Effect of sodium fluoride on oral biofilm microbiota and enamel demineralization

Publication date: Available online 20 February 2018
Source:Archives of Oral Biology
Author(s): T. Thurnheer, Georgios N. Belibasakis
ObjectiveFluoride is widely used as an anti-caries agent, e.g. in toothpastes and mouth rinses. However, the nature of the anti-caries action is not entirely clear. Mechanisms suspected to explain the cariostatic effect include inhibitory effects on microbial acid formation, inhibition of extracellular polysaccharide (EPS) production, inhibition of enamel demineralization and enhancement of remineralizaton or combination there off. The aim of this study was to examine with the supragingival Zurich in vitro biofilm model the effect of fluoride in NaF formulation, on the microbiota and on demineralization.MethodsBiofilms consisting of Actinomyces oris, Candida albicans, Fusobacterium nucleatum, Streptococcus oralis, Veillonella dispar and Streptococcus sobrinus, were grown anaerobically on sintered hydroxyapatite or bovine enamel disks, exposed to 200, 400, and 1400 ppm of NaF, or 0.1% chlorhexidine (positive control). The biofilms were harvested after 64 h and CFUs were assessed for total bacteria. Demineralization of enamel disks was measured by quantitative light-induced fluorescence.ResultsNaF did not affect the bacterial numbers. No enamel mineral loss was observed at 1400 and 400 ppm of fluoride, whereas the pH of the surrounding medium was increased to 5.5 and 5.0, respectively, compared to the untreated control (pH 4.5 and mineral loss □F of −32%). At 1400 ppm NaF the biofilm's EPS volume was also significantly reduced.ConclusionsNaF completely prevented demineralization without affecting biofilm composition and growth. This protective effect may be attributed to the observed decrease in acid production or EPS volume, or to a shift in the de/remineralization balance.



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