Lyophilizing canine allogeneic mandible:meeting the requirements for rebuilding strength, shape and support capabilities / 中国组织工程研究

ABSTRACT

BACKGROUND:The favorable structure and biological characteristics of al ogeneic temporomandibular joint become an effective solution for condylar defect, but immunologic rejection and slow ossification are the main problem for the presence of bone al ograft. OBJECTIVE:To meet the requirements of rebuilding mandible defect by lyophilizing canine mandible. METHODS:The periosteum, soft tissue, and cartilage of 12 canine mandibles were removed. 1 mm diameter hole was dril ed with 1 to 2 cm intervals in their cortical bones with a fissure bur. After washing, they were placed into a-4 ℃ refrigerator for 12 hours, and then stored at-80℃gradual y for 1 week. The mandibles were put in a drier. When the moisture content of osseous tissue decreased to 5%, the bones were packed in aseptic environment, radio pasteurized, and stored in vacuum container at atmosphere temperature. A biomechanical test was conducted after the lyophilization. RESULTS AND CONCLUSION:The maximum shifts of lyophilized mandibles in compression and bending tests were slight according to the steep load-shift curve. The plastic zone was insignificant and fractures appeared immediately when the pressure exceeded the plastic zone. The maximum load, maximum shift, and rigidity in the compression test were (5 163.10±730.16) N, (0.78±0.19) mm and (11 069.17±1 758.12) N/mm, respectively. The data in bending test were (486.67±134.12) N, (0.67±0.15) mm and (1 151.67±256.46) N/mm, respectively. It is concluded that the dehydrated and lyophilized canine mandibles have good shape and support ability and can meet the mechanical requirements in repairing and reconstructing mandibular defect.