Objectives: The purpose of this study was to evaluate the nanoleakage patterns of four dentin bonding systems.
Methods: The dentin bonding systems used in this study were: Single Bond, One Coat Bond, Prime & Bond NT/Non Rinse Conditioner (NRC), and PermaQuik. Flat occlusal dentin surfaces from extracted human molars were finished with wet 600-grit silicon carbide paper, and bonded with one of the dentin bonding systems. After 24 h storage at 37 degrees C in water, margins were finished with polishing discs and the surrounding tooth surfaces coated with nail varnish. The samples were immersed in a 50% (w/v) solution of silver nitrate for 24 h, and exposed to photodeveloping solution for 8 h. The samples were cut longitudinally, polished, and mounted on stubs, carbon coated and observed in a Field Emission-SEM using backscattered electron mode.
Results: Different nanoleakage patterns were observed with the different adhesive systems. However, accumulations of silver particles were often noted at the base of the hybrid layer for all materials. Single Bond and One Coat Bond demonstrated uptake of silver particles both within the hybrid layer and the adhesive resin. Prime & Bond NT/NRC showed silver staining throughout almost the entire thickness of the hybrid layer. The leakage pattern of PermaQuik revealed loose silver deposition within the hybrid layer. The composition of each adhesive system may play a role in forming the different leakage patterns.
Significance: The current dentin bonding systems used in this study do not achieve perfect sealing at the restoration/dentin interface, which may influence the durability of the bond to dentin.