title: A potential MRI hazard: forces on dental magnet keepers.
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.
authors.affiliation: College of Dentistry, Ohio State University, Columbus 43210.
authors.forename: A G
authors.initials: AG
authors.lastname: Gegauff
authors.forename: K A
authors.initials: KA
authors.lastname: Laurell
authors.forename: A
authors.initials: A
authors.lastname: Thavendrarajah
authors.forename: S F
authors.initials: SF
authors.lastname: Rosenstiel
mesh_terms: D003722:Dental Alloys; D003779:Denture Design; D003781:Denture Retention; D004574:Electromagnetic Fields; D006801:Humans; D008279:Magnetic Resonance Imaging; D008280:Magnetics; D008962:Models, Theoretical; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003722:Dental Alloys