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': 'A 20 year old female patient complains of brownish discoloration of her teeth. She has a history of frequent tea consumption. Intra-oral examination reveals brownish staining of all teeth. Patient was suggested bleaching with CO2 laser by the dentist.\nHowever, this treatment is currently not recommended  because: \nSelect and explain. \nA. Alteration in color post-bleaching, B. Potential for hard and soft tissue damage, C. Chemical changes in bleaching mixture, D. Inadequate bleaching', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Use of a CO2 laser to heat the bleaching mixture and accelerate the bleaching treatment currently is not recommended according to a recent report of the American Dental Association, because of the potential for hard\xa0or soft tissue damage.\nSturdevant’s Art and Science of Operative Dentistry, Mosby, 4th Edition, Page No: 610', 'role': 'assistant'}]