Antibacterial effect of a resin incorporating a novel polymerizable quaternary ammonium salt MAE-DB against Streptococcus mutans.

The antibacterial properties of resins incorporating MAE-DB and the underlying mechanisms of action were evaluated. Antibacterial effects against Streptococcus mutans were tested using the film contact method, with accumulation and membrane integrity observed by scanning electron microscopy and confocal laser scanning microscopy, respectively. Quantitative PCR was used to determine expression of the S. mutans glucosyltransferase B (gtfB) gene on the surface of resins containing 10% MAE-DB. Bacterial growth was inhibited on resin containing 10% MAE-DB as compared with the control at 1 day, 7 days, 30 days, or 180 days (p < 0.05). For the 10%-MAE-DB resin, no significant differences in bacterial viability were found regardless of the time of incubation (p > 0.05). The number of bacteria attached to resin containing 10% MAE-DB was considerably lower than the control. The proportion of bacteria with damaged cell membranes was increased in the experimental resin over controls. Expression of gtfB was reduced by 10% MAE-DB compared with the control (p < 0.05). These findings demonstrate that MAE-DB can be incorporated into resin materials at sufficient concentrations for long-term antibacterial effects against S. mutans after polymerization by attenuating gtfB expression and impairing membrane integrity.

[Influence of luxS of Streptococcus mutans on biofilm of dental plaque].

OBJECTIVE: To construct luxS mutant aften luxS gene of Streptococcus mutans (S. mutans) was knocked out, and examine their ability of biofilm formation. METHODS: A recombinant plasmid containing the flanking fragment of luxS of S. mutans was transformed into S. mutans UA159, and selected by brain heart infusion (BHI) agar medium with kanamicin. The luxS mutant further confirmed via polymerase chain reaction (PCR) and the autoinducer-2 (AI-2) bioluminescence assay of Vibrio harveyi (V. harveyi), and ability of luxS mutant and S. mutans UA159 biofilm formation was examined in different phases, in BHI medium with 1% sucrose and 1% glycose by scanning electron microscopy (SEM). RESULTS: LuxS-deficient S. mutans strains were successfully constructed. Compared with S. mutans UA159, the luxS mutant maintained in BHI medium containing 1% sucrose displayed an apparent defect in biofilm formation, while they showed no significant deviation in BHI medium containing 1% glycose. CONCLUSION: luxS gene in S.mutans can play a role in dental plaque biofilm formation, and the luxS gene is possible to regulate sucrose-dependent biofilm formation.