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

## TL;DR

This study examines how different ways of applying silver diamine fluoride affect dentin hardness and its resistance to acid over time.

## Contribution

The study introduces a comparison of SDF application methods to determine their impact on dentin microhardness and durability under acid exposure.

## Key findings

- All SDF application methods significantly increased dentin microhardness after demineralization.
- The acid challenge showed no significant difference in microhardness between SDF-treated and control groups.
- Reapplication of SDF may be needed to maintain its effectiveness over time.

## Abstract

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.

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.

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).

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.