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: Unknown
[{'content': 'Newly erupted teeth is covered by: \nSelect and explain. \nA. Perikymata, B. Nasmyth’s membrane, C. Enamel Pearls, D. Dentin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref. Gray’s anatomy.\xa0 41st edition. Page. 520\nNASMYTH’S MEMBRANE\n\nCovers newly erupted tooth.\nMembrane replaced by pellicle.\nMicrobes invade pellicle to form plaque.\n\nENAMEL PEARLS\n\n\xa0Occasionally found on root surface towards cervical margin.\nImportance: Predisposed to plaque accumulation following gingival recession.\n\nPerikymata\n\n\xa0Transverse wave like grooves appear to be the external manifestations of external manifestations of striae of retziusstriae of retzius.\nSeen in freshly erupted teeth or in tooth which is not subjected to abrasive forces.not subjected to abrasive force\nAverage of 30 perikymata/mm in cervical regionin cervical region and 10/mm in occlusal region\nThese may contribute to adherance of plaque material which results in caries.', 'role': 'assistant'}]