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Advisory Committee Chair

Chung H Kau

Advisory Committee Members

Andre Ferreira

Amjad Javed

Christos Vlachos

Document Type

Thesis

Date of Award

2012

Degree Name by School

Master of Science in Dentistry (MScD) School of Dentistry

Abstract

The purpose of this study was to determine if ultra short echo time magnetic resonance imaging (UTE-MRI) technology could be used to image teeth in orthodontics. The objectives of this study were to determine the accuracy and resolution of UTE-MRI on dental morphology and its application to the field of orthodontics with respect to appliance affect on morphology. Teeth were collected from the Orthodontic clinic at the University of Alabama at Birmingham and the Institutional Review Board of the University of Alabama at Birmingham approved the study. High-resolution 3-Tesla UTE-MRI was preformed on sixty extracted human premolar teeth with fixed ceramic orthodontic appliances at the University of Ulm, Germany. Linear measurements of the tooth morphology and orthodontic bracket dimensions were acquired with calipers and compared with `virtual' MRI images. Three ceramic bracket types including 3M Clarity, American Radiance, and Ormco Ice were studied. Both the caliper and UTE MRI measurements were highly reliable and accurate. Comparisons between the two methods showed no statistically significant differences in any of the bracket or tooth dimensions with a P-value > 0.05. In general, the differences in the values ranged from -0.01mm to 0.06mm. A visual evaluation scale was used to assess the quality of the obtained UTE-MRI images when assessing the delineation of dental hard tissues. The visual evaluation scale (VES) of the images revealed that enamel, dentin, pulp and ceramic orthodontic appliances could be subjectively delineated at a high level with the use of UTE-MRI. The following can be drawn from this prospective study; (1) Ceramic orthodontic appliances, without metal components, cause no dental image distortions and are readily visible on the UTE-MRI scans. (2) The measurement comparing linear tooth measurements to virtual MR images demonstrated that MRI has statistically and clinically significant accuracy on external tooth and bracket measurements. (3) Visual evaluation of the images revealed that enamel, dentin, pulp and ceramic orthodontic appliances could be subjectively delineated at a high level with the use of UTE-MRI. (4) Metallic slots in ceramic appliances cause severe image distortions. These distortions are localized and should not affect surrounding tissues in full volume MRI.

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