Silas Braley

The Chemistry and Properties of the Medical-Grade Silicones

Abstract The medical grade silicones are probably the most widely used of all the synthetic polymers for permanently implanted subdermal devices. This paper reviews the chemistry of these materials from the original polymer manufacturing through the various stages necessary to obtain the types of heat vulcanizing silicone rubber, room temperature vulcanizing silicone rubber, and silicone rubber adhesive most commonly used in medical applications.

THE SILICONES AS SUBDERMAL ENGINEERING MATERIALS

During the past ten years, the emergence of the silicones as implant materials has greatly changed the subdermal prosthetics field. For the first time, the surgeon has a soft material which can duplicate many of the physical properties of living tissue and yet can be implanted in the tissue without fear of adverse reaction from the tissues, nor of deterioration of the implant itself. For many years, certain types of stainless steel and some of the chrome-cobalt, nonferrous alloys have proven successful for bone replacement; but until the advent of the silicones, there was no adequate soft-tissue replacement.

THE SILICONES AS TOOLS IN BIOLOGICAL ENGINEERING.

The paper discusses the requirements of a material for implantation in body tissues and deals briefly with the shortcomings of some traditional materials in this application. The silicone rubbers are then introduced, and attention is drawn to properties, peculiar to these rubbers, which makes them highly suitable for biological implantation. Extensive reference is made to many examples of such implantation.

The Current Status of Silicone Injection Therapy

Clinical uses of silicones. Factors influencing persistence of the original size of the injected area.

The status of injectable silicone fluid for soft tissue augmentation.

This paper begins with a summary: Before a drug can be generally distributed in the United States of America, it is necessary under Federal law to prove that it is both safe and effective. In the case of the silicone fluids for soft tissue augmentation, this has not yet been done; therefore the fluid is not generally available for this purpose.

Biomaterials in Clinical Use

The source and nature of presently used biomaterials are examined, and a hypothesis made as to where we should look for new ones for the future.