This document discusses oroantral communication (OAC), which is a connection between the oral cavity and maxillary sinus that can occur after maxillary molar surgery. Risk factors for OAC include anatomical features like proximity of tooth roots to the sinus. Small OACs under 2mm may heal on their own with proper blood clot formation and sinus precautions. Larger openings may require closure techniques like buccal advancement flaps or palatal pedicle flaps to prevent chronic oroantral fistula formation. Postoperative care includes antibiotics, oral rinses, and avoiding nose blowing or drinking through a straw to allow the opening to heal.