Characterization of the periapical surgical specimen. A morphologic and histochemical study of the inflammatory...

Biopsies of human periapical lesions obtained during endodontic surgery were studied morphologically and histochemically to determine the nature of the inflammatory reaction. Evaluation was based on cell types, morphologic patterns, degree of cellular infiltration, extracellular components, and their interrelationships. Almost all periapical lesions showed the characteristic features of granulomatous inflammation; chronic (nongranulomatous) inflammation was a lesser component of the reaction. Acute inflammation was seen either as focal concentrations or as scattering of polymorphonuclear neutrophilic leukocytes in variable numbers throughout the chronic and granulomatous inflammatory tissue. Epithelium was noted in one third of the specimens. Granulation tissue was not seen. Thus, granulomatous inflammation appears to be a consistent inflammatory reaction pattern in periapical lesions.