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Teeth whitening – external or internal?

white teeth whitening bleachingHumans have always preferred white teeth. Already more than 2000 years ago the Egyptians tried to develop a whitening technique using urin. The somewhat more hygienic whitening technique that is used today, however was only invented a little more than 50 years ago. This article will discuss the two most common teeth whitening techniques used today: External and internal whitening.

External whitening

If the stains on your teeth are external, they are quite simple to treat with external teeth whitening. This can be done either at the dental clinic by the dentist or in your home, using a tray and a whitening gel that you apply yourself. The ‘active ingredient' in the products for both professional and at-home teeth whitening is usually hydrogen peroxide or carbamide peroxide. As the active ingredient is broken down, oxygen gets into the enamel on the teeth and the colour of the teeth is made lighter.


If you choose to do the whitening in your home, you will first need to go to the dentist to have a tray made. The tray is designed to fit your teeth perfectly, but with a gap for the whitening gel between the tray and the front side of your teeth. If the tray does not fit closely to the teeth, excess whitening gel might spread from the tray to your mouth with the risk of you swallowing some of it. Before making the tray, your dentist will make impressions of your teeth and produce a model according to which the tray will be made. When the tray is finished, your dentist will give you the whitening gel and instruct you on how to use it in your home. You will normally need to use the tray every day for 1-2 hours (or all night) for 2 to 4 weeks untill the desired results are achieved. The price for this kind of teeth whitening can vary from clinic to clinic so ask around before you make your decision.

A both simpler and faster solution is to have your whitening treatment performed by your dentist in the clinic. With this method the same results can be achieved as with at-home whitening products, but in much shorter time (as little as one visit). The reason that teeth whitening in the dental office is faster is, that the gel used by the dentist has a much higher concentration of carbamide peroxide (up to 35%) than the at-home products (10%). The higher concentration of whitener would not be safe for you to use in your home, but when the whitening procedure is performed by a professional, it is safe enough. Many dentists choose to supplement the whitening treatment with laser light which supposedly accelerates the whitening proces. The greatest disadvantage of the professional whitening is that it is much more expensive than the at-home procedure.

Internal whitening

If the discoloration of a tooth originates from within, e.g. from a root canal treated tooth, internal whitening is an effective method to improve it's appearance. In order to bleach the tooth from the inside, it is necessary to remove the surface filling and part of the root filling as well. The crown chamber is cleansed and a whitening agent is placed inside. A temporary filling is placed on top to close the opening. After one week the tooth is opened again, the whitening agent removed and the procedure is repeated. It will often be necessary to repeat the procedure three to four times before the desired results are achieved. When the whitening treatment is done, a light glasionomer cement filling is placed in the deepest part of the tooth with a plast filling on top. This treatment might be a good alternative to having the tooth capped. Especially if the tooth is otherwise healthy and the only problem is the discoloration.

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