Experimental Odontogenic Tumors by Laser Cell Micromanipulation

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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.