title: Comparison of ProTaper, RaCe and Safesider instruments in the induction of dentinal microcracks: a micro-CT study.
abstract: OBJECTIVE
  To evaluate ex vivo the incidence of microcracks in root dentine after canal preparation with ProTaper Universal (PTU), RaCe or Safesider instrumentation systems using microcomputed tomography (micro-CT).
  
  
  METHODS
  Thirty freshly extracted mandibular molars with two separate mesial canals and foramina were used. The roots were allocated into three similar groups according to curvature angles and radii of the canals and lengths of the roots. Distal roots were removed and mesial roots were embedded in acrylic resin and instrumented with the PTU, RaCe or Safesider systems up to size 30 (F3 for PTU, size 30, 0.04 taper for RaCe and Safesider) for all instrumentation groups. Dentinal microcracks were evaluated on micro-CT images of the apical 10 mm of the roots with 1-mm intervals. Two experienced observers evaluated the images twice in a blinded fashion. The presence of dentinal microcracks (complete/incomplete cracks and craze lines) was noted and analysed statistically using McNemar and chi-square tests (P = 0.05).
  
  
  RESULTS
  There were microcracks on uninstrumented root sections. All instrumentation systems significantly increased the number of dentinal microcracks when compared to preoperative specimens (P < 0.05). There were new microcracks on the postoperative samples. The PTU system (42%) led to greater number of post-instrumentation microcracks than Safesider (35%) and RaCe (25%) systems, respectively. The difference between PTU and RaCe system was significant (P < 0.05).
  
  
  CONCLUSIONS
  All instrumentation systems significantly increased the number of microcracks compared with preoperative specimens. The PTU system generated more post-instrumentation dentinal microcracks than the RaCe system.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: K T
authors.initials: KT
authors.lastname: Ceyhanli
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ege University, İzmir, Turkey.
authors.forename: N
authors.initials: N
authors.lastname: Erdilek
authors.affiliation: Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
authors.forename: I
authors.initials: I
authors.lastname: Tatar
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: D
authors.initials: D
authors.lastname: Celik
mesh_terms: D003804:Dentin / Q000293:injuries*; D006801:Humans; D008963:Molar / Q000000981:diagnostic imaging / Q000293:injuries; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation*; D014082:Tooth Fractures / Q000000981:diagnostic imaging* / Q000209:etiology; D055114:X-Ray Microtomography
keywords: dentine defects; microcomputed tomography scan; reciprocation; rotary