A filling is a substance that dentists use to replace a decayed or
broken portion of a tooth. Commonly used substances for fillings include metal,
alloy, plastic, porcelain, or a combination of materials (composite).
Composite resins are made from plastic materials (glass and resin)
and are usually similar to tooth color. They are often used on the front teeth
where a natural appearance is important. Composite resins can sometimes also be
used on the back teeth.