The use of a rubber dam, together with water spray and high-velocity evacuation, was responsible for a further significant reduction of exposure to particles when compared with water spray and high-velocity evacuation alone. The dentist, however, was exposed to moderate levels of fully respirable particles for all conditions tested. It is therefore recommended that all dental personnel wear face masks while removing existing amalgam restorations.

Using water spray coolant can reduce mercury vapor levels caused during amalgam removal and therefore lessen one source of ambient mercury vapor in the dental office. With wet cutting, mercury levels generally decreased as distance from amalgam cutting increased. Dry cutting caused similar levels of mercury vaporization when measured within 24 inches. A mercury-filtering mask (Mercury Vapor Respirator, Item No. 8707, 3M Co., St. Paul, Minn.) is commercially available and recommended for use during amalgam removal.

This study has shown that there can be measurable elevation in a patient’s level of expired mercury following the removal of a single amalgam restoration. That change appears to be small; lasts only briefly (10 minutes); and is completely avoidable through the use of procedures such as wet cutting, high-volume evacuation, and the rubber dam. The significance of repeated exposure to small amounts of mercury vapor is not entirely understood, but consideration should be given to techniques that minimize exposure to both patients and dental personnel.