A dental filling is a procedure used to repair and restore the function, integrity, and morphology of a tooth that has been damaged by decay, fracture, or wear. The most common types of dental fillings are INLAY, AMALGAM, GOLD, GAS, CEMENT, and ORAL. An INLAY is a filling made of porcelain, composite resin, or GOLD that is custom-made to fit the cavity. AMALGAM is a silver-colored alloy made of mercury, silver, tin, and copper that is used to fill cavities. GOLD fillings are made of GOLD alloy and are used to fill cavities. GAS fillings are made of a combination of argon and oxygen and are used to fill cavities. CEMENT fillings are made of a combination of glass ionomer and acrylic and are used to fill cavities. ORAL fillings are made of a combination of acrylic and glass ionomer and are used to fill cavities.