Skin fillers are used to add volume to the skin where it may be hollowed or sunken in (Sculptra, fat) or alleviate lines or folds in the skin itself (Restylane, Juvederm, Perlane, Radiesse, Prevelle, etc.) In some cases, both classes of fillers are used together. Most of the time they are injected into the skin in a sterile fashion with or without anesthesia. Some fillers show immediate results, while others build up over time. The duration of their effect ranges from several months to years and if your own fat is injected, the better part of your life. Keep in mind nothing can stop the aging process, therefore, nothing is permanent.