Is the enamel damaged, which bleaching procedures are available and which teeth are suitable for bleaching at all? Two professors will answer your questions.
What’s white needs to get whiter.
Brita Willershausen holds the Chair of Dental Conservation in Mainz and tries to explain to her dentistry students in the lecture what they do to their future patients when they whiten their teeth with hydrogen peroxide. She knows what she is talking about, because before she decided on dentistry, she was a chemist and therefore knows the aggressive potential of this substance. Brita Willershausen: “I haven’t bleached my teeth yet and I won’t bleach them in the future. But the young people like to have bleached teeth or white teeth and then I try together to find a mild preparation.” Of course, Professor Willershausen can’t resist this trend from the USA, who has elevated bright white teeth to the ideal of beauty and often knows no limits. The industry provides masses of products for this purpose. Also for do-it-yourself application.
Bleaching: Not all teeth are suitable
Teeth with fillings, veneers, crowns, etc. should not be bleached under any circumstances, as the foreign materials cannot change their colour. After bleaching the remaining teeth, the restorations remain in the denture as unattractive, dark areas and must then be removed and replaced with new materials. For example, fillings that may have been used by the dentist many years ago are often forgotten by the patient. For this reason, every person interested in bleaching must be advised to seek advice during their next visit to the dentist as to whether their own teeth are suitable for such a treatment. Individual dark teeth, for example, usually refer to a root dead tooth that can only be bleached by the dentist (walking bleach technique).
Root dead tooth that can only be bleached by the dentist using a walking bleach technique. (Source: Prof. Brita Willershausen)
Caution with “tooth whiteners” that are available for sale
In 2012, the free sale of bleaching products containing hydrogen peroxide (H2O2) above 6 percent was banned in Europe. However, there are still “tooth whiteners” to buy in the drugstore, but they are less effective. Warning must be however before tooth pastes, which are to whiten the teeth. They contain abrasive scouring particles to quickly remove stubborn plaque from, for example, coffee or tea. Unfortunately, tooth enamel is always lost when these “whitening creams” are used. Those who use these pastes too often brush the enamel off their teeth, so that at some point the darker dentin under the enamel shines through and the teeth become darker instead of brighter.
The enamel surface loses hardness during bleaching
Bleaching gels with a stronger effect are only available from dentists over the age of 18. The range of active agent concentrations extends from 6-7 percent for use at home with splints, up to 40 percent H2O2 in the dental practice. For Mrs. Willershausen, such high concentrations are out of the question: “Some practices go up to 30.40 percent H2O2. That’s really a concentration, you get abdominal pain.”
In her own studies, she was able to prove in the laboratory that the use of such bleaching gels massively removes minerals such as calcium from the enamel and the enamel therefore loses its hardness.
Calcium loss in the melt surface after a six-hour bath in apple juice or a 12% hydrogen peroxide solution. (Source: Prof. Brita Willershausen/)
If bleaching is already necessary, then she advises your patient to have gentler home bleaching, where the dentist makes a custom-fit splint and gives the patient an approximately seven percent gel to take home. During the night or about four hours a day, the patient can then wear the splint filled with a little gel for a few weeks and decide for himself when his teeth are white enough. The therapy can be repeated with the same splint even after a few years.
However, not everyone who wants white teeth wants to wear a splint at home. Many patients therefore rely on so-called “power bleaching” or “in-office bleaching” in the dental practice. With this procedure, the dentist works with significantly higher concentrations and can thus achieve a stronger tooth whitening in a short time. Brita Willershausen rejects this procedure because of the concentrated bleaching gels. But also because it can be very painful for the patient. Nevertheless, “in-office bleaching” is offered in many German practices. The patient must therefore be informed of any pain before the treatment, which usually recurs within a few days. In fact, studies have shown that the bleaching gels pass through the enamel to the nerves of the teeth and cause the first symptoms of inflammation, such as an enlargement of the blood vessels (see links). Prof. Claus-Peter Ernst, who has done his own research on bleaching and still uses this method in his practice, points out that there are no known studies in which – apart from initial toothache – clinical symptoms have occurred in patients. This means that it could not be shown in the studies that tooth decay occurs more frequently after bleaching or that teeth become so brittle that they break off more frequently.
Attention with highly concentrated bleaching gels
Nevertheless, sensitive dental necks and gums must be covered with protection before the highly concentrated gel is applied, otherwise pain and gum injuries can occur immediately. In order to further reduce the exposure time of the bleaching gels, procedures have been developed that accelerate the bleaching effect by means of heat, light or laser. Here the scientific data is still relatively thin. During the bleaching process, however, there should always be someone from the practice team in the room who can intervene if pain occurs.
Reduction of the exposure time of high-percentage bleaching gels by light activation
With both methods, “home bleaching” and “power bleaching”, clear whitening of dark and medium teeth can be achieved. However, if the teeth are already at the upper end of the brightness of natural tooth colours with an A1, B1 or C1 before the treatment, further whitening is difficult to achieve. Here highly concentrated bleaching gels show more chances, but also with the known risks. Ultimately, everyone must decide for themselves how far they want to go and whether teeth that are too bright are not more likely to look unnatural. How long your teeth stay bright depends on how much you enjoy nicotine, coffee, tea or red wine. Before a bleaching, a professional tooth cleaning makes in any case sense, since by removing the solid deposits, usually already a clear whitening can be achieved.