Cellular mechanics of dentinal bridge repair using 3H-thymidine.

Cellular reorganization in the pulp following mechanical pulp exposure involves three steps: First, lysis and macrophage resolution of the clot form; second, there is an invasion of the clot area by fibroblasts and endothelial cells, i.e., formation of granulation tissue; third, an organization and differentiation of these cells into functional odontoblasts occurs as early as 9 days after exposure. Autoradiographic results showed an increased DNA synthesis in the fibroblast and endothelial cell populations which coincided with a histologically-observed increase in those populations. A relative increase in fibroblastic activity, as compared to endothelial cell activity, suggested that fibroblasts may be the cells that replace odontoblasts.