April 18, 2006
No brain damage from dental fillings, studies show
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, 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
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
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.