Oronasal fistula following spontaneous exfoliation of a maxillary third molar in a patient receiving concurrent CPAP therapy: a case report.

Background: Continuous positive airway pressure (CPAP) therapy is the first-line treatment for obstructive sleep apnea (OSA) and is generally considered safe. The reported adverse effects, such as nasal dryness, congestion, and mask-related discomfort, are usually mild and localized. Severe structural complications involving the oral or nasal cavities are exceedingly rare. Case presentation: A 59-year-old man with severe OSA, successfully managed with nasal CPAP therapy for four years, presented with air leakage during CPAP use and nasal regurgitation of fluids while drinking. Two months prior to presentation, spontaneous exfoliation of the left maxillary third molar had occurred, suggesting underlying odontogenic and maxillary pathology. Subsequently, an oronasal fistula developed. Computed tomography revealed a fistulous tract extending from the nasal floor to the posterior maxillary region, accompanied by localized bone defects. Conservative management was unsuccessful, and surgical closure using a local mucoperiosteal flap was performed. Complete symptom resolution was achieved, and CPAP therapy was successfully resumed without recurrence during follow-up. Conclusion: This case describes a rare occurrence of an oronasal fistula as a potential complication following spontaneous exfoliation of a maxillary third molar in a patient receiving concurrent long-term CPAP therapy. While underlying odontogenic and maxillary pathology was considered the primary structural vulnerability, sustained positive airway pressure may have acted as a perpetuating or aggravating factor by interfering with normal wound healing. Clinicians managing patients with long-term CPAP therapy should be aware of potential interactions between positive airway pressure and pre-existing dental or maxillary conditions, underscoring the importance of interdisciplinary collaboration.