Dermal fillers are products that are injected into or under the skin to fill wrinkles or scars. Although they can be used to restore the natural body shape after an operation, they are mainly used for cosmetic purposes. In 2006 RIVMNational Institute for Public Health and the Environment conducted a literature search into permanent dermal fillers (which remain in the body permanently), with another literature study being performed in 2008 on non-permanent dermal fillers (which are degradable and disappear from the body after periods of 6 months or more).