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 :
(c) How does fluoride protect our teeth ?

Explanation

The `F^(-)` ions make the enamel on the teeth much harder by converting hydroxypatite, `[3Ca_(3)(PO_(4))_(2),Ca(OH)_(2)]`, the enamel on the surface of teeth into much harder fluorapatite `[3Ca_(3)(PO_(4))_(2).CaF_(2)]`.