Open Pulpitis: Histology
A. The carious process has destroyed much of the dentin, and bacteria have entered the pulp chamber; the result is ulceration as well as a massive accumulation of inflammatory cells. From the ulcerative pulpal tissue, granulation tissue begins to emerge and literally grow out of the coronal opening. The bacterial infiltration of the coronal pulpal tissue leads to necrotization with tissue destruction; within the ulcerated tissue is an accumulation of polymorphonuclear leukocytes; at the transition to the root canals one observed a mononuclear leukocytic wall. Granulation tissue is also visible in the periapical area.
B. The coronal pulpal tissue is epithelialized and consists primarily of dense connective tissue; it is collagen fiber-rich, relatively frees of vasculature, and contains numerous nerve fibers that reach even to the epithelium, as well as areas of persisting chronic inflammatory infiltration.
D. This enlarged view of the coronal third of the root canal reveals an infiltration with inflammatory cells, tissue components, as well as destruction of the odontoblastic layer.
E. The inflammatory infiltrate is dominated by monocytes. In addition to lymphocytes, note also the plasma cells, an expression of a local immune reaction.