Teeth-whitening is a method of lightening the colour of natural teeth. The following information relates to the use of dental whitening techniques, which use Natrium-Perborate or Carbamide-peroxide with the content of up to 6% hydrogen peroxide (H2O2).
The colour of teeth varies between individuals and at different ages. Teeth can gradually darken over time. Tooth colour is influenced by a person's genetic makeup and any surface stains or deposits in or on the teeth. If our teeth are dark due to stains or deposits, they will need to be cleaned before teeth-whitening is undertaken.
A gel is used to whiten the teeth, and there are two main ways of doing this:
The dentist takes impressions of the teeth to make an individual custom made flexible whitening tray that fits around the teeth. The whitening gel is placed in the tray following the dentist's instructions. The teeth will become gradually lighter over some time. The tray must be specially made to apply the whitening gel to those teeth to be bleached. This specially constructed tray also helps keep the gel away from gums and protected from the saliva, which inactivates it.
The whitening tray is worn for several hours at a time, usually at night time or whenever it is most convenient. A course of treatment takes a variable number of weeks. Results may vary depending on the initial darkness of the teeth, the gel's concentration, and the frequency of application.
The dentist applies a higher strength of hydrogen peroxide (H2O2) directly to the teeth in the surgery to achieve whitening results in the shortest possible time. During the procedure, the whitening gel will be applied to teeth and depend on the process, they may be exposed to light for a few sessions of 10- 15-minutes. During the entire treatment, a plastic retractor will be placed in the mouth to help keep it open, and the soft tissues (i.e., lips, gums, cheeks and tongue) will be covered to ensure they are not exposed to either the gel or light. To achieve the most efficient outcome, chair-side whitening could be combined with home whitening protocol.
Home tooth whitening takes typically about two to four weeks. The dentist will advise on how many hours a day (or night) to wear the gel-filled tray. Depending on the product varies between one and six hours.
There is a risk that teeth whitening will not work quickly, and the dentist will discuss the possible reasons why it might not work particularly well or why it might take longer than average. Not all teeth get lighter to the same extent, particularly deeply discoloured or multicoloured teeth. Some teeth whiten more effectively or more quickly than others. Teeth that are already entirely white will only lighten a little further. Some teeth do not get lighter evenly. This can be a problem where the gum has receded and the darker root surface (dentin) is exposed. Such teeth can become sensitive to bleaching. Certain types of tooth discolouration do not respond quickly and may require special treatment by a dentist.
Fillings, veneers or crowns that match the existing teeth will not change with whitening. The costs of replacing these to match the new lighter colour of the natural teeth can be considerable. This needs to be discussed with the dentist before undertaking the teeth whitening.
The extensive clinical data continue to support the safety and effectiveness of this kind of tray-based tooth whitening with 6% Hydrogen peroxide and 16-18% Carbamide Peroxide. However, during teeth whitening, teeth may become sensitive for a while. This is usually only temporary. A fluoride gel or special toothpaste within the tray can be worn for 30 minutes before bleaching to minimize sensitivity. Temporary irritation of the soft tissues in the mouth, particularly the gums, is rare but can occur if too much gel is loaded into the trays. The dentist will advise how to help avoid this problem.
The effects of home whitening may last longer than chairside in-surgery bleaching. However, it takes longer to have the desired result.
Teeth that have been bleached have a gradual tendency to return to their standard colour. This means that teeth may need to be bleached again at some time in the future. Because the gel used in the whitening process degrades fairly rapidly (six months shelf-life), it should be stored in a cool place. The new gel should be bought if repeating the treatment. The existing whitening trays can be used again for top-up treatments. The trays should be kept safely.
Tooth whitening has the particular advantage that it does not involve any destruction of existing healthy tooth structure.
Tooth whitening may not be 'the right' or 'the only' aesthetic treatment. There is also the alternative of making no change to your tooth colour or applying white (composite) filling material to disguise the colour of the teeth. The provision of crowns or veneers can be used to alter the colour of the teeth to make them appear lighter, but this usually involves the removal of a significant amount of sound natural tooth tissue and is destructive compared to tooth bleaching. However, a crown or veneer may be a reasonable option if a tooth is already heavily filled or root-filled.
The evidence from the literature suggests that the management of discoloured endodontically treated teeth utilizing combined intracoronal teeth whitening technique bleaching is a valid treatment modality in terms of safety, efficacy, time efficiency and aesthetic outcome. The result from the 16-year prospective study by Amato et al. (2006) also demonstrated the chromatic stability of nonvital discoloured teeth when subjected to the combined intracoronary teeth whitening technique. The clinical outcome has vastly improved the poor appearance of the upper right central incisor.