The radiosensitive stages of the rat incisor odontoblast as demonstrated by autoradiography

— Five μCi 3 H‐glycine/g body weight were administered to six rats 30 min prior to, and to six rats 24 h after, exposure to a single head roentgen dose of 500 r. Autoradiographic investigations of the incisors demonstrated that the most radiosensitive cells, the preodontoblasts just prior to dentin production, proceeded to mantle dentin deposition while the cells were partially deprived of their capacity of circumpulpal dentin production. Slightly less sensitive were mantle dentin‐producing cells, the injury to which was also reflected as a partial lack of circumpulpal dentin production. The radiosensitive period (500 r) was approximately equivalent to a maximum of 48 h, and a minimum of 24 h.