Objectives: This study aimed to compare retreatment times of different NiTi enstrumantationsystems used for removal of different root canal filling materials.Materials and Methods: Sixty single rooted human mandibular premolar teeth were used. Theroot canals were prepared with Mtwo NiTi rotary files and irrigated with 2 mL of 5.25% NaOClbetween each file. Specimens were divided into 4 groups (n=15). The root canals were obturatedwith gutta-percha and root canal sealer by cold lateral compaction. Resin sealer was used inGroup 1 and 2, while MTA based root canal sealer was used in Group 3 and 4. Following settingof sealers, ProTaper Retreatment set was used to remove the root canal filling in Groups 1 and3, whereas Reciproc R25 was used to remove the root canal filling in Groups 2 and 4. Durationto reach the working length was recorded with chronometer. Data was analyzed with one-wayANOVA.Results: MTA based root canal sealer was detected to be removed faster than resin sealers.When comparing retreatment systems, ProTaper Retreatment file system reached to theworking length faster than Reciproc R25 did.Conclusions: In conclusion, we report that ProTaper retreatment set is more efficient thanReciproc R25 file for removal of root canal filling, and removal of MTA based root canal sealersare easier than resin sealers
