Inhibitory Effect of Silver-Diamine-Fluoride on Demineralization of Sound Enamel

Objectives: Fluoride has been used in many forms to strengthen tooth enamel by being incorporated into hydroxyapatite crystals and reducing degree of enamel solubility. However, the degree of bioavailability of fluoride in Silver-Diamine-Fluoride (SDF) to reduce the solubility of enamel remains unclear. We hypothesize that SDF could strengthen enamel and enhance its resistance to acid solubility.
Methods: Twelve extracted human teeth sectioned mesio-distally were used in control and experimental groups (n=12/group). Specimens were covered by acid-resistant nail varnish, except for a 2X3mm window. Experimental group (SDF) was treated twice with 1 drop of SDF with 2min soak-in time per manufacturer’s instructions. Control group (CON) received no treatment. Both groups were subjected to 9-days pH challenge following Queiroz protocol (8 days demineralization and remineralization solution + 1-day remineralization solution). In the 4^th day of the pH-cycle the SDF group received the second treatment. To measure the preventive effect of the treatment, Vickers Surface Microhardness (SMH) of enamel surface was measured at baseline and following pH-cycle (load 200g, 20s dwelling time). Difference in SMH (post-pre) and percent change in surface microrhardness were calculated.
Results: Paired t-test used to test intra-group differences showed significantly less SMH average-values compared to the sound baseline SMH within each group (p≤0.05). Independent T-test was used to test between group differences and it showed significantly less drop in the SMH average values of the SDF group compared to CON group.
Conclusions: Within the limits of this study in spite of the statically significant drop in the SMH, SDF group showed added resistance to carries challenge and showed an enhanced resistance to solubility in a lower pH environment compared to no treatment control.