Studies evaluating health effects of dental amalgam fillings in children confirm safety

June 28, 2006

For the first time at a major international meeting, scientists are reporting the results of the first-ever randomized clinical trials to evaluate the safety of placing amalgam fillings, which contain mercury, in the teeth of children. The findings will be presented today during the 84th General Session of the International Association for Dental Research, convening at the Brisbane Convention & Exhibition Centre.

Both studies--one conducted in Europe, the other in the United States--independently reached the conclusion that children whose cavities were filled with dental amalgam had no adverse health effects. The findings included no detectable loss of intelligence, memory, coordination, concentration, nerve conduction, or kidney function during the 5-7 years the children were followed. The researchers looked for measurable signs of damage to the brain and kidneys, because previous studies with adults indicated that these organs might be especially sensitive to mercury.

The authors noted that children in both studies who received amalgam, informally known as "silver fillings", had slightly elevated levels of mercury in their urine. But after several years of analysis, they determined that the mercury levels remained low and did not correlate with any symptoms of mercury poisoning.

The two studies are: the New England study, which was undertaken in the urban Boston (MA) area and rural Farmington (Maine), and the Portuguese study, conducted in Lisbon, Portugal. Each study enrolled over 500 children who had existing untreated decay in permanent posterior, or back, teeth, but no previously placed dental amalgam fillings. Each child was randomly assigned to receive either amalgam or composite resin (tooth-colored) fillings while participating in the research studies. All were evaluated for several years thereafter to determine if any health changes occurred, with emphases on IQ changes in the New England study and on memory, concentration, coordination, and nerve conduction measures in the Portuguese study.

The scientists noted that children in both groups were in great need of dental care. Among those in the amalgam group, children had, on average, 10.1 tooth surfaces treated upon entry into the study. By year seven of the study, they had received, on average, a total of 18.7 surface restorations. Each tooth has either four or five defined surface areas, totaling 128 surfaces in the 32 permanent teeth.
The studies were supported by the National Institute of Dental and Craniofacial Research (NIDCR), part of the U.S. National Institutes of Health.

This is a summary of two abstracts-- "Randomized Clinical Trial of Neurobehavioral Effects of Amalgam in Children", by T. DeRouen et al., of the University of Washington (Seattle, USA) and the Universidade de Lisboa (Lisbon, Portugal), and "Randomized Clinical Trial of Safety of Dental Amalgam in Children", by S. McKinlay et al., of the Harvard Medical School, New England Research Institutes, Sahlgrenska Academy (Sweden), Forsyth Institute, University of Rochester (NY, USA), and University of Maine (Farmington), to be presented at 1:00 p.m. on Wednesday, June 28, 2006, in the Room M3 of the Brisbane Convention & Exhibition Centre, during the 84th General Session of the International Association for Dental Research.

International & American Associations for Dental Research

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