); and (2) Dentin sealing approach (delayed sealing/DDS and immediate sealing/IDS). Following 1-week provisionalization, CAD/CAM composite blocks (Brilliant Crios, COLTENE), 4 mm², were cemented over conditioned dentin surfaces. After 24 h, bonded assemblies were thermo-cycled for 5000 cycles. Specimens were tested for MTBS. Failure mode was analyzed under stereomicroscope. Data were statistically analyzed using ANOVA. DDS showed significantly higher MTBS values than IDS when using LC and DC adhesives. While, IDS produced significantly higher MTBS values than DDS when using SC adhesive. Predominant failure mode was adhesive in all groups, except for SC adhesive in IDS group, mixed failure was the predominant mode. Light- and dual-cured universal adhesives improved bond strength in delayed dentin sealing approach. Self-cure universal adhesive produced better bond strength when applied to immediately sealed dentin.