How Do Teeth Whitening Treatments Work?
Before covering how do teeth whitening treatments work, it helps to know what the teeth are made of.
Your teeth consist of a hard outer shell of enamel; the hardest substance found in the human body. Enamel is formed mostly from calcium phosphate; this mineral accounts for 96% of tooth enamel. This shell is inert and does not contain any living cells. Directly underneath is dentin which is a living tissue consisting of cells that secrete minerals. In the center of the tooth is the pulp cavity which is soft and contains the blood supply and the nerves. The upper portion of the tooth – the part visible above the gums – is called the crown, while the part that is embedded in the gums and bone is called the root.
How does tooth enamel get stained?
Although the tooth enamel is incredibly hard and feels smooth when you run your tongue over it, it contains small grooves where food items can get stuck. Very tiny pits and fissures can form from the actions of bacteria in the mouth. The bacteria feed on sugars from food and drinks and produce acids. Those acids eat away at the enamel and ultimately lead to tooth decay.
Plaque forms – a material mostly comprised of bacteria and food particles – which causes further damage. When plaque hardens it forms tartar. This is a very hard material that builds up over time. Tartar is yellow or brown and is clearly visible on the teeth and is a major cause of discoloration.
Extrinsic discoloration of the teeth
Once pits have formed they are permanent. Strongly colored foods and drinks can easily enter these pits, with beetroot and blackcurrant major offenders that can easily discolor the teeth. Tannins in tea, coffee, Coca Cola and red wine also stain the teeth, and the nicotine and tar in cigarettes cause severe yellowing. All of these causes of tooth discoloration stain the surface of the enamel – what dentists call extrinsic discoloration. This surface staining can be removed by whitening toothpastes and by cleaning and polishing treatments by dental hygienists.
Intrinsic discoloration of the teeth
Staining agents can penetrate the pits and fissures in enamel causing discoloration of the dentine. Once this happens it cannot be removed by brushing and even dentists cannot whiten the teeth and remove the stains by using standard polishing techniques. Once this happens the only way of whitening the teeth is by professional dentist whitening treatments or by using teeth whitening at home kits.
Disease, aging, genetic problems, environmental issues – such as excessive fluoride exposure – as well as medical treatments can discolor the teeth. Chemotherapy and taking tetracycline antibiotics during pregnancy or during the first 8 years of life – when the teeth are formed – also cause discoloration.
How do teeth whitening at home kits work?
Teeth whitening at home kits bleach the teeth to get them lovely and white again, and they can also whiten the teeth beyond their original color. The bleaching effect is not limited to the outer surface, because the bleaching agents penetrate the enamel and pass through the dentin, bleaching as they pass through. While treatment with a teeth whitening kit is highly effective, if your staining is the result of root canal treatments or antibiotics, the only choice is to hide the stain with a veneer or crown. The best bet before you go to those extremes is to try a teeth whitening at home treatment first.
Image Source: BruceBlaus CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0), via Wikimedia Commons