EVALUATION OF EXPANDED POLYTETRAFLUOROETHYLENE AS A SOFT-TISSUE FILLING SUBSTANCE - AN ANALYSIS OF DESIGN-RELATED IMPLANT BEHAVIOR USING THE PORCINE SKIN MODEL

Soft-tissue augmentation using the synthetic nonfluid biomaterial expa nded polytetrafluoroethylene (ePTFE) has been supported by number of r ecent reports citing the favorable characteristics of biocompatibility , soft and natural feel, ease of use, and permanent augmentation. Conc ern has been expressed about this application for ePTFE material becau se of the proximity of the implants to the skin surface and potential problems with infection and extrusion. We evaluated the behavior of a series of specific ePTFE implant designs using a long-term subcutaneou s augmentation model. By using a porcine model, 466 implants of ePTFE in the form of strips, rolls, or tubes were placed using a percutaneou s insertion device subcutaneously over the dorsum and face. Thp animal s were divided into three study groups by length of implantation (3 we eks, control; 6 months, intermediate term; and 12 months, long-term) a nd en-bloc tissue specimens, including skin, implants, and underlying soft tissue, were harvested for gross and histologic examination. Impl ants were removed at the earliest sign of infection, exposure, or extr usion and the difficulty of removal was ascertained and recorded. Thes e data reveal that ePTFE material elicits acceptable levels of tissue activity with low extrusion rates over the short and long term support ing its use for soft-tissue augmentation. The data show a clear differ ence, however: in the lost response and behavior of the implants fbr t his application based on shape or-design. A statistically significant difference in the low, but measurable, extrusion rates was observed am ongst these implant designs. ePTFE tubes showed greater stability and predictable augmentation over other implant designs for soft-tissue au gmentation and seem to represent a substantial improvement for this ap plication.