Impairment of molar tooth eruption caused by x-radiation.

The effect of x-radiation on erupting molars is presented. New born, 5 day old Wistar rats were locally irradiated in the molar area with doses of 20 Gy. They were killed in two groups, 30 and 60 days postirradiation respectively. Two other groups of non irradiated, age matched rats were killed at the given times. In addition a control group of 5 day old animals was also studied. Radiographic and histologic studies were performed. Odontoblastic atrophy, odontodysplasia, rootless formation, and ankylosis of tooth to bone by osteodentin formation with the resulting lack of tooth eruption were observed. The relation between the histologic alterations and tooth eruption is discussed.