title: Numeric comparison of the static mechanical behavior between ProFile GT and ProFile GT series X rotary nickel-titanium files.
abstract: BACKGROUND
  This article aims to evaluate how different superelastic nickel-titanium (NiTi) alloys determine the static mechanical performance of endodontic files during bending and torsion.
  
  
  METHODS
  Two NiTi rotary instruments with similar geometries and equal cross sections, ProFile GT (GT) and a GT Series X (GTX), were selected. The latter file is made from M-Wire, a NiTi alloy that, according to its manufacturer, has been thermomechanically processed to have larger flexibility at body temperature. The mechanical response was studied for a series of static bending and torsional loads by using finite element (FE) models. The materials were characterized according to previously published stress-strain curves.
  
  
  RESULTS
  For the same load and boundary conditions, the GTX material significantly increased the instrument's performance. For instance, the deflection for a 1N force at the tip of the file was found to be 28.5% larger for the GTX file, whereas the maximum stress decreased 13.2%.
  
  
  CONCLUSIONS
  Although not fully reflective of the instrument's behavior in a dynamic rotation intracanal system, the static results showed that the GTX file is more flexible and capable of stress relief at the most critical sections than the GT file, suggesting that it has a lower risk of fracture inside the root canals during its clinical use.
authors.affiliation: Department of Mechanical Engineering, Instituto Superior Técnico, Technical University of Lisbon, Lisbon, Portugal. diogo.montalvao@ist.utl.pt
authors.forename: Diogo
authors.initials: D
authors.lastname: Montalvão
authors.forename: Francisca S
authors.initials: FS
authors.lastname: Alçada
mesh_terms: D017076:Computer-Aided Design; D003722:Dental Alloys; D003762:Dental Instruments; D003799:Dental Stress Analysis / Q000379:methods / Q000706:statistics & numerical data; D004548:Elasticity; D004867:Equipment Design; D020342:Finite Element Analysis; D008422:Materials Testing; 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