title: Efficacy of Quantec rotary instruments for gutta-percha removal.
abstract: OBJECTIVE
  The purpose of this study was to evaluate Quantec SC rotary instruments for removal of gutta-percha during retreatment of straight root canals.
  
  
  METHODS
  The root canals of 30 central incisors were instrumented and obturated before the teeth were randomly divided into three groups of 10 specimens each. Quantec SC rotary instruments and a 16:1 reduction handpiece powered by an electric motor were then used to remove the gutta-percha and sealer from canals. A different speed was used in each group (group 1, 350 r.p.m.; group 2, 700 r.p.m.; and group 3, 1500 r.p.m.). The followings factors were evaluated: time taken to reach working length, time for gutta-percha removal, total time, apically extruded material during filling removal and number of fractured instruments. Radiographs were taken after the filling removal and after the canal wall cleanliness was evaluated. The teeth were grooved longitudinally, divided, and the walls of each half were evaluated visually for cleanliness. They were then digitized using a scanner and the residual debris measured.
  
  
  RESULTS
  The group in which a speed of 1500 r.p.m. was used had significantly faster treatment than the other groups. The amount of apically extruded material was not significantly different between groups. The only significant difference between groups for canal cleanliness was the middle third by radiographic evaluation: the group of 350 r.p.m. had larger amount of debris than the others. In group 1, six instruments fractured; in group 2, four instruments fractured; and in group 3, one instrument fractured.
  
  
  CONCLUSIONS
  Cleanliness and residual debris were equivalent for each group, but the use of 1500 r.p.m. speed was more rapid and fewer instruments fractured.
authors: Department of Endodontics, Bauru School of Dentistry, University of São Paulo, Brazil. bramante@usp.br
authors: C M
authors: CM
authors: Bramante
authors: L V
authors: LV
authors: Betti
mesh_terms: D000704:Analysis of Variance; D003754:Dental High-Speed Equipment; D003762:Dental Instruments; D004868:Equipment Failure; D006171:Gutta-Percha; D006801:Humans; D007180:Incisor; D009532:Nickel; D019233:Retreatment; D018915:Root Canal Preparation / Q000295:instrumentation*; D018709:Statistics, Nonparametric; D013997:Time Factors; D014025:Titanium
chemical_list: C040654:titanium nickelide; D009532:Nickel; D006171:Gutta-Percha; D014025:Titanium