Influence of self-etching primer treatment on the adhesion of resin composite to polished dentin and enamel

Objective. This study investigated the effectiveness of the self-etching primer treatment on the adhesion of resin composite to both dentin and enamel. Methods. Two types of self-etching primer were prepared. One was an aqueous solution of 2-methacryloyloxyethyl phenyl hydrogen phosphate (Phenyl-P) and 2-hydroxyethyl methacrylate (HEMA), and the other was an aqueous solution of 10-methacryloxydecyl dihydrogen phosphate (MDP) and HEMA. Influence of the concentration of Phenyl-P and MDP, and that of the application time on the adhesiveness were examined by measuring the tensile bond strengths of resin composite to dentin and enamel. The data were analyzed using the analysis of variance and Scheffe's test for multiple comparison among the means. Results. After the 20P and 30P treatment for 30 s, bond strengths to dentin were significantly higher than those after 5P and 10P treatment for 30 s. The 30M treatment of dentin for 15 s significantly increased the bond strength compared with 5P, 10P and 20P for 15 s. In enamel, bond strength with 30P for 60 s was significantly higher than with 5P for 60 s and 30P for 15 s. The 30M for 60 s resulted in significantly higher bond strength than for 15 s. The smear layers on the dentin and enamel were partially dissolved by the self-etching primer treatment. A hybrid layer with a thickness of 1–1.5 μm was formed in dentin-bonded specimens. Significance. The self-etching primer containing Phenyl-P or MDP showed good adhesion to dentin and enamel, and this primer is a promising material for resin composite restoration.