There were no statistically significant differences in neuropsychological and neurobehavioral effects among children whose dental caries were treated with mercury amalgam fillings and those treated with a composite dental restorative material, according to two studies in the April 19 issue of JAMA: The Journal of the American Medical Association.
Dental (silver) amalgam is a widely used restorative material containing 40 - 50 percent elemental mercury that emits small amounts of mercury vapor, according to background information in the articles. Because mercury is an acknowledged neurotoxin, there are widespread concerns about the health effects of exposure to this metal. But no randomized trials have been previously published that address the concern that inhalation of mercury vapor released by amalgam dental restorations causes adverse health effects. It is estimated that more than 70 million dental amalgam restorations are placed annually in the U.S.
David C. Bellinger, Ph.D., M.Sc., of Children's Hospital Boston, and colleagues compared the neuropsychological and renal (kidney) function of children whose dental caries (cavities) were restored using amalgam or mercury-free materials. Between September 1997 and March 2005, the researchers studied 534 New England children, aged six to ten, who were randomly assigned to receive either amalgam or resin composite materials. The children had an average of 15 tooth surfaces restored during a five-year follow-up.
"In this study, there were no statistically significant differences in adverse neuropsychological or renal effects observed over the five-year period in children whose caries were restored using dental amalgam or composite materials," the authors report.
Children randomly assigned to the amalgam group had higher average urinary mercury levels than those in the resin-based composite group. But there were no statistically significant differences between the groups in terms of five-year change in full-scale IQ score, four-year change in general memory index, visual motor composite score, or urinary albumin levels.
"Under the conditions of use represented in this trial, there is no reason to discontinue use of mercury amalgam as the standard of care for caries in posterior teeth," the authors conclude.