Teeth-whitening - also known as teeth-bleaching - is a common dental treatment. Despite that it is called bleaching, bleach is not used during the procedure. Recommended whitening agents contain hydrogen peroxide in some form and are safe to use if current guidelines are followed. Guidelines can differ depending on the country, so it is important to be aware of the recommendations in your region. To be able to advise consumers as a health care professional, you need to understand why the teeth change colour (discolouration) and know about customary whitening methods and the efficiency and side-effects of teeth-whitening.
Teeth discolouration is a natural process that gradually occurs over time. It is divided into external discolouration (the outside of the tooth) and internal discolouration (the inside of the tooth). Smoking, coffee and tea are examples of agents causing external discolouration. These discolouration’s can be managed with good oral hygiene routines but are best removed by a dental professional, using special instruments and polish paste. The internal discolouration is usually a combination of the natural thickening of the dentin (internal tooth structure), which is yellow in colour, and thinning of the enamel through normal wear. There are also other factors that affect the internal colour of the teeth, such as the use of antibiotic in young ages, different filling materials and root-canals.
In the dental practice, the most common treatment is home-whitening and is also considered to be the gold standard. Impressions of the teeth are taken, and customised trays are made. Whitening gel are thereafter applied in the trays and worn either daytime or night-time for 2-6 weeks. There is also chairside whitening, where the whitening is carried out in the dental practice over one or several sessions. The third technique, non-vital whitening, is used on teeth with root canals. These three treatments use hydrogen peroxide gel as a base, and the dental professional decides on a case-by-case basis which treatment is suitable depending on individual preferences and the origin of the discolouration.
Over-the-counter (OTC) products are also common, and they contain a range of substances that promotes whiter teeth. Whitening toothpastes containing hydrogen peroxide can slightly change the colour of the teeth, but some toothpastes contain abrasive ingredients to remove external stains easier and these can permanently damage the tooth enamel if used frequently. Whitening mouthwashes typically contain a low concentration of hydrogen peroxide or essential oils (extracts from plants) . Current studies show that mouthwashes have a minor effect on teeth colour. As with other mouthwashes, it is not recommended to use straight after toothbrushing since this will remove fluoride and other active ingredients from the toothpaste. Whitening strips - hydrogen peroxide-based - are intended to be placed on the front surface of the teeth, usually 30 minutes twice a day for two weeks. A contraindication is crowded teeth since the strips will not have contact with the surface of instanding teeth and results in an uneven coloured smile. Generic tray systems – one size fits all – exist in different hydrogen peroxide compositions and concentrations, for either daytime or night-time use. It is important to inform the individual that gel can leak from the trays and be swallowed, especially when using the night-time system.
Even though studies related to OTC-products are limited, the research share the same conclusion that OTC-products only have a minor short-lasting effect on the tooth colour.
Common side-effects of whitening
Common side-effects are teeth sensitivity or sore gums, during and after the whitening treatment. Sore gums are usually caused by an ill-fitting tray or leakage of whitening gel. Sore gums and sensitive teeth tend to subside after treatment but a toothpaste for sensitive teeth can be used during and after the treatment to minimise tooth sensitivity.
Be aware that whitening treatment does not change the colour of, for example, fillings, crowns and veneers. Therefore, these must be identified before the treatment in order to avoid mismatch of colours, which can lead to unnecessary replacement of, e.g. fillings. The whitening result is individual and depends on the origin and severity of the discolouration. Whitening is not a permanent treatment and how long it lasts is also individual, but two years is a fair expectation from a completed home whitening treatment, and less for over the counter products.
Always advise a customer to consult a dental professional before a teeth-whitening, regardless of method. They should be healthy and free from caries (cavities) and periodontal disease (gum disease). Pregnant or breastfeeding individuals should be discouraged from all whitening procedures and products.
A whiter smile can have a positive effect on a social level and from an oral health perspective, for example, a boosted confidence and a tendency of keeping up our oral hygiene routines after a whitening treatment. However, all dental treatments have risks, and whitening is not for everyone. Remember that the foundation of oral health is a good oral hygiene routine and that a healthy smile is not measured by the colour of the teeth.