How safe are amalgam dental fillings?

Dentists have been using amalgam fillings to repair teeth for nearly two centuries. Although other types of fillings are available, amalgam is strong and budget friendly. But is it safe? There are two sides to the silver coin.

"Silver" dental fillings aren't made exclusively from that precious metal. Instead, they're formed from a powder consisting of silver, tin, copper and other metals combined with liquid mercury.

• These fillings are called "amalgams".

No. Studies have failed to show consistently that people with amalgam fillings experience any related health problems.

• Dentists used to insist that the mercury in amalgam fillings remained safely in the teeth. It's now clear, however, that fillings emit mercury vapour, especially when you chew. It's also long been known that chronic exposure to large amounts of mercury can harm the kidneys and cause tremors, depression, irritability, memory loss and other problems.
• Worries about mercury-based fillings date back to at least the mid-19th century.
• Skeptics have claimed that mercury leaching from fillings causes a variety of conditions, particularly of the central nervous system. But there is no clear proof that these fillings cause brain damage or any other ailments, even if you have a mouth full of them.
• The medical literature was surveyed in 2006 and no scientific evidence that people who have amalgam fillings have an increased risk of chronic fatigue syndrome or kidney disease was found.

Past research raised concerns that exposure to mercury increased the risk of conditions such as Alzheimer's and Parkinson's disease. But those studies looked only at occupational exposure to mercury and never linked amalgam fillings to neurological diseases.

• Some inconclusive research suggests that mercury from fillings may cause multiple sclerosis.
• Several recent studies appear to rule out claims that children with amalgam fillings are at risk for learning disabilities. One study found that kids have normal memory, concentration, motor skills and other neurological measurements seven years after receiving amalgam fillings.

No. There is no evidence that removing amalgam fillings cures or relieves the symptoms of any disease.

• "Holistic" or "biological" dentists often claim that removing mercury-based fillings relieves pain and symptoms of chronic disease.
• In many supporting studies, researchers typically asked patients to describe their symptoms before and after removal of their amalgam fillings. These studies may be greatly influenced by the placebo effect, which casts doubt on their results. That is, people may feel better because they believed strongly that their fillings were toxic.
• In one experiment, researchers in Norway found that patients with various chronic disorders who had their amalgam fillings removed rated their symptoms as improved seven years later. However, their symptom ratings matched those of a group of similar patients who did not have their fillings removed.

If you are concerned about having mercury in your mouth, talk to your dentist about composite fillings the next time you have a cavity. These tooth-coloured alternatives to amalgam are made of glass or quartz combined with resin.

• Not only do they look more natural, but they also require the removal of less of an existing tooth, so they're usually smaller, too.
• Composites may cost up to twice as much as amalgam fillings, however, and typically need to be replaced within five to 10 years. (Amalgam fillings last 15 years or longer, on average.)
• Some studies show that amalgam fillings may be the longest-lasting choice for repairing bicuspids and molars, the large teeth in the back of the mouth that do the most chewing.

Keep these tips in mind and contact your dentist for more information on amalgam fillings.