SummaryAim: to evaluate the amount of debris extruded apically as well as the time needed for removal of root canal filling material using ProTaper, MTwo, REndo NiTi rotary retreatment systems and hand files.Materials and methods: 60 freshly extracted human single-rooted teeth were instrumented with Protaper files and obturated with gutta-percha and MTA Fillapex sealer with the cold lateral compaction technique. Teeth were then randomly assigned to 4 groups. ProTaper, MTwo, REndo rotary retreatment systems and Hedstroem hand files were utilized for root canal filling removal. Debris extruded apically was collected into pre-weighed vials. The weight of the dry extruded debris was established by subtracting the pre-retreatment and post-retreatment weight of vials. Time needed for reaching WL, complete removal of gutta-percha and total retreatment time were also recorded with a stopwatch. The data obtained were analyzed using One-way ANOVA (the level of significance was set at P=0.05).Results: Hand instrumentation caused significantly more debris extrusion compared with rotary systems (P<0.001). There was no significant difference among the other groups (P>0.05). Hedstroem hand files needed significantly more time for the completion of the retreatment procedure than rotary systems (P<0.001). Among rotary retreatment files, ProTaper completed the procedure significantly quicker than MTwo and REndo (P<0.001).Conclusion: Rotary retreatment files caused less apical extrusion of debris and needed less time for the completion of the retreatment procedure compared to hand files.

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