Effects of water and carboxylic acid monomer on polymerization of HEMA in the presence of N-phenylglycine.

This research was designed to study the effect of water or carboxylic acid monomer on the polymerization of 2-hydroxyethyl methacrylate (HEMA) in order to understand the bonding mechanism of dentin bonding systems using N-phenylglycine (NPG). The polymerization of HEMA in the presence of NPG was studied by adding various amounts of water and/or 4-(2-methacryloyloxyethoxycarbonyl) phthalic acid (4-MET) and evaluated using differential scanning calorimetry (DSC). The addition of water promoted the polymerization of HEMA. Polymerization was further promoted through the addition of 4-MET as a carboxylic acid monomer. Polymerization was promoted at the molar ratio of 4-MET to NPG of 1.0-7.0. Moisture on the dentin surface could contribute to improving bond strength in dentin bonding systems using NPG by promoting polymerization at the dentin interface.