Biocompatibility of carbon-carbon materials: in vivo study of their erosion using 14carbon labelled samples.

Several uncertainties have to be resolved concerning the in vivo erosion of carbon-carbon composite materials and the outcome of the resulting particles. We studied these phenomena with implants superficially doped with 14carbon, specially prepared using the usual production processes of these materials. The samples implanted in rats presented changes in their measured radioactivity which proved erosion. Autoradiographies of the whole animal as well as pathological studies of peri-implanted tissues with histoautoradiographies of the related sections revealed the presence of carbon at a distance from the implant. However, the majority of the eroded particles were retained in the fibrous capsule surrounding the implant. The methods of electron-diffraction, associated with electron microscopy, seem to be a tool suitable to characterize the nature (fibrous or pyrolytic) of the carbon particles present in the capsule.