Limiting Factors Affecting Stage I Treatment: A Biomechanical Perspective Public Deposited

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  • March 21, 2019
  • Gibson, Christopher
    • Affiliation: School of Dentistry, Department of Orthodontics
  • Objectives: Stage 1 orthodontic tooth movement plays a critical role affecting the efficiency of treatment. However, the limiting factors to stage I tooth movement are poorly defined. We hypothesize that resistance to sliding (RS) between the archwire and the bracket in Stage 1 therapy can contribute to tooth movement and is dependent upon the hyperelastic behaviors of archwire materials and the type of geometric malalignment. Methods: A device was fabricated that allows manipulation of three brackets into multiple malocclusion scenarios (In-out, rotation, tipping, and vertical step). Using an Instron®, a straight segment of archwire was pulled through each configuration at a constant rate and the force required was recorded. In each malocclusion scenario, a series of data was collected on Resistance to Sliding (RS) related to magnitude of archwire deflection. For each malocclusion scenario, 10 increments were tested, and each sequence was repeated five times. One-way ANOVA and piecewise linear regression analysis were used to analyze the data. Results: Using a 0.016” CuNiTi archwire, critical angles and deflections were defined as the point where a rapid significant increase in the RS response was observed. These points were determined for in-out, rotation, tipping, and vertical step to be 2.23mm, 4.83˚, 2.58˚, and 1.88mm, respectively. Conclusion: Clinical implications can be extrapolated regarding the frictional forces present in differing malocclusion scenarios, and could be utilized to help determine proper selection of archwire size and material to achieve more ideal mechanical control in the early stages of treatment.
Date of publication
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Rights statement
  • In Copyright
  • Phillips, Ceib
  • Ko, Ching-Chang
  • Lin, Feng-Chang
  • Master of Science
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2016

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