Comparison of debris extruded apically and working time used by proTaper Universal rotary and ProTaper retreatment system during gutta-percha removal

Objective: the aim of this study was to evaluate the in vitro action of protaper retreatment files and protaper universal in the retreatment of mandibular premolars. material and methods: the amount of debris extruded apically was measured and the time to reach the working length and to complete the removal of gutta-percha was observed. thirty teeth had their canals prepared using protaper universal files and were obturated by the single cone technique. the teeth were then stored at 37°c in a humid environment for 7 days. during the use of the rotary instruments for root canal filling removal,the apical portions of the teeth were attached to the open end of a resin tube to collect the apically extruded debris. results: protaper universal files were significantly faster (p=0.001l) than the protaper retreatment files to perform gutta-percha removal,but no significant difference was found between the files regarding the time to reach the working length or the amount of apical extrusion. conclusions: protaper universal rotary had better results for endodontic retreatment,and both techniques promote similar apical extrusion of debris.