ABSTRACT
PURPOSE: The objective of this study was to test the hypothesis that NaOCl treatment of acid-etched dentin would not lower the tensile bond strength of adhesive resins, but would eliminate the hybrid layer. MATERIALS AND METHODS: One hundred twenty teeth and three different bonding agents were used for SEM- and CLSM-visualization of the dentin-composite interface and for bond strength measurements. After etching with phosphoric acid, 75 dentin samples were pretreated with 10% NaOCl. The other 75 samples were etched only with phosphoric acid and were kept as controls. Composite was bonded to the pretreated surfaces with a bonding resin. RESULTS: NaOCl-treated samples: hybrid layers were not visible, but resin tags and resin penetration through lateral branches of tubules were prominent. Layers of unfilled resin were not apparent for Gluma CPS and Prime & Bond 2.1. Hypochlorite treatment of acid-etched dentin resulted in reduced bond strengths for specimens bonded with Syntac and Gluma CPS, but such treatment increased bond strength for Prime & Bond 2.1 bonded specimens. CONCLUSION: The removal of the collagen layer with NaOCl can enhance or decrease bond strengths, depending on the bonding agent used.
