The Biologic Basis for the Clinical Application of the Silicones

The polysiloxanes (silicones) are a group of inert and inorganic compounds that were introduced over two decades ago. The pure form, termed medical-grade silicone, has a wide variety of clinical applications. Almost all surgical fields have used a product made of silicone. Silicone has been found to be an inert material, with minimal reaction of the biologic system to its presence. However, multiple clinical problems still exist due to certain applications of silicone products. The problems are related to its surface properties; In the blood thrombi form around silicone implants that may dislodge and cause symptoms around the implants. Scar formation may occur, and internal wound healing problems in the breast cause spherical contracture. In the eyes, where transparencies are needed, as in the intraocular lens implant, the scar interfaces with the visual image transmissions. Some of these internal problems relate to the hydrophobic nature of the silicone surface and have been resolved in part by adsorbing a wetting agent, such as povidone, to the surface. Such obviation has gained wide clinical application in surface coating of the intraocular lens. In search of an ideal implantable material, silicone, the most applicable, is still far from being called the ideal implant. Perhaps with the changes of its surface properties, such as introducing wetting agents to its surface, a new dimension in clinical applications will open the horizons of silicone in the 1980s.