[Studies on adhesion to tooth substrate. 5. The relationship between the structure of monomers and their adhesiveness].

The relationship between the structure of monomers with amide groups and their adhesiveness to tooth was investigated. The monomers used were methacrylamide (MA), p-methacryloxybenzamide (p-MBA), and 3,5-dimethacryloxybenzamide (3,5-DMBA). MA was commercially available. p-MBA and 3,5-DMBA were prepared from the reaction of methacryloyl chloride with p-hydroxybenzamide or 3,5-dihydroxybenzamide, respectively, in acetonitrile. The bovine enamel and dentin were etched with 10% citric acid -3% FeCl3 solution. The monomers were dissolved in MMA, and TBB-O was used as a polymerization initiator. The test samples were immersed in 37 degrees C water for 1 day, 1 month, or 3 months. Then the tensile bond strengths were measured. The bond strengths to enamel were almost the same, irrespective of the kinds of monomers after 1 day immersion. Although the bond strengths of MA (1.0%) and 3,5-DMBA (3.0%) decreased after 1 month immersion, those of MA (0.5%) and p-MBA (0.5%) did not decrease after 3 months immersion. There was no relationship between the bond strengths to enamel and the bending strengths of the resins. The bond strengths of 3,5-DMBA (1.0%) and 3,5-DMBA (3.0%) to dentin were about 5-7 MPa. The bond strengths of MA (0.5%) or MA (1.0%) decreased after 3 months or 1 month immersion, respectively. The bond strength of p-MBA (0.5%) did not decrease after 3 months immersion.