Silicone medical

Despite of the silicon breast implant campaign which is a serious issue in the United States but evidently not in the rest of the world, the above statement on the environmental impact of silicones is also applicable to the impact on health of silicon medical devices and silicon implants, which are daily used in hospitals worldwide due to their excellent biocompatibility to human tissue and blood [11-13] There is also a long lasting experience clinically documented over decades on their reliability in specific applications. 

Dion et al. (1993) evaluated the in vitro platelet retention of the new prosthetic heart valve that was designed by FII Company and Pr. Baudet, composed of Ti6A14V titanium alloy coated with DLC (obtained by CVD). The retention and adhesion of platelets was evaluated by analyzing radioactivity on the exposed wall of test or control tubes through which a blood cell suspension containing In-labelled platelets had circulated. Their results showed that on DLC/Ti6A14V, platelets adhered twice the amount that they did on the reference material (a silicone medical-grade elastomer the behaviour of which in contact with blood is the same as that observed with the National Institutes of Health-recommended polydimethyl siloxane) (Dion et al., 1993). 

Polymer Solutions Incorporated received a molded silicone medical part that contained a small discoloration on the tip. It was of interest to identify the composition of this defect region in order to discover its origin. Testing showed that the defect was composed of an alloy of cobalt, chromium, and molybdenum, embedded in a silicone matrix. This alloy was present in another process in the same manufacturing facility and contaminated the silicone part. 

The sample was analyzed using the SEM, which is shown at the right. A reference spectrum was acquired of a silicone region where there were no defects (Figure 15-2-2). Silicon, oxygen, and alnminnm were detected. The presence of silicon and oxygen were generated from the silicone medical part, and alnminum may have derived from interference from the SEM vacnnm chamber components or the sample monnt. 

Figure 15-2-1. Optical micrograph of the tip of silicone medical part containing the defect region (32x magnification).

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