title: Three-dimensional quantification of pretorqued nickel-titanium wires in edgewise and prescription brackets.
abstract: OBJECTIVE
  To quantify the three-dimensional moments and forces produced by pretorqued nickel-titanium (NiTi) rectangular archwires fully engaged in 0.018- and 0.022-inch slots of central incisor and molar edgewise and prescription brackets.
  
  
  METHODS
  Ten identical acrylic dental models with retroclined maxillary incisors were fabricated for bonding with various bracket-wire combinations. Edgewise, Roth, and MBT brackets with 0.018- and 0.022-inch slots were bonded in a simulated 2 × 4 clinical scenario. The left central incisor and molar were sectioned and attached to load cells. Correspondingly sized straight and pretorqued NiTi archwires were ligated to the brackets using 0.010-inch ligatures. Each load cell simultaneously measured three force (Fx, Fy, Fz) and three moment (Mx, My, Mz) components. The faciolingual, mesiodistal, and inciso-occluso/apical axes of the teeth corresponded to the x, y, and z axes of the load cells, respectively. Each wire was removed and retested seven times. Three-way analysis of variance (ANOVA) examined the effects of wire type, wire size, and bracket type on the measured orthodontic load systems. Interactions among the three effects were examined and pair-wise comparisons between significant combinations were performed.
  
  
  RESULTS
  The force and moment components on each tooth were quantified according to their local coordinate axes. The three-way ANOVA interaction terms were significant for all force and moment measurements (P < .05), except for Fy (P > .05).
  
  
  CONCLUSIONS
  The pretorqued wire generates a significantly larger incisor facial crown torquing moment in the MBT prescription compared to Roth, edgewise, and the straight NiTi wire.
authors.affiliation: Department of Orthodontics and Oral Facial Genetics, Indiana University School of Dentistry, Indianapolis, IN 46202, USA.
authors.forename: Nitika
authors.initials: N
authors.lastname: Mittal
authors.forename: Zeyang
authors.initials: Z
authors.lastname: Xia
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Kelton T
authors.initials: KT
authors.lastname: Stewart
authors.forename: Sean Shih-Yao
authors.initials: SS
authors.lastname: Liu
mesh_terms: D000704:Analysis of Variance; D003722:Dental Alloys; D008422:Materials Testing / Q000379:methods*; D003765:Models, Dental; D009532:Nickel / Q000737:chemistry*; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D014025:Titanium / Q000737:chemistry*; D019415:Torque
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium