Dental amalgam contains mercury. Mercury in certain forms can be toxic. Doesn’t the use of dental amalgam lead to toxic effects?
If dental amalgam is classified as a hazardous material, how can it be safe when it is in the mouth?
No. Not all forms of mercury are the same. Dental amalgam is a durable alloy of silver, copper, tin, zinc, and mercury. The elemental mercury found in dental amalgam is inorganic, in contrast to organic forms such as methyl mercury, found largely in fish and seafood, and thimerosal, an ethyl mercury-based preservative found in pharmaceuticals. It is methyl mercury that is found in our food supply and is a cause for concern. Dental amalgam is a stable alloy that has been studied extensively and has an established record of safety and effectiveness.
“Hazardous,” in this context, is a regulatory classification that dictates appropriate handling procedures. It does not correctly characterize amalgam’s usefulness or safety as a medical device, or its actual environmental effects. Other devices, such as batteries, mercury-containing lamps, computer and television monitors, are common, widely used devices, and are considered hazardous once they are no longer in use. The “hazardous” label ensures such devices are properly disposed or recycled.
Amalgam fillings are known to emit minute quantities of mercury vapor during vigorous chewing or grinding. The amounts of mercury vapor emitted by amalgams fall well within levels considered safe, that is, they show no toxicity and cause no adverse health reactions.
An estimated 0.4 tons of mercury from dental facilities annually enter surface waters in the U.S. via Publically Owned Treatment Works (POTW) effluents, sewage and sludge incinerator emissions. Chair side traps and vacuum systems capture 78% of amalgam waste from dental offices; amalgam separators increase the amount of amalgam particulate captured to about 97%.
The California Dental Association has policy recommending that all dentists install amalgam separators to ensure that the amount of mercury entering the water supply from dental fillings is reduced to extremely low levels. Amalgam captured in dental offices via traps and amalgam separators can be recycled instead of incinerated as a biosolid, which reduces the amount of mercury emitted into the air and subsequently into surface water.
Other materials are effectively used for dental fillings, however, they can not completely replace amalgam. There are situations where tooth colored materials, which must be bonded, are difficult to use and where amalgam is the optimal restorative material. The dental material fact sheet, required by the California Dental Board to be distributed to patients, was developed to inform patients of the benefits and risks of each restorative material. The choice to use amalgam, which is a safe and effective filling material, should remain an informed choice that is made by the dentist in consultation with each individual patient.