title: A comparative evaluation of gutta percha removal and extrusion of apical debris by rotary and hand files.
abstract: OBJECTIVE
  The aim of this study was to evaluate the efficacy of Protaper retreatment files in comparison with RaCe, K3 and H-files for removal of gutta-percha and apically extruded debris using volumetric analysis.
  
  
  METHODS
  Forty extracted single rooted maxillary incisor teeth with straight canals and mature apices were selected for the study. After access cavity preparation, apical patency was confirmed with a size 10 K-file extending 1mm beyond the point at which it was first visible at the apical end. Working lengths were determined with the use of size 15 K-file. The canals were prepared in a step-back technique and the master apical file was size 30 for all teeth. 3% sodium hypochlorite was used as an irrigant after each instrumentation. Before final rinse, size 20 K-file was passed 1mm beyond the apex to remove any dentinal shaving plugs and maintain the apical patency. Then the canals were dried with paper points. The root canal was filled using standard gutta-percha points and zinc oxide eugenol sealer under lateral condensation technique. The teeth were then randomly divided into four groups of ten teeth each based on the instrument used for gutta percha removal. All the rotary instruments used in this study were rotated at 300rpm. The instruments used were: Group 1 - RaCe Files, Group 2 - ProTaper retreatment Files, Group 3 - K3 Files and Group 4 - H Files. The volume of the obturating material was calculated before and after removal using volumetric analysis with spiral CT. The removal efficacy with each instrument was calculated and statistically analysed.
  
  
  RESULTS
  The results of the study show that the ProTaper retreatment files (Group 2) (97.4%) showed the highest efficiency in the removal of obturating material, which was followed by RaCe (95.74%), K3 (92.86%) and H files (90.14%) with the efficiency in the decreasing order. Similarly the mean apical extrusion in H files (0.000 ± 0.002) was significantly lower than all the rotary instruments. However, the difference among the rotary files were not statistically significant (p>0.05).
  
  
  CONCLUSIONS
  ProTaper retreatment files show significant difference over other groups in removal of obturating material and can be the system of choice in endodontic retreatment procedures.
authors.affiliation: Lecturer, Department of Conservative Dentistry & Endodontics, JKK Dental College , Komarapalayam, Tamilnadu, India .
authors.lastname: Chandrasekar
authors.affiliation: Professsor, Department of Conservative Dentistry & Endodontics, Madha Dental College , Kundrathur, Chennai, Tamilnadu, India .
authors.forename: A V Rajesh
authors.initials: AV
authors.lastname: Ebenezar
authors.affiliation: Professsor, Department of Conservative Dentistry & Endodontics, JKK Dental College , Komarapalayam, Tamilnadu, India .
authors.forename: Mohan
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Principal and Professor, Department of Conservative Dentistry & Endodontics, JKK Dental College , Komarapalayam, Tamilnadu, India .
authors.forename: A
authors.initials: A
authors.lastname: Sivakumar
keywords: Extruded debris; Gutta-percha; Protaper retreatment file