INCORPORATION OF ANTIBACTERIAL MONOMER MDPB INTO DENTIN PRIMER

The polymerizable monomer methacryloyloxydodecylpyridinium bromide (MD PB) shows antibacterial activity when immobilized in a resin-based mat erial. In this study, the antibacterial effect of a dentin primer inco rporating MDPB was investigated. The influence of incorporation of MDP B on bond strength to dentin and on the curing performance of the adhe sive system was also evaluated. Experimental primers were prepared by addition of MDPB into a proprietary primer at 1, 2, or 5%. Antibacteri al effects of experimental primers were compared with those of control primer and two other proprietary primers by an agar disc-diffusion me thod and bactericidal activity test. Experimental primers produced gre ater inhibition zones against Streptococcus mutans, Actinomyces viscos us, and Lactobacillus casei than any of three proprietary primers, and inhibition increased as the concentration of MDPB was increased. Bact ericidal activity of MDPB-containing primers against Streptococcus mut ans was greater than those of the other three primers, with incorporat ion of MDPB at 5% showing complete killing of bacteria after 30 s cont act. No decrease in tensile bond strength was observed for materials c ontaining MDPB. On the contrary, the primer incorporating 1 and 20% MD PB showed higher bond strength than all the others, including the cont rol (p < 0.05). When the degree of conversion of the complex of primer and adhesive resin was determined with Fourier Transform Infrared Spe ctroscopy, there were no significant differences between any of the ex perimental primers and the control (p > 0.05). These results indicate that incorporation of the antibacterial monomer MDPB enhanced the anti bacterial effect of a proprietary dentin primer before curing, and had no adverse influence on bond strength to dentin and curing of the adh esive system.