The Science Behind Teeth Whitening
Many people are interested in whitening their teeth or getting into the teeth whitening business. Whereas not everyone needs to understand how the tooth is actually whitened at the molecular level, anyone wanting to offer teeth whitening services should definitely be able to explain to customers how it really works. If you are looking to whiten your own teeth, it will help you to understand how it really works so you can choose the solution that best helps you meet your goals.
What is teeth whitening? Teeth whitening, also known as bleaching, is the act of removing stains from the teeth, which in turn makes them look whiter. There are surface stains that reside on the tooth’s enamel, and these can usually be removed by simple mechanical means such as tooth brushing or polishing. Tooth polishing is usually done by the dentist, but even polishing only removes surface stains, and those usually come back quite readily.
What we mean by teeth whitening is the bleaching or whitening of the stains on the dentin layer of the tooth. If you look at an anatomical drawing of a tooth, you’ll see that the outer layer of the teeth (the layer you feel when you touch your teeth), is the enamel. The enamel is a transparent layer, and it does not retain any stains in it, just on the surface of it.
Below the enamel is the dentin layer, which is the one that gives the tooth its color. It is here that your teeth get stained. The enamel layer is porous, so staining particles from coffee, tobacco, wine, tea, etc. can seep through these pores to reach the dentin, and that’s where they accumulate. The more of these particles get through, the more discolored (stained) your teeth become.
In order to whiten your teeth, you need to get a bleaching substance to the dentin layer. The best way to bleach anything is with oxygen radicals, but you can’t pump pure oxygen (or especially oxygen free radicals) to your teeth, much less through the enamel. The best-known teeth whitening chemical in the world at the time this was written is hydrogen peroxide. Hydrogen peroxide (H2O2) is NOT the same as oxygen (O2), but when hydrogen peroxide reacts, it breaks down into water (H2O) and oxygen radical (of which there are a few varieties). Oxygen radicals only live a fraction of a second, but in that time they desperately look for something to oxidize (or react with), and the stains on your teeth are just what the doctor ordered.
When hydrogen peroxide or carbamide peroxide gel is applied to the teeth, the hydrogen peroxide breaks down on the tooth’s surface and travels through the pores in the enamel of the tooth until it reaches the dentin layer. There, the oxygen radicals react with the stained particles on the dentin and whiten them. They do NOT remove the staining molecules, but simply bleach them, removing their color. If you do this long and often enough with the appropriate strength of hydrogen peroxide gel (or some derivative form of it, such as carbamide peroxide), your teeth will appear significantly whiter.