The present study reports a case of a mandibular buccal bifurcation cyst (MBBC) associated with a partially erupted mandibular first molar. The intraoral examination revealed vestibular swelling in the right mandibular permanent first molar region. Panoramic radiography and cone-beam computed tomography (CBCT) showed a well-delimited radiolucent image involving the roots and part of the crown of the right mandibular permanent first molar with bulging and areas of buccal cortical bone resorption. An incisional biopsy was performed and the diagnosis was MBBC. The lesion was surgically removed by enucleation and curettage. Bone repair was observed seven months after the surgical procedure.