title: Comparison of Time Required by D-RaCe, R-Endo and Mtwo Instruments for Retreatment: An in vitro Study.
abstract: BACKGROUND
  To evaluate and compare the amount of time required by three rotary NiTi instruments in removing gutta-percha from root canal during retreatment with hand file as control.
  
  
  METHODS
  Eighty human mandibular premolars with single straight root canals were prepared and obturated by cold lateral condensation with gutta-percha and AH Plus sealer. After two weeks, the 80 teeth were divided into one control group and 3 retreatment groups (n = 20 each). Gutta-percha was removed using H-files, the D-RaCe, or the Mtwo or the R-Endo retreatment systems. Retreatment time was calculated using stopwatch.
  
  
  RESULTS
  D-RaCe and Mtwo required significantly less time than R-Endo and hand file. Hand file took maximum time, which was significantly slower than all groups. However, D-RaCe and Mtwo retreatment time was statistically insignificant.
  
  
  CONCLUSIONS
  D-RaCe and Mtwo remove gutta-percha faster than R-Endo and Hand files.
authors: Post graduate Student, Department of Conservative Dentistry & Endodontics, Kanti Devi Dental College and Hospital , Mathura, Uttar Pradesh, India .
authors: Akansha
authors: A
authors: Garg
authors: Reader, Department of Conservative Dentistry & Endodontics, Kanti Devi Dental College and Hospital , Mathura, Uttar Pradesh, India .
authors: Ajay
authors: A
authors: Nagpal
authors: Professor and Head, Department of Conservative Dentistry & Endodontics, Kanti Devi Dental College and Hospital , Mathura, Uttar Pradesh, India .
authors: Shashit
authors: S
authors: Shetty
authors: Assistant Professor, Department of Conservative Dentistry & Endodontics, Kanti Devi Dental College and Hospital , Mathura, Uttar Pradesh, India .
authors: Sunil
authors: S
authors: Kumar
authors: Post Graduate Student, Department of Conservative Dentistry & Endodontics, Kanti Devi Dental College and Hospital , Mathura, Uttar Pradesh, India .
authors: Kamal Krishan
authors: KK
authors: Singh
authors: Reader, Department of Conservative Dentistry & Endodontics, Kanti Devi Dental College and Hospital , Mathura, Uttar Pradesh, India .
authors: Amit
authors: A
authors: Garg
keywords: Endodontic treatment; Gutta-Percha removal; Rotary endodontic Files