Hosokawa Yoichiro, Sakakura Yasunori, Tanaka Likinobu, Okumura Kazuhiko, Yajima Toshihiko, Kaneko Masayuki
Department of Dental Radiology, School of Dentistry, Health Sciences University of Hokkaido, Kanazawa, Hokkaido.
J Radiat Res. 2007 Jul;48(4):273-80. doi: 10.1269/jrr.06069. Epub 2007 May 31.
We examined effects of local and whole body irradiation before tooth extraction on appearance and differentiation of osteoclasts in the alveolar bone of rat maxillary first molars. Wistar rats weighting 100 g were divided into three groups: non-irradiation group, local irradiation group, and whole body irradiation group. In the local irradiation group, a field made with lead blocks was placed over the maxillary left first molar tooth. In the whole body irradiation group, the animals were irradiated in cages. Both groups were irradiated at 8 Gy. The number of osteoclasts around the interradicular alveolar bone showed chronological changes common to non-irradiated and irradiated animals. Several osteoclasts appeared one day after tooth extraction, and the maximal peak was observed 3 days after extraction. Local irradiation had no difference from non-irradiated controls. In animals receiving whole body irradiation, tooth extraction one day after irradiation caused smaller number of osteoclasts than that 7 day after irradiation during the experimental period. Whole body-irradiated rats had small osteoclasts with only a few nuclei and narrow resorption lacunae, indicating deficiency of radioresistant osteoclast precursor cells. Injection of intact bone marrow cells to whole body-irradiated animals immediately after tooth extraction recovered to some content the number of osteoclasts. These findings suggest that bone resorption in the wound healing of alveolar socket requires radioresistant, postmitotic osteoclast precursor cells from hematopoietic organs, but not from local sources around the alveolar socket, at the initial phase of wound healing.
我们研究了拔牙前局部和全身照射对大鼠上颌第一磨牙牙槽骨中破骨细胞外观和分化的影响。将体重100 g的Wistar大鼠分为三组：未照射组、局部照射组和全身照射组。在局部照射组中，用铅块制作一个区域覆盖在上颌左侧第一磨牙上。在全身照射组中，动物在笼中接受照射。两组均以8 Gy的剂量进行照射。根间牙槽骨周围破骨细胞的数量在未照射和照射动物中均呈现出随时间变化的规律。拔牙后1天出现几个破骨细胞，拔牙后3天观察到最大峰值。局部照射与未照射对照组无差异。在接受全身照射的动物中，照射后1天拔牙导致的破骨细胞数量在实验期间比照射后7天拔牙时少。全身照射的大鼠破骨细胞较小，核少，吸收陷窝窄，表明抗辐射破骨细胞前体细胞缺乏。拔牙后立即向全身照射的动物注射完整的骨髓细胞，破骨细胞数量部分恢复。这些发现表明，牙槽窝伤口愈合中的骨吸收在伤口愈合初期需要来自造血器官的抗辐射、有丝分裂后的破骨细胞前体细胞，而不是来自牙槽窝周围的局部来源。
