Effect of long-term water aging on microtensile bond strength of self-etch adhesives to dentin.

PURPOSE To evaluate the effect of water storage on the microtensile dentin bond strength of one total-etch and four self-etching adhesives to dentin. METHODS The adhesive materials were: one total-etch adhesive (Admira Bond) and four self-etch adhesives (Clearfil S tri Bond, Hybrid Bond, Futurabond NR, Adhe SE). Freshly extracted human third molar teeth were used. For each tooth, dentin was exposed on the occlusal surface by cutting with an Isomet saw and the remaining part was mounted in a plastic ring using dental stone. After adhesive application, a composite resin (Grandio) was placed in 5-6 mm height to form a crown segment. For each tested adhesive, two test procedures (n=6 teeth) were carried out. Procedure A: the teeth were stored in water for 24 hours, and then sectioned longitudinally, buccolingually and mesiodistally to get rectangular beams of 1 +/- 0.1 mm thickness on which a micro-tensile test was carried out. Procedure B: The specimens were stored in water at 37 degrees C for 3 years before sectioning and microtensile testing. During microtensile testing the beams were placed in a universal testing machine and load was applied at cross-head speed of 0.5 mm/minute. RESULTS For the 24-hour water storage groups, there was no significant difference in the bond strength between the different adhesives. After 3 years of water storage, the bond strength of all self-etch adhesives was significantly reduced compared to the control groups (24 hours). In contrast, the bond strength of Admira Bond was not significantly reduced.