title: Canal transportation and centring ability of RaCe rotary instruments.
abstract: OBJECTIVE
  Evaluate, through computerized tomography, canal transportation and centring ability of RaCe rotary instruments after preparation of mesiobuccal root canals in maxillary molar teeth.
  
  
  METHODS
  Twenty-seven teeth were submitted to three cone beam tomographic analyses, one preoperatively, and two after preparation with file size 35, .02 taper and size 50, .02 taper. Canal transportation and centring ability were measured with reference to the distance between the noninstrumented portion of the root canals and the mesial and distal periphery of the root, compared with images obtained after the preparation with size 35 and 50 instruments.
  
  
  RESULTS
  Canal transportation after preparation with the size 35 file was 0.030 +/- 0.253 mm and after the size 50 file was 0.057 +/- 0.317 mm. The centring ratio values after preparation with the size 35 file was 0.42 +/- 0.32 and after the size 50 file was 0.54 +/- 0.29, with no significant statistical difference between the groups.
  
  
  CONCLUSIONS
  RaCe instruments allowed the preparation of curved root canals with preparation diameters larger than those normally used with minimal canal transportation and adequate centring ability.
authors.affiliation: Department of Endodontics, University of Ribeirão Preto (UNAERP), Ribeirão Preto, SP, Brazil.
authors.forename: B
authors.initials: B
authors.lastname: Pasternak-Júnior
authors.forename: M D
authors.initials: MD
authors.lastname: Sousa-Neto
authors.forename: R G
authors.initials: RG
authors.lastname: Silva
mesh_terms: D054893:Cone-Beam Computed Tomography; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D004867:Equipment Design; D006801:Humans; D008437:Maxilla; D008963:Molar; D018915:Root Canal Preparation / Q000295:instrumentation*; D019227:Tooth Apex / Q000033:anatomy & histology* / Q000000981:diagnostic imaging