Immediate and delayed effects of repeated doxorubicin injections on rat incisor mesenchymal cells.

Effects of multiple injections of the cytotoxic drug doxorubicin hydrochloride (Adriamycin) on incisor mesenchymal cells were studied by light microscopy. Rats were killed 1 day after two and three injections, and 1 day and 5 days after four injections. Doses of 5 and 10 mg/kg were used and given on consecutive days. Necrotic alterations expanded in preodontoblast and basal pulp regions when the total dose was increased and finally embraced the entire progenitive part of the incisor. The necrotic area became encapsulated by cellular predentin produced by differentiated pulp cells to prevent further tissue damage, and commencing regeneration was observed after 5 days. When the total dose was split up, the cytotoxicity of doxorubicin increased.