Effects of a self-etching resin coating system to prevent demineralization of root surfaces

OBJECTIVES: The purpose of this study was to evaluate the ability of an experimental self-etching resin coating system to protect against demineralization of the root surface in vitro, comparing its effectiveness with two commercial one-step self-etching adhesives. METHODS: The experimental resin coating system (EC), consisting of a self-etching primer and an acrylate-based resin, or the two commercial self-etching adhesives, Adper Prompt-L Pop (AD) and Clearfil Tri-S Bond (S3), was applied to the cementum of a human extracted tooth root. The specimens were immersed in acetate buffer at pH 5.5 for 4 weeks, and the degree of demineralization underneath the materials was evaluated by microscopic observation and contact microradiography. Each material's sealing and interfacial ultrastructure on the cementum was morphologically examined by scanning electron microscopy, and their bonding ability to cementum was determined by microtensile bond strength (MTBS) tests. RESULTS: Application of AD and S3 showed limited effects to protect against demineralization, but no demineralization was observed for EC. EC showed greater coating thickness than the other two materials, with formation of integral hybridized layers with cementum. Although the MTBS values for EC were significantly lower than those for AD and S3, cohesive failure in resins was the prevalent fracture mode for EC, showing no possible disadvantages in bonding ability. SIGNIFICANCE: The experimental resin coating system effectively prevented acid demineralization on root surfaces due to its ability to produce an appropriately thick coating and an integral hybridized layer.