Dental amalgam is made from a combination of metals that include mercury, silver, tin, and copper. Sometimes described as “silver-colored” fillings, dental amalgam has been used by dentists for more than 100 years because it lasts a long time.
Because of their durability, these silver-colored fillings are often the best choice for large cavities or those that occur in the back teeth where a lot of force is needed to chew. Amalgam hardens quickly so it is useful in areas that are difficult to keep dry during placement, such as below the gum line. Because it takes less time to place than tooth-colored fillings, amalgam is also an effective material for children and special needs people who may have a difficult time staying still during treatment.
One disadvantage of amalgam is that these types of fillings are not natural looking, especially when the filling is near the front of the mouth, where it may show when you laugh or speak.
Although dental amalgam is a safe, commonly used dental material, you may wonder about its mercury content. It’s important to know that when combined with the other metals, it forms a safe, stable material. Be assured that credible scientific studies affirm the safety of dental amalgam. Study after study shows amalgam is safe and effective for filling cavities. The American Dental Association, U.S. Centers for Disease Control and Prevention, U. S. Food and Drug Administration and World Health Organization all agree that based on extensive scientific evidence, dental amalgam is a safe and effective cavity-filling material. The Alzheimer’s Association, American Academy of Pediatrics, Autism Society of America and National Multiple Sclerosis Society—all science-based organizations like the ADA—also say that amalgam poses no health risk.
The Mayo Clinic recently stated that dental amalgam is a safe and durable choice for dental fillings. They also note that "there are several kinds of mercury. The mercury [methylmercury] found in water that can build up in fish and lead to health problems if you ingest too much is not the same type of mercury used in amalgam."