In-vitro comparative study of the use of 2 % chlorhexidine on microtensile bond strength of different dentin adhesives: A 6 months evaluation

The aim of this study was to evaluate the effect of chlorhexidine (CHX) dentin treatment on microtensile bond strength (μTBS) of adhesive systems in different storage times. Occlusal enamel was removed from ninety third-molars and flat surfaces of middle dentin were exposed. Teeth were randomly divided in 6 groups according to adhesive system (etch-and-rinse: Adper Scotchbond 1XT- ASB; self-etch: Adper Prompt L-Pop – APP; and universal: Single Bond Universal- SBU) and chlorhexidine (CHX) dentin treatment (2 % CHX application for 20 s prior Primer). After resin composite build up, teeth were sectioned to obtain beam specimens and divided in 3 subgroups (n=5): 72h, 3 and 6 months storage times. After the storage times, teeth were tested in tension until failure (0.5 mm/min). SEM was performed to observe hybrid layer of adhesive systems. Data were analyzed using one-way ANOVA and Tukey tests. At 72 h, all equivalent groups (same adhesive system, different dentin treatments) maintained their μTBS when compared CHXtreatment. At 3 and 6 months, non-treated CHX groups showed less μTBS than CHX-treated ones. Six months storage time did not significantly decrease μTBS, except for G2-ASB. The effect of CHX on dentin μTBS depends on storage times and adhesive systems. While immediate μTBS was not affected by CHX treatment, CHX improved dentin μTBS after 3 and 6 months.