Pathologic study of periapical lesions 1. Periapical granulomas: clinical, histopathologic and immunohistopathologic studies.

Seventy periapical granulomas were histopathologically examined. They were divided into four types: exudative, granulomatous, granulo-fibrous, and fibrous types. Clinicopathologically, those having marked lymphocytic infiltration were found more frequently in cases having had endodontic treatment; further, the size of a radiolucent area did not exceed that of the involved tooth crown. In contrast, a predominant plasma cell infiltrate was more frequent in cases with open pulp chambers (no treatment). In those cases, the radiolucent area was larger than the crown. Foci with very large radiolucent areas were often of the exudative type. Epithelial proliferation was more frequent in cases without treatment. These findings indicate that endodontic treatment not only stops invasion of injurious factors but also proliferation of epithelium. Furthermore, in frozen sections of 26 granulomas, IgE-containing cells and IgG and C3 fluorescence in the connective tissue were often observed. It appears that IgE-mediated reaction and antigen-antibody complexes may play a role in periapical pathosis.