Microscopical analysis of fractured restorative resin/etched enamel bonds

The purpose of the present work was to analyze the boundary structures of fractured restorative resin/etched enamel bonds. The fracture patterns were studied by scanning electron and optical microscopy. The three main types of failure observed were classified as: apparent interfacial failure, failure in the bulk of the restorative resin and failure in the bulk of the enamel. The fracture of the resin/etched enamel bond in the case of the apparent interfacial failure was located in the resin very near the interface. No true interfacial debonding occurred in any of the bonds studied.