title: Comparative analysis of torsional and bending behavior through finite-element models of 5 Ni-Ti endodontic instruments.
abstract: OBJECTIVE
  The objectives of this study were to compare numerically the bending and torsional mechanical behavior of 5 endodontic rotary Ni-Ti instruments with equivalent size and various designs for tapers, pitch, and cutting blades.First, the geometries of Hero (20/0.06), HeroShaper (20/0.06), ProFile (20/0.06), Mtwo (20/0.06), and ProTaper F1 were generated by finite element code. Then, the 2 most representative clinical loadings, i.e., bending and torsion, were studied with an ad hoc model for the superelasticity of Ni-Ti. Bending was generated by tip deflection and torsion by a constant twist-angle of the tip.
  
  
  RESULTS
  Mechanical behavior of these 5 endodontic rotary Ni-Ti instruments could be evaluated and compared. Protaper F1 presented the greatest level of bending stress and torque. Hero and HeroShaper were more rigid than ProFile and Mtwo.
  
  
  CONCLUSIONS
  This numerical comparison evaluated the effects of the geometrical parameters on the instrumental mechanical behavior. The 5 endodontic instruments, investigated in the present study, do not have the same bending and torsional mechanical behavior. Each clinician must be aware of these behavior differences so as to use the adequate file according to the clinical situation and to the manufacturer's recommendations.
authors.affiliation: Centre Hospitalier Universitaire-Service d'Odontologie/Université européenne de Bretagne-Faculté d'Odontologie, Brest, France. arbab@univ-brest.fr
authors.forename: Reza
authors.initials: R
authors.lastname: Arbab-Chirani
authors.forename: Valérie
authors.initials: V
authors.lastname: Chevalier
authors.forename: Shabnam
authors.initials: S
authors.lastname: Arbab-Chirani
authors.forename: Sylvain
authors.initials: S
authors.lastname: Calloch
mesh_terms: D003722:Dental Alloys; D003762:Dental Instruments; D003799:Dental Stress Analysis / Q000379:methods; D004548:Elasticity; D004867:Equipment Design; D020342:Finite Element Analysis; D009532:Nickel; D018583:Pliability; D018915:Root Canal Preparation / Q000295:instrumentation*; D014025:Titanium; D054159:Torsion, Mechanical
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium