Trace metals in dental practitioners: a three-year study.

Concern regarding the hazard of mercury to the health of dentists has been widely expressed. Three groups of patients have been followed for three years to evaluate the effect of dental practice on mercury levels in the serum of dentists. At the beginning of the study and again three years later, only dental practitioners with at least twenty years of active practice had significantly higher levels of mercury in their sera. In no patient, however, was a serum mercury level higher than 5 mu g/dl obtained and this value is far below that which usually precipitates clinical symptoms of mercury toxicity. Thus, the occupational hazard of mercury to dentists may be overstated. Copper and zinc are also used in dental practice and the serum levels of these metals were investigated. None of the three groups had mean serum values that were beyond the normal ranges expected. There may be some differences related to age, diet or, possibly, occupation, but further investigation with a larger control group is needed.

The accumulation of the base metals (copper, zinc and mercury) in the human body.

Overdramatized, unscientific investigations have contributed to the misconception that the cumulative effects of dental alloys are a serious threat to the clinician and other dental personnel. The reliability of the instrumentation and analytical techniques used for the analyses in this investigation has been well-documented. The following conclusions, therefore, may be drawn from the data: The absolute serum values for all groups involved in the study appear to be within the normal concentration range for the metals tested. Zinc concentrations appear to increase with the age of the individual; however, the values are still within the normal range. Copper and mercury serum-concentrations do not appear to increase with age; however, continued ingestion of foods contaminated with methyl mercury could lead to increased levels of this compound. There is no significant increase in serum copper or zinc in dentists who have been in active practice for twenty years; however, the increases in blood-mercury as measured in this study indicate that occupational exposure may not be as harmful as previously believed. When one considers that only a part of the total concentration is toxic organic mercury, the elevated value after twenty years of exposure appears to be insignificant in terms of danger to the clinician.