Persistent Periradicular Lesion Associated With Concurrent Root Fracture and Odontogenic Keratocyst: A Case Report.

Persistent periradicular lesions in root canal-treated teeth present a diagnostic challenge, as they may result from failed endodontic treatment, root fracture, or non-endodontic pathoses. Accurate diagnosis is essential, given the significant differences in their management. This report describes a case of a persistent periradicular lesion associated with a root canal-treated maxillary lateral incisor in a 45-year-old male. Despite nonsurgical root canal retreatment, a chronic apical abscess persisted. Cone-beam computed tomography revealed a well-defined radiolucency and a suspected root fracture. Exploratory surgery with methylene blue staining confirmed the root fracture. Histopathological examination of the curetted intraosseous lesion revealed a cystic lumen lined by para-keratinized stratified squamous epithelium with palisaded basal cells and surface corrugation, confirming the diagnosis of an odontogenic keratocyst (OKC). The co-occurrence of a root fracture and an OKC is a rare finding. This case underscores the non-specific clinical and radiographic features of such entities that can mimic endodontic disease. A definitive diagnosis and successful treatment planning depend on the correlation of clinical, radiographic, and histopathological findings, highlighting the critical role of biopsy in persistent lesions.