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: Dental
[{'content': 'Name the injury seen in the colour plate: \nSelect and explain. \nA. Crown fracture, B. Enamel infraction, C. Crown fracture without pulp exposure, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: A crack line or chip of the enamel is the key clinical feature\xa0of enamel infarction.\nENAMEL INFARCTION\nCLINICAL FINDINGS: Visual examination\xa0by DYES (Methylene Blue). Tooth is not tender on percussion. If tender on percussion, check for luxation injury/root fracture.\nTREATMENT: Etching and sealing with resin to prevent discoloration of infarction line.', 'role': 'assistant'}]