Method: Twenty extracted third molars were sectioned 3 mm below the occlusal surface and polished with 600 grit silicon carbide papers. After that, teeth were divided into 4 groups: G1(control): distilled water, G2: 5,25% NaOCl + distilled water, G3: 5,25% NaOCl + 5% Proanthocyanidin + distilled water and G4: 5,25% NaOCl + 1 week storage in distilled water. NaOCl was apllied for 30 s, proanthocyanidin for 10 min and distilled water for 30 s. All specimens received the self-etching adhesive system (Single Bond Universal - 3M ESPE). Then, resin composites (Z550 3M ESPE) were built up to a height of approximately 5 mm on dentin surfaces of all teeth. After this, each specimen was serially sectioned to obtain sticks with cross sections of 1 mm2and the microtensile bond strengths (µTBs) of these sticks were determined. The data were statistically analyzed by One-way Anova and multiple comparisons were done by Tamhane’s T2 test.
Result: Mean µTBs values and standard deviations in MPa were: G1: 29,48±6,86, G2: 20,69±5,73, G3: 25,82±5,12, G4: 26,52±8,61. Group 2 had significantly lower bond strength than the control group (p<0.01). The application of PA and waiting 1 week before restoration significantly increased the compromised bonding to NaOCl-treated dentin (p<0.01). On the other hand, there were no significant difference between group 3 and group 4 (p>0.05).
Conclusion: Sodium hypochlorite significantly reduced the bond strengths of the adhesive. The application of PA on sodium hypochlorite treated dentine significantly improved the bond strengths.