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 most effective means of reducing microbes in root canal: \nSelect and explain. \nA. Frequent medication of root canal, B. Complete debridement through instrumentation, C. Systemic antibiotics, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Following measures should be taken to be completely rid of these irritants:\n\nThorough cleaning and shaping of the root canal\xa0system: Thorough cleaning and shaping followed by three-dimensional obturation of the root canals have shown to produce complete healing of periradicular tissue. Complete debridement of canal should be done with adjunctive use of irrigants like sodium hypochlorite, which efficiently removes bacteria as well as their substrate from irregularities of canal system, where instruments cannot reach such as fins, indentations, cul\xa0de-sacs, etc.\nOxygenating a canal simply by opening it is detrimental to anaerobes. Use of oxygenating agents as glyoxide can be of great help, but care should be taken to avoid the inoculation of these oxygenating agents into periapical tissues.\xa0\nA tooth with serous or purulent or hemorrhagic exudate should be allowed to drain with rubber dam in place for a time under supervision. An abscess which is a potent irritant, has an elevated osmotic pressure. This attracts more tissue fluid and thus more edema and pain. Drainage by canal or by soft tissues decrease discomfort caused by inflammatory mediators.\xa0\nAntibiotics should also be considered as adjunctive in severe infections. The choice of antibiotic agent should be done on the knowledge of microorganisms associated with endodontic infections.\xa0\nIntracanal medicaments play an important role in\xa0combating the microorganisms.', 'role': 'assistant'}]