This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Social & Preventive Medicine
[{'content': 'Dental fluorosis is best seen in: \nSelect and explain. \nA. Central & Lateral Incisors, B. Central Incisors & 1st Molars, C. 1st & 2nd Molars, D. Canines', 'role': 'user'}, {'content': "Answer: B \nExplanation: Dental fluorosis Occurs when excess fluoride is ingested during first 7 years of the (years of tooth calcification). MC source is drinking water. Optimal level of fluorine intake is 0.5-0.8 ppm; Acceptable level of intake is 1-2 ppm. Dental fluorosis occurs when > 1.5 mg/litre levels of fluorine is taken. Characterized by 'Mottling', which is best seen on Upper central Incisors & 1st molar. - Skeletal fluorosis occur when fluorine intake is b/w 3-6ppm. - Crippling fluorosis if intake is > 10ppm.", 'role': 'assistant'}]