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 new method of caries detection, which is based on the principle of fluorescence: \nSelect and explain. \nA. FOTI., B. DIAGNOdent., C. Cariogra., D. All of the above.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The principle of FOTI (Fiber Optic Transillumination) is that there is a different index of light transmission for decayed and sound tooth. Since tooth decay has a lower index of light transmission than the sound tooth structure, an area of decay shows up as a darkened shadow. The use of FOTI is proved to be effective in the anterior region.\nDIAGNOdent is a new method of caries detection, which is based on the principle of fluorescence. The system has a range of -9 to 99 with -9 being the value where the tooth is the healthiest. The advantage lies in the early, precavitation stage of caries detection.', 'role': 'assistant'}]