title: Comparison of the mechanical behavior between controlled memory and superelastic nickel-titanium files via finite element analysis.
abstract: BACKGROUND
  The aim of this study was to evaluate the flexibility and torsional stiffness of a controlled memory (CM) nickel-titanium (NiTi) file and compare its mechanical responses with those of a superelastic NiTi file with the same geometry using finite element simulation.
  
  
  METHODS
  A commercially available instrument with a tip size of 30 and a 0.06 taper was selected for this study. The geometric model for finite element analysis was generated by micro-computed tomographic scanning, and the data for the constitutive model of controlled memory NiTi were obtained from the literature. The numeric analysis was performed in ABAQUS (SIMULIA, Providence, RI) with boundary conditions that were based on the ISO 3630-1 specification.
  
  
  RESULTS
  The CM NiTi file exhibited the least bending moment and maximum stress value (523 MPa) under 45° bending simulation. However, the least torsional stiffness was calculated for this same instrument.
  
  
  CONCLUSIONS
  The higher flexibility and potential fatigue resistance of the CM NiTi files were confirmed, indicating that this new technology represents an improvement in the mechanical behavior of the rotary NiTi files.
authors.affiliation: Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Leandro de Arruda
authors.initials: Lde A
authors.lastname: Santos
authors.forename: Maria Guiomar de Azevedo
authors.initials: MG
authors.lastname: Bahia
authors.forename: Estevam Barbosa
authors.initials: EB
authors.lastname: de Las Casas
authors.forename: Vicente Tadeu Lopes
authors.initials: VT
authors.lastname: Buono
mesh_terms: D003198:Computer Simulation; D003722:Dental Alloys / Q000737:chemistry*; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D008422:Materials Testing; D008962:Models, Theoretical; D009532:Nickel / Q000737:chemistry*; D018583:Pliability; D018915:Root Canal Preparation / Q000295:instrumentation*; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013674:Technology, Dental; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D054159:Torsion, Mechanical; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium
keywords: Controlled memory NiTi files; NiTi rotary files; finite element analysis; mechanical behavior; superelastic NiTi files