Comparative Evaluation of the Remineralizing Potential, Antibacterial Efficacy and Discoloration of Silver Diamine Fluoride, Acidulated Phosphate Fluoride Gel and Their Combination: An in Vitro Study.

AbstractBackground: Dental caries remains highly prevalent despite multiple preventive regimens. Silver diamine fluoride (SDF) is a potent caries-arresting and remineralizing agent, but its major limitation is tooth discolouration, whereas acidulated phosphate fluoride (APF) gel promotes remineralization with minimal staining. Combining SDF with APF gel may enhance remi-neralization and antibacterial efficacy while reducing SDF-associated darkening.Aim: To evaluate and compare the effect of SDF, APF gel and a combination of SDF + APF gel on enamel microhardness, antibacterial efficacy and darkening effect in vitro.Materials and Methods: Sixty extracted sound permanent anterior teeth were demineralized and randomly divided into three groups (n = 20): 38% SDF, APF gel and SDF + APF gel. Baseline and post-treatment microhardness were measured using a Vickers hardness tester. Colour change was assessed with a spectrophotometer, and antibacterial efficacy against Strep-tococcus mutans was evaluated on Mitis salivarius agar using the agar well diffusion method.Results: All three agents increased enamel microhardness and showed antibacterial activity. The SDF + APF group exhibited microhardness and antibacterial efficacy comparable to SDF alone, with a relatively reduced darkening effect. APF gel alone produced effective remineralization and antibacterial action with minimal discolouration but was less effective overall than the combination.Conclusion: SDF, APF gel and their combination effectively enhanced remineralization and inhibited bacterial growth in vitro. The SDF + APF combination appears to be a promising esthetic, antimicrobial and remineralizing option, though further clinical studies are needed to confirm these findings.