The Preventive Effect of SDF-Modified Salivary Pellicle on Dental Erosion

Objectives: To investigate the preventive effect of silver diamine fluoride (SDF) modified salivary pellicle (SP) against dental erosion on human enamel and dentine.
Methods: 120 enamel and 120 dentine blocks were randomly allocated to 4 experimental groups. Blocks were covered by SP, followed by SDF treatment in Group 1, treated by SDF in Group 2, covered by SP in Group 3. Group 4 was control. The blocks were subjected to erosive challenge by citric acid at pH 3.2 for 2 mins, 5 times per day for 14 days. Salivary pellicle morphology was assessed by atomic force microscopy (AFM). Surface loss, percentage of hardness loss (%SMHL), crystal characteristics and surface morphology of the blocks were examined using non-contact profilometry, microhardness test, X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Data were analysed using ANOVA or Kruskal-Wallis One-way ANOVA.
Results: AFM confirmed the presence of SP in Groups 1&3 and showed the modified SP morphology by SDF in Group 1. The profilometry showed the median (Interquartile Range in μm) of surface loss in Groups 1- 4 were 2.65(0.59), 4.49(0.87), 5.87(0.88), and 8.49(0.63) in enamel (P<0.034) and 3.18(0.40), 5.72(0.42), 7.91(0.66), and 11.82(0.42) in dentine (P<0.036), respectively. %SMHL (±SD in %) of Groups 1-4 were 33.01±3.18, 37.25±3.11, 50.44±3.22, and 58.02±3.13 in enamel (p<0.012) and 15.31±2.29, 19.61±2.30, 27.80±2.31, and 44.60±2.28 in dentine (p< 0.001), respectively. XRD of enamel and dentine blocks of Groups 1&2 found hydroxyapatite, silver chloride, silver phosphate and silver fluoride on the surface. Fluoroapatite was found in Group 1 only. SEM showed less enamel demineralization pattern and more dentinal tubular occlusion in Groups 1&2 compared to Groups 3&4.
Conclusions: The SDF-modified SP provided a better protective effect against dental erosion on human enamel and dentine compared to SP without SDF modification and SDF treatment alone.