Repair of Extensive Apical Root Resorption Associated with Apical Periodontitis: Radiographic and Histologic Observations after 25 Years

Root resorption is a frequent finding in teeth with apical periodontitis. In cases of severe apical periodontitis, root resorption may involve not only cementum but also dentin. Resorbed tooth structures can only be repaired with cementum because stem cells in the periradicular tissues are not capable of differentiating into odontoblasts. This article reports the repair of extensive apical root resorption associated with apical periodontitis 25 years after treatment.A 51-year-old man presented with pulp necrosis and symptomatic apical periodontitis in tooth #7. The periapical radiograph showed a large radiolucent periradicular lesion and severe root resorption. Nonsurgical root canal therapy was performed. Twenty-five years after treatment, a crown fracture developed, and the tooth could not be restored. The periapical radiograph revealed complete healing of the previous apical periodontitis lesion and restoration of the resorbed root structure. The tooth was removed and examined histologically.The apical canal was almost completely filled with a cementumlike tissue with some strands of entrapped vital uninflamed connective tissue. Areas of cementum and dentin resorption in the apical third were repaired by a combination of cellular and acellular cementum to which periodontal ligament fibers were attached.Root resorption caused by apical periodontitis can be restored almost to its normal structure after adequate nonsurgical root canal treatment that succeeded in controlling infection. The mechanisms behind this process are not clear but probably involve signaling pathways regulating root development, cell-cell and cell-matrix interaction, and morphogens.