Investigation of the effect of boric acid in different concentrations on dentin microhardness

Purpose: This study compared the effects of different irrigation solutions on the microhardness of root dentin.
Methods: Fifty single-rooted human teeth were chosen, and the roots were randomly divided into five groups (n = 10) according to the irrigant used for 5 min: 17% ethylenediaminetetraacetic acid (EDTA), 2% boric acid (BA), 5% BA, 10% BA, and distilled water (DW). After the irrigation procedure, dentin surface microhardness was calculated using a Vickers indenter 100 μm from the root canal lumen. Comparisons between the groups were performed with a two-way ANOVA test and and Tukey’s multiple comparison test (p = 0.05).
Results: All irrigation solutions decreased the microhardness of root canal dentin. The DW and 2% BA had a minimum effect on the microhardness of root canal dentin, whereas a significant decrease in surface microhardness was found in 10% BA group (p < 0.05). The coronal third of the 10% BA group showed the lowest percentage decrease, with a significant difference between the apical and middle thirds (p < 0.05).
Conclusion: In this study, 5% BA and 17% EDTA showed similar effects on the microhardness of root canal dentin. Further clinical research is required to evaluate the biocompatibility and safety of BA solutions.