Editorial Type:
Article Category: Research Article
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Online Publication Date: 24 Feb 2025

Orthodontic forces and moments of three-bracket geometries

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DOI: 10.2319/043024-339.1
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ABSTRACT

Objectives

To test the hypothesis of Burstone and Koenig that a three-bracket geometry can be simplified into two adjacent two-bracket geometries, to evaluate the impact of a third bracket on two-bracket geometries, to identify the force systems of 36 three-bracket geometries using archwires of different materials, and to apply these principles to clinical scenarios.

Materials and Methods

A custom-designed orthodontic force jig supported three force transducers fitted with passive self-ligating brackets (Brackets A, B, and C). In Experiment 1, the force system of a three-bracket geometry was compared with two adjacent two-bracket geometries. In Experiment 2, 36 three-bracket geometries were tested when straight wires of varying materials were engaged.

Results

Experiment 1 results showed that the force system of a three-bracket geometry could be simplified into two adjacent two-bracket geometries. Experiment 2 results showed that the impact of the third bracket (Bracket C) affected the force system of the adjacent bracket only (Bracket B), with Bracket C having no statistically significant effect on the force systems at Bracket A. A distinct pattern of forces and moments was found in each of the 36 three-bracket geometries.

Conclusions

In this study, we experimentally validated the hypothesis of Burstone and Koenig, showing that a three-bracket geometry can be simplified into two adjacent two-bracket geometries. The force system of 36 three-bracket geometries was determined, assisting clinicians with better anticipating previously unpredicted and undesirable movements, thereby improving treatment efficiency.

Copyright: © 2025 by The EH Angle Education and Research Foundation, Inc.

Contributor Notes

 Private Practice, Melbourne, Australia.
 Associate Professor, Melbourne Dental School, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Carlton, Australia.
 Professor and Convenor of Orthodontics, Melbourne Dental School, Faculty of Medicine, Dentistry The University of Melbourne, Carlton, Australia.
 Professor of Research, Melbourne Dental School, Faculty of Medicine, Dentistry The University of Melbourne, Carlton, Australia.
Corresponding author: Dr Paolo M. Cattaneo, Professor of Research, Melbourne Dental School, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, 720 Swanston St, Carlton VIC 3053, Australia (e-mail: paolo.cattaneo@unimelb.edu.au)
Received: 30 Apr 2024
Accepted: 28 Dec 2024
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