AN ELECTRON MICROSCOPIC STUDIES OF RADIATION EFFECTS ON THE ENAMEL DEVELOPMENT OF THE RAT MOLAR

방사선조사가 백서구치법랑질발육에 미치는 영향에 관한 전자현미경적 연구

Mandibular first molars of the rats were undertaken to observe the radiosensitivity of amelogenesis. Twenty four Sprague-Dawley rats received 396cGy radiation with the MK Cell irradiator using Cs-137, and twenty four rats served as control. They were devided into two groups; Group 1 which received radiation at the 14th day after gestation and group 2 which received radiation at the 19th day after gestation. Light Microscopy and Transmitted Electron Microscopy investigation was undertaken in the group 1 at the 15th, 18th, 20th, 22nd(2 days after birth), and 25th day(5 days after birth) after gestation, and in the group 2 at the 21th(birth day), 22nd(2 days after birth), and 25th(5 days after birth) day after gestation. The following histopathologic findings were obtained. 1. Compared with control group, experimental group showed a delayed formation of enamel and dentin due to slow rate of differentiation of undifferentiated mesenchymal cells. 2. In the experimental groups, the arrangement of the inner enamel epithelium was irregular and there were many vacuoles in the cytoplasm. There were dilated rER and mitochondria, increase of the intercellular space, and loss of the cellular polarity. 3. In the group 1, early enamel without Tomes' process, and early organic matrix was observed at the 25th day after gestation. 4. In the group 2, histopathologic changes were similar to those of the group 1, but the degree of changes was more severe than that of the group 1.