OBJECTIVE To propose a modified protocol of mandibular osteoradionecrosis induction in rats with external beam radiation therapy. MATERIAL AND METHODS A total of 45 male Wistar rats were used in this study. Firstly, 25 rats were divided into 5 groups (n = 5) according to the radiation dose protocol: without irradiation and irradiated with 15 Gy, 20 Gy, 25 Gy, or 30 Gy using a linear accelerator. Secondly, 15 other rats were divided into 3 groups (n = 5) according to the time of extraction of the three right mandibular molars: 7, 10, or 14 days after irradiation of 20 Gy. Lastly, dental extractions were performed in 5 other rats without irradiation (C-E10) for comparison with those of the group of dental extractions 10 days after irradiation (I-E10). RESULTS The irradiated animals survived throughout the study period only at single doses of 15 Gy and 20 Gy. The suitable time for dental extractions after irradiation to induce mandibular osteoradionecrosis was defined as 10 days. Macroscopic evaluation of the right hemimandibles showed presence of osteoradionecrosis in I-E10 group and complete gingival healing in C-E10 group. CONCLUSION A single radiation dose of 20 Gy focused on head and neck region combined with the extraction of the three mandibular molars 10 days after irradiation constitutes a feasible protocol of mandibular osteoradionecrosis induction in rats with external beam radiation therapy. CLINICAL RELEVANCE Establishing a solid and widely available protocol of mandibular osteoradionecrosis induction is essential in the search for methods to prevent this complex disease.

中文翻译：

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改良的外束放射疗法诱导大鼠下颌骨放射性坏死的方案。

目的提出一种改良的外照射治疗大鼠下颌骨放射性坏死的方法。材料与方法本研究共使用45只Wistar雄性大鼠。首先，根据放射剂量方案将25只大鼠分为5组（n ＝ 5）：不进行辐照，并使用线性加速器辐照15 Gy，20 Gy，25 Gy或30 Gy。其次，根据右下颌三个磨牙的提取时间，将另外15只大鼠分为3组（n = 5）：20 Gy照射后第7、10或14天。最后，在另外5只未进行辐照的大鼠（C-E10）中进行了拔牙，以与辐照后10天（I-E10）的一组拔牙者进行比较。结果受辐照的动物在整个研究期间仅以15 Gy和20 Gy的单剂量存活。辐射后引起下颌骨放射性坏死的拔牙时间为10天。右半定量的肉眼观察显示，I-E10组存在骨放射性坏死，C-E10组完全牙龈愈合。结论聚焦于头颈部区域的20 Gy单一辐射剂量加上辐射后10天拔除三个下颌磨牙构成了在外照射治疗下诱导下颌骨放射性坏死的可行方案。临床相关性建立可靠且广泛使用的下颌骨骨坏死诱导方案对于寻找预防这种复杂疾病的方法至关重要。