[Macroscopic and microscopic study of local compatibility of silicone rubber in short- and long-term experiments]

Extended trials were carried out on the purpose of finding optimal silicone rubber materials for endotheses, among others macroscopical and microscopical examinations of local compatibility after implantation in rats and dogs. Short-term experiments on 7 kinds of silicone rubber (VEB Chemiewerk Nünchritz) showed that subcutaneous and intramuscular implantation was well tolerated by rats. Optimal terms for removal were the 7th and the 28th day. Long-term trials of 4 kinds of silicone rubber in rats and dogs up to 1 year yielded no significantly different results compared with control materials from the Dow Corning Corporation. After comparing trials for biostability, 2 silicone rubbers were recommended for clinical use. Optimal terms for removing in long-term experiments were the 3rd, 6th, and 12th month. In the rat experiments after 6 months the thickness of the capsule remained constant, as morphometrically determined. This might be crucial in the assessment of long-term compatibility.