Antimicrobial activity of nanoemulsion on cariogenic planktonic and biofilm organisms

Introduction: Nanoemulsions (NE) are a unique class of disinfectants produced by mixing a water immiscible liquid phase into an aqueous phase under high shear forces. NE have antimicrobial properties and are also effective anti-biofilm agents. Materials and Methods: In vitro antimicrobial susceptibility of nanoemulsion on Streptococcus mutans, Lactobacillus casei, Actinomyces viscosus, Candida albicans and mixed cultures was determined by serial dilution techniques for the determination of minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC). Efficacy was tested by kinetics of killing, adherence and biofilm assay. Results: NE concentrations ranging from 243 to 19683 dilutions were effective against S. mutans, L. casei, A. viscosus, C. albicans and mixed cultures of these four stains as shown through MIC/MBC assays. NE showed antimicrobial activity against planktonic cells at high dilutions, confirmed by time kill studies. The level of adhesion on glass surface was reduced 94.2 to 99.5 % in nanoemulsion treated groups (p < 0.001). 4-day-old S. mutans, L. casei, A. viscosus, C. albicans and mixed cultures biofilms were treated with NE; subsequent reductions of bacterial counts were noticed with decreasing dilutions (p < 0.001). The highest inhibition of biofilm formation was observed at 250 ìl level. Conclusion: These results suggest that nanoemulsion has effective anti-cariogenic activity against cariogenic microorganisms and may be a useful medication in the prevention of caries.