A dental restoration or dental filling is a dental restorative material used to restore the function, integrity and morphology of missing tooth structure. The structural loss typically results from caries or external trauma. Dental restoration also refers to the replacement of missing tooth structure that is supported by dental implants. Dental composites are also called white fillings, used in direct cosmetic bonding. Crowns and in-lays can be made in the laboratory from dental composites. These materials are similar to those used in direct fillings and are tooth-colored. Their strength and durability is not as high as porcelain or metal restorations.