Bond strength and micromorphology of resin-dentin interface of etch-and-rinse dentin bonding agents after 1-year of water storage

This study compared the microtensile bond strength (BS) and the micromorphology of resin-dentin interface (MI) of a conventional adhesive to two-steps etch-and-rinse bonding agents after 1 year of water storage. Twenty-eight human third molars were used (n = 7). Teeth were divided into four groups (GCB: Gluma Comfort Bond; OPB: OptiBond FL; OCB: One Coat Bond SL; PUB: Peak Universal Bond). Specimens were tested in tension after 24 h or 1 year of water storage. Dentin BS strength data were analyzed by split-plot two-way ANOVA followed by Tukey–Kramer tests (α = 0.05). Water-storage for 1 year significantly decreased BS for OCB; however, no significant difference was noted between OCB and GCB and PUB adhesives after 1 year of water-storage. OPB showed the highest BS values at both storage times. All adhesives formed a hybrid layer with resin tags, and both interfacial structures were maintained after 1 year. However, degradation signals within interfacial structures were observed only for the adhesive with a bond strength reduction. BS test showed that only one adhesive declined after 1 year of water storage. The degradation of some structures of the interface collaborated this finding. The classic three-step etch-and-rinse (OPB) presented higher values of bond strength than GCB and OCB after 1 year, but it was not statistically different from PUB.