Smile Design Dental Practice
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Dentistry » Cosmetic & Restorative Dentistry

Tooth Whitening

Whitening is any process that will lighten the existing natural colour of your teeth without removing any of the tooth surface. This can be achieved in two ways:

  • A product can bleach a tooth, which means that it actually changes the natural tooth colour. Bleaching products contain peroxides that help remove deep (intrinsic) and surface (extrinsic) stains
  • Non- bleaching whitening products can be used which contain agents that work by chemical or physical action to help remove surface stains only.

Tooth whitening has been practiced by dentists for over 100 years. The history of 'modern day' tooth bleaching however began in 1989 and is credited to Haywood and Heymann who introduced the night guard method of vital tooth bleaching. At the same time, Omnii International (USA), working with a dentist named John Munro, developed and marketed the first commercially available home- bleaching product to be used under dentist supervision.

The colour of our hair, skin and teeth is genetically determined, therefore varies between individuals. Teeth tend to naturally darken as we get older.

Teeth can be stained on the surface by food and drinks such as tea, coffee and red wine. Tobacco smoking also stains the teeth. Acidic food and drink such as fizzy drinks, fruit juice and yoghurt cause erosion of the outer enamel layer allowing the colour of the underlying yellow dentine to shine through, making the teeth appear more yellow. Discolouration can also be caused by illness or by the use of tetracycline antibiotics while the teeth are forming. Minocycline, a tetracycline antibiotic, can cause staining in adult teeth.

Deposits of calculus (tarter) that form around the necks of the teeth can pick up unsightly stains.

Examination

A thorough oral examination carried out by a dentist is essential to determine whether you are an ideal candidate for tooth whitening and what type of tooth whitening system would provide the best results. The dentist will check to see if you have signs of gum disease or any cavities present. If diagnosed, they will need to be treated before you can have your teeth whitened either at Smile Design Dental Practice or with your own dentist.

Only a trained clinician can diagnose the type of stain present. In some cases, it may be sufficient to whiten teeth by removing surface stains which can be achieved with a session with the hygienist. The hygienist will ensure that all discolourations from food stuffs, cigarettes and alcohol are polished away.

Before the tooth whitening procedure takes place, the dentist will make a note of the baseline tooth shade using a natural tooth shade guide. A photograph will also be taken.

Home whitening

Impressions of your teeth are taken by the dentist and custom made upper and lower bleaching trays are constructed. The trays are lightweight, clear and fit closely around the teeth. The bleach is administered from small syringes into the trays and these are worn for 45 minutes every day for up to 2 weeks. The strength of the home bleach is 6% Hydrogen Peroxide. It is considerably weaker than the chair side bleach which is why a prolonged exposure to the gel is needed

Bleaching Gels

The bleaching gels contain hydrogen peroxide which is the active ingredient. The success of any bleaching agent is based on the ability of the bleaching agent to permeate tooth structure to the source of the discolouration. Hydrogen Peroxide has a low molecular weight and therefore passes easily through enamel and dentine. Bleaching is an oxidation of the molecules that cause discolouration within the tooth. Peroxides release free radicals which interact chemically with large organic pigment molecules contained in enamel and dentine. These molecules are reduced into smaller, less pigmented molecules.

Who is suitable for tooth whitening?

Patients with mild general staining, age yellowing teeth, mild tetracycline staining, fluorosis or greying teeth are suitable for tooth whitening.

Who may not be suitable for tooth whitening?

Individuals with a history of extreme sensitivity to hot and cold food or drink, fracture lines in their teeth, large dental pulps, and severe loss of enamel may not be suitable candidates for tooth whitening as the procedure may precipitate sensitivity.

Decay and gum disease should be treated before any tooth whitening procedure is carried out. Tooth whitening should not be carried out on individuals with a peroxide or a plastic allergy or during pregnancy and breast feeding. Patients with severe tetracycline staining or sever fluorosis may need to consider veneers.

Will tooth whitening damage my teeth or gums?

Safety studies have shown that whitening the teeth using the home whitening kit prescribed by the dentist is perfectly safe on the teeth, cheeks, gums and tissues of the mouth. Sometimes, if the gel touches the gum for a prolonged period of time, white areas may appear where the gum has dehydrated slightly. This will resolve within several days.

Tooth whitening will not damage teeth if the instructions given by the dentist are followed. Over bleaching can cause teeth to become chalky, translucent, brittle and dehydrated.

Several studies have been carried out to investigate the reaction of the pulp (contains the nerve and blood supply to the tooth) to the bleaching process. Evidence shows that bleaching may either have no effect or may cause an initial, mild, localised pulp reaction which is reversible several weeks post treatment.

There are no reports in the literature indicating that bleaching may exert a negative impact on existing restorations. Defective restorations should, however, be replaced before bleaching to minimise potential sensitivity.

How can I look after my teeth during and after whitening?

Personal habits may need to be modified t achieve and maintain the desired goal of whiter teeth.

Teeth should be dry and cleaned of debris before any bleaching agent is applied; this is done very simply by visiting the hygienist first. During bleaching, teeth may be slightly dehydrated and consumption of food and drinks which can cause staining should be kept to a minimum. These foodstuffs should also be kept to a minimum after tooth whitening. Stopping smoking will also prevent staining of teeth.

What happens if the teeth do not whiten evenly?

If the teeth have white spots on them before whitening, these spots will appear whiter during the first few days, however, the contrast between the spots and the rest of the tooth will be less as the whitening progresses.

You may notice new white spots occurring on the teeth while you are undertaking the whitening treatment. These white spots were already present on the teeth before whitening. As the teeth become lighter, the white spots can become more visible.

Some teeth may appear banded with lighter/ whiter areas. This is because these bandings are originally present on the tooth but when the tooth was dark, these bandings were not obvious. As the tooth becomes lighter, the lighter parts of the tooth will lighten first followed by the darker banded area.

The necks of the teeth (near the gum) do not lighten as much as the rest of the tooth because the Enamel is much thinner in this area and the dentine will show through the teeth more than before they are whitened.

Possible side effects of using hydrogen peroxide?

The most commonly observed side effects to Hydrogen Peroxide are tooth sensitivity to cold and occasional irritation of the soft tissues in the mouth, particularly the gums.

Tooth sensitivity often occurs in the early stages of bleaching treatment. About 67% of patients develop transient sensitivity during whitening, normally around the necks of the teeth where the gums have receded. If sensitivity occurs, stop the whitening process and use the trays with desensitising toothpaste (containing potassium nitrate) for an hour a day. Alternatively, you can rub the desensitising toothpaste into the gum margins with your finger 5 times per day for a few days. This may take up to 2-4 days after which treatment can be continued. Usually, sensitivity will completely disappear once whitening stops.

In most cases, gum irritation is caused by an ill fitting bleaching tray rather than the actual bleaching agent. Both of these conditions are usually temporary and disappear within a few days of the treatment finishing. If you encounter any of these side effects you can consult your dentist.

How long does tooth whitening last?

Some individuals experience better effects from tooth whitening than others. Tooth whitening should last for approximately 18 months to 2 years. At this point you may choose to have a touch up treatment and the colour will usually change to the optimal shade readily. The effect is less likely to last as long if you smoke, or eat or drink products that can stain teeth, for example, red wine, tea, coffee and berries.

Is tooth whitening safe?

The evidence on safety published to date tends to suggest that bleaching is a relatively safe procedure. Hydrogen peroxide breaks down into water and oxygen. Urea breaks down into carbon dioxide and ammonia. Normal body processes easily handle all four products.

It has been suggested that peroxides are mutagenic and can boost the effects of known carcinogens. The American Dental Association (ADA), however, has found no evidence that when used as directed, tooth whiteners increase cancer risk or cause other problems.

'Over the counter' whitening products

Cheaper, over the counter bleaching kits often contain an insufficient concentration of Hydrogen Peroxide to be effective. Some may contain acetic or citric acid as active ingredients. These acids have too low a pH (too acidic) and can cause significant structural damage to enamel when used for extended periods of time and worsen the discolouration through erosion. Bleaching trays provided are not made to fit your mouth and can therefore cause increased leakage and soft tissue irritation.

Whitening toothpastes do not affect the natural colour of teeth but may be effective at removing surface (extrinsic) staining because they contain abrasives.

Before you use a tooth whitening product you should consult your dentist.

When might tooth whitening not work?

Tooth whitening only works on natural teeth and will have no effect on fillings crowns and veneers. If you have white fillings in your front teeth, these should be replaced approximately 2 weeks post- bleaching to ensure a good colour match and bond strength.

Very severe tetracycline stained teeth may not respond or have a limited response to tooth whitening. In these cases, porcelain veneers may be the treatment of choice. Mild to moderate tetracycline staining does, however, respond to extended bleaching regimes of 3-6 months. White fluorosis spots do not tend to bleach but will become less obvious as a result of lightening of the surrounding tooth area.

It is very rare, but sometimes teeth do not lighten at all.

Can I whiten my teeth during pregnancy?

The effect of the bleaching gel on the foetus is unknown. You will swallow some of the gel while you are bleaching with home kits. It is now generally accepted to avoid unnecessary medical interventions during pregnancy in order to minimise any possible risks to the health of the foetus.

The British Dental Association states that there is nothing illegal or unsafe about the technique of tooth whitening, as confirmed by the Chief Dental Officer in March 2000.

If you have any other questions please do not hesitate to contact the practice on 01296 624 163.

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