Coating Effects of Antibacterial Resins Containing MDPB on Root Surface

Objective: We previously reported that applying a coating resin with a self-etching primer onto the root surface effectively prevented demineralization. Incorporation of an antibacterial monomer MDPB into the coating resin is possibly useful to improve this preventive method by providing anti-plaque activity. This study aimed to evaluate the effectiveness of the coating resins containing MDPB at various concentrations to prevent demineralization on root surface.

Methods: The experimental coating resins, prepared by incorporating MDPB at 1, 2, 5, 10 or 15% into the multifunctional methacrylate-based resin (Top Coat, Kuraray Medical), was applied to the cervical area of the roots of human extracted teeth using Clearfil Protect Bond primer. Five specimens for each group were immersed in pH 5.5 acetate buffer at 37ºC for 4 weeks and sliced, and the presence of demineralization was evaluated by microscopic observation and contact microradiography. Each resin was applied to the additional six roots and sectioned. The thickness of the resin layer was measured on SEM images of the three specimens, and formation of hybridized layer was observed on the other three specimens after treatment with H₃PO₄ and NaOCl.

Results: In the acid demineralization tests, no demineralized area or only small localized demineralized spots were observed for all groups. There were no significant differences in the thickness of coating layer among the materials (ANOVA, p>0.05), showing 30-72 µm, although thicker coating in the mean value was obtained for the resins containing lower amount of MDPB. Formation of hybridized layer of 1.5 to 3 µm with cementum was observed for all MDPB-containing resins.

Conclusion: The experimental resins containing MDPB were found to be able to prevent root surface from acid demineralization by production of moderately thick coating layer and integral hybridization with cementum. (supported by a Grant-in-Aid for Scientific Research No. 19209060 from JSPS)