Fractography of the Bonding between Light-cured Resin and Tooth Substrates

Abstract

The failure of bonding between tooth substrates and the light-cured bonding resin containing 6-methacryloyloxyethyl naphthalene-1, 2, 6-tricarboxylate anhydride (MENTA-126) was examined by fractography. The dependence of the bond strength on the infiltration of the monomer into dentin was also investigated.
Scanning electron microscopic fractographs of failed bonding to treated enamel showed a cohesive fracture in the resin. Fractographs of the bonding to treated dentin suggested a complex failure including an interface fracture between the resin and the dentin and cohesive fractures in the resin and just under the resin-infiltrated dentin layer. The bond strength was slightly dependent on the infiltration of the monomer only when dentins treated with an aqueous solution of 10% citric acid and 3% FeCl₃ were employed. In the other cases examined, there was not any significant dependence.