STUDY OF AGING OF SILICONE-RUBBER BIOMATERIALS WITH NMR

Multinuclear nuclear magnetic resonance (NMR) spectroscopy (Si-29, C-1 3, H-1) is used to characterize the aging process of silicone rubber-b ased biomaterials in a rat model. H-1 NMR relaxation measurements (spi n-lattice, T-1, and spin-spin, T-2, relaxation times) were performed t o better understand the molecular dynamics of polysiloxane chains in i mplants. After 1 year of implantation in animals, changes in the H-1 T -2 relaxation times and the NMR spectra were observed in polydimethyls iloxane, Silastic(R) sheets and chin implants, while these measurement s remain unchanged in finger joints. Very small amounts of fat were de tected in all types of silicone rubber implants at the end of the impl antation period. This work shows that free silicone migrates from the implants to adjacent tissues and distant sites, such as spleen or live r, and is chemically modified. (C) 1995 John Wiley and Sons, Inc.