Years back, amalgam fillings were the only restorations available for cavity treatment. These fillings, also known as mercury or silver-colored fillings, are composed of a mixture of metals, including silver, zinc, copper, tin, and mercury. Because it's liquid at room temperature, when mixed with other powdered metals, mercury forms an adaptable amalgam that's easily pressed into a tooth cavity. Once it hardens, it creates a durable seal that can function for many years.  Composite fillings are metal-free. Also known as white or tooth-colored fillings, composite fillings are made from resin materials. Composite resin fillings are tooth-like, delivering undetectable results when used in your mouth.