title: Effect of electrical spot welding on load deflection rate of orthodontic wires.
abstract: BACKGROUND
  One of the methods used for joining metals together is welding, which can be carried out using different techniques such as electric spot welding. This study evaluated the effect of electric spot welding on the load deflection rate of stainless steel and chromium-cobalt orthodontic wires.
  
  
  METHODS
  In this experimental-laboratory study, load deflection rate of 0.016 × 0.022 inch stainless steel and chromium cobalt wires were evaluated in five groups (n =18): group one: Stainless steel wires, group two: chromium-cobalt wires, group three: stainless steel wires welded to stainless steel wires, group four: Stainless steel wires welded to chromium-cobalt wires, group five: chromium-cobalt wire welded to chromium-cobalt wires. Afterward, the forces induced by the samples in 0.5 mm, 1 mm, 1.5 mm deflection were measured using a universal testing machine. Then mean force measured for each group was compared with other groups. The data were analyzed using repeated measure analysis of variance (ANOVA), one-way ANOVA, and paired t-test by the SPSS software. The significance level was set as 0.05.
  
  
  RESULTS
  The Tukey test showed that there were significant differences between the load deflection rates of welded groups compared to control ones (P < 0.001).
  
  
  CONCLUSIONS
  Considering the limitation of this study, the electric spot welding process performed on stainless steel and chromium-cobalt wires increased their load deflection rates.
authors.affiliation: Dental Materials Research Center and Department of Orthodontics, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Shiva
authors.initials: S
authors.lastname: Alavi
authors.affiliation: Department of Orthodontics, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Arezoo
authors.initials: A
authors.lastname: Abrishami
keywords: Elastic modulus; orthodontic wires; welding