INVIVO DEGRADATION OF SILICONES

Si-29 nuclear magnetic resonance (NMR) spectroscopy is applied to stud y the degradation of polysiloxanes (silicones) in vivo. Our results wi th animal models show that silicone migrates from the implant to the l iver (Si-29 resonance at -20 ppm) and new silicon containing compounds form after the silicones are introduced into the rats. The new Si-29 resonances in the chemical shift range of -40 to -85 ppm are related t o hydrolyzed silicone, those at -90 to -115 ppm are indicative of the presence of silica (SiO2), and the peaks observed at -120 to -150 are related to high coordinated silicon complexes. These resonances are no t present in the Si-29 spectra of the silicones before implantation. O ur findings demonstrate that silicones are not metabolically inert.