ABSTRACT
OBJECTIVE To establish an modified model of osteonecrosis in the rat and observe the clinical, pathological and imaging manifestations dynamically. METHODS Healthy male SD rats were divided into 5 groups randomly, including the control group (N, 8 rats), and radiation groups (a, b, c and d, 6 rats each group). For radiation groups, the left mandible of each rat was irradiated at doses of 7.0 Gy for 5 fractions, other rats were sham irradiated, serving as control groups.7 days after irradiation, the left mandibular molars of all rats were extracted. The radiation groups rats were sacrificed at 7, 14, 21, 28 days after irradiation randomly, the 2 rats in control group were sacrificed respectively. All the rats' mandibles were taken and examined by clinical manifestation and Micro-CT and histology methods. The data was analyzed with SPSS 18.0 software package. RESULTS In clinical observation, ulcers were seen in the irradiated site at the 7th day, after then, alopecia, occlusion disorder, and pus discharged from buccal side were seen. Weight loss rightly after radiation and weight gain were seen at the 14th day. In pathological observation, marrow cavity changed first. Many adipose cell was first seen at the 7th day, and inflammations, necrosis, and fibrosis were found in medulla in the irradiated groups after that. Significant increment of empty lacunae and decrement of osteocytes were observed in all irradiated groups at the 7th day. Necrotic bone of the irradiated mandible was only found at the 28th day. Lack of new bone formation within the socket was seen in the Micro-CT three-dimensional at 28th day, and there are no more changes at the early-stage in this model. CONCLUSION An modified rat model of osteoradionecrosis was successfully established, which can shorten experimental period, and this model early stage and deserved to be further researched. Can be used to observe clinical, pathological and imaging magnification, which play a basic role in the protection in early stage and deserved to be further researched.