Aim: The cemento-ossifying fibroma (COF) is a benign fibro-osseous neoplasm of non-odontogenic origin, that is preferentially localised on the molar and premolar mandibular area. Our goal is to present cases of COF that occurred within the same family, describing clinical, radiological and histological characteristics, in addition to treatment and monitoring of each case.

Methods: Two patients who are brothers, treated at the Carabineros Hospital, who had mandibular COF, were included in this study. The complete evolution of each case is presented, highlighting the family component of this uncommon disease.

Results: All patients were treated with complete removal of the lesion and filling the bone defect with autologous iliac crest graft or synthetic cancellous bone graft (ChronOS ^® ). One patient had recurrence of the injury and then present a new COF on the contralateral side.

Conclusion: In this type of injury is very important to use all the diagnostic tools that are within our reach. The rarity of these lesions, and the great similarity of both clinical, radiological and histological features with other pathological conditions of the jaws, make a study done poorly, can lead to wrong diagnosis and treatment, affecting the quality of life of patients. The treatment of these lesions is conservative, and relapses are rare.

Conflict of interest: None declared.