Amalgam, the most widely used dental filling for over a century, is a silver colored metal alloy comprising mercury, silver, tin, copper and possibly traces of other metallic elements such as zinc. They are also commonly referred to as silver fillings. Amalgam is easy to use, strong and durable. It is also the most affordable of the dental filling options. The cost of obtaining amalgam fillings is covered by most dental insurance companies. 

However, there is an ongoing controversy and concerns about the safety of amalgam fillings due to their mercury content. 

Advantages of Amalgam 

Being the most widely tested, researched and used dental restorative material, amalgam has many advantages: 

• Strength – Being a stable metal alloy, a metal composed of more than one element, it is extremely strong and able to withstand high levels of bite pressure. Because of this they are used primarily for back teeth which bear the most chewing pressure.

• Durability – Fillings can last at least 10 to 15 years; and amalgam usually outlasts composite fillings.  

• Inexpensive – It is more affordable compared to alternative filling materials currently in use.

• Ease of use – Amalgam is relatively easy to use, compared to alternatives. Amalgam is useful for deep fillings below the gum line and in other areas where it is difficult to maintain a dry cavity for the filling process.  

All these qualities, and the fact that most dental insurance companies cover amalgam fillings, explain why it is still the most widely used dental restorative material. However, it is not without advantages. 

Disadvantages of Amalgam

Disadvantages of amalgam include:

• Not natural looking - Silver colored fillings do not look natural or match the color of natural teeth. As a result they are not the ideal filling for restoration of especially at the front, and those which are visible when laughing or talking.   

• Tendency to discolor - Amalgam fillings sometimes give a grayish hue to the surrounding tooth.

• Requires removal of more tooth structure – Compared to using other materials, more healthy parts of the tooth need to be removed in order to make a sufficiently large space to hold amalgam fillings.  

• Short-term sensitivity – There may be sensitivity to hot or cold after the filling process. It also takes some time for amalgam to harden. This is why dentists usually advice patients to stay away from extremely hot or cold drinks and to avoid eating for a couple of hours after the filling.  

• Cracks and fractures – Being a metal alloy, the amalgam filling may contract and expand more, compared with other fillings, when exposed to hot and cold food and liquids, leading to cracks and fractures. 

• Allergic reactions – Around 1 in 100 people are allergic to the mercury in amalgam fillings.  

Amalgam and toxicity

In discussing the controversy of whether amalgam fillings are safe for use, the American Dental Association acknowledges that "some concern has been raised because of its mercury content". The Association maintains that "the mercury in amalgam combines with other metals to render it stable and safe for use in filling teeth". It goes on to support its stance as follows:

"While questions have arisen about the safety of dental amalgam relating to its mercury content, the major U.S. and international scientific and health bodies, including the National Institutes of Health, the U.S. Public Health Service, the Centers for Disease Control and Prevention, the Food and Drug Administration and the World Health Organization, among others have been satisfied that dental amalgam is a safe, reliable and effective restorative material."

But, in 2008, in an agreement to settle a lawsuit by Moms Against Mercury, the FDA agreed to change their website to acknowledge possible dangers associated with amalgam fillings. This is because these fillings contain mercury, and thus could have neurotoxic effects on the nervous systems of developing fetuses and children.

However, there is no denying that millions of people around the country continue to get amalgam fillings.

You can learn more about the more popular dental filling options in our article on Dental Fillings – An Overview of Options [plz link to # 56]. More about other alternatives to amalgam fillings are covered in our series of articles on Gold Dental Fillings, Porcelain Dental Fillings and Composite Resin Dental Fillings. [Link to # 58, 59, 60]