兔下颌骨放射性骨坏死模型的建立及评估

目的 建立兔下颌骨放射性骨坏死动物模型,并通过大体观察、单光子发射计算机体层摄影（SPECT）、显微CT及组织病理学方法对该模型进行评估。方法 将24只新西兰兔随机分为对照组和低、中、高3个剂量组,根据生物学等效公式,以低分割多次照射法,使用直线加速器对各组动物的左侧下颌区分别进行0、8.0、8.9和9.7 Gy照射,共5次。45 d后,拔除所有动物左侧下颌磨牙,3个月后,进行大体观察、SPECT、显微CT及组织病理学检查,采用SPSS17.0软件包对数据进行统计学处理。结果 高剂量组动物死亡率较高。高、中剂量组出现照射区皮肤脱毛及照射侧拔牙创不愈合、下颌骨死骨形成并暴露;低剂量组脱毛不明显、拔牙创形成完整黏膜覆盖。组织学观察显示,高、中剂量组下颌骨有死骨形成及骨髓腔纤维化改变,低剂量组主要表现为髓腔炎症。SPECT显示,高、中剂量组代谢率较对照组显著降低。Micro-CT显示,高、中剂量组有死骨分离及骨皮质破坏,BV/TV、Tb.Th、Tb.N值下降,Tb.Sp值增加。结论 以 8.9 Gy剂量对兔下颌区进行分割照射并在照射后拔牙,可成功建立下颌骨放射性骨坏死模型,在各项指标中均有明显放射性骨坏死表现,可重复性好,是研究下颌骨放射性骨坏死较为理想的动物模型。

Establishment of a rabbit model for mandibular osteoradionecrosis

PURPOSE： The present study was performed to establish a standard animal model of mandibular osteoradioneerosis （ORN） in rabbit and to evaluate the irradiated mandibles based on clinical manifestation, single-photon emission computed tomography （SPECT）, micro-CT, and histological observation. METHODS： According to the biological equivalent formula and hypofractionation radiation method, twenty-four rabbits were randomly divided into 4 groups： group 1 served as control, the left mandibles in group 2, 3 and 4 received iron irradiation at doses of 8.0, 8.9 and 9.7Gy every two days and 5 times respectively using linear accelerator. Forty-five days after irradiation, the left mandibular molars were extracted in all groups. Three months later, the mandibles in all groups were examined by clinical manifestation, SPECT, micro-CT, and histological observation to select the most suitable model. The data was analyzed with SPSS17.0 software package. RESULTS： Two rabbits died in group 4 because of malnutrition. Alopecia of the irradiated skin, sequestration and bone exposure in irradiated mandibles, and fibrosis in medulla were found in Group 3 and 4. In group 2, alopecia was less significant, and the mandibles had mainly showed medullary infection. Group 3 and 4 showed decreased BV/TV, Tb.Th, Tb.N and increased Tb.Sp compared to group 1 and 2. SPECT showed that bone metabolic rate in group 3 and 4 decreased significantly. CONCLUSION： We successfully established a reproducible rabbit model with mandibular osteoradioneerosis using iron radiation at dosage of 8.9 Gy with postradiation dental extractions. This model can serve as a platform for future studies on pathogenesis and treatment of ORN.