Antimicrobial Effect of a Lauric Acid on Streptococcus Mutans Biofilm.

Background: The purpose of this study was to compare the antimicrobial activity of a synthetic fatty acid sodium laurate (Lauric acid) comprising dodecanoate fatty acids with chlorhexidine (CHX) or calcium hydroxide (CH) against S. mutans biofilm. Methods: S. mutans was grown on cover glass bottom dishes or human dentin disks for 3 days, and then treated with sodium laurate (20 μg/ml), non-functional fatty acid(sodium decanate, sigma Aldrich, C4151) ( (NP, 20 μg/ml), CH (20 μg/ml), 1% CHX, or saline for 5 days at 37℃. On cover glass, live and dead microbials in the biomass were measured by the Film Tracer™ Biofilm viability assay, and observed by confocal laser scanning microscopy (CLSM). On dentin disk, normal, diminished, or ruptured microbials were observed by field-emission scanning electron microscopy (FE-SEM). The results were subjected to two-tailed t-test, one-way analysis variance and post hoc test at a significance level of P=0.05. Results: Live/Dead Biofilm viability assay and CLSM demonstrated that sodium laurate treated biofilms had a significantly less bio-volume than CH, NP, and saline (P < 0.05), but had no significant difference from the CHX-treated group (P > 0.05). FE-SEM demonstrated that there was a marked decrease in aggregations of microbials and biofilm and wrinkled or ruptured microbials were frequently observed in the CHX and sodium laurate. Conclusion: Synthetic sodium laurate fatty acid exhibited significantly higher antimicrobial activity than CH by inhibiting microbial survival and biofilm growth against S. mutans, but had no significant difference compared to CHX.