Synonym
teeth whitening, bleaching English: bleaching methods
The Bleaching Process
Bleaching (tooth whitening) is a method of artificially lightening the colour of teeth and restoring discoloured teeth to a brilliant white. In most cases, hydrogen peroxide (H2O2)-based preparations are used for bleaching. These substances can penetrate the tooth substance and release so-called oxygen radicals.
Radicals in general are molecules that have one or more unpaired electrons and for this reason are particularly fond of reacting with other molecules. The oxygen radicals released in the tooth substance try to react chemically with colour particles. As a result, the colour property of these particles is lost and they therefore appear colourless. From this mechanism of action it can be concluded that bleaching agents are not without danger for the tooth. There are several methods of whitening teeth, the simplest of which can be used by the patient at home.
Forms of bleaching
In oxidative bleaching, a chemical gel is applied to the tooth surface, which leads to a chemical reaction with the tooth. The cause of the reaction is the chemical content of the gel. This is hydrogen peroxide, which is also known from hair dyeing.
The reaction between the gel and the enamel produces hydrogen radicals which decolorize the tooth. The chemical process can be accelerated by a special lamp that is held on the teeth after the gel has been applied to the tooth surface. The reason for this acceleration is that the light rays cause the hydrogen peroxides to decay more quickly.
In reductive bleaching, a chemical substance is also applied to the tooth surface. In this case, however, no colour is removed from the tooth but specific oxygen molecules. The applied gels mostly consist of sulphur compounds, which have a particularly strong ability to remove oxygen.
In laser bleaching, after the bleaching gel is applied, a laser is directed at the pre-treated areas. This laser beam leads to an accelerated reaction and thus to a faster bleaching. The irradiation time by the laser is about 1 minute.
In home bleaching, an impression of the teeth is first made. This impression is then used to make a dental splint, which is then filled with a chemical gel. In the case of home bleaching, the patient should wear the splint for different lengths of time each day.
The wearing time should be between one and eight hours a day. As a rule, about seven applications, five hours each, are sufficient to remove slight discoloration. Power bleaching” involves the use of high-dose agents, which is why it can only be carried out in the dental practice.
To protect the gums from possible damage, a cofferdam must be placed before the actual treatment. Then the bleaching agent is applied to the teeth and irradiated with short-wave light. The application lasts between 15 and 45 minutes and can be repeated if the result is insufficient.
The “Walking- Bleach- Technique” is a little more drastic, because the whitening gel is placed in the tooth during this bleaching method. However, this is only possible for teeth treated with root canal treatment. Dead teeth (e.g.
due to injuries or trauma) or dead teeth (e.g. after an inflammation of the nerves) have the peculiarity of discolouring themselves and thus show a difference in colour to their neighbouring teeth, sometimes a significant one. In this case, the so-called Walking Bleach technique can be applied, in which a chemical is injected into the still open tooth. Then the tooth is closed as usual.
The whitening agent remains inside the tooth for about 1-2 days and is then removed again. Only then the final closure of the tooth follows. During the procedure the bleaching agent does not work from the outside to the inside but the other way round.
Most whitening procedures are chemical procedures. One procedure, however, is a purely mechanical procedure, but is not used as often as the others. It is a technique in which teeth that are to be whitened are coated with an extremely thin foil.
The foil can be lighter or darker, depending on the desired colour. Mostly the foil technique is used to whiten the incisors. The reason is that these teeth have the largest flat surface and can therefore be coated most easily.
Molars and lateral teeth are often more asymmetrical and angular and are not suitable for foil bleaching. During the procedure it must be taken into account that there can be considerable differences in colour between the coated teeth and the neighbouring teeth, which can lead to cosmetically unattractive results. The durability of foil bleaching is approximately the same as that of other procedures. In rare cases, wrinkling or tearing of the foil may occur.
