Effect of air abrasion and thermocycling on resin adaptation and shear bond strength to dentin for an etch-and-rinse and self-etch resin adhesive

This study examined the effect of air abrasion and thermocycling on the adaptation and shear bond strength, of composite resin bonded to dentin using etch-and-rinse and self-etch resin adhesives. Confocal microscopy showed both adhesives closely adapted to dentin and a significantly (p<0.001) greater number of resin tags were observed for the etch-and-rinse adhesive. Air abrasion significantly increased resin tag length (p<0.05) for the etch-and-rinse adhesive and significantly increased the number (p<0.001), length (p<0.001) and thickness (p<0.01) of tags for the self-etch adhesive. However, air abrasion resulted in defect formation within the hybrid layer and thermocycling caused separation of the hybrid layer from adjacent dentin containing resin tags. A significant (p<0.05) reduction in shear bond strength was observed for the etch-and-rinse adhesive following thermocycling. Both adhesive systems adapted well to dentin in vitro and shear bond strengths were similar. The area of tag penetration into dentin was significantly (p<0.0001) enhanced following air abrasion.