title: Load Deflection Characteristics of Nickel Titanium Initial Archwires.
abstract: OBJECTIVE
  The aim of this study was to assess and compare the characteristics of commonly used initial archwires by their load deflection graphs.
  
  
  METHODS
  This study tested three wire designs namely copper nickel titanium (CNT), nickel titanium (NiTi), and multi-strand NiTi (MSNT) archwires engaged in passive self-ligating (PSL) brackets, active self-ligating (ASL) brackets or conventional brackets. To evaluate the mechanical characteristics of the specimens, a three-point bending test was performed. The testing machine vertically applied force on the midpoint of the wire between the central incisor and canine teeth to obtain 2 and 4mm of deflection. The force level at maximum deflection and characteristics of plateau (the average plateau load and the plateau length) were recorded. Two-way ANOVA and Tukey's test were used at P <0.05 level of significance.
  
  
  RESULTS
  Force level at maximum deflection and plateau length were significantly affected by the amount of deflection. The type of archwires and brackets had significant effects on force level at maximum deflection, and plateau length. However, the bracket type had no significant effect on the average plateau force.
  
  
  CONCLUSIONS
  With any type of brackets in deflections of 2 and 4mm, MSNT wire exerted the lowest while NiTi wire exerted the highest force level at maximum deflection and plateau phase. The force level at maximum deflection and the plateau length increased with raising the amount of primary deflection; however the average plateau force did not change significantly.
authors.affiliation: Associate Professor, Department of Orthodontic, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Aghili
authors.affiliation: Professor, Department of Orthodontic, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Sogra
authors.initials: S
authors.lastname: Yasssaei
authors.affiliation: Professor, Faculty of Metallurgy and Material Engineering, University of Tehran, Tehran, Iran.
authors.forename: Mahmoud Nilli
authors.initials: MN
authors.lastname: Ahmadabadi
authors.affiliation: Assistant Professor, Department of Orthodontic, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Neda
authors.initials: N
authors.lastname: Joshan
keywords: Orthodontic Wires; Titanium Nickelide [Supplementary Concept]