EXPERIMENTAL ANALYSIS IN WISTAR RATS OF BONE GRAFTS PREPARED BY DIFFERENT STERILIZATION METHODS.

Objectives: To evaluate in vitro the bone graft preparations sterilization (BG) by freezing, gamma irradiation and ethylene oxide and compare in vivo their osseointegration in Wistar rat femurs.

Method: This basic controlled experimental study carried out in two phases, in vitro. First, in vitro, it was evaluated the sterilization of bone allografts exposed to S. aureus, A. baumanii, M. tuberculosis and C. albicans. In the second phase, in vivo, bone allografts osteointegration was compared in thirty-two Wistar rats, separated into four groups. In the control group (CG), fenestrations were carried out in the femur and not given a graft. Other groups received bone allografts prepared by freezing to -70ºC, ethylene oxide and 25KGy gamma irradiation. After thirty days, femurs were histologically evaluated by Hematoxylin-Eosin and Alcian Blue colorations and the Fisher's Exact test was used with p≤0.05.

Results: In the in vitro study was observed lower level of decontamination by freezing method (26.6±21.09%) meanwhile and the other methods being 100% efficient. In the in vivo study, we observed no significant differences between the inflammatory reaction, mineralization and osteointegration. The percentage of proteoglycans was higher in the Gamma Irradiation Group and Ethylene Oxide Group. However, there were no significant differences. In the Frozen Graft Group, there was an absence in 37.5% of proteoglycans.

Conclusion: The preparation of the bone allografts by freezing is less effective than the other methods and there were no differences in the osteointegration of the bone allografts in rat femurs.