Dental amalgam is a dental filling material used for more than 150 years to fill cavities. This filling material is a mixture of metals, consisting of toxic mercury and a powdered alloy composed of silver, tin, and copper. You are constantly exposed to small amounts of toxic, poisonous mercury vapor when amalgam fillings are put in your teeth, for as long as they remain in your teeth, and when they are removed from your teeth. A strong immune system can be a very effective barrier against the health depleting effects of mercury. In addition, much safer composite filling materials that match the color of your teeth have been available for many years, and should always be chosen if you need fillings.