This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
[{'content': 'Most common cause of oroantral fistula ? \nSelect and explain. \nA. TB, B. Penetrating injury, C. Tooth extraction, D. latrogenic', 'role': 'user'}, {'content': "Answer: C \nExplanation: 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.", 'role': 'assistant'}]