Mercury is a component of dental amalgam, the silver filling material used after the decayed part of a tooth has been removed. Exposure to mercury and mercury vapor is a recognized potential health hazard. Because mercury is liquid at room temperature, it can form alloys with other metals without being heated. It is also easily vaporized at room temperature. Exposure can occur either through direct skin contact with mercury or mercury-containing compounds or through the inhalation of mercury vapor.

Sources of mercury contamination in the clinic environment include expression of excess mercury from amalgam, leakage from dispensers, improper storage of scrap amalgam, leakage from amalgam capsules during mixing, mercury vaporization from contaminated instruments placed in sterilizers, grinding of amalgam during removal of restorations, and amalgam condensation with ultrasonic condensers (packing down the amalgam). Mercury spills and the subsequent accumulation of mercury in carpeting or cracks in flooring material seem to be the major source of mercury contamination in the dental office.

Other dental office equipment can act as indirect sources of mercury contamination. Such equipment includes amalgamators, sterilizers, cabinets and countertops, cuspidors, drains, filters in heating and cooling systems, waste containers, capsule storage areas, and drapes.

Dental Mercury Hygiene Recommendations, published by the ADA Council on Scientific Affairs, provides information on preventing mercury exposure.

ADA’s publication, Best Management Practices for Amalgam Waste, is a series of amalgam-waste-handling and disposal practices, such as initiating bulk mercury-collection programs, using chairside traps, amalgam separators and vacuum collection, inspecting and cleaning traps, and recycling or using a commercial waste-disposal service to dispose of the amalgam collected.

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