Filler Material Requirements

For a filler material to be useful in correcting soft tissue abnormalities, it should be able to produce permanent, aesthetically pleasing cosmetic results with a minimum of undesirable reactions.1 An ideal filler is autologous, easy for the physician to use with respect to material injectability and injection techniques, minimally painless on injection, and inexpensive. It is also preferred that such a filler be permanent while producing minimal side effects, such as bruising, bleeding, infection, migration, scarring, tissue loss, or reaction. In addition, physicians in the United States prefer the material to be approved by the U.S. Food and Drug Administration (FDA).

Significant factors associated with fillers and their uses include defect selection and injection technique (skill of administration).1 Many types of filler have been used to correct postsurgical, posttraumatic, or inherited facial deformities and irregularities.2–12 It should be noted that the only liquid filler substance that maintains precision and permanence in improving and correcting soft tissue defects is medical-grade liquid silicone, a silicone preparation purified and sterilized so that it can be used for medical and biological purposes.6

Silicone

Two liquid injectable silicone (LIS) products are currently approved by the FDA: Silikon 1000 (Alcon, Fort Worth, TX) and Adato Sil-ol 5000 (Bausch and Lomb, Rochester, NY). Although these products were approved for use in the eye as a tamponade for retinal detachments, they can be used off-label for correcting external nasal defects and treating scars. Physicians must keep in mind that commercial advertisement of off-label use of a product is not permitted under FDA guidelines. Silikon 1000 and Adato Sil-ol 5000 are forms of sterile purified polydimethylsiloxane of different viscosities. The viscosity of liquid silicone is expressed in centistoke (cs) units with one stoke (i.e., 100 cs) being the viscosity of water. Silikon 1000 has a viscosity of 1,000 cs and is less viscous than Adato Sil-ol 5000, which has a viscosity of 5,000 cs.

The higher the viscosity of the silicone, the larger the needle needed for its injection; the larger the needle, the more bruising, bleeding, and discomfort for the patient. Therefore, of the two available FDA-approved products, the less-viscous Silikon 1000, which can be injected with a 27-gauge half-inch needle, is preferred over the Adato Sil-ol 5000, which requires a 25-gauge 5/8 inch needle. Other syringe–needle configurations can be used based on individual physician preferences. Before these LIS products, another medical-grade liquid silicone product was available at 350 cs, which was even less viscous then Silikon 1000.

LIS fulfills most of the criteria for an ideal filling substance.13–16 It is a clear, colorless, odorless, tasteless, and stable substance. It lacks mutagenic, carcinogenic, and teratogenic effects; no true allergies to silicone have been documented. The hypothesized mechanism of action is a combination of the displacement of the dermal connective tissue by silicone microdroplets, and the possible production of thin-walled collagen capsules that surround the silicone microdroplets.17 LIS can be stored for long periods of time at room temperature and does not allow for the growth of micro-organisms.16 It does not soften or harden, remains unaltered within the range of human body temperature, and is chemically unaltered by exposure to sunlight, air, and most chemicals.13 Although technique dependent, the advantages of LIS over other injectable filler substances are its precision and permanence. Zappi et al reported on the long-term histological host response to liquid silicone, demonstrating its permanence and inertness, reflected by the lack of any adverse reaction to its presence.18

The senior author (JGB) has used LIS for correcting nasal defects, acne scarring, and other scars for more than 40 years. He has reported on the use for treating acne scars for up to 30 years13 and also for correcting nasal defects.14 Many other authors have reported on the beneficial use of LIS for correcting facial defects.6,19–24

External Nasal Defects

The nasal contour is a series of gentle curves and arches that allow the individual elements of the nose to blend seamlessly. The concavity of the nasal root should flow smoothly into the nasal dorsum, which, in turn, gently courses into the nasal tip. The nasal tip, alae, and columella consist of several interrelated curves. Distortion of any of these parts can adversely affect the appearance of the nose.

Subtle nasal defects can be seen in a variety of circumstances, including natural evolution, post-traumatic injury, postcosmetic surgical rhinoplasty, postnasal lesion removal, and after Mohs nasal reconstructive surgery. External nasal imperfections and deformities that are not expected to improve can be corrected without having to surgically manipulate the nose. In the absence of functional compromise, relatively more conservative approaches and problem-focused solutions are available.

The ability to readily improve or correct irregularities and asymmetries in the nose with an injectable material is very appealing because imperfections, especially after surgical treatment and rhinoplasty, are common. The use of a filler in correcting external nasal defects minimizes patient discomfort and financial expense, and it eliminates anesthetic risk and downtime, all usually associated with surgical intervention. Cutaneous fillers are less traumatic and more ideal for contour deformities than operative implants or incisions.

Efficacy means that the material fills the defect to create a natural appearance with a seamless transition from treated to untreated skin, maintaining the natural contours. Ideally, the filler should be permanent to avoid the need for retreatment after reaching the desired outcome. The use of LIS for the improvement or correction of nasal defects provides a simple, minimally invasive, permanent solution in the form of a nonsurgical rhinoplasty.

Acne, Traumatic, and Surgical Scarring

Acne can produce many different types of skin defects, including inflammation and scarring. Acne scarring can be described as deep, shallow, wide (broad-based), pitted, ice-pick, depressed, hypo- and hypertrophic, keloidal, or hypo- and hyperpigmented. The choice of corrections, therefore, is dependent on the type of scar or acne defect. Several techniques for facial acne scar revision have been described. These include laser, dermabrasion, shave excision, punch elevation, punch excision with full-thickness graft replacement, silicone augmentation, electro-desiccation, and scar reduction with intralesional corticosteroids.13,25,26

Owing to the fibrous nature of both pitted and ice-pick scars, the benefit of treating these two types of scars by soft tissue augmentation is limited compared with the benefit obtained in treating depressed or broad-based scars. The use of augmentation in the treatment of broad-based depressed scars was first reported in 1983, and the two filler substances mentioned at that time were silicone and collagen.25 The senior author has treated several thousand patients over the course of 40 years for different types of acne scars. Minor bleeding and bruising at the injection sites can occur with treatments, but persistent redness or swelling does not occur. Although no significant adverse reactions have occurred in any of these patients, fewer than 10 have had areas of minimal overcorrection, meaning that the scar was injected with slightly more silicone than was needed. Such overcorrections can be treated with minor surgical corrections, such as light electrosurgery, shave excision, or injections of small quantities of low-concentration triamcinolone acetonide.

In the case of traumatic or postsurgical scars, soft tissue augmentation can restore the appearance of the skin′s surface. Silicone is an ideal filler for this type of scar revision because it is precise and permanent.