# Evaluation of the effect of gallic acid dentin treatment on the shear bond strength of the composite resin by using universal adhesive, in self-etch and total-etch strategies

## TL;DR

This study shows that treating dentin with gallic acid increases the bond strength of composite resin using a universal adhesive in both self-etch and total-etch methods.

## Contribution

The study demonstrates that gallic acid enhances the shear bond strength of composite resin to dentin when used with a universal adhesive.

## Key findings

- 1% and 2% gallic acid significantly increased shear bond strength compared to controls in both etching methods.
- 1% gallic acid produced higher bond strength than 2% in both self-etch and total-etch strategies.
- Total-etch method consistently showed higher bond strength than self-etch, regardless of gallic acid concentration.

## Abstract

Gallic acid (GA), as a material with potentially beneficial effects in dentistry, was used in this study to investigate whether it affects the shear bond strength of composite to the dentin via self-etch and total-etch strategies of a universal adhesive.

Sixty intact molars with sectioned flat occlusal surfaces were treated with 1 wt.% and 2 wt.% GA solution before applying the universal adhesive in self-etch and total-etch modes. They were randomly divided into six groups (n=10): 1) self-etch control, 2) total-etch control, 3) 1% GA + self-etch, 4) 2% GA + self-etch, 5) 1% GA + total-etch, and 6) 2% GA + total-etch. Teflon molds were fixed on the prepared dentin surface, and then the composite was inserted into the molds and light cured. After spending 24 hours in a storage condition with 100% humidity at room temperature, specimens underwent the SBS test. The SBS values calculated by the universal testing machine were analyzed using ANOVA and Tukey’s post hoc tests (p< 0.05).

The application of 1% and 2% GA before using the universal adhesive revealed a significant increase in the mean SBS values compared to respective control groups (p< 0.001, p< 0.001), and the mean values for 1% GA were significantly higher than 2% GA in both etching strategies (p< 0.001, p< 0.001). The groups that utilized the universal adhesive with the total-etch method exhibited statistically higher SBS values than those using the self-etch approach, irrespective of applying GA and its concentration (p< 0.001).

Applying 1% and 2% GA improved the shear bond strength of composite resin to the dentin in both self-etch and total-etch approaches with the universal adhesive. These findings indicate that GA holds great potential for expanded clinical applications.

Key words:Gallic acid, shear bond strength, universal adhesive.