Experimental Odontogenic Tumors by Laser Cell Micromanipulation

本研究旨在通过激光微束细胞操纵技术研究牙源性肿瘤的组织发生。用连续波激光(全牙胚照射)照射C3H小鼠钟状期下颌第一磨牙牙胚。将照射后的牙胚移植到同基因小鼠肾被膜下，移植后3、5、7周取材进行组织学检查。经照射的牙胚移植后与未照射的牙胚相比，成釉细胞和牙本质的发生基本正常。主要的组织学改变是牙骨质形成。照射后的牙胚表现为根尖周区细胞牙骨质的进行性增生。仅有一个结节状的成牙骨质细胞增生伴牙骨质形成。这些结果提示激光对成牙骨质细胞的生长促进作用是可能的，激光照射牙胚的热点被认为是牙周环区，该区域负责牙周组织的形成，包括牙骨质的形成。将聚焦的He-Ne激光微束聚焦照射到钟状期牙胚的颈环或牙乳头。无论是照射在颈环上的牙胚，还是照射在牙乳头上的牙胚，移植后均未见组织病理学改变。虽然激光和He-Ne激光照射均不能促进牙胚的釉质上皮细胞增殖，但本系统在牙源性肿瘤的组织发生机制研究中具有许多优势。

This research project is designed to study the histogenesis of odontogenic tumors by laser microbeam cell manipulation.The mandibular first molar tooth germs in the bell stage obtained from the C3H mice were irradiated with the continuous wave Nd:YAG laser(whole tooth germ irradiation). The irradiated tooth germs were transplanted under the renal capsule of the syngeneic mice .The grafts were harvested 3,5 and 7 weeks after transplantation for histological examination. Irradiated tooth germs showed almost normal amelogenesis and dentinogenesis compared with the unirradiated tooth germs after transplantation .The chief histological changes were found in the cementogenesis.The irradiated tooth germs showed progressive hyperplasia of the cellular cementum of the periapical regions.Only one nodular lesion of the cementoblastic proliferation with cementicles was also found.These findings suggested the possibility of the growth promotion effects of the laser on the cementoblasts,and the hot spot of the laser irradiation on the tooth germs was thought to be the peri-cervical loop region which was responsible for the formation of the periodontium including the cementogenesis.Secondly;the focused microbeam of He-Ne laser was focused and irradiated on the cervical loop or on the dental papilla of the bell stage tooth germs. Neither the tooth germs irradiated on the cervical loop not the tooth germs irradiated on the dental papilla showed any histopathological change after transplantation.Although both the Nd:YAG laser and the He-Ne laser irradiation failed to proliferate the enamel epithelium of the tooth germs,our system seems to have many advantages for detailed investigation of the histogenesis of the odontogenic tumors.