Remineralisation of enamel with silver diamine fluoride and sodium fluoride

Abstract

Objective: To evaluate the remineralising effect of the adjunctive application of 38% silver diamine fluoride (SDF) solution and 5% sodium fluoride (NaF) varnish on artificial enamel caries lesions. Methods: Forty-eight demineralised enamel specimens were allocated into four groups. Group 1 received 38% SDF and 5% NaF; Group 2 received 38% SDF; Group 3 received 5% NaF; and Group 4 received deionized water. After pH cycling, the surface morphology and fluoride content of the specimens were studied via scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS). The lesion depth and crystal characteristics were assessed using micro-computed tomography and X-ray diffraction (XRD) respectively. The crystallization reaction was performed by incubating hydroxyapatite powder with NaF or SDF for 48 h. The precipitates were studied via transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Results: SEM demonstrated the destruction of the enamel surface in Group 4. EDS revealed that the mean fluoride weight percentage of Groups 1–4 were 1.28 ± 0.15, 1.33 ± 0.19, 1.03 ± 0.09 and 0.87 ± 0.04 respectively. The mean lesion depths of Groups 1–4 were 129 ± 14 μm, 131 ± 16 μm, 153 ± 10 μm and 181 ± 21 μm respectively. The addition of NaF to SDF did not reduce the lesion depths (p = 0.779). XRD revealed that silver chloride formed as a main product in Groups 1 and 2. Meanwhile, TEM analysis indicated that silver nanoparticles were incorporated into hydroxyapatite crystal in SDF-treated hydroxyapatite. XPS spectra suggested that the chemical state of the silver was metallic. Significance: The adjunctive application of SDF and NaF varnish had a similar remineralising effect to that of SDF on enamel caries.