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. 1990 Sep;17(5):403-10.
doi: 10.1111/j.1365-2842.1990.tb01411.x.

A potential MRI hazard: forces on dental magnet keepers

A G Gegauff  1 , K A Laurell, A Thavendrarajah, S F Rosenstiel
Affiliations

A potential MRI hazard: forces on dental magnet keepers

A G Gegauff et al. J Oral Rehabil. 1990 Sep.

Abstract

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.

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