In Vitro Primary Coronal Caries Prevention with Silver Diamine Fluoride

Objectives: Silver diamine fluoride (SDF) has been shown to be a viable option in the arrest of secondary caries extending into dentin. Little information, however, exists as to SDF’s ability in the primary prevention of coronal (enamel) caries.
The present laboratory study investigated whether SDF can prevent coronal caries.
Methods: Polished enamel specimens were obtained from human teeth and assigned to five treatment groups (n=18 per group) based on sound enamel Vickers surface microhardness [VHN(sound)]: 38% SDF (Advantage Arrest; SDF); 38% SDF followed by application of a saturated solution of potassium iodide (stain control; SDF+KI); 42% AgNO₃ (silver control; 253,900 ppm Ag); KF (fluoride control; 44,800 ppm F); deionized water (negative control). All solutions were applied using a microbrush, mimicking the clinical application of SDF. Specimens were then demineralized using a solution containing 0.1 M lactic acid, 4.1 mM CaCl₂, 8.0 mM KH₂PO₄, 0.2% Carbopol 907, pH adjusted to 5.0 for 5 days. Vickers surface microhardness was determined again [VHN(post)] and ΔVHN calculated [VHN(post) – VHN(sound)]. Data were analyzed using one-way ANOVA.
Results: ΔVHN (mean ± standard deviation) values were as follows: SDF (2±13); SDF+KI (-7±16); AgNO₃ (-294±13); KF (-35±16); deionized water (-288±17). There were no statistically significant differences between SDF and SDF+KI (p=0.07) in preventing coronal caries. Both were superior in their ability to prevent caries lesion formation than KF, AgNO₃ and deionized water (all p<0.0001). KF was more effective than AgNO₃ and deionized water (both p<0.0001). There was no difference between AgNO₃ and deionized water (p=0.27).
Conclusions: SDF appears to be a viable option in preventing primary coronal caries. KI application after SDF treatment does not appear to impair SDF’s ability to prevent demineralization. There appear to be synergistic effects between silver and fluoride. Further research using microbial and ultimately clinical models will be needed to establish conclusive evidence.