X-線 照射가 齒牙發育에 미치는 影響에 關한 實驗的 硏究

EXPERIMENTAL STUDY ON THE EFFECTS OF X-RAY IRRADIATION ON TOOTH DEVELOPMENT

In order to observe the effect of X-Ray irradiation on the tooth development, the rats weighing 180Gm. to 210Gm. were irradiated with single dose of 1050rads and 2040rads When X-Ray irradiation, the body of rats were covered with 0.8cm. thick lead plate except the head portion. The rats were devided into three groups; a) control group. b) 1050rads irradiation group c) 2040rads irradiation group. The radiation equipment and manipulation were as follows. GE Maximer IV, Model 250, 200Kvp, 10mA. Filter: 1/4mm Cu. Target-skin distance: 50cm. Exposure dose rate: 25.5rads/min. After irradiation the animals were sacrificed and decapitated at the intervals of 24hours, three days, one week, two weeks, three weeks and four weeks. And they were decalcified and made histologic sections for microscopic study. The results were as follows: 1. There was no significant difference in tissue changes between 1050rads and 2040rads irradiation groups. 2. Congestion and thrombosis of vascular channels, and extravasation of red blood cells of the pulp, periodontal membrane and surrounding structures of the enamel organ were persisted from the first day to the fourth week after irradiation, the end of the experiment. 3. The enamel matrix of the experimental group was thin in compare with the control group. 4. The dentine which formed between the first and third week after irradiation was thin, and dentine dysplasia was showed. 5. At fourth week it showed that the dysplastic dentine was remarked toward the incisal edge and the newly formed dentine was replaced at the apical end.