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Silver amalgam, also known as dental amalgam, is a mixture of mercury, silver and various other metals used for dental fillings. This material has long been favored in dentistry because it is relatively cheap, easy to apply, durable, and bacteriostatic, meaning it inhibits the growth of bacteria. In recent years, the safety of silver amalgam has been questioned, and concerns have been raised over whether the mercury in it can be absorbed by the body and cause health problems. About 70% of all dental fillings are now done using various resins and composite materials rather than dental amalgam. Scientific opinion differs on the safety of silver amalgam, with some experts recommending that it not be used at all, others claiming it is safe, while others advise that the material should not be used for pregnant women, children, people with metal allergies, and those suffering from renal problems.
In chemistry, the term "amalgam" refers to a substance created by a chemical reaction between mercury and any other metal. Various kinds of silver amalgams have been used in dentistry since the 19th century. The silver amalgam used today is commonly made up of 43-54% mercury and 20-35% silver, with the remainder consisting of tin, copper, and zinc.
The fact that silver amalgam is a mercury mixture, and that mercury is toxic, has caused many people to question the use of this material in dental fillings. In its natural state, mercury is a liquid at room temperature, and toxic exposure usually occurs if the mercury is absorbed through the skin or inhaled as mercury vapor that is emitted by the material. It has been claimed that the exposure to the mercury in silver fillings can cause chronic illness, autoimmune disorders, mental disorders and other serious health problems.
Those who believe that silver amalgam is safe to use claim that the mercury used in dentistry is stable and durable enough to minimize possible toxic exposure. Very small amounts of mercury vapor are released from silver amalgam fillings when one chews or brushes one's teeth. Studies show that a person with eight silver amalgam fillings absorbs 1-3 micrograms per day of mercury, and that most of this is expelled from the body with the urine. Scientists and scientific studies made in recent years do not offer any conclusive evidence on whether this material is safe, with some studies showing it has no effects on personal health, while others show that some disease symptoms can ease when silver fillings are removed.
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