In-Situ Measurements of Low-Level Mercury Vapor Exposure from Dental Amalgam with Zeeman Atomic Absorption Spectroscopy

Abstract

Alongside food, emissions from amalgam fillings are an essential contribution to man's mercury burden. Previous methods for the determination of intraoral mercury vapor (Hg°) release used principally some form of preconcentration of Hg on gold (film or wool), allowing relatively few measurements with unknown precision and sensitivity at selected times. Recently available computer-controlled Hg detectors operating on Zeeman atomic absorption spectroscopy (ZAAS) facilitate the direct real-time measurement of Hg° concentrations. It was the aim to adapt this method for a comparative investigation of emission processes from fillings in situ and from amalgam specimens in vitro. In addition to the ZAAS instrument, the apparatus consisted of a pump, magnetic valves, an electronic flow controller and a handle with a disposable mouth piece for aspiration of oral air. A programmable timer integrated the computer-controlled instrument operation and the data collection into a standard sampling protocol. A fast exponential decay of the emission was found after stimulation of amalgam specimens and of fillings in situ (halftimes 8.6 and 10.7 min). Precision was evaluated by a series of measurements on a single patient which indicated a consistently low coefficient of variation between 18% and 25%. After insertion of a few new fillings, sensitivity was high enough to detect a significant increase in emission against the background emission from the majority of old fillings. Zeeman-AAS in connection with a semi-automated sampling protocol and data storage provides precise in-situ measurements of Hg° emission from dental amalgam with real-time resolution. This facilitates the detailed exploration of the Hg° release kinetics and the applicability to large-scale studies.

Keywords :

• Amalgam
• Mercury Vapor
• Mercury Emission
• Oral Air
• Zeeman Atomic Absorption Spectroscopy

The support given by the GSF-Research Center and the Stifterverband für die Deutsche Wissenschaft is gratefully acknowledged. Many thanks are expressed to Carola Jacobsen for her patience in volunteering for most of the measurements and to Dr. G. Csanady for serving as a control person.