Characterising Three Dimensional Deformations and Strains of Orthodontic Archwires under Torsion

  • Author / Creator
    Tran, Bill Thien Tam
  • In orthodontics, braces are commonly used to correct dental misalignments. Third-order torque refers to the application of torsion to correct angular inclinations of teeth. Its application involves the use of a twisted archwire inside of an orthodontic bracket to generate the required forces and moments to achieve tooth movement. Third-order torque is continually researched in hopes of gaining fundamental knowledge with regards to its biomechanics. Understanding the interactions between an archwire and bracket are important in the application of torque. The Orthodontic Torque Simulator (OTS) is an in vitro simulator of third-order torque mechanics. Studying archwire and bracket mechanics using the OTS can be aided with the use of three-dimensional (3D) digital image correlation (DIC). The implementation of 3D DIC enables surface deformations and strains to be measured throughout an applied third-order rotation, where the response of the archwire can be quantified. The 3D DIC system was rigorously verified to ensure measurements were representative of actual third-order mechanics. In applying third-order torque, comparisons were made between 0.019”x0.025” stainless steel and titanium molybdenum alloy archwires. Surface shear strains were used to characterise the archwire behaviour during third-order torque, using both orthodontic brackets as well as a custom rigid dowel. It was found that surface shear strains vary due to differing contact conditions. Further, archwires may undergo permanent deformation as determined by the presence of residual shear strains. The application of 3D DIC with third-order torque experiments aids in the assessment of archwire and bracket interactions under applied loads, which can be used to better understand the biomechanics of third-order torque.

  • Subjects / Keywords
  • Graduation date
    Fall 2020
  • Type of Item
  • Degree
    Master of Science
  • DOI
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