Inhibitory effect of silver diamine fluoride on dentine demineralisation and collagen degradation

Objective: To investigate the inhibitory effects of 38% silver diamine fluoride (SDF) on demineralised dentine. Methods: Human dentine blocks were demineralised and allocated to four groups: SF, F, S and W. The blocks in group SF received a topical application of 38% SDF solution (253,900 ppm Ag, 44,800 ppm F), group F received a 10% sodium fluoride solution (44,800 ppm F), group S received a 42% silver nitrate solution (253,900 ppm Ag) and group W received deionised water (control). They were subjected to pH cycling using demineralisation solution (pH 5) and remineralisation solution (pH 7) for 8 days. The surface morphology, crystal characteristics, lesion depth and collagen matrix degradation of the specimens were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-CT testing and spectrophotometry with a hydroxyproline assay. Results: The surface morphology under SEM showed evident demineralisation with exposed collagen in groups S and W, but not in group SF. Clusters of granular spherical grains were observed in the cross-sections of specimens in groups SF and F. XRD revealed precipitates of silver chloride in groups SF and S. The mean lesion depths (+/- SD) of groups SF, F, S and W were 182 +/- 32 mu m, 204 +/- 26 mu m, 259 +/- 42 mu m and 265 +/- 40 mu m, respectively (SDF, F < S, W; p < 0.01). Groups SF and S had significantly less hydroxyproline liberated from the dentine matrix than groups F and W (p < 0.01). Conclusion: The use of 38% SDF inhibited demineralisation and preserved collagen from degradation in demineralised dentine. Clinical significance: SDF application positively influences dentine remineralization. (C) 2013 Elsevier Ltd. All rights reserved.