title: Evaluation of the root canal shaping ability of two rotary nickel-titanium systems.
abstract: OBJECTIVE
  The aim was to investigate the canal shaping abilities of the twisted file (TF) and GT series X file (GTX) systems.
  
  
  METHODS
  Sixty mesial root canals of mandibular molars with curvatures of 15-50° were divided randomly into two groups of 30 canals each. The teeth were sectioned horizontally at 3, 6 and 9 mm from the apex. Root canals were prepared with TF and GTX files, respectively, and the shaping abilities of the systems were evaluated at three levels (coronal, middle and apical) based on the comparison of pre- and post-instrumentation photographs using AutoCAD software. Preparation time was also assessed. Data from the two groups were compared statistically using the Student's t-test.
  
  
  RESULTS
  There was no significant difference between the rotary systems in terms of change in root canal cross-sectional area, root canal transportation, centring ability or minimum dentine thickness. Remaining dentine thickness at the coronal and middle levels was similar in the TF and GTX groups, but GTX instruments left significantly less dentine than TF instruments on the mesial aspects of root canals at the apical level. Root canal preparation with TF instruments required significantly less time than with GTX instruments.
  
  
  CONCLUSIONS
  The TF and GTX NiTi rotary instruments showed similar shaping abilities, but root canal preparation was more rapid with the TF than with the GTX system.
authors.affiliation: Division of Endodontics, Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
authors.forename: K K
authors.initials: KK
authors.lastname: Al-Manei
authors.forename: S M S
authors.initials: SM
authors.lastname: Al-Hadlaq
mesh_terms: D003786:Dental Pulp Cavity; D004708:Endodontics / Q000295:instrumentation*; D006801:Humans; D009532:Nickel; D014025:Titanium
chemical_list: D009532:Nickel; D014025:Titanium
keywords: GTX; canal preparation; preparation time; rotary nickel-titanium instruments; shaping ability; twisted file