Clinical, radiological, and histological diagnoses of periapical periodontitis spreading to the adjacent tooth: A case of endodontic failure.

ABSTRACT Aims: This article describes the apical infection in endodontically treated tooth 4.5 that spread to adja- cent tooth 4.4. Case Report: A 52-year-old woman was referred for the presence of radiolucency extend- ing from tooth 4.5 and mental foramen. Spontaneous symptoms were present. Tooth 4.5 showed poor-qua- lity endodontics. The vitality of tooth 4.4 was negative, even though no mechanical trauma had been re- ported, nor was caries present. Both teeth were sensi- tive to percussion. Endodontic re-treatment of 4.5 and endodontic treatment of 4.4 were performed in a sin- gle visit. A large amount of endodontic sealer sque- ezed mesially from the root of tooth 4.5, where a par- tial horizontal root fracture was hypothesized. 6-, 12-, and 18-month radiographic follow-ups, by both peri- apical and cone-beam computed tomography (CBCT) analyses, showed incomplete osseous healing. CBCT excluded root fracture on 4.5. Local symptoms were still present. Clinical and radiological conditions led to extractions, and a cystic lesion was enucleated for histopathologic analyses. Histopathologic diagnosis was a periapical cyst. The supposed partial horizontal root fracture of 4.5 was actually a large lateral canal. Although the root canal treatments followed high standards in terms of quality, a persistent chronic in- fection developed histologically. The cystic lesion was one consistent reason for the unsuccessful healing of 4.5