Increased mercury release from dental amalgam restorations after brain magnetic resonance imaging

The introduction of magnetic resonance (MR) technology as a clinical imaging method has substantially increased the patient exposure to static, gradient and radio frequency of electromagnetic fields. The aim of this study was to assess the release of mercury from human dental amalgam restorations after exposure to electromagnetic fields produced by conventional MR imaging. The pre- and post-interventional study design was used for this investigation. The study participants were composed of individuals who were scheduled for brain MRI and those who had at least 4 teeth with amalgam restorations. These restorations had to be at least one week or older. Thirty individuals, who met the inclusion criteria, were referred to magnetic resonance imaging (MRI) department. A questionnaire was used for each patient to collect basic information on past exposures to electromagnetic fields, occupation and life style. Biological specimens (5cc stimulated saliva) were collected just before and after MRI procedures. The magnetic flux density was 0.23 T, and the patient’s duration of exposure to magnetic field was 30 minutes. The collected saliva samples were analyzed by laboratory for mercury level by using cold-vapor atomic absorption technique. The SPSS software and paired t-test were used for statistical analysis of mercury levels. The mean concentrations of mercury in saliva before and after MRI were 0.86 ± 0.3 mg /dl and 1.13 ± 0.5, mg /dl respectively. Data analysis using paired t-test showed a statistically significant difference between the mean concentrations of saliva mercury before and after MRI procedures. This study showed significant relationship between increased mercury levels in saliva of patients exposed to magnetic resonance imaging.