Introduction: This study aimed to compare the efficacy of MTAD, GLYDE and EDTA in removing the post-preparation smear layer and debris produced in apical third of curved molar root canals.Materials and Methods: Forty extracted human maxillary first molars with curved mesiobuccal canals (30°-35°), similar root lengths and morphologies were divided into 3 experimental groups (n=12) and one control group (n=4). Canals were prepared by RaCe rotary files and were treated with the following materials between each two files: Group A (control group); 5 mL of distilled water, Group B; 1 mL of 17% ethylenediamine tetra-acetic acid (EDTA) for 1 min, Group C; BioPureTM MTAD (according to the manufacturer’s instruction; 5mL for 5 min), and Group D; GLYDE File Prep alternated with sodium hypochlorite (NaOCl) between each two files. Debridement of the apical third was evaluated using scanning electron microscope (SEM) (×5000). The data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U tests (P<0.05).Results: Statistical analysis of the data showed that MTAD and 17% EDTA were effective in removing smear layer and debris from the apical thirds. MTAD was more effective than EDTA in smear layer removal. GLYDE did not adequately debride curved root canals of molar teeth. Conclusion: MTAD and 17% EDTA were effective in debriding the apical third of curved molar root canals during endodontic treatment, whereas GLYDE File Prep does not provide adequate debridement.

Objectives: Different chelators may be used during root canal treatment, offering various advantages including lubricant effect inside the canal and smear layer removal. However, chelator residues in narrow root canals can lead to apical microleakage. The aim of this in-vitro study was to compare apical microleakage following the use of three root canal chelators via fluid filtration method in root canals instrumented with ProTaper rotary system.Methods: Sixty-eight distobuccal canals of maxillary first molars were randomly divided into six groups of four experimental (n=15) and a positive and a negative control group (n=4). In groups one to three, RC-Prep, 17% EDTA and GLYDE File Prep were used as chelators, respectively and sodium hypochlorite (NaOCl) was used as irrigant in all groups except for group four. In group four, root canals were instrumented without chelators and only saline was used for irrigation. Root canals in all groups were prepared using ProTaper rotary system up to F2 file and filled using cold lateral condensation technique with gutta-percha and AH26 sealer. Apical microleakage was assessed by fluid filtration method. The data were subjected to Kruskal-Wallis test.Results: No significant differences were noted among the experimental groups regarding apical microleakage (p>0.05). However, preparations with RC Prep+NaOCl and GLYDE File Prep+NaOCl yielded the highest and the lowest values of apical microleakage, respectively.Conclusion: Use of different chelators did not cause statistically significant difference in apical microleakage of root canals.