Effect of Endodontic Irrigants on Microtensile Bond Strength to Dentin After Thermocycling and Long-Term Water Storage

Objective: The bond strength of adhesives in irrigated dentin behaves differently over time. The aim of this study was to evaluate the influence of long-term water storage and thermocycling on the microtensile bond strength of adhesive systems to dentin irrigated with endodontic solutions. Materials and Methods: Sixty human molars were used after removal of the oc- clusal portion and exposure of the dentin by grinding. The specimens were irri- gated with 2.5% NaOCl for 30 minutes and then 17% EDTA for 5 minutes and assigned to six groups according to the adhesive system (n=10): G1 and G2– Clearfil SE Bond; G3 and G4–Single Bond 2; and G5 and G6–XP Bond. The teeth were restored with composite and were subjected to water storage for different time periods. G1, G3 and G5 were stored for 24 h; G2, G4 and G6 were stored for 6 months and were subjected to thermocycling (12,000 cycles, 5°C to 55°C, 500 cycles per week for 6 months). After storage, the tooth/restoration assembly was sectioned to obtain four sticks of approximately 1 mm2, for microtensile bond strength testing. The results were analyzed by two-way ANOVA and Tukey’s test. Results: Significant differences were observed among the adhesives (p<0.01). No significant differences were observed in the microtensile bond strength between samples after 24 hours of storage without thermocycling and after 6-month storage with 12,000 cycles (p<0.05). Conclusion: The bond strengths of G5 and G6 after irrigation with 2.5% NaOCl and 17% EDTA were significantly different from those of other groups. Long- term water storage/thermocycling had no effect on bond strength to dentin.