title: Torsional properties of pathfinding instruments.
abstract: BACKGROUND
  This study compared the torsional properties of 2 stainless steel endodontic pathfinding instruments: C-Pilot (VDW, Munich, Germany) and C(+) files (Maillefer/Dentsply, Ballaigues, Switzerland). Stainless steel conventional K-type instruments (KCC(+), VDW) were used as controls.
  
  
  METHODS
  File sizes 10 were subjected to a torsional assay in clockwise rotation. The 2 parameters evaluated were maximum torque and angular deflection at failure. The fractured surfaces and the helical shafts of the fractured instruments were then examined by scanning electron microscopy (SEM).
  
  
  RESULTS
  The results indicated that the angular deflection to fracture decreased in the following order: KCC(+) > C-Pilot > C(+). As for the maximum torque values, the results revealed the following descending order: C(+) > KCC(+) > C-Pilot. SEM analysis revealed that plastic deformation occurred along the helical shaft of the fractured instruments and that the fractured surfaces were of the ductile type.
  
  
  CONCLUSIONS
  The instruments tested showed different torsional behavior depending on the parameter evaluated. Considering that high angular deflection values may serve as a safety factor for instruments used as pathfinders, the conventional K file showed significantly better results than both C-Pilot and C(+) files.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: Hélio P
authors.initials: HP
authors.lastname: Lopes
authors.forename: Carlos N
authors.initials: CN
authors.lastname: Elias
authors.forename: Giorgiana
authors.initials: G
authors.lastname: Amaral
authors.forename: Victor T L
authors.initials: VT
authors.lastname: Vieira
authors.forename: Edson J L
authors.initials: EJ
authors.lastname: Moreira
authors.forename: Marcelo
authors.initials: M
authors.lastname: Mangelli
authors.forename: José F
authors.initials: JF
authors.lastname: Siqueira
mesh_terms: D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000601:surgery*; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D018915:Root Canal Preparation / Q000295:instrumentation*; D054159:Torsion, Mechanical