Effects of a silver nanoparticle and fluoride solution on enamel remineralization: an in situ study

This in situ study evaluated the remineralizing effect of a silver nanoparticle and fluoride solution (NanoF) compared with silver diamine fluoride (SDF) on dental enamel with initial caries lesions. This blind, randomized, crossover in situ study was conducted in two experimental phases (10 days each), separated by a 10-day washout period. Eighteen volunteers (n = 18) used palatal devices containing six bovine enamel blocks: one sound enamel (SE), one initial caries lesion (IC), two treated with NanoF, and two treated with SDF. Initial caries lesions were formed in situ before treatment, and baseline surface microhardness (Mi) was obtained. Participants then applied a 20% sucrose solution to the samples eight times daily for eight days to induce demineralization, followed by a second microhardness assessment (Ml). After treatment, final surface microhardness (Mf) was measured, and the percentage of surface microhardness recovery (%SMR) was calculated. Cross-sectional microhardness (CSMH) was assessed after longitudinal sectioning of the samples, and mineral volume percentage (%MV) was calculated at depths of 20-200 μm. Data were analyzed using Kruskal-Wallis followed by Dwass-Steel-Critchlow-Fligner tests (α = 0.05). NanoF showed %SMR values statistically similar to SDF and SE, but significantly higher than IC (p = 0.028). For CSMH, NanoF and SDF did not differ, whereas SE presented higher values and IC the lowest values (p < 0.001), regardless of depth. NanoF demonstrated comparable in situ remineralization potential to SDF in initial enamel caries lesions.