In order to study the toxic effect of adriamycin on the formation of dentin of the rat, adriamycin (5mg/kg body weight) was injected intravenously, and animals were sacrificed at 1, 3, and 10 days after administration.
In the light micrographic observation, aggregation of densely stained cells were observed along the wall of the pulp canal and the odontoblastic layer disappeared after 1 and 3 days. The predentin was not even in thickness and irregular in
boundary
compared to normal predentin. The formation of osteodentin, which has cellular inclusions in the matrix, was noted after 10 days.
Electron microscopic observation revealed that the cells in aggregation had long slender cytoplasmic processes and contained more profiles of endoplasmic reticulum and secretory granules. The odontoblasts showed degenerative changes such as
cytoplasmic
vacuolation and fragmentation of rEr. The cells in the osteodentin and on the surface of irregular osteodentin contained dilated cisternae of rEr and secretory granules. Some cells showed necrotic and degenerative changes. There were no
odontoblastic
processes and dentinal tubules in the osteodentin matrix, central region of which was densely packed with collagen fibers.
It therefore appears that osteodentin formation was observed in the pulp of root canal after adriamycin administraion and it is the result of an abnormal differentiation of pulp mesenchymal cells.
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