title: Influence of Heat Treatment of Nickel-Titanium Rotary Endodontic Instruments on Apical Preparation: A Micro-Computed Tomographic Study.
abstract: BACKGROUND
  The aim of this study was to make a 3-dimensional comparison of the canal transportation and changes in apical geometry using micro-computed tomographic imaging after canal preparation with K3 (SybronEndo, Orange, CA) and K3XF (SybronEndo) file systems.
  
  
  METHODS
  Twenty-eight mandibular molars were randomly divided into 2 groups according to the rotary system used in instrumentation: K3 or K3XF. The specimens were scanned by micro-computed tomographic imaging before and after instrumentation. Images before and after instrumentation from each group were compared with regard to canal volume, surface area, and structure model index (SMI) (paired t test, P < .05). After instrumentation, the canals from each group were compared regarding the changes in volume, surface area, SMI, and canal transportation in the last 4 apical mm (t test, P < .05).
  
  
  RESULTS
  Instrumentation with the 2 rotary systems significantly changed the canal volume, surface area, and SMI (P < .05). There were no significant differences between instrument types concerning these parameters (P > .05). There were no significant differences between the 2 groups with regard to canal transportation in the last 4 apical mm (P > .05).
  
  
  CONCLUSIONS
  Both rotary systems showed adequate canal preparations with reduced values of canal transportation. Heat treatment did not influence changes in root canal geometry in the apical region.
authors.affiliation: Department of Dental Clinic, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Bernardo Corrêa
authors.initials: BC
authors.lastname: de Almeida
authors.affiliation: Department of Dental Clinic, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Fabíola
authors.initials: F
authors.lastname: Ormiga
authors.affiliation: Department of Dental Clinic, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Marcos César Pimenta
authors.initials: MC
authors.lastname: de Araújo
authors.affiliation: Nuclear Instrumentation Laboratory, Federal University of Rio de Janeiro, Centro de Tecnologia, Ilha da Cidade Universitária, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Ricardo Tadeu
authors.initials: RT
authors.lastname: Lopes
authors.affiliation: Nuclear Instrumentation Laboratory, Federal University of Rio de Janeiro, Centro de Tecnologia, Ilha da Cidade Universitária, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Inayá Corrêa Barbosa
authors.initials: IC
authors.lastname: Lima
authors.affiliation: Nuclear Instrumentation Laboratory, Federal University of Rio de Janeiro, Centro de Tecnologia, Ilha da Cidade Universitária, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Bernardo Camargo
authors.initials: BC
authors.lastname: dos Santos
authors.affiliation: Department of Dental Clinic, Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address: heloisagusman@gmail.com.
authors.forename: Heloisa
authors.initials: H
authors.lastname: Gusman
mesh_terms: D000497:Alloys; D003722:Dental Alloys; D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006358:Hot Temperature; D006801:Humans; D008334:Mandible; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D018915:Root Canal Preparation / Q000295:instrumentation*; D055114:X-Ray Microtomography
chemical_list: D000497:Alloys; D003722:Dental Alloys; C013616:nitinol
keywords: Canal transportation; heat treatment; micro–computed tomography; nickel-titanium instrument