Bond strength of composite to air-abraded enamel and dentin

Human enamel and dentin were prepared with an air abrasion unit (KCP-2000), using two particle sizes (27 micrometers and 50 micrometers) of aluminum oxide. In vitro tensile bond strengths of a composite resin were determined after three enamel and three dentin surface treatments. Enamel treatments were: air abraded only, E-1; air abraded + adhesive, E-2; air abraded + acid etch + adhesive, E-3. Dentin surface treatments were air abraded only, D-1; air abraded + adhesive/no primer, D-2; air abraded + primer + adhesive, D-3. Etched enamel and dentin prepared with 600-grit SiC paper and adhesive served as controls. There were 10 replications for each condition. A dentin bonding system (Optibond) and a composite resin (Herculite XRV) were bonded to treated surfaces by light curing in an inverted, truncated cone die with a bond diameter of 3 mm. Samples were stored at 37 degrees C and 100% relative humidity for 24 hours and debonded in tension using a Universal Testing Machine at a 0.05 cm/min crosshead speed. Based on analysis of variance, there was no statistical difference between 27 micrometers and 50 micrometers aluminum oxide abrasive for both enamel and dentin. For enamel bond strengths, E-2 was significantly higher than E-1, and E-3 was significantly higher than E-1 and E-2. E-1 and E-2 were significantly lower than the control, while E-3 was not significantly different from the control (P < or = 0.05). For dentin bond strengths, D-2 was significantly higher than D-1, and D-3 was significantly higher than D-1 and D-2. All treatments except D-3 were significantly lower than the control (P < or = 0.05). Air-abrasion treatment of enamel and dentin alone resulted in reduced in vitro bond strengths as compared to etched enamel and dentin prepared with dentin adhesive and dentin primer.