title: Analysis of forces developed during mechanical preparation of extracted teeth using RaCe rotary instruments and ProFiles.
abstract: OBJECTIVE
  To compare the torque and load during instrumentation with ProFile and RaCe nickel-titanium rotary instruments.
  
  
  METHODS
  Thirty human incisor roots 12 mm in length were embedded in epoxy resin, and divided into three groups of 10 specimens each. Instruments employed in each group were as follows: RaCe .02 Step Back Files in group 1; RaCe .04 Step Back Files in group 2; and .04 ProFiles in group 3. Two load cells, whose outputs were connected to a digital oscilloscope, recorded torque and vertical load. Data were analysed by one-way anova.
  
  
  RESULTS
  Torque values were statistically different between groups 1 and 3, and between groups 2 and 3 (torque was higher in group 3 than in groups 1 and 2). Vertical loads were statistically higher in group 3 than in groups 1 and 2.
  
  
  CONCLUSIONS
  Torsional and vertical forces can be evaluated during instrumentation of straight root canals using the device and methods described in this study. When the step-back technique was employed, torque and vertical load obtained with RaCe instruments were lower than that obtained with ProFiles.
authors.affiliation: Pulp Biology and Endodontics, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo 113-8548, Japan. fabiendo@tmd.ac.jp
authors.forename: F M
authors.initials: FM
authors.lastname: da Silva
authors.forename: C
authors.initials: C
authors.lastname: Kobayashi
authors.forename: H
authors.initials: H
authors.lastname: Suda
mesh_terms: D000704:Analysis of Variance; D003722:Dental Alloys; D003762:Dental Instruments; D003799:Dental Stress Analysis; D006801:Humans; D007180:Incisor; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D013193:Stainless Steel; D014025:Titanium; D019415:Torque
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium