Evaluation of the force generated by gradual deflection of orthodontic wires in conventional metallic, esthetic, and self-ligating brackets

J Appl Oral Sci. 2016 Sep-Oct;24(5):496-502. doi: 10.1590/1678-775720150405.


Objective:: The purpose of this study was to evaluate the deflection forces of Nitinol orthodontic wires placed in different types of brackets: metallic, reinforced polycarbonate with metallic slots, sapphire, passive and active self-ligating, by assessing strength values variation according to gradual increase in wire diameter and deflection and comparing different combinations in the different deflections.

Material and methods:: Specimens were set in a clinical simulation model and evaluated in a Universal Testing Machine (INSTRON 3342), using the ISO 15841 protocol. Data were subjected to One-way ANOVA, followed by Tukey tests (p<0.05).

Results:: Self-ligating brackets presented the most similar behavior to each other. For conventional brackets there was no consistent behavior for any of the deflections studied.

Conclusions:: Self-ligating brackets presented the most consistent and predictable results while conventional brackets, as esthetic brackets, showed very different patterns of forces. Self-ligating brackets showed higher strength in all deflections when compared with the others, in 0.020-inch wires.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Alloys / chemistry*
  • Analysis of Variance
  • Elasticity
  • Friction
  • Materials Testing
  • Nickel / chemistry
  • Orthodontic Appliance Design
  • Orthodontic Brackets*
  • Orthodontic Wires*
  • Polycarboxylate Cement / chemistry
  • Reference Values
  • Statistics, Nonparametric
  • Titanium / chemistry


  • Alloys
  • Polycarboxylate Cement
  • titanium nickelide
  • polycarbonate
  • nitinol
  • Nickel
  • Titanium