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 common consequence of bleaching nonvital teeth is: \nSelect and explain. \nA. Discolouration, B. Cervical resorption, C. Apical periodontitis, D. Root resorption', 'role': 'user'}, {'content': 'Answer: B \nExplanation: There have been reports of external cervical root resorption following intracoronal bleaching procedures.\nThis is probably caused due to the diffusion of hydrogen peroxide through unprotected dentinal tubules leading to resorptive changes in the periodontium.\xa0\nThe caustic nature of hydrogen peroxide can cause the necrosis of the cementum and the periodontium, which in turn results in initiation of inflammation and subsequent resorption.\xa0\nResorptive process may be worsened with the application of heat for bleaching agent activation. Hence, application of an appropriate intracoronal barrier is mandatory for intracoronal bleaching procedures.', 'role': 'assistant'}]