Abstract

Introduction: Magnetic resonance imaging (MRI) machines provide 2D as well as 3D images that are excellent in contrasting soft-tissue in the maxillofacial region and are void of ionizing radiation. The drawbacks include the lack of depiction of cortical bony detail and image degradation caused by substances in the scanned area. Specifically, in the orthodontic field stainless steel brackets cause more distortion of MR images then any other bracket material. It is unknown what type of stainless steel alloy causes the most MRI distortion. The purpose of this study is to evaluate the degree of craniofacial MR distortion caused by various stainless steel orthodontic brackets.

Methods: Seven subjects had two polyvinylsiloxane impressions taken, one of the maxillary and mandibular arches. Three plaster model sets were poured from each impression, two model sets had stainless steel brackets incorporated into essix trays and the remaining model was the control. The two stainless steel brackets used in this study were: 17-4 (bracket / base) and 18-8 (bracket / base). Three scan sequences per patient were performed on the 1.5T and the 3.0T machines, resulting in a total of 6 scan sequences per patient. The MR images were then scored for distortion by a neuroradiologist. The Friedman test and the Wilcoxon signed rank test were used to analyze statistical significance of the differences in distortion between the anatomic sites, imaging modalities and brackets. Calculation of the values were done by using the mean plus or minus the standard deviation. A p value of less than .05 was considered a significant difference.

Results: The 17-4 stainless steel bracket/base caused the most image distortion compared to the 18-8 stainless steel bracket/base and the control.

Conclusion: It is recommended to removed brackets that are 17-4 stainless steel alloy prior to MRI scans, due to the distortion these appliances create in the resultant image. The 18-8 non-magnetic stainless steel bracket alloy does not affect diagnostic quality of an MR image on a 1.5T or 3.0T machine.

LLU Discipline

Orthodontics and Dentofacial Orthopedics

Department

Orthodontics and Dentofacial Orthopedics

School

Graduate Studies

First Advisor

V. Leroy Leggitt

Second Advisor

Joseph Caruso

Third Advisor

Udo Oyoyo

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2009

Date (Title Page)

9-2009

Language

English

Library of Congress/MESH Subject Headings

Orthodontic Brackets -- contraindications; Orthodontic Brackets; Magnetic Resonance Imaging; Stainless Steel; Reproducibility of Results

Type

Thesis

Page Count

x; 65

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

Download

Share

COinS