title: An improved model of 3-dimensional finite element analysis of mechanical behavior of endodontic instruments.
abstract: OBJECTIVE
  The aim of this study was to develop a numeric method to study the mechanical behavior of an endodontic instrument during different loading paths and to demonstrate the importance of the behavior model in the finite element results.
  
  
  METHODS
  A numeric study of an endodontic instrument was carried out. At first, the geometry was meshed with a finite element code. Then, 3 among the most representative loadings in clinical use, i.e., bending, torsion, and nonproportional bending-torsion, were studied. Each of them was simulated by setting 3 different behaviors: elasticity, elastoplasticity, and an ad hoc model for the superelasticity.
  
  
  RESULTS
  The simulations with nonproportional bending-torsion loading showed that the mechanical behavior of Ni-Ti shape memory alloy was strongly affected by change in the loading direction. Elastic and elastoplastic models were unable to consider this feature of Ni-Ti behavior. Only a superelastic model taking into account the effects of nonproportional loading proved to respect this crucial point.
  
  
  CONCLUSIONS
  To realize valid simulations of the mechanical behavior of Ni-Ti instruments during different mechanical loading paths, it is necessary to use an ad hoc mechanical behavior model.
authors.affiliation: Service d'Odontologie, Centre Hospitalier Universitaire; Faculté d'Odontologie, Université Européenne de Bretagne, Brest, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Chevalier
authors.forename: Reza
authors.initials: R
authors.lastname: Arbab-Chirani
authors.forename: Shabnam
authors.initials: S
authors.lastname: Arbab-Chirani
authors.forename: Sylvain
authors.initials: S
authors.lastname: Calloch
mesh_terms: D001696:Biomechanical Phenomena; D003198:Computer Simulation; D003762:Dental Instruments; D003799:Dental Stress Analysis / Q000379:methods*; D004548:Elasticity; D004867:Equipment Design; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D008962:Models, Theoretical; D018915:Root Canal Preparation / Q000295:instrumentation*; D013314:Stress, Mechanical