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': 'After more than 1 hour of extraoral time, an avulsed tooth is soaked in sodium hypochlorite solution, then it should be soaked in: \nSelect and explain. \nA. 10% NaF for 10 min, B. 2% NaF for 20 min, C. 8% SnF2 for 10 min, D. 2% SnF2 for 10 min', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Closed apex, extraoral dry time greater than\xa060 minutes, suggesting non-viable cells.\nDelayed replantation has a poor long-term prognosis.\xa0\nThe periodontal ligament will be necrotic and cannot be\xa0expected to heal. The goal in delayed replantation is, in\xa0addition to restoring the tooth for aesthetic, functional,\xa0and psychological reasons, to maintain alveolar bone\xa0contour. However, the expected eventual outcome is ankylosis and resorption of the root, and the tooth will be\xa0lost eventually.\xa0\nTreatment\xa0\n\n\u200bClean the area with water spray, saline, or chlorhexidine.\xa0\nRe-implant the tooth in the socket.\xa0\nSuture gingival lacerations, if present.\xa0\nVerify normal position of the replanted tooth both clinically and radiographically.\xa0\nApply a flexible splint for up to 2 weeks.\xa0\nAdminister systemic antibiotics.\xa0\nIf the avulsed tooth has been in contact with soil and\xa0if tetanus coverage is uncertain, refer to physician for a\xa0tetanus booster.\xa0\nInitiate root canal treatment 7-10 days after replantation\xa0and before splint removal.\xa0\n\nTo slow osseous replacement of the tooth, treatment of\xa0the root surface with fluoride prior to replantation has been\xa0suggested (2% sodium fluoride solution for 20 minutes).\nReference: McDONALD AND AVERY’S DENTISTRY for the CHILD and ADOLESCENT, 10th ed page no 594', 'role': 'assistant'}]