<prompt> Most common cause of oroantral fistula ?TBPenetrating injuryTooth extractionlatrogenic  <response>: Ans. is c i.e., Tooth extraction Oroantral fistula It is communication between the antrum and oral cavity. Etiology Dental extraction :- Most impoant cause and maxillary first molar accounts for 50 of oral-antral fistulas caused by extractions. Maxillary second and third molar extractions account for other 50. Infection :- TB, syphilis, leprosy of maxillary bone. Malignant neoplasm :- Causes erosion of antrum. Fracture or penetrating injuries of maxilla. Midline granuloma a form of lymphoma Failure of sublabial incision to heal after Caldwell - Luc operation. Clinical features Regurgitation of food Discharge often foul smelling Inability to built positive or negative pressure in mouth. 