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: Surgery
[{'content': "According to SAWHNEY'S classification of TMJ ankylosis, complete joint architecture is destroyed by osseous union and no sigmoid notch is identifiable, this is: \nSelect and explain. \nA. Type 1, B. Type 2, C. Type 3, D. Type 4", 'role': 'user'}, {'content': "Answer: D \nExplanation: SAWHNEY'S GRADING OF ANKYLOSIS\xa0\n\nTYPE 1: Flattening or deformity of the condyle with little joint space seen on the radiograph. Extensive fibrous adhesions seen during operations.\xa0\nTYPE 2: Bony fusion of the outer edges of the articular surfaces with no fusion in the deeper areas of the joint.\xa0\nTYPE 3: A bridge of bone is seen between ramus of the mandible and zygomatic arch.\xa0\nTYPE 4: Entire joint is replaced by a mass of bone.", 'role': 'assistant'}]