Silicone or polymerized siloxanes (polysiloxanes) are mixed inorganic-organic polymers. Silicones can be synthesized with a wide variety of properties and compositions. They also vary in consistency from liquid to gel and rubber to hard plastic.15
The physical properties of silicone make it an ideal biomaterial. It is chemically inert, non-carcinogenic, capable of sterilization, not physically modified by soft tissue, non-inflammatory, capable of resisting mechanical strains and produces no state of allergy or hypersensitivity.15,16
Silicone elastomers have also been incorporated into the design of implanted medical devices for decades. Medical devices that use silicone include pacemakers and heart valves, shunts, catheters, drains and tubing, penile and testicular implants, artificial urethra, breast implants, implants for paralyzed vocal cords, implants for cosmetic facial repair, intraocular lenses following cataract removal, birth control implants, and joint replacement implants for the hands and feet.
Fluid silicone is included in the group of implantable medical devices by the United States Food and Drug Administration (FDA) and the United Kingdom Medical Devices Agency. Silicone oil was used 45 years ago to lubricate needles and syringes. Coating the exterior of single use disposable needles with silicone reduces the pain of needle entry while lubricating the syringe interior facilitates plunger involvement.
Virtually every injection leaves a trace of silicone oil at the injected site. People with insulin dependent diabetes who require a lifetime of daily insulin injections accumulate silicone fluid in their bodies. However, the exact amounts are not clear. The fact that there is no known adverse reaction with silicone is indicative of excellent biocompatibility. A similarly safe application is the lubrication of surgical suture needles, which allows for easier passage through tissue.
The first silicone fluid injection for the treatment of complicated retina detachment was approved in the U.S. in 1994. Silicone also has a long history of use as facial soft tissue filler for the treatment of wrinkles and facial atrophy.15,16 Many consider liquid injectable silicone to be a unique soft tissue augmenting agent that one may effectively utilize for the correction of specific cutaneous and subcutaneous atrophies.17 Orentreich, et al., found liquid silicone to be a safe and effective method for treating HIV-associated facial lipoatrophy and it reportedly compares favorably with other methods of tissue agumentation.18
Zappi, et al., examined 35 skin biopsies by light microscopy. They obtained these biopsies from target areas where liquid silicone had been injected in 25 patients between one and 23 years prior for the correction of depressed scars on the face.16 In 100 percent of the cases, the authors found the continued presence, in significant amounts, of the silicone previously injected into the target areas, where it failed to elicit any significant adverse reaction.
Although some authors have noted complications, likely resulting from the presence of adulterants and impurities, physicians may employ modern purified silicone products approved by the FDA for injection into the human body with minimal complications as long as they follow strict protocol.14,15,17