Scanning electron microscopic and energy dispersive x-ray evaluation of two smear layer-mediated dentinal bonding agents

Teeth treated with smear layer-mediated dentinal bonding agents and restored with composite resin were examined at the dentin-restoration interface by means of scanning electron microscopy used in conjunction with energy dispersive x-ray analysis. Results indicated that these dentinal bonding agents actually banded to the smear layer, and samples demonstrated delamination of the smear layer from underlying dentin following thermocycling. This fmding suggests that the stresses developed within the composite resin exceeded the adhesive strength of the smear iayer to dentin. Thus, the bond strength for dentinal bonding agents that require the presence of the smear layer cannot exceed the adhesion of the smear laver to dentin.