title: Incidence of Dentinal Cracks after Root Canal Preparation with Twisted File Adaptive Instruments Using Different Kinematics.
abstract: BACKGROUND
  The purpose of the present study was to assess the effect of root canal instrumentation using Twisted File Adaptive instruments (Axis/SybronEndo, Orange, CA) with different kinematics (adaptive motion, 90° clockwise [CW]-30° counterclockwise [CCW], 150° CW-30° CCW, 210° CW-30° CCW, and continuous rotation) on crack formation.
  
  
  METHODS
  One hundred five mandibular central incisor teeth were selected. Fifteen teeth were left unprepared (control group), and the remaining 90 teeth were assigned to the 5 root canal shaping groups as follows (n = 15): adaptive motion, 90° CW-30° CCW, 150° CW-30° CCW, 210° CW-30° CCW, continuous rotation, and hand file. All the roots were sectioned horizontally at 3, 6, and 9 mm from the apex with a low-speed saw under water cooling, and the slices were then viewed through a stereomicroscope at 25× magnification. Digital images of each slice were captured using a camera to determine the presence of dentinal cracks.
  
  
  RESULTS
  No cracks were observed in the control group, and the continuous rotation group had more cracks than the reciprocation groups (90° CW-30° CCW, 150° CW-30° CCW, and 210° CW-30° CCW) (P < .05). Both the continuous rotation and adaptive motion groups had significantly more dentinal cracks than the hand file group (P < .05). Regarding the different sections (3, 6, and 9 mm), there was a significant difference between the experimental groups at the 9-mm level (P < .05).
  
  
  CONCLUSIONS
  The incidence of dentinal cracks is less with TF Adaptive instruments working in 210° CW-30° CCW reciprocating motion compared with working in continuous rotation and adaptive motion.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey. Electronic address: dtertu@windowslive.com.
authors.forename: Ertuğrul
authors.initials: E
authors.lastname: Karataş
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: Hakan
authors.initials: H
authors.lastname: Arslan
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: Meltem
authors.initials: M
authors.lastname: Alsancak
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: Damla Özsu
authors.initials: DÖ
authors.lastname: Kırıcı
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Şifa University, İzmir, Turkey.
authors.forename: İbrahim
authors.initials: İ
authors.lastname: Ersoy
mesh_terms: D003804:Dentin / Q000293:injuries*; D004868:Equipment Failure; D006801:Humans; D007180:Incisor / Q000293:injuries; D009038:Motion; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation
keywords: Cracks; Twisted File Adaptive system; kinematics; root canal instrumentation