The effect of load cycling on the nanoleakage of dentin bonding systems

Objectives: The purpose of this study was to evaluate the effects of load cycling on nanoleakage of occlusal flat surface or cervical restorations bonded with three self-etching priming systems and a single bottle system. Methods: The dentin bonding systems used in this study were Clearfil SE Bond, Unifil Bond, Prompt L-Pop and Single Bond. Flat occlusal dentin surfaces and cervical cavities from extracted human molars were bonded with one of the dentin bonding systems. After load cycling of 90 N for 5000 cycles, samples were immersed in a 50% w/v solution of silver nitrate for 24 h, and exposed to photodeveloping solution for 8 h. Specimens were sectioned, mounted on stubs, carbon-coated and observed in a Field Emission-SEM using backscattered electron mode. One-way ANOVA was used for statistical analysis of the leakage scores. Results: FE-SEM images showed that samples subjected to load cycling had leakage patterns similar to non-load-cycled samples for all dentin bonding systems. Load cycling did not affect leakage lengths in any system. Prompt L-Pop had greater silver deposition and leakage score than the other systems. Significance: The dentin bonding systems tested were unable to prevent nanoleakage, and the extent of nanoleakage was not increased by load cycling.