The in vitro assessment of enamel remineralization and cytotoxicity of experimental silver diamine fluoride.

Abstract

Objective: This in vitro study evaluated the enamel remineralization potential and cytotoxicity of an experimental 38% silver diamine fluoride prepared using a silver nitrate precursor (EXP-SDF; Dentalife, Melbourne, Australia). EXP-SDF was compared with commercial 38% SDF (Topamine; Dentalife), 5% NaF varnish (Duraphat; Colgate-Palmolive, USA), and 2.1% NaF gel (ClinproClear; 3M ESPE Dental Products, USA).

Materials and methods: Fluoride and silver concentrations, as well as the pH of EXP-SDF, were initially examined. Enamel specimens were prepared and randomized into five groups: Topamine, EXP-SDF, Duraphat, ClinproClear, and deionized water (control). The enamel specimens were demineralized and treated with materials and then subjected to a 14-day pH-cycling regimen. Enamel surface remineralization was quantified as the percentage of surface microhardness recovery (%SMHR). Mineral precipitation on the surface was then examined using Raman spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Cytotoxicity of the experimental SDF was also evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Results: EXP-SDF exhibited a higher fluoride concentration but comparable pH to Topamine. The increase in enamel surface microhardness of EXP-SDF (35%) was similar to that of Topamine (34%) (p = 0.98). The SDF groups also showed significantly higher %SMHR than Duraphat (-7%) and ClinproClear (-45%) (p < 0.05). Raman spectroscopy showed a reduction in the phosphate peak after demineralization, but the peaks after pH cycling were comparable across all groups. XRD patterns identified hydroxyapatite peaks in all groups, with the silver-containing phases only detected in the SDF-treated groups. SEM-EDX revealed high levels of Ag and F on the enamel surface of both Topamine and EXP-SDF. The cell viability of Topamine (77%) was also comparable to that of EXP-SDF (70%) (p = 0.32).

Conclusion: EXP-SDF promoted comparable remineralization of demineralized enamel and in vitro cytotoxicity comparable to that of commercial SDF. The remineralizing effects of SDF groups were also higher than those of professional NaF products.