Aim To compare the weight of apically extruded debris produced during the removal of root canal filling material using various files in extracted teeth with simulated apical root resorption. Methodology The root canals of one hundred and twenty extracted mandibular premolar teeth were prepared with Revo-S files and filled using a cold lateral compaction technique with gutta-percha and a resin-based sealer (AdSeal; Meta-Biomed, Cheongwon, Korea). Sixty teeth were randomly assigned to four control groups (hand file, ProTaper Universal retreatment file, D-RaCe retreatment file, and Reciproc file) for the removal of root canal filling material. The apical portion of the remaining 60 teeth was modified to simulate apical root resoption, and the teeth were then randomly divided into 4 experimental groups (using the same techniques as in the control groups) for the removal of root canal filling material. Apically extruded debris was collected into pre-weighed Eppendorf tubes and then dried. The mean weight of the apically extruded debris was assessed with an analytical balance to an accuracy of 10(-4) g. Data were analysed using two-way analysis of variance and a Tukey's post hoc test. Results In the simulated apical root resorption groups, all file systems were associated with significantly more debris extrusion compared to the groups without simulated resorption (P < 0.05). The amount of apically extruded debris was greatest in the hand file groups compared with the other groups (P < 0.05). In the groups with simulated apical root resorption, the Reciproc system was associated with the least weight of apically extruded debris (P < 0.05), whereas there was no significant difference between the ProTaper Universal retreatment and D-RaCe files (P > 0.05). In the groups without simulated apical root resorption, there was no significant difference between Reciproc, ProTaper Universal retreatment and D-RaCe retreatment files (P> 0.05). The time required to remove the root canal filling material was as follows: hand file > ProTaper Universal retreatment = D-RaCe retreatment > Reciproc (P < 0.05). Conclusions The weight of apically extruded debris was significantly greater in teeth with simulated apical root resorption than in those teeth without simulated apical root resorption. Hand files were associated with significantly more apically extruded debris in all groups during removal of root canal filling material.