DOI

10.17077/etd.8te7478p

Document Type

Thesis

Date of Degree

Spring 2017

Access Restrictions

.

Degree Name

MS (Master of Science)

Degree In

Orthodontics

First Advisor

Nathan E. Holton

First Committee Member

Nathan E Holton

Second Committee Member

Steven D Marshall

Third Committee Member

Thomas E Southard

Abstract

Introduction: The hyperdivergent facial form is typically characterized by a long lower anterior facial height (LAFH), steep mandibular plane angle, and skeletal open bite. The purpose of our study was to further explore morphologic variation within long LAFH subjects using geometric morphometric methods. Methods: Cephalograms of 147 individuals (n= 147; 87 female, 60 male; age range: 16-68 years) with LAFH to total anterior facial height (TAFH), ratio (LAFH/TAFH), at or above 57.4% were studied. Cluster analysis and canonical variate analysis captured phenotypic variation and identified homogenous groups. Results: Cluster analysis resulted in three discrete long LAFH phenotypes that varied along vertical and anteroposterior dimensions. Conclusions: We found significant morphologic variation within the sample population of long LAFH individuals. Three phenotypes with varied vertical and anteroposterior discrepancies were revealed through the cluster analysis. Within our sample, we found both convergent and divergent facial patterns with concomitant cranial base rotation and posterior ramal border displacement. Vertical variation was largely independent of anteroposterior discrepancies.

Public Abstract

All three dimensions of space must be considered when straightening teeth in orthodontic treatment. A common measurement used to assess the vertical dimension is lower anterior facial height, which is the distance from the base of the nose to the chin. People with a long lower anterior face can have other similar facial characteristics that can complicate orthodontic treatment. The purpose of this study was to explore facial patterns in people with long facial heights and to see if there are distinguishing features that could help orthodontists better diagnose and treat their patients. We did this by analyzing x-rays of 147 people who had long lower anterior face heights using a technique called geometric morphometrics. Our findings indicate that even among a group of people with similar characteristics, there are many differences. These results should improve recognition and diagnosis of orthodontic problems and hopefully improve treatment outcomes.

Keywords

facial height, hyperdivergence, hyperdivergent, open-bite, vertical

Pages

vii, 39 pages

Bibliography

Includes bibliographical references (pages 36-39).

Copyright

Copyright © 2017 Kate Elizabeth Finlen

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