For a long time there has been a desire among people to have white teeth, which led to attempts to whiten teeth several hundred years ago. At that time, the whitening of the teeth was done with damaging agents such as urine or even acids. In the meantime, there are good, ph-neutral agents that do not cause damage to the teeth or other side effects when used properly. A modern method against tooth discoloration is bleaching.
What is bleaching?
Yellow teeth not only look unsightly, they are also often a sign of dental disease. Bleaching can bring good results here. Bleaching (English “to bleach” – bleach) is a method of whitening human teeth. Teeth whitening is usually done for aesthetic and cosmetic reasons. As a rule, it is the patient’s ideal of beauty that provides the motivation for teeth whitening. From a medical point of view, bleaching is usually only necessary when tooth discoloration has a stressful effect on the patient on a psychological level. In the case of tooth discoloration, coloring substances are deposited in the tooth enamel and dentin. These discolorations can no longer be removed with simple tooth cleaning, which is why bleaching is then often the only way to whiten the teeth. It is important that a dental check for damage to the teeth and gums and, if possible, a professional dental cleaning be performed before a bleaching treatment.
Function, effect and goals
Bleaching can be performed in different ways. Generally, preparations with hydrogen peroxide are used here. These penetrate into the tooth and split off the oxygen radicals there. Oxygen radicals can affect the colorants in the tooth in such a way that they are no longer recognizable. It is important that the agents used for bleaching have a neutral pH value in order to prevent the teeth from roughening and thus becoming discolored again. The following methods are used for bleaching:
1. whitening through individually made dental trays (“home bleaching”).
In this method, a splint is made based on an impression of the teeth before the actual bleaching treatment. The splint is usually made of plastic and is custom-fitted to the patient’s dentition. A whitening gel containing peroxide is applied to the splint, and the splint then covers the teeth. The concentration of peroxide used in home bleaching is usually 10 to 20 percent. Depending on the initial color of the teeth and the concentration of the gel, the patient must wear the trays for between 1 and 8 hours. Depending on the degree of discoloration, sometimes 5 to 7 treatments are necessary (e.g. for age discoloration) or more than 15 treatments (e.g. for discoloration caused by tetracyclines). If the entire dental arch is to be whitened, home bleaching is particularly suitable. 2. whitening by direct application (“in-office bleaching” or “power bleaching”)
In so-called power bleaching, the concentration of the whitening gel is usually higher than in home bleaching. Therefore, the treatment is performed directly at the dentist’s office. In preparation, the gums are protected with the help of the so-called rubber dam (rubber-like coating) or another flowable material. The bleaching agent is then applied directly to the teeth, where it can take effect. With bleaching lamps, more intense results can be achieved by light irradiation when special gels are applied that can be activated under UV light. The gel is then usually removed after 15 to 45 minutes. In most cases, an initial treatment requires one to two more treatments until the desired degree of whitening is achieved. Power bleaching is usually used when only individual teeth that are still alive need to be whitened. 3. whitening by means of tooth inlays (“walking bleach technique”)
The walking bleach technique is usually used when only individual (usually dead) teeth are to be whitened. In this case, the tooth crown is opened and a suitable inlay is placed in the tooth cavity. The whitening agent usually remains in the tooth for a few days, which is then sealed with a temporary restoration. After the whitening agent is removed, the crown is permanently sealed. With this method, whitening is always delayed, as it takes a few days for the peroxide to work its way through the enamel inside the tooth.It is possible to perform another treatment if the desired degree of whitening has not been achieved. For this reason, many dentists do not close the crown until the result is what the patient wants. In general, for all methods, the teeth do not remain permanently whitened. As a rule, however, the result remains for several years, but this also depends on the quantity and quality of oral hygiene as well as the patient’s consumption habits (e.g. drinking coffee, tea, smoking). Bleaching must be repeated if the teeth darken significantly. These so-called refresher treatments are usually much gentler on the teeth, as the amount of peroxide does not have to be chosen as high. Bleaching is always used when unsightly tooth discolorations are to disappear. These are usually caused by the consumption of staining foods such as tea, coffee, juices, red wine or tobacco smoke. However, discoloration of the teeth can also be caused by medication, accidents, caries, malnutrition and death of the dental pulp. If bleaching is performed, the colors of dental fillings, bridges or even crowns do not change. Especially in the visible area, fillings, crowns or even bridges and veneers usually have to be renewed after bleaching and adjusted to the new color. The problem with this is the amount of money it can cost, because teeth whitening is not permanent and with each booster treatment it can happen that bridges, crowns, fillings and veneers have to be renewed again. About the effects and the cost of bleaching, the dentist should therefore always have an informative discussion with the patient before the treatment, because the costs are not covered by the statutory health insurance.
Risks, side effects and dangers
Bleaching treatment can cause some side effects in the patient. The first often appear during the treatment in the form of a painful sensitivity reaction to the bleaching agent. In addition, teeth that have just been treated are usually sensitive to sweet and sour, as well as to cold or heat. Generally, however, these sensations are only temporary and often disappear within a few days. It is important that all whitening agents are ph-neutral, because if the ph value is too low, a superficial roughening of the tooth substance is to be expected. If bleaching is performed professionally and with appropriate preparations, bleaching can even protect against caries. However, bleaching can remove minerals from the teeth and thus weaken the protective layer of the tooth, at least temporarily, which may also cause masking white spots. However, these also disappear again within a few days after treatment, which can be supported with the help of a special gel. In any case, patients should always keep in mind that bleaching can cause a weakening of the tooth structure and, as a result, tooth brittleness. Irritation of the mucous membrane must also be expected when the bleaching agent comes into contact with the oral mucosa. In the meantime, there are research results that show that bleaching can cause damage to the tooth surface. It is also estimated that about 25 percent of the gel is swallowed during bleaching, which can cause damage to the mouth and throat as well as the stomach. However, these estimates refer to home use. In the meantime, tooth whitening agents (e.g. for brushing on or adhesive strips) are also available on the open market. Since these agents have different quality characteristics, some agents may cause lasting tooth damage or even insufficient and uneven whitening. In addition, there is a lack of preliminary diagnosis here, because as a layperson it is difficult to assess the causes of tooth discoloration. As a result, more serious damage to teeth may be overlooked (e.g. caries, root inflammation). For this reason, a dentist should always be consulted in advance so that any necessary treatment can be carried out.
