title: [The properties of different orthodontic rectangular arch wires in torsion].
abstract: OBJECTIVE
  To study the properties of orthodontic rectangular arch wires in torsion.
  
  
  METHODS
  By using the torsion measurement apparatus, torsion moments and angles of four kinds of orthodontic wires (0.46 mm x 0.63 mm and 0.48 mm x 0.63 mm stainless steel wires, and the same size nickel-titanium wires) were tested respectively in a 0.56 mm-slot first maxillary incisor bracket. According to the torsion moments and angles, scatter graphs were drawn to fit the load-deflection curves of four kinds of wires and their linear equations were calculated. According to the equations, the torsion stiffness and the play angles of the wires at 20 N mm correspondingly were calculated.
  
  
  RESULTS
  The torsion stiffness of four kinds of wires were 4.909, 6.417, 1.325 and 1.363 N mn/degrees, the torsion angles of different wires were 19.14 degrees, 15.33 degrees, 36.83 degrees and 35.07 degrees at 20 N mm respectively.
  
  
  CONCLUSIONS
  The torsion stiffness of stainless steel wires was bigger than that of the same cross-section dimensional nickel-titanium wires. The difference of torsion stiffness between two dimensional nickel-titanium wires is smaller, while the difference of torsion stiffness between two stainless steel wires is larger.
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Huang
authors.forename: Min
authors.initials: M
authors.lastname: Gu
authors.forename: Xiang-Long
authors.initials: XL
authors.lastname: Han
authors.forename: Ding
authors.initials: D
authors.lastname: Bai
mesh_terms: D007180:Incisor; D009532:Nickel; D009969:Orthodontic Wires; D013193:Stainless Steel; D014025:Titanium
chemical_list: C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium