The Element
Summer 2022
Chemistry behind teeth whitening
The tooth stains often fall into two categories, intrinsic, where the colour difference occurs within the tooth, and extrinsic, where the colour inconsistency occurs on the surface of the tooth. The actual compounds that cause the colour disparities are called chromogens which are either metal containing elements or large organic compounds that contain alternating single and double bonds. When the teeth have colour due to the latter reason, they are whitened with hydrogen peroxide which reacts with the double bond to oxidise it. This oxidation causes the chromogens to become lighter in colour. When the colouring is caused by chromogens containing metal elements, it is much harder to remove this colour so the teeth need professional products that contain chemicals like sodium hypochlorite (NaOCl). This operates in the same way that hydrogen peroxide does by reacting with the double bonds in the chromogen, however often the end result isn’t usually as white as desired so people tend to opt for veneers or composite bonds as an alternate method of achieving whiter teeth.
It’s no lie that over the past few years we have become more conscious about the way we look, dress, and present ourselves, so are more willing to make adjustments to our appearance. Many surveys done by dental companies have found that the first thing people notice when they look at someone is their smile. It is therefore understandable why people spend years and years perfecting it, using composite bonds, veneers and braces until they are satisfied with their shape, alignment and nowadays even colour. The once ‘natural’ colour of teeth has been overlooked with a new pristine white colour that can almost only be achieved through the use of some form of whitening, unless you are of course the woman from the Colgate adverts who only eats apples and manages to maintain the crisp, pearl white colour through just brushing her teeth. However, whilst whitening might appear to just be lightening the colour of our teeth and leaving a more pleasant colour, the act of whitening can also cause damage to your teeth if not done correctly. There is general awareness that teeth whitening can affect the sensitivity of your teeth, however scientists have recently found that there are other risks that can occur through the process of whitening. Some of these include tooth surface roughening and softening and increased risk of demineralization especially with the enamel in your teeth.
There are many different methods and products that can be used to achieve different levels of lightness. For lighter stains, a simple toothpaste can be used, but for more severe stains, it's best to get them professionally whitened. For the more milder cases, one might opt for whitening strips and gel, whitening toothpaste or whitening rinses. Whitening toothpastes don't contain sodium hypochlorite but in some cases they may contain low concentrations of hydrogen peroxide. Because of this, whitening
The general process of teeth whitening often involves the chemical hydrogen peroxide (H2O2) which is also commonly found in the form of carbamide peroxide - a compound that breaks down in contact with water to release hydrogen peroxide. 14
