There was a medical check-up of teeth of a particular class in a school. It was found that some students had cavities in their teeth. The teacher asked them two questions. First, how many chocolates or sweets do they eat? Second, which toothpaste do they use for brushing their teeth, i.e., does it contain fluoride or not? After reading the above paragraph, answer the following questions : (b) What is the limiting value of the fluoride that should be present in the toothpaste? What happens if this limit is exceeded?

There was a medical check-up of teeth of a particular class in a schoo

1.	There was a medical check-up of teeth of a particular class in a school. It was found that some students had cavities in their teeth. The teacher asked them two questions. First, how many chocolates or sweets do they eat? Second, which toothpaste do they use for brushing their teeth, i.e., does it contain fluoride or not? After reading the above paragraph, answer the following questions : (b) What is the limiting value of the fluoride that should be present in the toothpaste? What happens if this limit is exceeded?
Answer» Solution :The FLUORIDE present in the paste should be UPTO 1 ppm. If if it exceeds 1 ppm and is present upto 1.5 ppm, the TEETH become mottled. If it exceeds 1.5 ppm, it BECOMES a poison (USED for rats as NaF).