A potential MRI hazard: forces on dental magnet keepers

The objective of this study was to determine the forces on dental prosthetic magnet keepers, with a view to assessing the potential for patient injury during magnetic resonance imaging (MRI). Four pre-formed keepers and one castable keeper alloy were tested. Magnetizations and high field susceptibil...

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Bibliographic Details
Published inJournal of oral rehabilitation Vol. 17; no. 5; p. 403
Main Authors Gegauff, A G, Laurell, K A, Thavendrarajah, A, Rosenstiel, S F
Format Journal Article
LanguageEnglish
Published England 01.09.1990
Subjects
Dental Alloys
Denture Design
Denture Retention
Electromagnetic Fields
Humans
Magnetic Resonance Imaging
Magnetics
Models, Theoretical
Stress, Mechanical
Surface Properties
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Summary:The objective of this study was to determine the forces on dental prosthetic magnet keepers, with a view to assessing the potential for patient injury during magnetic resonance imaging (MRI). Four pre-formed keepers and one castable keeper alloy were tested. Magnetizations and high field susceptibilities were determined for each of the five specimens using data from a vibrating sample magnetometer. The magnetic field intensity with respect to distance from the main magnet coil was obtained from the manufacturer (1-5 tesla General Electric Signa Imaging System). A plot of force versus distance from the main coil and the maximum force at the magnet portal was determined for each specimen. The maximum forces ranged from 0.12-0.24 N for the pre-formed keepers and 3.67 MNm-3 for the castable alloy. It was concluded that the risk of patient injury by displacement is minimal, if the keepers are properly attached to supporting structures.
ISSN:0305-182X
1365-2842
DOI:10.1111/j.1365-2842.1990.tb01411.x