The effect of magnetic resonance imaging on mercury release from dental amalgam at 3T and 7T

James R Allison; Karthik Chary; Chris Ottley; Quoc C Vuong; Matthew J German; Justin Durham; Peter Thelwall

doi:10.1016/j.jdent.2022.104322

The effect of magnetic resonance imaging on mercury release from dental amalgam at 3T and 7T

J Dent. 2022 Dec:127:104322. doi: 10.1016/j.jdent.2022.104322. Epub 2022 Oct 10.

Authors

James R Allison¹, Karthik Chary², Chris Ottley³, Quoc C Vuong⁴, Matthew J German⁵, Justin Durham⁶, Peter Thelwall²

Affiliations

¹ School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, UK; Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK. Electronic address: James.allison@newcastle.ac.uk.
² Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK; Centre for In Vivo Imaging, Newcastle University, Newcastle upon Tyne, UK.
³ Department of Earth Sciences, Durham University, UK.
⁴ Biosciences Institute, Faculty of Medical Sciences, Newcastle University, UK.
⁵ School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK.
⁶ School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, UK; Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK.

PMID: 36228805
DOI: 10.1016/j.jdent.2022.104322

Abstract

Objectives: To measure mercury release from standardised hydroxyapatite/amalgam constructs during MRI scanning and investigate the impact of static field strength and radiofrequency (RF) power on mercury release.

Methods: Amalgam was placed into 140 hydroxyapatite disks and matured for 14-days in artificial saliva. The solution was replaced, and samples split into five groups of 28 immediately prior to MRI. One group had no exposure, and the remainder were exposed to either a 3T or 7T MRI scanner, each at high and low RF power. Mercury concentration was measured by inductively coupled plasma mass spectrometry. Groups were compared using one-way ANOVA, and two-way ANOVA for main effects/ interaction of field strength/ RF power.

Results: Mercury concentration was increased in the 7T groups (high/ low: 15.43/ 11.33 ng mL^-1) and 3T high group (3.59) compared to control (2.44). MRI field strength significantly increased mercury release (p < .001) as did RF power (p = .030). At 3T, mercury release was 20.3 times lower than during maturation of dental amalgam, and for the average person an estimated 1.50 ng kg^-1 of mercury might be released during one 3T investigation; this is substantially lower than the tolerable weekly intake of 4,000 ng kg^-1.

Conclusion: Mercury release from amalgam shows a measurable increase following MRI, and the magnitude changes with magnetic field strength and RF power. The amount of mercury released is small compared to release during amalgam maturation. Amalgam mercury release during MRI is unlikely to be clinically meaningful and highly likely to remain below safe levels.

Keywords: Dental amalgam; Dental materials; Humans; Magnetic resonance imaging; Mass spectrometry; Mercury; Saliva.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Dental Amalgam* / chemistry
Humans
Hydroxyapatites
Magnetic Resonance Imaging
Mercury* / analysis
Mercury* / chemistry

Substances

Dental Amalgam
Mercury
Hydroxyapatites