Several non-biodegradable fillers are available (Table 1.2). As well as being expensive, frequent injections can be quite tiresome for both the patient and the physician, and so the application of a non-biodegradable or permanent filler holds a certain attraction. Conversely, there are certain disadvantages that should be taken into account. First, patients of all ages can be treated in aesthetic medicine. It may therefore be quite uncertain how a permanent depot will appear after 3 or even 4 decades, by which time age and solar- induced elastosis has reduced the dermal and epidermal layers. Second, there is always a possibility of adverse reactions to fillers. The most common subacute or late reaction to permanent fillers is the development of a granuloma. Treatment of an adverse reaction to a filler material is much more difficult when the filler is non-biodegradable because it will provide a permanent stimulus for the surrounding tissue.
Silicone Dermal Filler
Injectable silicone filler is one of the oldest injectable filler materials used. Medical-grade silicon is a clear, oily, colorless liquid composed of long chains of polymerized dimethylsiloxane. There are several methods of injection for this product. One of the recommended techniques is the microdroplet technique (Orentreich 2000; Webster et al. 1986). Fluid silicone is injected into the dermis as 0.01 ml microdroplets. Each mircodroplet is separated by 1 mm. Undercorrection is recommended as the main side effect is a foreign body ( fibrotic) reaction. In fact, as a result of severe adverse reactions, the FDA declared the use of injectable silicone illegal in 1991. Nevertheless, silicone oil is still widely used in other countries.
Polyacrylamide (trade name Aquamid) is composed of 97.5 % water and 2.5% cross-linked poly- acrylamide. It is recommended for folds, skin sculpturing, and facial atrophy. It is not effective for new wrinkles. Aquamid should be injected deeply using the subcutaneous tunneling tech- nique (Breiting et al. 2004; De Cassia Novaes and Berg 2003).
Combination of Non-biodegradable and Biodegradable Fillers
Some fillers are a combination of non-biodegradable (permanent) and biodegradable (temporary) materials. The purpose of the biodegradable material is to act as a carrier and to ensure an immediate effect until the fibrotic foreign body reaction induced by the non-biodegradable filler leads to visible effects.
Polymethylmethacrylate PMMA and Collagen – Bellafill / ArteFill
The combination of polymethylmethacrylate (PMMA) and collagen (Artefill / Bellafill) was introduced at the end of the 1980s and is the oldest available combination preparation. PMMA beads are suspended in a solution of 3.5% bovine collagen (as a carrier) and 0.3 % lidocaine (for pain relief). While the collagen resorbs over a period of 2–3 months, the PMMA spheres become en- capsulated by fibrotic material. Bellafill PMMA has been used for a variety of aesthetic indications.
Artecoll / Artefill / Bellafill PMMA should be injected into the lower third of the dermis with a 26- to 27-gauge needle using the tunneling technique. The material should not be injected too supercially; the needle should never be visible through the skin. Careful massage with a fingertip after application helps to distribute the material more evenly. Overcorrection is not advisable; however, a second implantation may be necessary after 3 months (Lemperle et al. 2003). Although the preparation contains collagen, in Europe a skin test is not mandatory (personal communication Ro l Medical International).
Hydroxyethylmethacrylate and Hyaluronic Acid – DermaLive
Hydroxyethylmethacrylate (HEMA) and ethylmethacrylate microspheres suspended in hyaluronic acid have been available in Europe as DermaLive since the end of the 1990s. This product consists of 40% bacterial hyaluronic acid and 60% acrylic hydrogel particles (diameter of 45–65 μm). A similar formulation with larger- sized particles (about 85–110 μm) and a somewhat higher hyaluronic acid content is marketed as DermaDeep and is intended to be injected deeper.
DermaLive should only be injected with a 27.5-gauge needle into the deeper layers of the dermis, at the junction between the dermis and the hypodermis, with the tunneling technique, while DermaDeep is supposed to be injected with a slightly bigger needle (26.5-gauge) deeper into the subperiosteal layer or the hypodermis. Overcorrection must be avoided. In addition, it is recommended that a period of at least 3 months should be le between two injection sessions (Bergeret-Galley et al. 2001).