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': 'Which of the following is a disadvantage of topically applied sodium fluoride solution? \nSelect and explain. \nA. Need to prepare a fresh solution for each patient, B. Taste is not well accepted by patients, C. Patient must make four visits to the dentist within a relatively short period of time, D. The solution should be allowed to dry for 5 minutes', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Advantages of neutral sodium fluoride solution-\n1. It is relatively stable when kept in a plastic container and there is no need to prepare a fresh solution for each patient.\xa0\n2. The taste is well accepted by patients.\xa0\n3. The\xa0 solution\xa0 is non-irritating\xa0 to the gingiva.\xa0\n4. It does not cause discoloration of tooth structure.\xa0\n5. Once applied to the teeth, the solution is allowed to dry for 3 minutes. Thus the clinician in public health programs can pursue a multiple-chair procedure.\xa0\n6. The series of treatments must be repeated only four times in the general age range of 3\xa0 to\xa0 13, rather than\xa0 at annual or\xa0semiannual intervals, therefore in a public health program, other groups of children can be treated in theJintervening years.\xa0\nDisadvantage of neutral sodium fluoride solution-\n1. The major disadvantage of the use of sodium\xa0fluoride is that the patient must make four\xa0visits to the dentist within a relatively short\xa0period of time.', 'role': 'assistant'}]