PURPOSE:The purpose of this study was to evaluate the effects of concentration and pH of silver nitrate solution on nanoleakage in occlusal flat surfaces bonded with three dentin bonding systems. MATERIALS AND METHODS:The dentin bonding systems used in this study were Single Bond, PermaQuik, and Prompt L-Pop. Flat occlusal dentin surfaces from extracted human molars were bonded with one of the dentin bonding systems. The teeth from each subgroup (n = 4) were placed in one of the following silver nitrate solutions: 50% w/v, 25% w/v, 10% w/v, and 2% w/v (pH 3.4, 4.2, 4.4, and 4.9, resp), and 50% w/v buffered to pH 6 in total darkness for 24 h, rinsed in running water for 5 min, immersed in photodeveloping solution for 24 h, and exposed to light for 8 h. Specimens were sectioned, mounted on stubs, carbon coated and observed in a Field Emission SEM using backscattered electron mode. RESULTS:FE-SEM images showed that samples from different concentrations of silver nitrate solution had leakage patterns similar to that of samples from 50% w/v for all dentin bonding systems. The concentrations and pH values of silver nitrate solutions did not affect leakage patterns in any of the systems. CONCLUSION:A lower concentration of silver nitrate solution may be used in a nanoleakage study, although the present results need to be replicated to determine an ideal concentration.