Anti-Biofilm and Antimicrobial Activity of Sodium Fluoride Against Various Pathogenic Microbes

Purpose: Many dietary supplements, dental products, few medications like antifungal and antibacterial drugs contain fluoride, typically in the form of sodium fluoride. Fluoride has been widely used for oral hygiene but the anti-biofilm and antimicrobial activity of pure sodium fluoride solutions has not been reported. Methods: In the present study, antimicrobial properties of different concentrations of sodium fluoride against eleven clinical isolates of bacterial and two clinical isolates of fungal strains were evaluated. The effect of sodium fluoride on the biofilm formation of the most sensitive strains was also examined Results: Sodium fluoride efficiently suppresses the growth of all pathogens in a concentration-dependent manner. 10% sodium fluoride showed the highest inhibition against E. faecalisamong gram-positive strains and P. aeruginosa among gram-negative strains with the inhibition zone of 25 +/- 1.0 mm and 27 +/- 0.0 respectively whereas both fungal strains showed almost the same results of 15 mm of inhibition. Sodium fluoride successfully reduced biofilm formation at concentrations of 7% in dose-dependent anti-biofilm activity against S. epidermidis andE. faecalis; 8% against E. cloacae, P. aeruginosa, and C.tropicalis Conclusions: Our results indicate that various pathogenic microbes cannot tolerate high exposure to sodium fluoride. Fluoride-containing products can help to reduce pathogens and biofilm formation. However, products containing high amounts of sodiumfluoride as the active ingredient should be used carefully in order to avoid any toxicity and adverse effects