Quantitation of total mercury vapor released during dental procedures

An in vitro method is described in which measurements were made of the total amount of mercury vapor released from three types of amalgam during routine dental procedures. It was found that the greatest amount of mercury was released during dry polishing of one amalgam (44 micrograms). Removal of amalgam from a Class I cavity under water spray and high volume evacuation also generated large amounts of mercury as expected (15-20 micrograms). However, under the more clinically relevant conditions of extending evacuation for one minute to remove residual amalgam and mercury after cutting, this value was reduced by approximately 90%. The total amount of mercury generated during placement (6-8 micrograms), wet polishing (2-4 micrograms) and trituration (1-2 micrograms) were also measured. The study showed that dental procedures associated with amalgam do potentially expose the patient and operator to mercury vapor. However, the total amount of mercury released during any procedure was far below the total exposure level calculated from the daily threshold limits established by regulatory agencies for occupational exposure.