Introduction: Odontogenic mixomas (OMs) are a locally infiltrating slow-growing intraosseous nonmetastasizing tumors of the maxilla and the mandible that have the potential for bone destruction and cortical expansion, showing high recurrence rates. Their frequency varies around the world, accounting for 3-20% of all odontogenic tumors, ranking third among odontogenic tumors. They predominantly affect young adults, but may occur in various age groups. Report: A 37-year-old female patient who in August 2005 sought treatment at the Maxillofacial Dental Unit at Hospital Higueras, Talcahuano, Chile, for a left maxillary bone lesion. An increase in volume was observed in the left maxillary region in the clinical analysis of the oral cavity. The neoplasm was sessile and painless, measuring approximately 3 cm, with a greater diameter in the vestibule, firm on palpation and without signs of gangliopathy. Computed cone beam tomography imaging showed an extensive infiltrating osteolytic lesion in the left maxillary sinus, with no involvement of the orbital bone structure. Analysis of incisional biopsy yielded the diagnosis of Odontogenic Fibromixoma. It was proposed to perform the conservative treatment of the lesion, consisting of enucleation and surgical curettage, obtaining excellent postoperative results and absence of relapse after 11-year follow-up. Conclusion: The present case report provides evidence that supports the conservative surgical approach for the treatment of odontogenic myxomas, which contributes to a better postoperative quality of life for the patient.