title: Comparison among manual instruments and PathFile and Mtwo rotary instruments to create a glide path in the root canal preparation of curved canals.
abstract: BACKGROUND
  Nickel-titanium rotary instruments reduce procedural errors and the time required to finish root canal preparation. The goal of this study was to evaluate the occurrences of apical transportation and canal aberrations produced with different instruments used to create a glide path in the preparation of curved root canals, namely manual K-files (Dentsply Maillefer, Ballaigues, Switzerland) and PathFile (Dentsply Maillefer) and Mtwo (Sweden and Martina, Padua, Italy) nickel-titanium rotary files.
  
  
  METHODS
  The mesial canals of 45 mandibular first and second molars (with curvature angles between 25° and 35°) were selected for this study. The specimens were divided randomly into 3 groups with 15 canals each, and canal preparation was performed by an endodontist using #10-15-20 K-type stainless steel manual files (group M), #13-16-19 PathFile rotary instruments (group PF), and #10-15-20 Mtwo rotary instruments (group MT). The double digital radiograph technique was used, pre- and postinstrumentation, to assess whether apical transportation and/or aberration in root canal morphology occurred. The initial and final images of the central axis of the canals were compared by superimposition through computerized analysis and with the aid of magnification. The specimens were analyzed by 3 evaluators, whose calibration was checked using the Kendall agreement test.
  
  
  RESULTS
  No apical transportation or aberration in root canal morphology occurred in any of the teeth; therefore, no statistical analysis was conducted.
  
  
  CONCLUSIONS
  Neither the manual instruments nor the PathFile or Mtwo rotary instruments used to create a glide path had any influence on the occurrence of apical transportation or produced any canal aberration.
authors.affiliation: São Leopoldo Mandic Dental Research Center, Campinas, SP, Brazil. vanessaoalves@hotmail.com
authors.forename: Vanessa de Oliveira
authors.initials: Vde O
authors.lastname: Alves
authors.forename: Carlos Eduardo da Silveira
authors.initials: CE
authors.lastname: Bueno
authors.forename: Rodrigo Sanches
authors.initials: RS
authors.lastname: Cunha
authors.forename: Sérgio Luiz
authors.initials: SL
authors.lastname: Pinheiro
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Fontana
authors.forename: Alexandre Sigrist
authors.initials: AS
authors.lastname: de Martin
mesh_terms: D003722:Dental Alloys / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008963:Molar / Q000033:anatomy & histology; D009532:Nickel / Q000737:chemistry; D015588:Observer Variation; D011858:Radiographic Magnification; D019252:Radiography, Dental, Digital; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D013193:Stainless Steel / Q000737:chemistry; D014025:Titanium / Q000737:chemistry; D019227:Tooth Apex / Q000033:anatomy & histology*
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium