Last updated on October 28, 2019
Controversy surrounds dental amalgam, the material sometimes used to fill cavities, because about half of it is composed of elemental mercury. Amalgam is a mixture of metals consisting of liquid mercury and a powdered alloy composed of tin, copper and silver. Elemental mercury reacts with and binds together with the alloy particles to form an amalgam. These fillings are also referred to as “silver fillings” due to their silver appearance.1
Elemental mercury releases mercury vapor that is primarily absorbed through the lungs, harmfully affecting them. Coughing, difficulty breathing and headaches are just a few of the symptoms of inhaling mercury. It is also possible for mercury to be absorbed through the skin; however, it is a much slower process.2
There are pros and cons for dental amalgam. Dental amalgam fillings are very durable and less likely to break than some other types of fillings. Amalgam is also the least expensive filling material. However, the elemental mercury in amalgam can pose a threat to people with amalgam fillings because the mercury can be absorbed through the lungs. Amalgam fillings are still considered safe for people six years and older according to the FDA.3
Composite resin and glass ionomer cement fillings are alternatives to dental amalgam. Composite resin fillings are more popular and consist of a type of plastic (acrylic resin) reinforced with powdered glass filler. Glass ionomer cement fillings are composed of organic acids and bases and may include acrylic resins. Both fillings are tooth-colored. Composite resin is harder to place than amalgam, not as strong as amalgam and more expensive. Glass ionomer cement can only be used in small restorations.4
It is important to dispose of amalgam correctly since it contains mercury. If dental amalgam is placed into the medical waste for disposal, it will end up in either an autoclave or an incinerator. Both of these disposal options result in the release of mercury vapors, which can be harmful to people and the environment. Several states have passed regulations, resulting in non-compliance for dentists who improperly disposal of amalgam. Amalgam can be handled either as hazardous waste and picked up or shipped to a hazardous waste disposal facility, or the dental office can recycle the amalgam. When the amalgam is recycled, the elemental mercury is extracted from the amalgam and reused in a number of different applications.
Sharps Compliance offers a Dental Amalgam Recycling System, composed of two pails. The inner pail is lined with a silver foil bag for small amounts of amalgam-containing items that have come in contact with blood and saliva, sludge from filters and teeth with amalgam. The outer pail can be used for safe recycling of other dental materials, such as lead foils, used lead aprons, non-contact amalgam (not contaminated with blood), containerized x-ray fixer and old radiographs.