Amalgam is a material composed of mercury and a mixture of several metals (e.g., silver, copper, tin). It is a strong and stable substance used in dental restorations for repairing tooth structure lost to tooth decay and cavities. Amalgam restorations are popularly known as silver fillings. It has been used for over 100 years and is the dominant material used for fillings. Use of amalgam has been declining over the past few decades due to the availability of alternative restoration materials (e.g., composite resin).

Due to the durability of amalgam and its ability to withstand substantial chewing stress, it can be used to restore decayed molars, which handle the greatest chewing load in the mouth. Amalgam is also used for fillings in areas that are difficult to keep dry during the dental procedure (e.g., deep fillings below the gumline).

To identify a need for fillings, patients need to see a dentist for a dental examination. A combination of physical examination and x-rays are used to identify tooth decay and cavities. Before the filling can be placed, the tooth is prepared by removing any decay. A portion of the healthy tooth structure often must also be cut away to help retain the amalgam filling.

There is usually little or no discomfort after an amalgam restoration has been placed, although some patients may experience some sensitivity to hot and cold. It is important to maintain diligent dental hygiene and see a dentist regularly for a dental examination and cleanings, because an amalgam filling does not protect the tooth from additional tooth decay.

Amalgam has many advantages over other restoration materials. It is very strong and wears away more slowly than other materials, except for gold. It also can be placed into the cavity more quickly. Furthermore, amalgam is the least expensive material available.

However, amalgam has certain drawbacks. The silver color of amalgam does not look like natural tooth enamel and the material often requires removing more of the healthy tooth structure than other materials. Sometimes, a small gray or blue discoloration can appear on the soft tissues (e.g., inner cheeks, gums) near the filling. This is completely harmless and is known as an amalgam tattoo. In rare cases, patients may have an allergic reaction to amalgam.