Incorporation of ³H Thymidine into Damaged Pulp of Rat Incisors

¹ First Department of Pathology and Second Stomatological Clinic, Medical Faculty, J. E. Purkyn University, Brno, Czechoslovakia

³H thymidine was injected intraperitoneally into six male rats on the first, second, and third days after injury to the pulp of the incisors. Forty minutes later the rats were decapitated; the teeth were fixed in formalin and prepared in the usual manner for histoautoradiography. Histologic preparations were stained with hematoxylin and eosin. No odontoblast nuclei labeled by ³H thymidine were observed on the histoautoradiographic pattern. After pulp injury, the odontoblasts behaved as irreversible postmitotic cells incapable of DNA synthesis.