Why do we need to get our teeth filled when we get a cavity? Plaque – a sticky, almost colorless layer of bacteria that forms on your teeth- mixes with the sugars in foods to produce decay causing acids. When bacteria create a cavity in the tooth, the dentist usually fills it with a durable material, most often a composite (a tooth-colored material), a metal alloy called amalgam or gold. A filling can last from five years to a lifetime, depending on its location, the material used, and the care you give your teeth. Make an appointment at our clinic to explore more tooth-filling options for yourself.