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.