Evaluating the Impact of Citric Acid Solution at Various Concentrations on MTA and Dentin Microhardness

Aim: Mineral trioxide aggregate (MTA) is widely used in endodontic treatments due to its sealing ability, biocompatibility, and osteoinductive properties. However, the removal of set MTA during retreatment procedures remains challenging. This study aimed to evaluate the effect of different concentrations of citric acid (10%, 25%, and 40%) on the microhardness of set MTA and dentin. Materials and Methods: Forty-eight extracted single-rooted human teeth were prepared, and 1.3 mm diameter cavities were filled with Bio-C Repair MTA. After a 21-day setting period, initial Vickers microhardness measurements were taken. The samples were randomly assigned to four groups: 10% citric acid, 25% citric acid, 40% citric acid, and 17% EDTA (control). Solutions were applied for 15 minutes with intermittent ultrasonic activation. Post-treatment microhardness values were recorded, and percentage reductions were calculated. Statistical analysis was performed using one-way ANOVA and paired-sample t-tests (α=0.05). Results: All tested solutions reduced MTA and dentin microhardness. The 25% and 40% citric acid groups showed the highest reduction in MTA microhardness, whereas 40% citric acid also caused significant dentin microhardness loss (p<0.001). The 25% citric acid solution effectively reduced MTA microhardness without a significant impact on dentin microhardness. Conclusion: The findings suggest that 25% citric acid may facilitate MTA removal while preserving dentin microhardness, making it a promising solution for retreatment procedures. However, higher concentrations (40%) may compromise dentin microhardness. Further studies are needed to determine optimal clinical conditions.