Action of Silver Nitrate and Sodium Fluoride on Dentine Demineralisation

Objectives: To investigate the action of 25% silver nitrate solution (AgNO3) and 5% sodium fluoride (NaF) varnish on artificial dentine carious lesion with acid challenge.
Methods: Eight dentine blocks with thicknesses of 2 mm were prepared from 8 sound human molars. Each slice was cut into 3 specimens for different treatments afterwards and thus 24 specimens were prepared. Artificial caries were created by acetic acid on the surfaces of specimens before experimental treatments. Subsequently, specimens of the SF group received topical application of 25% AgNO₃ solution followed by 5% NaF varnish. SDF group received a topical application of 38% silver diamine fluoride (SDF) solution (positive control). Specimens of the W group received deionized water (negative control). They were subjected to pH cycling for 8 days. The crystal characteristics, and lesion were investigated by X-ray diffraction (XRD), micro-CT testing.
Results: The XRD analysis indicates that the crystal composition on the dentine surfaces in all of the groups corresponded to hydroxyapatite. Apart from hydroxyapatite, the strong peaks at 27.8^o, 32.2^o and 46.2^o in groups SF and SDF were coincident with silver chloride (111), (200) and (220), which suggests that silver chloride was formed on the surfaces in these 2 groups. The mean lesion depths (±SD) of groups SF, SDF and W measured by micro-CT were 128±19 µm, 135±24 µm and 258±53 µm, respectively (SF, SDFConclusions: In this in vitro study, topical application of 25% AgNO₃ solution and 5% NaF varnish was effective in preventing dentine demineralisation.