Effect of endodontic irrigants on microtensile bond strength of a self-etching adhesive system

Aim: The aim of this in vitro study was to evaluate the effect of two different irrigation solutions, alone or in combination, with different application times on the dentin bond strength of a self-etching adhesive. Materials and Methods: Twenty-eight extracted non-carious human third molars were randomly distributed into seven groups according to the irrigant. The crowns of the molars were sectioned vertically through bucco-lingual direction. Solutions of 5% sodium-hypochlorite (NaOCl), 3% hydrogen-peroxide (H 2 O 2 ), and a combination of NaOCl and H 2 O 2 were applied to the dentin surface for various lengths of time. The adhesive system (Clearfil SE Bond; Kuraray, Japan) was applied according to the manufacturers′ directions and then the dentin surfaces were built up with a hybrid composite resin (Clearfil AP-X Kuraray, Japan). Specimens were sectioned into 15 sticks; each of them had a 0.65 mm 2 bonding area. Microtensile bond strength was determined (MPa), and the results were statistically analyzed using one-way ANOVA and Tukey′s HSD test. Results: Irrigation with NaOCl alone showed similar micro-tensile bond strength values with the control group (P > 0.05). In comparison to control group, irrigation with H 2 O 2 alone for 5 min and 30 min and the irrigation with H 2 O 2 /NaOCl combination each for 15 min decreased the microtensile bond strength. Conclusion: The use of H 2 O 2 significantly reduced the bond strengths of the self-etching adhesive when applied alone or in combination with NaOCl for a long time.