The use of amalgam "silver" fillings in dentistry has long been a point of controversy because of the fact that 50% of a dental amalgam is made up of mercury. Mercury is one of the most toxic materials on the earth and the US Environmental Protection Agency classifies mercury as a hazardous substance. It has always been believed that amalgam is a stable material that emits little or no mercury but the development of modern methods to detect trace amounts of mercury raises questions about this belief.
A large body of evidence has now been established to show that dental amalgams release significant amounts of mercury during chewing, grinding of the teeth, drinking hot liquids and especially during removal of old amalgam fillings by a dentist. Mercury is a potent neurotoxin and is absorbed quickly into fat, the liver and the spleen. It can also pass the blood-brain barrier and deposit in the brain. Mercury toxicity has been associated with causing confusion, tremors, weakening of the immune system (which would make someone more susceptible to infections and allergies) and memory loss. With this in mind, many patients now choose to have nonmetallic fillings placed.
The International Academy of Oral Medicine and Toxicology (IAOMT) and its members are very concerned about excess exposure to mercury when old amalgam fillings are removed. The process of drilling out amalgam fillings releases large amounts of mercury vapor and fine particulates that can be inhaled and absorbed through the lungs. They have therefore developed a protocol to reduce this exposure not only for the protection of the patient but also for the dentist and dental team. Some of the key points of this protocol are:
- The use of a "rubber dam" when removing amalgam. The rubber dam is a rubber sheet that covers the teeth and reduces the amount of particulates that go down the throat.
- The use of large amounts of water when removing the filling. This helps to contain the mercury vapor and fine particulate matter by cooling down the filling.
- The use of a "super" suction unit to contain the mercury vapor and particulate.
- The mercury/amalgam filling is removed in large sections and this helps to minimize the mercury particles generated.
- The use of supplemental air so that the patient does not have to breathe the air directly over the mouth during amalgam removal; this air would be high in mercury vapor.