Effect of Silver Diamine Fluoride Application Methods on Dentin Microhardness and Durability Under pH Cycling: An In Vitro Study

Objectives This study investigated the effects of various application methods of silver diamine fluoride (SDF) on dentin microhardness and its durability under a 14‐day acid challenge. The primary goal was to identify an optimal conservative SDF application protocol for clinical dentistry. Material and Methods Mid‐coronal dentin disc samples from human premolars were prepared through two horizontal cuts and polished. Samples were randomly divided into three groups of ten: (1) SDF‐NR (SDF applied for 3 min, excess removed with cotton); (2) SDF‐R‐R (SDF applied, rinsed, and polished after 24 h); (3) SDF‐R (SDF applied for 3 min, then rinsed). Vickers microhardness was measured at three stages: initial, post‐demineralization, and post‐SDF application. In the second phase, a control group (no SDF) and a test group (SDF‐R) underwent a 14‐day pH‐cycling regimen, with final hardness changes evaluated at a significance level of 0.05. Results Significant microhardness increases were observed in all groups following SDF application compared to demineralized conditions ( p = 0.001). Although the decrease in microhardness after acid challenge in the SDF group was less than in the control group, this difference was not statistically significant ( p = 0.423). Conclusion Different SDF application methods significantly enhance dentin microhardness post‐demineralization. Nevertheless, the acid challenge revealed minimal differences between the control and test group, indicating that reapplication of SDF may be necessary for sustained effectiveness.