title: Micro-computed tomography evaluation of the preparation of mesiobuccal root canals in maxillary first molars with Hyflex CM, Twisted Files, and K3 instruments.
abstract: BACKGROUND
  The aim of this study was to describe the canal shaping properties of Hyflex CM, Twisted Files (TF), and K3 rotary nickel-titanium files by using micro-computed tomography in maxillary first molars.
  
  
  METHODS
  A total of 36 mesiobuccal root canals of maxillary first molars were prepared with Hyflex CM, TF, or K3 system. Micro-computed tomography was used to scan the specimens before and after instrumentation. The volume of untreated canal, volume of dentin removed after preparation, amount of uninstrumented area, and the transportation for the coronal, middle, and apical thirds of canals were measured.
  
  
  RESULTS
  Instrumentation of canals increased their volume and surface area. TF group showed the greatest amount of volumetric dentin removal (P < .05), whereas no significant difference was found in Hyflex CM and K3 groups. There were no significant differences among instrument types concerning uninstrumented area. The TF system produced significantly less transportation than the K3 system in the apical third of canals. No significant difference was found between TF and Hyflex CM instruments relating to apical transportation.
  
  
  CONCLUSIONS
  In vitro, Hyflex and TF instruments shaped curved root canals in maxillary first molar without significant shaping errors.
authors: State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors: Dan
authors: D
authors: Zhao
authors: Ya
authors: Y
authors: Shen
authors: Bin
authors: B
authors: Peng
authors: Markus
authors: M
authors: Haapasalo
mesh_terms: D000704:Analysis of Variance; D006801:Humans; D008963:Molar; D018915:Root Canal Preparation / Q000295:instrumentation*; D018709:Statistics, Nonparametric; D055114:X-Ray Microtomography