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': 'The advantage of acidulated phosphate fluoride solution is- \nSelect and explain. \nA. It is good to taste and can be stored in glass container, B. No repeated suction evacuation needed, C. No effect on existing composite restoration, D. It has the ability to deposit fluoride in enamel to a deeper depth than neutral sodium fluoride or stannous fluoride', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Advantages of acidulated\xa0 phosphate fluoride\xa0\n\nRequires only 2 applications in a year and is thus suited for most dental office routines.\xa0\nThe gel preparation can be self applied and thus the cost of application also gets reduced.\xa0\nIt has the ability to deposit fluoride in enamel to a deeper depth than neutral sodium fluoride or stannous fluoride\xa0\nAPF is stable and need not be freshly prepared for each patient.\xa0\n\nDisadvantages of acidulated phosphate fluoride\xa0\n\nPractical difficulties like the teeth should be kept wet for 4 minutes. So repeated applications\xa0 necessitates\xa0 the\xa0 use\xa0 of\xa0suction thereby minimizing its use in the field. This also increases the chair side time making this method more expensive.\xa0\nIt is acidic, sour and bitter in taste.\xa0\nIt cannot be stored in glass containers.\xa0\nRepeated\xa0 or\xa0 prolonged\xa0 exposure\xa0 of porcelain or composite restorations to APF can result in the loss of materials,\xa0surface\xa0 roughening\xa0 and\xa0 possible cosmetic changes.', 'role': 'assistant'}]