Relationship between bond strengths and nanoleakage: Evaluation of a new assessment method

Purpose: To test if there was a correlation between resin-dentin bond stren gths and nanoleakage of total etch and self-etching primer bonding systems. Materials and Methods: Ten extracted third molars were ground flat with 60 0 grit SIC paper under running water to expose middle dentin. Clearfil Line r Bond 2V or Single Bond was applied to the dentin surface according to the manufacturers' instructions. A crown was built-up with Clearfil AP-X resin -based composite, and the specimens stored in water for 24 hrs at 37 degree sC. The bonded assemblies were cut mesio-distally perpendicular to the inte rface into approximately 0.7 mm thick slabs, and trimmed for microtensile b ond strength testing. Alternate slices from each tooth were either entirely double-coated with nail varnish leaving a 0.5 mm window around the interfa ce, or left uncoated to be immersed in water for 13 hrs as the control. The varnished (experimental) slabs were immersed in 50% AgNO3 for 1 hr, and th en immersed in a photo developing solution for 12 hrs. All specimens were s ubjected to microtensile bond test at a crosshead speed of 1 mm/min. After debonding, the specimens were embedded in epoxy resin and observed under a confocal laser scanning microscope for determination of lateral silver pene tration within the interface. Silver penetration was further analyzed under the SEM. Data were analyzed with one- and two-way ANOVA, Fisher's PLSD tes t (P < 0.05), and regression analysis. Results: The bond strengths of Clear fil Liner Bond 2V and Single Bond were not significantly different (P > 0.0 5); however the bond strengths of the specimens that were soaked in 50% AgN O3 for 1 hr significantly increased (P < 0.01). No correlation was observed between bond strengths and nanoleakage.