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': 'Disadvantage of minocycline in triple antibiotic paste used for disinfection of root canal prior to revascularization is: \nSelect and explain. \nA. Mutation of certain microbes, B. Development of resistance, C. Increase in brittleness of tooth, D. Crown discoloration', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Triple antibiotic paste\nConsists of metronidazole, ciproﬂoxacin, and minocycline in a macrogol propylene glycol ointment.\xa0 It is inserted into the canal with a sterile lentulospiral and left in the canal for 2-4 weeks.\nAdvantages:\n\nVery eﬀective in elimination of intracanal microbes.\nBroad spectrum action.\nEasy to prepare as ingredients are easily prepared.\n\nDisadvantages of Triple Antibiotic Paste:\n\nDiﬃcult to test the antimicrobial eﬀectiveness in endodontic models due to absence of an\xa0inactivator to prevent the carryover eﬀect.\nCombination of bactericidal and bacteriostatic antibiotic is not rational scientiﬁcally.\nTetracycline analogs like minocycline can cause discoloration of tooth due to diﬀusion into\xa0dentinal tubules. Hence the mix should never be left in the coronal pulp chamber.', 'role': 'assistant'}]