Diagnosis and Guided Surgical Management of a Mandibular Buccal Bifurcation Cyst: A Case Report.

Mandibular buccal bifurcation cyst (MBBC) is a rare inflammatory odontogenic cyst that frequently mimics chronic periapical pathosis, leading to potential misdiagnosis and unnecessary endodontic treatment. This case report describes the diagnosis and management of an MBBC associated with a vital mandibular left second molar (#18) in a healthy 16-year-old female, highlighting the value of pulp vitality testing, cone beam computed tomography (CBCT), and a custom 3D-printed surgical guide for conservative management. The patient presented with buccal bony expansion and a 12-mm periodontal probing depth with purulent exudate. The tooth responded normally to sensibility testing, with no history of caries or trauma. Interpretation of CBCT images revealed a well-corticated mid-root radiolucency with an expansile pattern and a well-corticated buccal lesion originating from the buccal cortex with an intact lamina dura. A custom surgical guide fabricated from intraoral scans and CBCT data enabled precise cyst enucleation while preserving tooth vitality. Histopathology showed fibrovascular tissue with a dense chronic inflammatory infiltrate composed of lymphocytes, plasma cells, macrophages, and multinucleated giant cells. The diagnosis of an MBBC was based on clinical, radiographic, and histological findings, enabling preservation of the tooth with a minimally invasive approach. At the 1-year follow-up, the tooth remained vital, with normal probing depths and satisfactory bone healing on CBCT compared with the initial presentation. This case report emphasizes the need to consider MBBC in the differential diagnosis of radiolucent periapical lesions. Early detection, along with evidence-based management and guided surgery, is essential to avoid misdiagnosis and unnecessary endodontic treatment.