Purpose: This study evaluated the effect of aging solutions on the durability of resin-dentin bonds by means of microtensile bond strength (μTBS) and nanoleakage (NL) tests.
Materials and Methods: The adhesive system Adper Single Bond 2 (3M ESPE) was applied according to the manufacturers instructions to the flattened occlusal surface of 40 extracted human molars. After bonding, teeth were sectioned to obtain bonded sticks (0.8 mm2 area) which were tested in tension immediately or after different storage periods (1 week, 1 month, or 6 months). Bonded sticks were kept immersed in 5 different solutions: 1) distilled water (DW); 2) 99.9% propionic acid (PA); 3) 99% acetic acid (AA); 4) 75% ethanol (ET), and 5) mineral oil (MO). To determine NL, bonded sticks from each experimental condition were immersed in silver nitrate and analyzed by SEM. Data were analyzed by two-way repeated measure ANOVA and Tukeys test (α = 0.05).
Results: Faster degradation of bond strength (1 week) could be seen for AA and ET (p < 0.05) in comparison with DW. Specimens stored in PA and DW showed bond strengths significantly reduced after one and six months, respectively (p < 0.05). No degradation of the resin-dentin bond strengths was observed for specimens stored in MO (p > 0.05). Nanoleakage increased for all groups except MO after storage.
Conclusion: Propionic acid, acetic acid, and ethanol can be used as alternative aging solutions to more quickly obtain results on the bond resistance to degradation.
Keywords: adhesive system, microtensile bond strength, degradation, silver nitrate uptake, dentin, oral simulating fluids