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': 'In which of the following conditions, the root can be left in the alveolar process? \nSelect and explain. \nA. Small root fragment, if size is 4-5 mm in length, B. The root must be deeply embedded in bone, C. The tooth involved must not be infected, and there must be no radiolucency around the apex., D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Conditions for a root to be left in the alveolar process:\n\nThe root fragment must be small, usually no more than 4 to 5mm in length.\nThe root must be deeply embedded in bone.\nThe tooth involved must not be infected, and there must be no radiolucency around the apex.\nWhen the risk is too great, if removal of the root will cause excessive destruction of surrounding tissue or damages important structures like inferior alveolar nerve or the root is pushed into tissue spaces or maxillary sinus.', 'role': 'assistant'}]