Effectiveness of Three Rotary NiTi Instruments and Hand Instrumentation in Removing Gutta Percha from Root Canals: an in Vitro Study

Objectives: The study aimed to assess variation in the remaining filling material by radiographic analysis and the time taken for retreatment system, with H-files; the ProTaper Universal Retreatment System; Mtwo Retreatment system and the SybronEndo K3. Methods: 120 human mandibular premolars with single straight ischolar_main canals were prepared with rotary twisted files (up to size 40/0.04) using the crown down technique and filled by cold lateral compaction and the radiographs were taken. After one week, teeth were divided into four groups (n = 30). Gutta-Percha was removed using H-files, the ProTaper Universal Retreatment System, Mtwo system and the K3 System. After retreatment radiographs were taken for each sample and the remaining material was calculated for each canal third. Results: Rotary NiTi instruments were significantly faster than the hand instrumentation technique in performing the retreatment. In radiographic analysis there was significant difference in between the groups for coronal third in ProTaper group and for apical third in H-file group. Conclusions: In the radiographic analysis the ProTaper Universal Retreatment System left less filling material in the coronal third and the H-files left less filling material in apical third as compared to other groups. Rotary instruments worked faster than H files.