In order to study the influence of acidic monomer in the self-etching primer, we prepared four kinds of primers. 4-MET/HEMA primer contained carboxylic acid monomer, and PA and PA/HEMA primers did not contain acidic monomer, and TA/HEMA primer contained carboxylic acid without double bond. The pH of PA and PA/HEMA primer is the same as that of 4-MET/HEMA primer.
Each primer was applied on the polished enamel or dentin surface for 60sec, and the tensile bond strengths were measured after 1 day immersion in 37°C water.
PA, TA/HEMA and 4-MET/HEMA primers were effective for improving the bond strength of composite resin to enamel, and 4-MET/HEMA primer was effective for the adhesion to dentin. The addition of 4-MET into the self-etching primer was remarkably effective for the dentin adhesion.
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