Buccal bifurcation cyst (paradental cyst) defined by ultrasonography and cone-beam computed tomography.

Buccal bifurcation cyst (BBC) is an uncommon inflammatory odontogenic cyst that generally occurs at the buccal region of the permanent mandibular first molars in children aged 6-8 years. The diagnosis of BBC cannot be made from the histopathologic features; therefore, diagnosis is primarily based on specific clinical and radiographic findings. In this case report, we present the clinical and radiological findings, including ultrasonography (USG) and cone-beam computed tomography (CBCT) images, of a 10-year-old boy who was referred with a complaint of swelling on the lower right jaw. According to the radiographic and clinical findings, the differential diagnosis of this lesion included lateral radicular cyst, lateral periodontal cyst, dentigerous cyst, eruption cyst, and others. Recently, in addition to classical radiographies and CBCT, USG has been considered important for diagnosis. In particular, if a cyst produces a perforation in the cortical bone, it is helpful to make a pre-diagnosis with USG.