EFFECTS OF PRESERVATION AND STERILIZATION ON CORTICAL BONE-GRAFTS - ASCANNING ELECTRON-MICROSCOPIC STUDY

The effects of preservation and sterilization on the structural proper ties of cortical bone were investigated. Specimens of cortical bone fr om rat tibiae were frozen (-70-degrees-C for 28 days), freeze-dried, i rradiated (1, 5, 25 and 50 kGy) or autoclaved (at 134-degrees-C for 3 or 5 min), and examined by scanning electron microscopy. Cryopreservat ion and irradiation had no deleterious effects on the surface structur e of the cortical bone. Freeze-drying caused microcracks running paral lel to the mineralized fiber bundles. After autoclaving, a time-depend ent distension, swelling and amalgamation of the fibrillary matrix was observed. This denaturation of the organic matrix was more pronounced after 5 min than 3 min autoclaving. The alterations of the fibrillary structure described above might be due to a preservation- and sterili zation-induced decrease of the biological and biomechanical potential of bone grafts.