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: Pathology
[{'content': 'Thistle-tube appearance is a characteristic feature of: \nSelect and explain. \nA. Radicular dentin dysplasia, B. Coronal dentin dysplasia, C. Amelogenesis imperfecta, D. Dentinogenesis imperfecta', 'role': 'user'}, {'content': "Answer: B \nExplanation: Radiographic features of type II (coronal) dentin dysplasia:\nThe permanent teeth exhibit an abnormally large pulp chamber in the coronal portion of the tooth, often described as ‘thistle-tube’ in shape, and within such areas radiopaque foci resembling pulp stones may be found.\nRef: Shafer's textbook of oral pathology 7th edition page 57", 'role': 'assistant'}]