Light and ultrastructural studies of human chronic periapical lesions.

Forty clinically chronic periapical granulomas and cysts and their corresponding teeth were removed. Diagnosis was by light and transmission electron microscopy. Ultrastructural features of the root surfaces concerned and the corresponding soft tissue were detected by scanning electron microscopy. Chronic periapical inflammation had caused root resorption which affected the cementum and/or the dentin. There were no ultrastructural differences between granuloma- and cyst-induced root resorption. Resorption lacunae were devoid of epithelial and connective tissue attachment. However, root surface exposed to granulomas and cysts also indicated spontaneous cementum repair. Moreover, at their periphery, cellular debris, cells defined as fibroblasts, and cell projections and fibrils could be seen which were continuations of the periodontal ligament.