mercury is a metallic element that has been listed as a hazardous material because of the severe damage it causes to health and the environment. inhalation of mercury vapor for an extended period causes mercury poisoning, which is a disease characterized by tremors erethism fine. in dentistry, mercury is used for the preparation of amalgams used in the restoration of carious teeth treated. poisoning in dental offices, is generally caused by a chronic exposure to mercury vapor and occurs for not taking precautions when handling the metal in the process leading to the preparation of amalgam. it has been shown that good dental work practices reduce levels of mercury in urine associated with behavioral disorders. the american dental association (ada) believes that the risks of mercury exposure in the work of dentistry are limited if the personnel working in that area meets the standards of existing mercury hygiene.