How does fluoride prevent cavities?



Chemically, Sodium Fluoride seems like it should be very similar to the sodium chloride we know and love, what’s big deal with flouride?

In: Chemistry

The enamel on your teeth is made out of a mineral called hydroxyapatite. It’s hard and durable, but becomes soft when acids are present. Bacteria produce acids as they eat the sugars in your mouth, which soften the enamel and cause it to erode away. Your saliva contains dissolved minerals that slowly rebuild small bits of damage, but with a modern diet, the bacteria erode your teeth faster than your saliva can rebuild them.

When fluoride is present, it reacts with the minerals in your saliva to form a closely related mineral called fluorapatite, which is then deposited into the minerals on the surface of your teeth. Fluorapatite is very similar to hydroxyapatite in most of its properties, but it’s more resistant to acid, so it doesn’t wear away as easily when bacteria grow on it.

As a side note, if fluoride was in your drinking water when you’re a kid, your whole tooth contains traces of fluorapatite (because fluoride was present in small amounts in your body when your teeth were being formed). This makes your teeth more resilient for life, and is why we add fluoride in small amounts to drinking water.