HNPM, Phenyl・P or 4-META is the methacrylate which contains the hydrophobic and hydrophilic groups in its molecule.These monomers have biocompatibilities or affinities for tooth substrates, so they are infiltrated to tooth hard tissues.Since these monomers have co-polymerizied in tooth substrates, high adhesion is achieved.To investigate the pulp response to MMA-TBB resins containing these adhesive monomers, we made a pathological study compared with Clearfil・F on dogs'permanent teeth.The results were as follows.1)Pulp response to MMA-TBB resins containing adhesive monomers was greater than that of Clearfil・F because of the stimulus of MMA at 1 and 4 weeks postoperative period.However, after 8 weeks, pulp response was low and there was little difference from Clearfil・F.2)Pulp response to MMA-TBB resin including HNPM was high during short term postoperative period compared with Phneyl・P or 4-META because of the difference of function of adhesive monomer.After 8 weeks, bacteria layers were found on some of the cavity floors of HNPM.