Influence of sodium hypochlorite and EDTA on the microtensile bond strength of a self-etching adhesive system

Chemical substances used during biomechanical preparation of root canals can alter the composition of dentin surface and affect the interaction with restorative materials. Objective: The purpose of this study was to evaluate the microtensile bond strength (mu TBS) of a self-etching adhesive system to dentin irrigated with sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA). Material and Methods: Thirty human third molars were sectioned 3 mm below the occlusal surface, polished with 600- to 1200-grit silicon carbide papers, and randomly divided into 3 groups: G1 (control): no irrigating solution; G2: 1% NaOCl; and G3: 1% NaOCl followed by the application of 17% EDTA. The specimens received the self-etching adhesive system (XENO III - Dentsply), restored with microhybrid composite resin (Z250 - 3M ESPE), sectioned and trimmed to create 4 hourglass-shaped slabs of each tooth. The slabs were tested in microtensile strength in a universal testing machine (Emic DL 2000) at a crosshead speed of 0.5 mm/min until fracture. The results were analyzed statistically by ANOVA and Newman-Keuls test. Results: Mean mu TBS values and standard deviations in MPa were: G1 = 11.89 +/- 4.22; G2 = 19.41 +/- 5.32; G3 = 11.34 +/- 4.73. 1% NaOCl increased the adhesive resistance significantly (p<0.001/F = 22.5763). The application of 1% NaOCl/ 17% EDTA resulted in statistically similar mu TBS to the control group. Conclusions: None of the irrigants affected negatively the mu TBS of XENO III to dentin. The use of 1% NaOCl alone resulted in higher bond strength than the other treatments. The combination of 1% NaOCl and 17% EDTA produced similar bond strength to that of untreated dentin.