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: Radiology
[{'content': 'The most common type of radiation caries is: \nSelect and explain. \nA. Cervical surface involvement of teeth, B. Widespread superficial lesion attacking buccal, occlusal, incisal and palatal surfaces, C. Spreading to occlusal and palatal surfaces, D. Dark pigmentation of the entire crown', 'role': 'user'}, {'content': "Answer: B \nExplanation: Clinically, three types of radiation caries exists.\n\nThe most common is widespread superficial lesions attacking buccal, occlusal, incisal, and palatal surfaces. Another type involves primarily the cementum and dentin in the cervical region. These lesions may progress around the teeth circumferentially and result in loss of the crown.\xa0\nThe third type appears as a dark pigmentation of the entire crown. The incisal edges may be markedly worn.\xa0\nCombinations of all these lesions develop in some patients. The location, rapid course, and widespread attack distinguish radiation caries.\xa0\nThere is also evidence that radiation caries is more likely to lead to periapical inflammatory lesions, if the periapical bone received a high dose of radiation.\n\nReference: White and Pharoah's Oral Radiology Principles and Interpretation 7th edition page no 22", 'role': 'assistant'}]