Book 27, Question 121
How does fluoride toothpaste help teeth?
The hard outer coat of your teeth, enamel, is made of tiny crystals of a calcium mineral.
Acids from sugary foods and germs can dissolve a bit of them. Fluoride, found in many toothpastes, can join the crystals and make them tougher against acid. That is why dentists recommend brushing with a small, pea-sized dab of fluoride toothpaste and not swallowing it.