title: Effectiveness of ProTaper, D-RaCe, and Mtwo retreatment files with and without supplementary instruments in the removal of root canal filling material.
abstract: OBJECTIVE
  To assess the efficacy of different retreatment rotary files in removing gutta-percha and endodontic sealer from canals.
  
  
  METHODS
  Ninety straight single-rooted premolars were prepared up to a size 30 and filled with gutta-percha and sealer and then randomly assigned to six retreatment groups (n = 15). Groups I, III, and V were retreated using rotary systems ProTaper Universal Retreatment (PTUR), D-RaCe, and Mtwo Retreatment, respectively. Groups II, IV, and VI were retreated using the additional instruments F4, size 40, .04 taper RaCe, and size 40, .04 taper Mtwo, respectively. The roots were split vertically, and images of the halves were obtained using a high-resolution scanner and evaluated with AutoCAD software to calculate the percentage of residual material. Data were analyzed with Kruskal-Wallis and Student-Newman-Keuls tests using a 5% significance cutoff (P < 0.05).
  
  
  RESULTS
  There were no statistically significant differences (P > 0.05) between groups when additional instruments were used. The percentage of residual material was lowest in the PTUR group and was statistically significant only when compared to the D-RaCe system (P = 0.0038).
  
  
  CONCLUSIONS
  All root canals had residual filling material after retreatment even when additional instruments were used.
authors.affiliation: Positivo University, Curitiba, Parana, Brazil.
authors.forename: B
authors.initials: B
authors.lastname: Marques da Silva
authors.forename: F
authors.initials: F
authors.lastname: Baratto-Filho
authors.forename: D P
authors.initials: DP
authors.lastname: Leonardi
authors.forename: A
authors.initials: A
authors.lastname: Henrique Borges
authors.forename: L
authors.initials: L
authors.lastname: Volpato
authors.forename: F
authors.initials: F
authors.lastname: Branco Barletta
mesh_terms: D001641:Bicuspid; D003762:Dental Instruments; D006171:Gutta-Percha; D006801:Humans; D009532:Nickel; D019233:Retreatment / Q000295:instrumentation; D012387:Root Canal Filling Materials; D012390:Root Canal Therapy / Q000295:instrumentation*; D018709:Statistics, Nonparametric; D014025:Titanium
chemical_list: D012387:Root Canal Filling Materials; C040654:titanium nickelide; D009532:Nickel; D006171:Gutta-Percha; D014025:Titanium