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'No mercury risk from children's fillings'
Studies on mercury in fillings are contradictory
Traditional dental fillings do not raise mercury levels in children to dangerous levels, according to a US study.

There have long been concerns that the mercury content of traditional fillings could be absorbed into the body, causing poisoning.

But previous research on potential harm has been inconclusive.

The study by researchers at the University of North Carolina at Chapel Hill analysed the amount of mercury in the baby teeth of more than two dozen children.

It found no link between the number of fillings a child had and the amount of mercury in the teeth.

Paediatric dentist Diane Dilley said: "From a treatment standpoint, when amalgam restorations (traditional fillings) are offered as an option, there's going to be very little of the mercury that is absorbed into the body.

"It is a safe alternative for dental fillings."

Milk teeth

The researchers analysed the level of mercury in the baby canine teeth of 26 children treated at the university's dental school.

Many of the children had several fillings and these were analysed after the teeth had fallen out naturally.

Looking at mercury levels in teeth is thought to be the most accurate predictor for long-term exposure to mercury.

The study, published in Paediatric Dentistry, also found that children did not appear to be susceptible to levels to mercury in the environment or to food, such as fish, which may contain mercury.

Mercury has been used in fillings because it is durable and flexible.

Studies have shown that mercury vapour is released from amalgam fillings on chewing.

But dentists dispute whether the amount released is toxic.

Poisoning

Mercury affects the central and peripheral nervous systems and the kidneys.

Early signs of mercury poisoning include small tremors in the fingers, eyelids and lips.

With increasing exposure, tremors in hands and arms can interfere with movements, such as writing.

Common behavioural symptoms of mercury toxicity include depression, irritability, exaggerated response to stimuli, excessive shyness, insomnia and emotional instability.

The British Dental Association (BDA) says it follows advice from the Department of Health's Committee on Toxicity.

It states that dental amalgam fillings have been in use for 150 years with little risk of systematic toxicity, except for a small number of people who are hypersensitive to mercury.

The BDA says children can have amalgam fillings.

But it adds that people with proven sensitivity to mercury should use other types of filling.

Some studies have shown that mercury can cross over from the placenta of the mother into the foetus.

The BDA says: "There is no evidence of any link between amalgam use and birth defects or still birth."

But it adds: "Generally, it is sensible to minimise health interventions during pregnancy, where this is clinically feasible."

See also:

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