The short answer to this question is fluoride is an ion that bonds to enamel and hardens its chemical structure. If you are curious about the chemistry behind it, keep reading. If you are fine with the previous answer, there is no need to suffer through this one!
Let’s take a journey back to middle school. Reach into the depths of your brain to find the periodic table. The periodic table is a chart of elements. Elements are building blocks for everything: trees, rocks, gases, skin, and food. Everything is made up of elements.
Fluorine is an element and fluoride is the ionic (active) form of fluorine. Most ions do not like floating around by themselves. They bind with other ions to create molecules which are more stable. For example, oxygen is not often found by itself. It binds to another oxygen element to form an oxygen molecule. Fluorine is a very special element. It has the highest electronegativity of any of the ions, forming strong ionic bonds.
Are you bored yet? Let me get to the point. Why is fluoride important in the dental field? To answer this, I must explain what enamel is. Enamel is the hardest substance in our bodies and is the white covering of our teeth. Enamel, like anything else, is made up of elements, such as calcium, phosphorus, and hydrogen. When our mouth becomes acidic after eating or drinking, the enamel releases hydroxide into the mouth to help bind the acidic ions and bring the mouth back to a neutral environment. When this happens, the enamel has two courses of action: it can continue to breakdown further (demineralization) and result in a cavity, or ions/compounds can bind to damaged enamel to restore the structure (remineralization).
When teeth are formed, the enamel is made up of interlocking molecules called hydroxyapatite. The fluoride can replace hydroxide in the molecule to create a stronger substance called fluorapatite. Fluoride changes the structure of the tooth at a chemical level to make it stronger. Fluorapatite is stronger than hydroxyapatite and is less likely to breakdown.
I hope this post did not stress you out, because it sure stressed me out! I am sorry it was dry and heavy in the sciences. I am, ultimately, a scientist and am tasked with the burden of learning the “why” behind everything I do. I am going to continue down the fluoride rabbit hole, but I think this is enough information for one blog post. Soon I will address the sources of fluoride and its beneficial and harmful effects. As always, I love your feedback and any additional questions you may have on this topic.