Attempts to produce resin composite with antibacterial properties by incorporation of an antibacterial agent such as chlorhexidine have been reported, but problems can arise due to release of the inhibitory agent from the composite. Such problems may include toxic effects, influence on mechanical properties, and loss of effectiveness. A new monomer, methacryloyloxydodecylpyridinium bromide (MDPB), was synthesized by combining an antibacterial agent and methacryloyl group. The monomer was incorporated into resin composite to develop a non-releasing antibacterial composite. The ability of composite incorporating MDPB to inhibit growth and plaque accumulation by Streptococcus mutans in vitro was assayed, elution of antibacterial components from the material was investigated, and the influence of incorporation of MDPB on the mechanical properties of composite was studied. Uncured MDPB revealed antibacterial activity against S. mutans and six other species of oral streptococci, with the minimum inhibitory concentration for S. mutans being comparable with that of triclosan. After composite incorporating MDPB was cured, no elution of the antibacterial components was observed from the material, even after 90 days' immersion in water or other solvents. Growth of S. mutans on agar under specimens of MDPB-containing composite was inhibited compared with controls. In a bacterial accumulation study, S. mutans accumulated to a lesser degree on the surface of composite incorporating MDPB (p < 0.05) than on control. Incorporation of MDPB had no significant influence on the mechanical properties of the composite.
The polymerizable monomer methacryloyloxydodecylpyridinium bromide (MDPB) shows antibacterial activity when immobilized in a resin-based material. In this study, the antibacterial effect of a dentin primer incorporating MDPB was investigated. The influence of incorporation of MDPB on bond strength to dentin and on the curing performance of the adhesive system was also evaluated. Experimental primers were prepared by addition of MDPB into a proprietary primer at 1, 2, or 5%. Antibacterial effects of experimental primers were compared with those of control primer and two other proprietary primers by an agar disc-diffusion method and bactericidal activity test. Experimental primers produced greater inhibition zones against Streptococcus mutans, Actinomyces viscosus, and Lactobacillus casei than any of three proprietary primers, and inhibition increased as the concentration of MDPB was increased. Bactericidal activity of MDPB-containing primers against Streptococcus mutans was greater than those of the other three primers, with incorporation of MDPB at 5% showing complete killing of bacteria after 30 s contact. No decrease in tensile bond strength was observed for materials containing MDPB. On the contrary, the primer incorporating 1 and 2% MDPB showed higher bond strength than all the others, including the control (p< 0.05). When the degree of conversion of the complex of primer and adhesive resin was determined with Fourier Transform Infrared Spectroscopy, there were no significant differences between any of the experimental primers and the control (p > 0.05). These results indicate that incorporation of the antibacterial monomer MDPB enhanced the antibacterial effect of a proprietary dentin primer before curing, and had no adverse influence on bond strength to dentin and curing of the adhesive system.
Vascular endothelial growth factor (VEGF) is a potent mitogen in endothelial cells, but little is known about its activity in other cell types. To clarify the role of VEGF in human dental pulp cells and pulp tissue, we investigated the effects of VEGF on the chemotaxis, proliferation, and differentiation of human dental pulp cells. VEGF induced a strong chemotactic response in human dental pulp cells in a dose-dependent manner. VEGF also marginally enhanced the proliferation of human dental pulp cells and induced an increase in alkaline phosphatase in human dental pulp cells. However, these effects of VEGF were not observed in reference to human skin fibroblasts. Analyses by the reverse-transcription/polymerase-chain-reaction method and flow cytometry showed that the mRNAs of two VEGF receptors, fins-like tyrosine kinase and kinase insert domain-containing receptor, were expressed in human dental pulp cells, whereas only fms-like tyrosine kinase mRNA was expressed in human skin fibroblasts. VEGF induced the activation of activator protein 1 (AP-1) and c-fos mRNA expression in human dental pulp cells. The AP-1 inhibitor curcumin strongly inhibited VEGF-induced alkaline phosphatase production in human dental pulp cells. In addition, VEGF antisense oligonucleotide suppressed the production of VEGF and alkaline phosphatase in human dental pulp cells. These results suggest that VEGF produced by human dental pulp cells acts directly upon human dental pulp cells in an autocrine manner, and may promote the chemotaxis, proliferation, and/or differentiation of human dental pulp cells via the utilization of kinase insert domain-containing receptor and in part through AP-1 by increasing c-fos.
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