Effects of60CO-γ-Irradiation on Teeth and Jaw Bone in the Rabbit

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Abstract
The jaw bone, including teeth, of 61 young adult rabbits was exposed to single doses of 60Co-μ-radiation ranging from 1000 to 4000 rads. The beam struck the jaw bone in a caudocephalad direction. The rabbits were injected with 3 different fluorochromes administered at specific intervals and sacrificed 2, 6, 12 or 24 weeks after irradiation. At the time of sacrifice they were infused with Indian ink. The jaws were examined by X-ray photography, microangiography, light and fluorescence microscopy. There was no damage in 15 of 16 investigated rabbits after 1 000 rads. Forty-one of 42 rabbits irradiated with ≥2 000 rads showed damage to the teeth. The first signs of damage occurred apically in the teeth, in the form of a stunted growth of the continuously growing teeth. The pulp cavity then became occluded by a mixture of irregular dentin and cellular cementum. As the irradiated teeth erupted, which occurred at a reduced rate, the empty part of the fundus of the alveolus after 2 000 rads was replaced by newly formed bone of normal appearance after 6 weeks, while after 3 000 rads new bone formation was atypical. Bone destruction was predominant and new bone formation was of an abnormal type 12 weeks after 3 000 rads and 24 weeks after 2 000 rads. Total avascularity of the pulp was not observed until 12 weeks after ≥2 000 rads and a pronounced reduction of functioning cortical vessels was not observed until 12 weeks after 3 000 rads and not until 24 weeks after 2 000 rads. Some time between day 47 and day 65 after ≥2 000 rads, there was no fluorochromic apposition on the outer circumference of the jaw bone, indicating a considerable reduction of the osteogenic capacity of the periosteal cells compared to that of the control side.