Long-term radiographic and histological observations of endodontically treated teeth.

Endodontic therapy was performed on 14 teeth in juveniles with inflamed or necrotic pulps. The patients were recalled at 6-month intervals for radiological and clinical examinations. After 1 yr, periapical surgery was performed on six teeth. After 18 months, 5 more patients were subjected to periapical surgery and, after 2 1/2 years, 3 more patients had periapical surgery. A small block section containing the root tip and surrounding tissues was removed from all of the patients. Radiographs showed reductions in size, but not elimination, of periapical lesions. Histological examinations revealed that most root canals were overfilled. Inflammation persisted around zinc oxide-eugenol particles beyond the tooth apexes. In addition, gutta-percha overfilling enhanced the proliferation of cell rests of Malassez. In some cases, dentin filings were found at and beyond the tooth apexes. The formation of new hard tissue was stimulated by the presence of dentin chips.