Filling materials are mainly divided into three categories: 1, silver amalgam: is a mixture of silver ions and free mercury, after 12 hours will become hard and solid, is a traditional material. Stronger, more durable, but the color is not too beautiful; 2, composite resin: is a resin material, delicate light curing will become hard solid, there are many different materials, color and hardness are different, bonding is strong, currently the most commonly used; 3, glass ion: glass ion is generally applied in the unstressed parts, such as the buccal side of the tooth, root surface, etc., bonding is better, but the color, strength is not good. Therefore, it is generally not used in the filling of anterior teeth and occlusal surfaces.