Effect of electrical spot welding on load defl ection 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 defl ection rate of stainless steel and chromium-cobalt orthodontic wires.

Materials and Methods: In this experimental-laboratory study, load defl ection rate of 0.016 ×

0.022 inch stainless steel and chromium cobalt wires were evaluated in fi ve 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 fi ve: chromium-cobalt wire welded to chromium-cobalt wires. Afterward, the forces induced

by the samples in 0.5 mm, 1 mm, 1.5 mm defl ection 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 signifi cance level was set as 0.05.

Results: The Tukey test showed that there were signifi cant differences between the load defl ection

rates of welded groups compared to control ones (P < 0.001).

Conclusion: Considering the limitation of this study, the electric spot welding process performed

on stainless steel and chromium-cobalt wires increased their load defl ection rates.

Key Words: Elastic modulus, orthodontic wires, welding