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

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.