Teeth whitening

Tooth whitening is arguably the most commonly requested procedure in cosmetic dentistry. Stained teeth can result from both lifestyle and genetics, and can deeply affect a person’s confidence – for both men and women.

Nowadays, there are numerous dental technologies that can enhance the whiteness of teeth and brighten the smile. Whether it’s to mimic the ‘Hollywood’ smile or rectify yellowing, the procedures on offer cater to different levels of discolouration and tooth sensitivity.

Available whitening treatments range from small to large budgets, from in-office whitening to at-home kits. It is advisable for patients to consult a dentist and have their teeth assessed before electing to undergo any bleaching procedure as overly sensitive teeth can mean that the treatment may not be safe. It is also important to note that it is not a permanent solution and requires maintenance for a prolonged effect.

Common causes of discoloured teeth

There are two kinds of tooth stains: extrinsic and intrinsic. Extrinsic stains occur on the surface of the tooth and are largely caused by consumable products such as tars found in tobacco, tannins in coffee and tea, excess consumption of coloured foods such as soy sauce, cola and red wine, and the overuse of some mouthwashes.

Extrinsic stains are easier to remove, often simply by increasing the frequency of brushing teeth. Whitening toothpastes contain a type of bleach called hydrogen peroxide that is activated by a catalyst (such as manganese gluconate) and combines with the gentle abrasion of brushing to remove extrinsic stains. However, these stains can be stubborn and may require further treatment.

Intrinsic stains result from coloured molecules or pigments that occur in the internal structure of the tooth. This can occur in the development of the tooth or as a result of certain conditions such as genetic discolouration, the use of antibiotics such as tetracyline and corrosion from amalgam fillings (silver fillings).

Differentiating between extrinsic and intrinsic stains, as well determining the cause of the stain, is important so that the dentist can decide on the best whitening treatment to proceed with.

In the dentist’s chair

Dentists can whiten teeth in a variety of ways, including polishing, tooth lightening and laser bleaching.

The removal of some surface stains can be achieved by a professional polishing of the tooth’s surface by a dentist or technician. This is a physical treatment that makes teeth reflect more light and thus appear brighter, and does not use peroxide or other bleaching chemicals. Special polishing pastes can be used in sequence to give a high-surface polish to the natural teeth and to any fillings that may also be present. This process does not alter the original colour of the tooth but can offer an effective treatment for stubborn stains.

A more intense whitening option is laser bleaching, also known as ‘power bleaching’. The benefit of the pure laser technique is that it achieves significant colour change in a short amount of time. The dentist uses laser beams to provide an intense light that activates a whitening agent (usually a peroxide gel) pasted onto the enamel of the tooth. A rubber dam protects the face and gums as the teeth are exposed to the laser. The gel is generally left on the teeth for around 15 to 20 minute intervals that add up to one and a half hours at the most. This process is repeated every three to six months for optimum results.

One of the most popular laser tooth whitening systems is Zoom!, which uses a mercury vapour halide light to activate the peroxide gel, with instant results lasting around three to six months. This system also includes a take-home whitening kit to maintain the results at home. Other systems include LaserSmile and Rembrandt, which have similar processes but use different forms of intense-light lasers.

Take-away treatments

Whereas the laser methods tend to be more costly, take-home kits are more affordable. The patient is fitted with a tailor-made tray that is filled with whitening gel and worn each night for around three weeks. This does not harm the teeth but slightly changes the composition of the dentine – the core material of the tooth that contains calcium and lies underneath the enamel – making it appear whiter and brighter.

The lower the percentage of peroxide in the gel, the safer it is and the longer it can be left on the teeth. A lower percentage of peroxide is used for overnight use, and the higher percentage gels are used for one to two hour treatments.

Tray whitening treatments are also available over the counter, but include a ‘one size fits all’ mouth tray that can be uncomfortable and require more whitening gel for optimum coverage. Gels supplied by dentists for home use have higher levels of peroxide compounds than over-the-counter products and are therefore more effective at treating internal stains.

Some people may experience slight gum irritation and heightened sensitivity of the teeth to cold or hot stimuli.

At home

Tooth whitening treatments are also available for purchase outside of the dentist’s office and work to minimise mild extrinsic strains and discolouration. These treatments are not suitable for deep internal discolouration but can work well to maintain the results of a professional tooth whitening treatment.

Paint-on whitening kits are very easy to use and do not require a mouth guard. The clear whitening gels are typically painted onto teeth once daily for 14 days. Saliva should be removed from teeth beforehand to avoid the peroxide being broken down too quickly. Similarly, eating, drinking, rinsing and brushing should be avoided immediately after applying the gel.

The gel contains a binding agent that adheres to the tooth’s surface, allowing the peroxide to break down surface stains more effectively. The gel contains about six percent peroxide, so it is typically safe to leave on for the entire day.

Adhesive whitening strips work in a similar way, using a strip of polyethylene plastic to apply peroxide gel to the teeth. The strip releases the gel from the underside of the plastic as it is pressed onto a row of teeth. The gel is then uniformly distributed over each tooth’s surface. The strips come in different sizes for top and bottom rows of teeth, and individual teeth, and are worn for 30 minutes twice daily for 14 days.

Like paint-on treatments, the gel contains only six percent peroxide but, because the treatment involves gently pressing the strip onto the teeth, a slight tingling or sensitivity might be felt on the gum that usually subsides within a few days.