title: Mechanical properties of NiTi and CuNiTi shape-memory wires used in orthodontic treatment. Part 1: stress-strain tests.
abstract: OBJECTIVE
  This research aimed to compare, through traction tests, eight types of superelastic and heat-activated NiTi archwires, by six trade companies (GAC, TP, Ormco, Masel, Morelli and Unitek) to those with addition of copper (CuNiTi 27°C and 35°C, Ormco).
  
  
  METHODS
  The tests were performed in an EMIC mechanical testing machine, model DL10000, capacity of 10 tons, at the Military Institute of Engineering (IME).
  
  
  RESULTS
  The results showed that, generally, heat-activated NiTi archwires presented slighter deactivation loadings in relation to the superelastic ones. Among the archwires that presented deactivation loadings biologically more adequate are the heat-activated by GAC and by Unitek. Among the superelastic NiTi, the CuNiTi 27°C by Ormco were the ones that presented slighter deactivation loadings, being statistically (ANOVA) similar to the ones presented by the heat-activated NiTi archwires from Unitek. When compared the CuNiTi 27°C and 35°C archwires, it was observed that the 27°C presented deactivation forces of, nearly, ⅓ of the presented by the 35°C.
  
  
  CONCLUSIONS
  It was concluded that the CuNiTi 35°C archwires presented deactivation loadings biologically less favorable in relation to the other heat-activated NiTi archwires, associated to lower percentage of deformation, on the constant baselines of deactivation, showing less adequate mechanical behavior under traction, in relation to the other archwires.
authors.forename: Marco Abdo
authors.initials: MA
authors.lastname: Gravina
authors.forename: Ione Helena Vieira Portella
authors.initials: IH
authors.lastname: Brunharo
authors.forename: Cristiane
authors.initials: C
authors.lastname: Canavarro
authors.forename: Carlos Nelson
authors.initials: CN
authors.lastname: Elias
authors.forename: Cátia Cardoso Abdo
authors.initials: CC
authors.lastname: Quintão
mesh_terms: D000704:Analysis of Variance; D003300:Copper / Q000737:chemistry*; D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000379:methods*; D004548:Elasticity; D006358:Hot Temperature; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry*
chemical_list: D003722:Dental Alloys; D003300:Copper; D009532:Nickel; D014025:Titanium
keywords: Copper; Dental movement; Nickel; Orthodontic archwires; Physical properties.; Titanium