Effect of ethanol and NPG-GMA on replica patterns on composite restorations performed in vivo in acid-etched cavities

29 experimental Class V restorations using a chemically cured composite resin were inserted in human third molars in cavities which after acid-etching had been treated with absolute ethanol. After extraction and demineralization of the teeth, the fillings were examined in SEM concerning their enamel and dentin replica patterns on the inner cavity-faced surface. The SEM findings were compared with previous findings concerning the replica patterns on fillings from acid-etched cavities and from cavities which after acid-etching had been treated with an ethanol solution of the surface active comonomer N-phenylglycine-glycidyl methacrylate (NPG-GMA). It was found that cavity treatment with absolute ethanol further improved the increased enamel replica patterns obtained with the NPG-GMA/ethanol comonomer solution while only the NPG-GMA/ethanol treatment improved the dentin replica patterns. Based on these results the effect of each of the two main components in the comonomer solution on replica patterns on resin restorations could be disclosed.