Tissue reaction to silicon: Evaluation through experimental implants

The authors reports their experience on implants of three different silicones: medical grade silicon elastomer, collagen-coated elastomer, and gel of silicon used for filling breast prosthesis. Materials were implanted in subcutaneous pocket of Sprague-Dawley rats; histocompatibility was assessed 7, 30 and 60 days after surgery. Peri-implant tissues were analyzed by means of immunohistochemical techniques to identify lymphocyte subpopulations and expression of interleukin 2 receptor. Image analysis led to a quantitative assessment. As a conclusion, the tested materials did not show acute local toxicity and induced the development of a fibrous tissue layer which, although differently extended, was always moderate. Silicon gel showed a remarkable tendency to spread out. Neither B nor T lymphocytes foci were demonstrated.