Impact of sodium fluoride and nano silver fluoride-based varnishes on remineralisation of enamel caries: an in-vitro study

Abstract

Background: The aim of this study was to perform a comparative evaluation of 5% Sodium fluoride varnish, neutral nano silver fluoride (NSF) varnish and acidulated nano silver fluoride varnish in remineralising artificially induced enamel caries of primary teeth. Methods: 39 primary anterior teeth were sectioned 2mm below the cemento-enamel junction (CEJ) and mounted in acrylic resin blocks. Incipient enamel caries were induced on the samples artificially and primary Vicker’s surface microhardness (SMH) was assessed. Samples were divided equally and applied varnishes; Group 1: 5% Sodium fluoride varnish; Group 2: Neutral NSF varnish, and Group 3: Acidulated NSF varnish. A pH cycling protocol of 7 days was followed, and second Surface microhardness (SMH) testing was carried out. One sample from each group was observed for Scanning electron microscopy and Energy Dispersive Spectroscopy (SEM EDS). Statistical analysis was conducted using HSD Tukey and one way ANOVA tests. Results: There was a statistically significant difference between the pre-treatment and post-treatment values of all three groups. The difference in SMH after applying 5% Sodium fluoride varnish and acidulated NSF varnish was statistically significant (p<0.01). Similarly, neutral NSF varnish and acidulated NSF varnish also showed statistical significance (p<0.01). However, SMH after application of 5% Sodium fluoride varnish and neutral NSF varnish was statistically not significant. The SEM EDS analysis revealed the presence of an even fine granular layer of minerals on the surface of treated enamel in the acidulated NSF group whereas other groups showed uneven deposits of minerals. EDS showed fluoride and silver in groups containing NSF. Conclusions: Acidulated NSF varnish has the highest efficacy followed by neutral NSF varnish and 5% Sodium fluoride in remineralisation of enamel caries in primary teeth.