Three-month water degradation of resin-dentin interfaces subjected to direct and: Indirect exposure

Abstract

Objectives: The aim of this study was to assess the effects direct or indirect water exposure on the 3 months hydrolytic degradation of three dentin bonding agents. Materials and Methods: The samples were divided in three groups: Clearfil SE Bond, Clearfil S3, Adper Singlebond 2; and the samples were restored with Filtek Z350. Subsequent to the restorative procedures, the specimens of each group were divided into three subgroups (immersed in water deionised): Control (24h-37°C), Direct Water exposure DWE for 3 months (37°), Indirect water exposure (IWE-3m) with enamel margins for 3 months (37°C). After the storage the samples were sectioned into sticks and μTBS testing (EZ test) and Scanning Electronic Microscopy assessed the failure mode. The μTBS data were statistically analysed using two-way ANOVA and Tukey's test at α=0.05%. The samples were processed for nanoleakage evaluation immersed in 50 wt% ammoniacal silver nitrate (24 h), rinsed and immersed in a photo-developing solution for 8 h. Results: After 3 months CSE was the least affected by water degradation regardless the aging strategy. IWE afforded very little variation on μTBS after 3 m. Intense nanoleakage was observed with DWE groups with increases incidence of mixed failures instead Conclusions: Bonded dentin margins are more prone to hydrolytic degradation than resin-enamel interfaces. The increased nanoleakage and the drop of bond strength showed this