Dental amalgam, also known as a silver filling, is made of a mixture of metals, including mercury, and is most commonly used to repair cavities in the back of the mouth. It is an extremely durable material and has been the go-to material for fillings for many years. However, over a long period of time, a tooth with an amalgam filling can develop cracks, and when not treated, this can have serious consequences for your oral health in the same way that mercury expands and contracts in a mercury thermometer. This too can happen in amalgam fillings. Years of temperature changes in your mouth make the filling expand and contract. Unfortunately, your teeth do not, thus increasing the likelihood of a crack. The larger the amalgam filling, the more likely you are to have a fracture or cracked tooth. Even small cracks can allow bacteria into the tooth causing decay or infection leading to further destruction. A cracked tooth may or may not be sensitive to hot and cold or be painful when biting or chewing. Cracks that progress too far can result in entire sections of the tooth breaking off, and in some cases, loss of the tooth entirely. It is important to consult with your doctor on the best course of action to repair a tooth cracked from a large amalgam filling.