We report an unusual case of a displaced maxillary molar and associated dentigerous cyst within the maxillary sinus in an adolescent presenting as recurrent sinusitis. Although a rare cause of sinusitis in children, dentigerous cysts should be included in the differential diagnosis for causes of persistent or recurrent sinusitis in this age group. This report provides further evidence for obtaining imaging studies when managing pediatric sinusitis that does not respond to standard antibiotic therapy. We discuss management options for these lesions including the differential diagnoses and need for follow-up.