Today we're writing about flouride and how it helps to guard against cavities on the surfaces of our teeth. We'll be going into the science of this mechanism and leaving other flouride topics (treatment methods, history, controversies) for another day.
We've all heard that flouride helps to prevent cavities, but few people actually know what is going on. First, we need to look at the surfaces of our teeth. The outer surfaces of natural teeth are made of a material named hydroxylapatite, which is a crystal containing a lot of calcium. All the time, acids in our mouths are breaking down the surface of this crystal, microscopically damaging our teeth. This is greatly accelerated in the presence of sugar, since bacteria in our mouths convert the sugar to acids, similar to the process of making vinegar from juice.
Fortunately, our saliva contains calcium and other ions that are also continuously repairing this damage. When the rate of damaging demineralization is greater than this remineralization, a cavity can result. This is one reason why dry mouth can be terrible for your teeth, since teeth don't receive as much of these reparitive ions.
So where does flouride come into play?
Flouride decreases the rate of demineralization by very strongly bonding to the crystal on the surfaces of our teeth, making them more resistant to acid attack. A thin layer of fluorapatite-like crystals are quickly formed on the surface of the teeth and this surface is much more resistant to demineralization. This tips the demineralization / remineralization balance in your favor and decreases the chance of cavities.
Fun Fact: While human teeth do not naturally contain fluorapatite, shark teeth do. Another reason you don't see many shark dentists. Not only are sharks' teeth continually replaced, they are more resistant to cavities than ours!
As always, if you have any questions or have any dental topics you'd like addressed, feel free to email us at firstname.lastname@example.org.