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Mercury No Culprit in Alzheimer's

Mercury used in dental fillings does not appear to cause Alzheimer's disease, according to a new study by University of Kentucky researchers. The study compared mercury levels in autopsied brains, and dental amalgam status and history in Alzheimer's disease subjects as well as control subjects. The researchers found no significant association of Alzheimer's disease with the number, surface area or history of dental amalgams.

"Our key finding is that there is no relationship whatsoever between mercury found in the brain and amalgam," says Stanley Saxe, one of the study's authors and a professor emeritus of periodontics and geriatric dentistry in the UK College of Dentistry.

"Although very small amounts of mercury are released from dental amalgam–generally when rubbed or abraded due to brushing or eating—it is not taken up by the brain." Funded by a grant from the National Institutes of Health, the study was prompted by scientific controversy that has been brewing for several years on the topic.

The study, which began in 1991, was a collaborative effort among researchers from the UK Sanders-Brown Center on Aging and the College of Dentistry. Saxe and William Markesbery, director of the Sanders-Brown Center on Aging, led the research team.

"The uniqueness of the collaborative effort between the departments of chemistry, statistics, the College of Dentistry and leadership from the Center on Aging, made this research possible and successful," Markesbery says. "This is the only study that has looked at this question in a large group of people," Saxe adds.

Dental amalgam has been used since the early 1830s and is considered an excellent restorative material in dentistry because of its strength and durability. However, because dental amalgam is comprised of 50 percent mercury, a neurotoxin, it has been the subject of continuing controversy as a possible public health risk.

"The fact that there was no differential found in brain mercury levels due to dental amalgams is very exciting news for the dentistry profession," Saxe says.

"It's good to know that dental amalgam is safe because it is a very good restorative material," says Steve Rider, of the Lange, Rider and Reynolds restorative dental practice in Lexington. It's also good news for dentists and dental assitants, he says."Though we don't actually touch amalgam, we're in close proximity to it on a daily basis." Rider adds that the scope of this research at UK is also important.

"There are millions of people with silver fillings around the world, which makes this finding even more significant."