Efficacy of EDTA, glycolic acid, and ethanol in removing calcium hydroxide from the apical third: A SEM study

Objective: This study aimed to evaluate the effectiveness of 17% ethylenediaminetetraacetic acid (EDTA), 10% glycolic acid (GA), and 70% ethanol as final irrigation solutions for removing calcium hydroxide [Ca(OH)₂] from the apical third of root canals. Materials and Methods: Seventy-six extracted single-rooted human mandibular premolars were instrumented and irrigated with 10 mL of 2.5% sodium hypochlorite followed by 2 mL of 17% EDTA. Ca(OH)₂ paste was placed in the canals, and specimens were stored at 37°C and 100% humidity for seven days. Samples were randomly assigned to three experimental groups (n=22 each) and two control groups (n=5 each). Final irrigation was performed using 6 mL of either 70% ethanol (Group 1), 17% EDTA (Group 2), or 10% GA (Group 3), with all groups receiving sonic activation. Control groups were irrigated with distilled water. Roots were sectioned buccolingually, and the apical third was evaluated using scanning electron microscopy (SEM) at 2000× m agnification. Residual Ca(OH)₂ was assessed using Salgado's five-grade scale. Results: Interobserver reliability was high (c = 0.737-0.835). EDTA and GA groups showed no significant differences in scores 1, 4, and 5 (p > 0.05). The ethanol group was significantly less effective than EDTA and GA (p < 0.001). No significant differences were observed among groups for score 2, and GA and ethanol were comparable for score 3 (p > 0.05). Conclusion: EDTA and GA demonstrated similar and superior efficacy in removing Ca(OH)₂ from the apical third. Ethanol was significantly less effective. Complete removal was not achieved with any solution.