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Three-Dimensional Skeletal and Dental Relations in Orthodontic Patients with Class I and Class II Division 1 Malocclusions
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- Author / Creator
- Sam, Alycia J
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Introduction: The fundamental purpose of this thesis was to develop a novel three-dimensional (3D) cephalometric analysis that utilizes a 3D Cartesian coordinate system to classify orthodontic patients into different malocclusion groups, per skeletal and dental relationships they share. A review of scientific literature identified reliable 3D landmarks that can potentially describe such relationships, and a reliability study using a pilot sample was conducted to ensure that any landmarks used in subsequent studies were indeed reliable. This process also provided the opportunity to compare two-dimensional (2D) normative values with those found in 3D and measurements taken from right and left sides. The two most common overall malocclusion types and of interest to this project were: Class I and Class II Division 1 (Class II-1).
Methods: Sixty pre-orthodontic cone beam computed tomography (CBCT) patient scans (Class I: n=30, Class II-1: n=30) were used as the sample population. Forty landmarks were identified on each, and appropriate measurements between them made. A multivariate statistical analysis, discriminant analysis (DA), testing 8 arbitrarily chosen measurements was run to determine which, if any, 3D linear and angular measurements discriminate ‘best’ between these two orthodontic classifications.
Results: The DA produced a non-significant overall result (p>0.05). Although not totally suggestive for, a univariate ANOVA model may lead to believe that 5 of these linear measurements be effectively useful in predicting malocclusion classification of orthodontic patients: infraorbital (right) – mental foramen (right), infraorbital (left) – mental foramen (left), 2.6 root apex – infraorbital (left) – 2.6 buccal, infraorbital (right) – infraorbital (left) – 2.6 buccal, 1.6 root apex – infraorbital (right) – 1.6 buccal). Use of various predictor measurements or combination of them will likely produce different results. Interestingly, linear distance infraorbital – menton was found to be greater in the Class I than Class II-1 malocclusion group bilaterally. Further research is required to refine the findings of this research.
Conclusion: Continued testing of different 3D measurements is needed, to reveal those that can ‘best’ discriminate between different malocclusion groups. The complexity of any malocclusion and fundamental overlaps between distinct traits of these different types makes the allocation of patients into clear-cut definitions challenging. It may be prudent to reconsider the way in which patients are classified into malocclusion groups and move away from the traditional Class I, Class II, and Class III definitions.
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- Graduation date
- Fall 2018
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.