Rapidly Progressing Radicular Cyst in an Endodontically Treated Tooth: Diagnostic Challenges, Advanced Imaging, and Surgical Management.

Radicular cysts in teeth that have undergone root canal therapy (RCT) are uncommon but clinically important, often presenting unique challenges for diagnosis. Although rare, radicular cysts can progress rapidly, leading to symptoms, such as discomfort or swelling shortly after the initial treatment. In this case, a 29-year-old female experienced mild discomfort localized to the maxillary right first premolar, which had received RCT several months prior. The patient had no history of systemic conditions or chronic infections. Upon clinical examination, tenderness was noted in the periapical region; however, conventional radiographs did not reveal detectable lesions. CBCT detected a well-defined cystic lesion at the distal aspect of the buccal root apex. Surgical intervention was performed, which included cystectomy and root-end filling with calcium-enriched mixture cement. Histopathological analysis confirmed the diagnosis of a benign radicular cyst with a fibrous capsule and squamous lining, indicating no malignancy. The postoperative recovery was smooth, and a follow-up 1 year later showed a normal appearance of the periodontal ligament in radiographs, confirming the success of the treatment and retention of the tooth. This case highlights the diagnostic benefits of CBCT in detecting periapical lesions that may not be visible on conventional radiographs. It emphasizes the effectiveness of surgical management in resolving such endodontic lesions while maintaining tooth function.