Amalgams, the mixture of metals used for filling teeth was invented in 1826. When mixed initially, it is soft and can be pushed into a tooth cavity. It sets in a few minutes and hardens fully within 24-48 hours. A typical amalgam contains about 50 per cent mercury with the rest made up of an alloy of silver, tin, copper and zinc.
Much cheaper to use than gold fillings, the use of amalgams meant that many more people could afford to have their teeth filled. However, there was significant resistance within the profession about the move away from using gold in the 1850s and some expressed their concerns about the possible health risks of using mercury.
In 1926, controversy erupted when a German chemistry professor, Dr Alfred Stock, proved that mercury leached from amalgam fillings. Since then, opposition to the use of amalgams in fillings has grown, with organisations such as the International Academy of Oral Medicine and Toxicology promoting research that dental amalgams are a source of significant mercury exposure.
In the EU, the Scientific Committee on Emerging and Newly Identified Health Risks continues to defend the use of amalgams. Yet some countries, including Sweden, Norway and Denmark, have banned all mercury products, including amalgams. In Ireland, most dentists continue to support the use of amalgams although they are gradually being replaced by composite filling “for cosmetic reasons”.