Comparative evaluation of enamel microhardness between silver diamine fluoride and fluoride varnish on artificially induced caries in primary teeth: an in vitro study

Background: Despite being entirely preventable, dental caries remains highly prevalent in children, often beginning as early enamel demineralization (white spot lesions). Fluoride-based products are the mainstay for prevention and remineralization, with 5% Sodium Fluoride Varnish (FV) and 38% Silver Diamine Fluoride (SDF) being the most commonly used. However, evidence on SDF’s remineralization potential in early primary tooth enamel caries is limited. Methods: This in vitro study evaluated the effectiveness of SDF and FV in remineralizing artificial enamel caries by measuring enamel microhardness (EMH). Sixty primary teeth were randomized into four groups (n = 15): sound enamel (healthy enamel), SDF, FV, and demineralized untreated control. Artificial caries was induced via an 8-day exposure to a pH 4.4 demineralizing solution. EMH was measured using a Vickers Microhardness tester. Data were analyzed via one-way analysis of variance (ANOVA) and Tukey’s post-hoc test (p ≤ 0.05). Results: Results showed significant differences among groups (p < 0.001). FV produced the greatest increase in EMH, significantly outperforming SDF and control. SDF also improved EMH compared to untreated teeth, but was less effective than FV. Conclusions: Under these in vitro conditions, FV demonstrated superior remineralization capacity compared to SDF for early enamel lesions in primary teeth. However, these findings should be interpreted within the context of a chemically-induced lesion model without biofilm, and clinical decision-making should consider that FV and SDF have different indications and may serve complementary roles depending on lesion type, substrate, and clinical circumstances.

Fluoride varnish; Silver diamine fluoride; Enamel microhardness; Remineralization; Caries prevention

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