Fillers of this type will require repeated injections for long-term results. Semipermanent fillers typically last longer than most non-permanent fillers, but can be expected to experience some resorption as well. Only permanent fillers can be expected to produce long-term results with a single injection. As the name implies, these products will persist within the tissue indefinitely; a characteristic that might raise concerns regarding safety and the potential for long-term side effects.

Although injectable facial fillers can offer an efficacious alternative to the surgery for the aging face, they also have their limitations. It is important for the plastic surgeon to recognize specific circumstances which may be best managed with an alternative to fillers, including superficial contour defects too shallow for fillers, areas with significant skin laxity in which filler injection may result in lumpiness, and deep defects or folds in areas of dynamic movement which may result in filler dislodgement or visible implants.

20.3 Available Facial Fillers

There are currently many soft-tissue fillers on the market today (Table 20.1). As stated above, these fillers fall within one of four major categories: autologous implants, collagens, hyaluronic acids, and biosynthetic polymers.

20.3.1 Autologous Fat

Despite Neuber’s successful use of autologous fat for soft-tissue augmentation in 1893, its use declined until the late 1970s. This decline was most likely due to the limited reproducibility of results; however, with the advent of suction lipectomy and improved harvesting techniques, autologous fat grafts have regained significant popularity. Overall correction and duration are similar to that of bovine collagen, although a high rate of resorption can occur.

20.3.2 Collagen

Collagen is a major component of human connective tissues such as bone, cartilage, skin, and vasculature.

The injectable forms consist of varying concentrations of purified bovine or human collagens. Bovine collagen, harvested from cattle skin, was the first Food and Drug Administration (FDA) approved product for softtissue augmentation in the USA. Prior to the development of hyaluronic acid fillers, collagen was the “gold standard” injectable filler. As the name implies, newer human collagens are derived from cadavers or laboratory cultures of human fibroblast cells. These collagens have gained popularity due to the reduced risk of hypersensitivity and immunologic reactions when compared to their bovine counterparts.

20.3.3 Hyaluronic Acids (HAs)

Like collagen, hyaluronic acid (HA) is also a major component of connective tissues. HAs are especially prevalent within the human dermis, where it provides a scaffold for collagen development. The main functions of HA include hydration, lubrication, and stabilization of connective tissues. During the aging process, the amount of HA within the connective tissues decreases, leading to a reduction in cell hydration, elasticity, and movement. In its natural form, injectable HA lasts only 1–2 days as a result of local degradation. Fortunately, Biotechnical companies have been successful in creating stabile HA molecules with longer-lasting effects. Most plastic surgeons would agree that the HA filler, Restylane, is currently the most commonly used facial filler worldwide.

20.3.4 Synthetic Polymers

Synthetic compounds are gaining favor as soft-tissue augmentation agents for several reasons: overall costeffectiveness, consistency of formulation with the possibility for reproducible mass production, limited immunogenicity, and the potential for long-term effects. As discussed previously, one of the first synthetics on the market was silicone. Despite a track record of excellent cosmetic results, reported problems with migration and foreign body reactions have precluded its approval for injectable cosmetic purposes within the USA and Europe. Synthetic facial fillers are typically composed of a biosynthetic polymer

Table 20.1 Available facial fillers (With permission from Buck et al. [8])

Fillers Facial Injectable 20

213

Source: Adapted from Johl [2], Murray [3], Broder [4], Eppley [5], Sengelmann [6]

Fillers Facial Injectable 20

215