BACKGROUND Ameloblastomas are benign asymptomatic intraosseous lesions that affect the bones of the maxillomandibular complex, interfering both in function and facial esthetic appearance. A 14-year-4-month-old girl was referred by her clinician complaining her anterior teeth were crooked and inclined forward. The lower left mandibular tooth presented with increased pericoronal space compatible with dentigerous cyst. RESULTS The aim of this report is to relate a case of unicystic ameloblastoma with conservative treatment and with indication for orthodontic treatment. The conservative therapy was performed and the lesion had been completely removed. The need for radiographic and clinical follow-up for up to 10 years, initially performed every 6 months during the first 2 years and afterwards annually, in addition to the risk of late recurrence were explained for patient and her guardian. CONCLUSIONS The histopathologic exam of the surgical tissue provided the final diagnosis of ameloblastoma, as the lesion had not presented in its classical form and in atypical locations, as in this case involving a tooth that had not yet erupted.