STUDIES ON EPOXY COMPOUND FIXATION

Bioprostheses derived from collagenous tissues have to be fixed and su bsequently sterilized before they can be implanted in humans, Clinical ly, the most commonly used fixative is glutaraldehyde, However, the te ndency for glutaraldehyde to markedly alter tissue stiffness and promo te tissue calcification are well-recognized drawbacks of this fixative . To address the deficiencies with the glutaraldehyde-fixed tissue, a new fixative, epoxy compound, was used to fix biological prostheses, T he study was undertaken to investigate the fixation rates and crosslin king densities of biological tissues fixed with various epoxy compound s. These epoxy compounds are different in their chemical structures, G lutaraldehyde was used as a control, The fixation rates and crosslinki ng densities of the fixed tissues were determined by measuring their f ixation indices and denaturation temperatures, respectively. Generally , the epoxy-fixed tissues were more pliable than the glutaraldehyde-fi xed one. Furthermore, the tissues fixed with monofunctional epoxy comp ound were more pliable than those fixed with multifunctional epoxy com pounds. With increasing pH or temperature, the fixation rate of epoxy compound increased, However, the number of epoxide functional groups d id not seem to affect the fixation rate of the epoxy compound. The fix ation rate of glutaraldehyde was faster than that of epoxy compounds, Additionally, the crosslinking density of the glutaraldehyde-fixed tis sue was greater than that of the epoxy-fixed counterparts, Moreover, i t was noted that the denaturation temperatures of the tissues fixed wi th glutaraldehyde or multifunctional epoxy compounds were significantl y higher than the fresh ones (p <0.05), while that fixed with monofunc tional epoxy compound stayed roughly the same throughout the entire fi xation process (p >0.05). The results obtained in this study may be us ed to optimize the fixation process for developing bioprostheses fixed with epoxy compounds. (C) 1996 John Wiley & Sons, Inc.