Randomized Trial of Silver Nitrate with Sodium Fluoride for Caries Arrest

Objectives: The aim of this noninferiority double-blind randomized clinical trial was to compare the effectiveness of the topical semiannual application of a 25% silver nitrate (AgNO₃) solution followed by a 5% sodium fluoride (NaF) varnish with that of a 38% silver diamine fluoride (SDF) solution in arresting caries among preschool children.

Methods: Healthy 3-y-old children with active dentine carious lesions were randomly allocated to 2 groups via computer-generated random numbers. Lesions in group A received applications of a 25% AgNO₃ solution followed by a 5% NaF varnish semiannually (every 6 mo). Lesions in group B received semiannual applications of a 38% SDF solution followed by a placebo varnish. A trained examiner recorded the status of caries and oral hygiene at baseline and during follow-up examinations. The examiner, children, and their caretakers were blinded to the intervention allocation. This study adopted an intention-to-treat analysis. A noninferiority test was conducted for the data analysis. Group A's noninferiority was accepted if the lower limit of the 95% CI for the difference in the mean number of arrested surfaces was >-0.5.

Results: A total of 1,070 children were recruited at baseline, with 535 children in each group. After 18 mo, the mean ± SD number of arrested surfaces was 3.3 ± 3.4 in group A (n = 484) and 3.2 ± 3.5 in group B (n = 476; P = 0.664). The difference in the mean number of arrested surfaces between the groups was 0.092 (95% CI, -0.322 to 0.505). Apart from black staining on the arrested lesions, no other significant side effect was observed.

Conclusion: A semiannual application of 25% AgNO₃ followed by 5% NaF is no worse than a 38% SDF in arresting dentine caries among preschool children over 18 mo. The Hong Kong Research Grants Council (GRF 17107315) funded this trial, which was registered at ClinicalTrials.gov (NCT02019160).

Knowledge transfer statement: This randomized clinical trial found that silver nitrate solution followed by sodium fluoride varnish is effective in arresting dentine caries among preschool children. As silver nitrate followed by sodium fluoride is a noninvasive and simple protocol, it can be an alternative strategy to manage dental caries among young children, especially in countries where silver diamine fluoride is not available.