CHICAGO (Reuters) - Silver dental fillings
widely used to fill cavities do not appear to cause brain damage in children even though the mercury in them is a known neurotoxin, according to studies published on Tuesday.
"Dentists and parents I think can be very assured from the results of this study that they can continue to put silver amalgam in children's mouths to fill cavities," said Sonja McKinlay of New England Research Institutes, Boston, who was involved in one of the studies.
That research involved 534 U.S. children aged 6 to 10 with cavities waiting to be treated, half of whom were given silver fillings and the rest a mercury-free white composite resin material. The children had an average of 15 fillings done over the five years the study lasted.
"We found that on IQ,/pages/ and other aspects of brain function, as well as kidney function, the group that received the mercury-based amalgam was exactly the same as those that received the composite," McKinlay said.
The study said silver-mercury fillings have been used for 150 years and 70 million are put into mouths in the United States each year. But because they can contain up to 50 percent elemental mercury, vapors released from the metal causes concern about possible nerve and kidney damage.
The New England study, published in the Journal of the American Medical Association and coordinated by Children's Hospital in Boston, said no previous research has been published comparing silver fillings with others to determine possible adverse impacts.
"In this study, there were no statistically significant differences in adverse neuropsychological or renal (kidney) effects observed over the five-year period in children whose caries (cavities) were restored using dental amalgam or composite materials," the study concluded.
In a second study in the same journal, researchers from the University of Washington in Seattle reported similar findings.
Their study covered 507 children aged 8 to 10 in Lisbon, Portugal, from 1997 to July 2005, who had either silver or composite fillings.
While children with silver fillings had higher levels of mercury in their urine, there were no statistically significant differences between the two groups in their scores on tests involving memory, attention or visual motor function.
"These findings ... suggest that amalgam should remain a viable clinical option in dental-restorative treatment," the study concluded.
In an editorial in the same publication commenting on the studies, Herbert Needleman, a physician at the University of Pittsburgh School of Medicine, said further research is needed on whether there are more "subtle effects" from the mercury.