Abstract. An increasing number of soft tissue filler substances have been introduced to the beauty market outside the U.S. which lack experimental and clinical data in support of their claim. Ten commercially available filler substances were examined for biocompatibility and durability: 0.1 cc of each substance was injected deep intradermally into the volar forearm of one of the authors and observed for clinical reaction and permanence. At 1, 3, 6, and 9 months the test sites were excised, histologically examined, and graded according to foreign body reactions classification. Collagen (Zyplast) was phagocytosed at 6 months and hyaluronic acid (Restylane) at 9 months. PMMA microspheres (Artecoll) had encapsulated with connective tissue, macrophages, and sporadic giant cells. Silicone oil (PMS 350) was clinically inconspicuous but dissipated into the tissue, causing a chronic foreign body reaction. Polylactic acid microspheres (New-Fill) induced a mild inflammatory response and had disappeared clinically at 4 months. Dextran microspheres (Reviderm intra) induced a pronounced foreign body reaction and had disappeared at 6 months. Polymethylacrylate particles (Dermalive) induced the lowest cellular reaction but had disappeared clinically at 6 months. Polyacrylamide (Aquamid) was well tolerated and remained palpable to a lessening degree over the entire testing period. Histologically, it dissipated more slowly and was kept in place through fine fibrous capsules. Polyvinylhydroxide microspheres suspended in acrylamide (Evolution) were well tolerated, slowly diminishing over 9 months. Calcium hydroxylapatite microspheres (Radiance FN) induced almost no foreign body reaction but were absorbed by the skin at 12 months.Host defense mechanisms react differently to the various filler materials, but all substances-resorbable or nonresorbable-appeared to be clinically and histologically safe, although all exhibit undesirable side effects. Since the mechanism of late inflammation or granuloma formation is still unknown, early histological findings are not useful in predicting possible late reactions to filler substances.

Summary Genuine granuloma formation following implantation of injectable dermal fillers is a rare complication, with incidences ranging from one in 100 patients (1 percent) to one in 5000 (0.02 percent). Foreign body granulomas occur several months to years after injection at all implantation sites at the same time. Without treatment, they may grow to the size of beans, remain virtually unchanged for some years, and then resolve spontaneously. Three clinical and histologic types of foreign body granulomas can be distinguished: 1. Cystic granulomas (synonyms: inflammatory, palisading, collagenolytic): these are caused mainly by injected biological gels such as collagens and hyaluronic acids. Their clinical signs are fluctuation (sterile abscess), extreme redness, and induration. Cystic granulomas are small and superficial, occur within the first year, and disappear spontaneously within another year. They are surrounded by a significant number of giant cells. 2. Edematous granulomas (synonym: lipogranuloma): these are caused by artificial fluids such as silicone and polyacrylamides. They appear suddenly years after injection with extensive swelling and are surrounded and infiltrated by mononuclear and inflammatory cells. 3. Sclerosing granulomas (synonyms: sarcoidal and xanthelasmic): these are caused by particulate injectables composed of polymethylmethacrylate, polylactic acid, hydroxyethylmethacrylate, calcium-hydroxylapatite, or dextran microspheres. Sclerosing granulomas occur generally 6 months to 3 years after implantation and are visible, often bluish confined nodules. Histologically, the implant is infiltrated by many macrophages and giant cells, fibroblasts, and collagen fibers but few inflammatory cells. Permanent implants are not characterized by a higher rate of foreign body granuloma per se than temporary implants; however, their clinical appearance is more pronounced and their persistence longer if not treated adequately. (Plast.

Summary: All fillers are associated with the risk of both early and late complications. Early side effects such as swelling, redness, and bruising occur after intradermal or subdermal injections. The patient has to be aware of and accept these risks. Adverse events that last longer than 2 weeks can be attributable to technical shortcomings (e.g., too superficial an implantation of a long-lasting filler substance). Such adverse events can be treated with intradermal 5-fluorouracil, steroid injections, vascular lasers, or intense pulsed light, and later with dermabrasion or shaving. Late adverse events also include immunologic phenomena such as late-onset allergy and nonallergic foreign body granuloma. Both react well to intralesional steroid injections, which often have to be repeated to establish the right dose. Surgical excisions shall remain the last option and are indicated for hard lumps in the lips and visible hard nodules or hard granuloma in the subcutaneous fat. (Plast. Reconstr. Surg. 118 (Suppl.): 92S, 2006.) The aesthetic benefit the patient achieves with temporary fillers is 90 percent technique and 10 percent substance. With permanent fillers, it's 99 percent technique.Jean Carruthers 1 A ll injectable dermal fillers can cause complications. Late side effects can be divided into those caused by insufficient training or technical errors during injection and those caused by immunologic (allergic and nonallergic) reactions to the injected substance. In the case of late, nonallergic reactions, the pathologic substratum differs from injectable to injectable but can always be classified into one of three distinct forms of foreign body granuloma.2 The histologic reaction is always similar, 3 and the trigger for this sudden stimulation of macrophages might be a systemic infection of the patient.

Most of the biologic filler materials that increase the thickness of the corium in a wrinkle line are phagocytosed within a certain time. Therefore, a lasting effect can only be achieved with nonresorbable synthetic substances. Artefill consists of 20 volume percent microspheres of polymethyl‐methacrylate and 80 volume percent of bovine collagen. Beneath the crease, the microspheres with their exceptional surface smoothness stimulate fibroblasts to encapsulate each individual one of the 6‐million microspheres contained in 1 mL of Artefill. Collagen is merely a carrier substance that prevents the microspheres from agglomerating during tissue ingrowth. The 20 volume percent of microspheres in Artefill provides the scaffold for the 80% volume of connective tissue deposition, a complete replacement of the injected collagen. The filler material beneath a crease acts like a splint and prevents the possibility of its further folding, thereby allowing the diminished thickness of the corium in a crease to recover. This recovery process is well known even in older patients with facial paralysis or after a stroke, whose facial wrinkles and furrows on the paralyzed side disappear over time.

The corium is diminished to about half of its thickness in skin defects and wrinkles. All biological materials that increase the thickness of the corium are resorbed within a certain time. Therefore, a lasting effect can be achieved only with nonresorbable synthetic substances. Artecoll consists of microspheres of 30-40 microm in diameter, of exceptional surface smoothness, purity, and homogeneity related to PMMA. These microspheres are suspended in atelocollagen which serves as a vehicle for subdermal implantation. Due to its smooth surface and consequential lack of electrical charges, each single microsphere is immediately encapsulated with the patient's own collagen fibers, thus preventing dislocation. Within 3 months, collagen (making up 75% of Artecoll) is replaced by the body's own connective tissue. The microspheres (25% of Artecoll) serve merely as a stimulus to the fibroblasts. Indications for Artecoll are all facial folds, lip- and philtrum augmentation, chin- and malar augmentation, dark-shadowed eyelids, enophthalmos, bony defects in face and hands, nipple reconstruction and augmentation, and urinary incontinence. Questionnaires were sent to all patients who had received Artecoll in 1993 and 1994. Of a total of 950 questionnaires sent, 515 were returned by September 1995. Satisfaction was rated "very good" in 29%, "good" in 38%, "satisfactory" in 23%, and "no difference" in 8% of the patients. The question, "Would you repeat the treatment again?" was answered by 91% of the patients with "yes." The overall complication rate was 3%. Strictly subdermal implantation will prevent longer lasting redness or visibility of the Artecoll.

After more than 25 years of research and development, in October 2006 ArteFill® became the first and only permanent injectable wrinkle filler to receive FDA approval. ArteFill is a third-generation polymeric microsphere-based filler, following its predecessor Artecoll®, which was marketed outside the United States between 1994 and 2006. ArteFill is approved for the correction of nasolabial folds and has been used in over 15,000 patients since its U.S. market introduction in February 2007. No serious side effects have been reported to date according to the FDA’s MAUDE reporting database. ArteFill consists of polymethylmethacrylate (PMMA) microspheres (20% by volume), 30–50 μm in diameter, suspended in 3.5% bovine collagen solution (80% by volume) and 0.3% lidocaine. The collagen carrier is absorbed within 1 month after injection and completely replaced by the patient’s own connective tissue within 3 months. Each cc of ArteFill contains approximately six million microspheres and histological studies have shown that long-term wrinkle correction consists of 80% of the patient’s own connective tissue and 20% microspheres. The standard injection technique is subdermal tunneling that delivers a strand of ArteFill at the dermal–subdermal junction. This strand beneath a wrinkle or fold acts like a support structure that protects against further wrinkling and allows the diminished thickness of the dermis to recover to its original thickness.

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