procedure for evaluating the effect of the test composition the labial surface of a fresh bovine foretooth which had been preserved frozen immediately after extraction was buffed with silicon carbide paper to prepare a smooth enamel or dentin surface then a spacer provided with an aperture having a specified area was placed on the polished surface the test composition preadjusted to the specified concentration was applied to the above enamel or dentin surface in the aperture and allowed to stand for 40 seconds the tooth was rinsed and dried in an air current the treated enamel or dentin surface was then coated with bonding containing phosphate monomer cleafil u00ae photo bond kuraray co ltd and allowed to stand for 30 seconds the volatile substance was evaporated off in an air current and using a light irradiator quick light j morita corporation the bonding agent was photopolymerized for 20 seconds a dental composition resin cleafil u00ae photo posterior kuraray co ltd was placed on the above suface then the resin was cured by exposure to said irradiator for 60 seconds the spacer was removed and a stainless steel bar was rigidly secured to the cured composite resin with a dental cement containing phosphate monomer panavia u00ae kuraray co ltd the tooth was allowed to stand in water.