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Stiffness-deflection behavior of selected orthodontic wires
J M Oltjen1, M G Duncanson, J Ghosh
1University of Oklahoma, College of Dentistry, Department of Orthodontics and Dental Materials, Oklahoma City 73190, USA. ram-nanda@uokhsc.edu
The Angle Orthodontist
|January 1, 1997
Summary
Orthodontic wire stiffness is crucial for leveling teeth. This study found that wire stiffness depends on size, alloy, and strand count, and significantly changes with deflection, impacting treatment force delivery.
Area of Science:
- Biomaterials Science
- Orthodontics
- Mechanical Engineering
Background:
- Effective orthodontic treatment for tooth discrepancies relies on controlled forces from low-stiffness wires.
- Understanding wire stiffness is essential for predictable leveling and alignment of teeth.
Purpose of the Study:
- To characterize the stiffness of various nickel-titanium and stainless steel orthodontic wires.
- To investigate how wire stiffness is affected by material composition, structure, and deflection.
Main Methods:
- Tested 24 types of solid and multistrand wires (nickel-titanium and stainless steel) in three-point and three-bracket bending modes.
- Determined stiffness by analyzing unloading force-deflection plots using polynomial regression and mathematical differentiation.
- Presented functional relationships between stiffness and deflection.
Main Results:
- Wire stiffness can be modified by altering wire size, strand count, and alloy composition.
- Most wires exhibited a significant dependence of stiffness on deflection.
- Stiffness values varied between three-point bending and three-bracket bending tests.
Conclusions:
- Orthodontic wire stiffness is a complex property influenced by multiple factors, including deflection.
- Clinicians can manipulate wire properties through material selection and structural design to achieve desired forces.
- The bending mode used for testing influences measured stiffness, highlighting the importance of clinically relevant testing.