Amalgam is the generic term applied to a variety of very similar products used in dentistry to fill cavities in teeth. Amalgam is also known as the silver filling (due to its shiny appearance), or the silver-mercury filling. Amalgam literally means mixed with mercury, and in the dental sense that is true.
Amalgam literally means mixed with mercury, and in the dental sense that is true. Powdered metals and metal compounds consisting of silver, copper, tin, and zinc, are mixed with approximately an equal weight of liquid mercury. Three different types of chemical reactions take place within this mixture, and the resultant amalgam will set at room temperature, and, most importantly, within a few minutes. Amalgam has been used as a filling material for 160 years and has enjoyed the reputation of being an inexpensive, long-lasting filling. Three times now, amalgam has been accused of mercury poisoning. The first was in the 1830's, again in the 1920's, and the third time a movement started in 1973 in which more substantial information has been available to determine the toxicity of the substance. Up until recently, it was felt that the mercury stayed within the filling. Now it is known that mercury potentially leaches out every minute of the day. In recent years, dentist have learned that the metal filling in your mouth act much like metal does outside the mouth. Exposed to heat and cold, such as hot coffee or ice cream, the metal fillings in your teeth expand and contract. As they shift, they can actually weaken the teeth they were meant to protect. Often the expansion and contraction leads to the entire tooth cracking. As the filling expands and contracts, it can also leave a small opening where harmful bacteria can enter and become trapped, leading to further decay of the tooth.