Enamel remineralization potential and antimicrobial effect of a fluoride varnish containing calcium strontium silicate

Objectives: To investigate enamel remineralization and antimicrobial effect of sodium fluoride (NaF) varnish containing calcium strontium silicate (CSR).

Methods: CSR was synthesized by sol-gel process and incorporated in 5 % NaF varnish at three different concentrations (1 %, 2 %, and 4 % w/v). The treatment/control groups were: 1 % CSR+NaF, 2 % CSR+NaF, 4 % CSR+NaF, NaF, and no treatment. Strontium and fluoride release from the varnishes was evaluated. Sound enamel specimens (n = 6) were demineralized, varnish-treated, and subjected to remineralization cycle. Mineral density of enamel specimens was evaluated using micro-CT. Antimicrobial effect of the varnishes on Streptococcus mutans and Lactobacillus acidophilus biofilms was assessed using confocal laser scanning microscopy. The HGF-1 cytotoxicity of the varnishes was examined using CCK-8 assay.

Results: Both 2 % and 4 % CSR+NaF varnishes showed significantly higher F release and remineralization potential than NaF varnish (p < 0.05). Dead bacterial proportion of 4 % CSR+NaF varnish was significantly higher than NaF varnish (p < 0.05). The CFUs values of both S. mutans and L. acidophilus were significantly lower in 4 % CSR+NaF group than NaF group (p < 0.05). No significant difference in cell viability was observed among the groups (p > 0.05).

Conclusions: Incorporation of 4 % CSR in a NaF varnish significantly enhanced its enamel remineralization and antimicrobial potential with no cytotoxic effect.

Clinical significance: Dental caries is a major public health problem globally. The study highlights the great potential of CSR-doped NaF varnish as a novel anti-caries agent with synergistic remineralizing and antimicrobial properties to combat early enamel caries lesions in the general population.