Ida-Yonemochi Hiroko, Saku Takashi
Division of Oral Pathology, Department of Tissue Regeneration and Reconstruction, Niģata University Graduate School of Medical and Dental Sciences, Niģata, Japan.
J Oral Pathol Med. 2002 Jul;31(6):374-8. doi: 10.1034/j.1600-0714.2002.00138.x.
Incisor tooth germs of osteopetrotic (op/op) mice are known to fail to erupt, but form odontomas in their root apices instead, due to invasion of alveolar bone trabeculae into the tooth germs. The purpose of this study is to determine if the tooth developmental failures in op/op mice are intrinsic or secondarily arise as a result of the defective bone metabolism due to lack of macrophage colony-stimulating factor (M-CSF).
We isolated mandibular first molar tooth germs from normal and op/op mice and cultured them under conditions with or without bone tissues which had been formed around tooth germs.
Tooth germs from normal mice, cultured for a week, showed almost the same developmental features as those of mice with the corresponding age. They were surrounded with dental follicular tissues and were never invaded by bone trabeculae. On the other hand, op/op tooth germs cultured in the presence of bone components were invaded by alveolar bone trabeculae around tooth germs in the same manner as shown in vivo. When cultured without bone, they developed without any interruptions.
These findings indicated that op/op tooth germs had potential for normal development and that their abnormal development was a secondary phenomenon caused by lack of bone remodeling in the early phase of odontogenesis.
已知骨硬化症（op/op）小鼠的切牙牙胚无法萌出，而是在牙根尖形成牙瘤，这是由于牙槽骨小梁侵入牙胚所致。本研究的目的是确定op/op小鼠的牙齿发育失败是内在性的，还是由于缺乏巨噬细胞集落刺激因子（M-CSF）导致骨代谢缺陷而继发产生的。
我们从正常小鼠和op/op小鼠中分离出下颌第一磨牙牙胚，并在有或没有在牙胚周围形成的骨组织的条件下进行培养。
正常小鼠的牙胚培养一周后，显示出与相应年龄小鼠几乎相同的发育特征。它们被牙滤泡组织包围，从未被骨小梁侵入。另一方面，在有骨成分存在的情况下培养的op/op牙胚，与体内情况一样，被牙胚周围的牙槽骨小梁侵入。在没有骨的情况下培养时，它们正常发育，没有任何中断。
这些发现表明，op/op牙胚具有正常发育的潜力，其异常发育是牙胚发生早期骨重塑缺乏所导致的继发现象。
