Comparative evaluation of different root canal irrigants on the mechanical properties of root dentin - an in vitro study

Different concentrations of Sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA), and Cetrimide have varied effects on the mechanical properties of endodontically treated teeth. AIM: This study aims to evaluate the mechanical properties of root dentin after exposure to different endodontic irrigating solutions. Methods: This in-vitro study evaluated the effect of different irrigation regimens on the flexural strength and Knoop microhardness of root dentin. The sample size was estimated to be a total of 56 samples (40 samples for flexural strength and 16 samples for microhardness). For flexural strength, dentin beams (12×2×1mm) were obtained from roots and randomly divided into five groups based on the irrigation regimen: Group I: 5% NaOCl + 17% EDTA, Group II: 5% NaOCl + 17% EDTA + 0.2% Cetrimide, Group III: 3% NaOCl + 17% EDTA. Group IV: 3% NaOCl + 17% EDTA + 0.2% Cetrimide, Group V (Control): Normal saline. Flexural strength was measured using a three-point bending test on a universal testing machine. while root dentin discs were tested for Knoop microhardness before and after irrigation. Statistical analysis was performed using SPSS (Version 26.0). Data were analyzed with descriptive statistics, paired t-test, and One-Way ANOVA followed by Tukey’s HSD post hoc test, after confirming normal distribution. A p-value < 0.05 was considered statistically significant. Results: Flexural strength testing showed that Group 2 had the greatest reduction in strength, which was significantly lower than the control (p < 0.05), though not significantly different from other experimental groups. Groups 3 and 4 showed moderate, non-significant reductions. For microhardness, all experimental groups showed a decrease in Knoop values post-irrigation, but no statistically significant differences were found among them. Conclusion: High-concentration NaOCl with cetrimide significantly reduced dentin flexural strength, while microhardness changes were minimal; lower NaOCl levels caused less structural weakening, indicating a safer irrigation approach. Cetrimide’s role as a surfactant improves penetration of irrigants but may amplify damage when used with strong oxidizers.