Injectable fillers are substances that can be injected into and under the skin to smooth fine wrinkles, enhance shallow regions and minimize the depth of scars. Usually injectable fillers are used to target discrete areas of the face and neck. There are a number of substances that can be injected as fillers including collagen, hyaluronic acid, hydroxyapatite, polymethylmethacrylate microspheres, polylactic acid and even a person’s own fat. Often these fillers are used in conjunction with BOTOX® injections to reduce the appearance of fine to moderate facial wrinkles.
Collagen is perhaps the most well-known injectable filler. Collagen is a protein that is found naturally in human skin, joints, and tissues. As we age, collagen breaks down and is not reformed as readily as it once did, leading to laxity of the skin, wrinkles and thinness. Collagen injections attempt to temporarily reverse this thinning, tighten and restore the skin of the face. Collagen that is derived from human skin is marketed under various names such as Cosmoderm® and Cosmoplast®. Other types of collagen are derived from bovine (cow) sources and are sold as Zyderm® and Zyplast®. Currently, human collagen is extracted from donor tissue and highly purified. Human-derived collagen has some advantages over bovine collagen but it is more expensive. Recent research has shown that it is possible to create synthetic human collagen in a laboratory and may reduce the cost of human collagen injections in the future.
Hyaluronic acid is also naturally occurring in humans but is closer to a carbohydrate (think sugar or starch) than a protein. It is one of the newer injectable fillers and is used to smooth fine lines and wrinkles. Hyaluronic acid is marketed under the brand names Juvaderm and Restylane though newer products include a local anesthetic (Juvaderm Ultra Plus and Perlane) are more comfortable for patients.
Hydroxyapatite is not a protein but rather a mineral, similar in composition to the substance found in bones. This injectable filler is suspended in a gel and has more bulk than other fillers. Hydroxyapatite is sometimes used to fill deep furrows, scars and wrinkles. This substance may also be used to raise the skin along the jaw line and chin when a full facial implant is undesirable.
Polylactic acid is the newest injectable filler on the block and has a unique mechanism of action. When the substance is injected into an area, such as a wrinkle, it stimulates the skin to produce its own collagen in that area. Thus the collagen that forms is presumably more natural and longer lasting than transplanted collagen. Currently Sculptra® is approved by the FDA for use in patients with HIV-related loss of skin fat but may be used by some physicians “off-label,” that is, for applications that are not approved by the FDA.
Polymethylmethacrylate microspheres (ArteFill and Radiesse) are used in conjunction with collagen to fill facial wrinkles. The biggest advantage of using microspheres is that they resist absorption and digestion by the body and therefore last longer.
Autologous Fat Transfer
Perhaps the safest injectable filler uses fat harvested from another part of the body. In this procedure, gentle liposuction is performed on an area such as the belly or thigh. The harvested fat is cleaned and purified and only whole fat cells are used (typical liposuction liquefies and destroys the fat cells). The clean, purified fat is then injected into specific trouble areas on the face.
Each injectable filler has its advantages and disadvantages. Speak with your plastic surgeon to determine with filler is right for you.