Initially, two matched groups, each consisting of eight individuals (three men and five women), were formed;then the groups were randomly divided into either control or MRI-exposed arms. Following approval by the Medical Ethics Committee of Shiraz University of Medical Sciences and obtaining informed written consents from the participants, identical dental amalgam restorations were performed for all participants. Mercury level was measured in the urine samples of the control participants before amalgam restoration (hour 0), and 48 and 72 hrs after the restoration.