Frequently asked questions...

What is the most effective tooth whitening procedure?

There is now laser whitening or ‘power whitening’. During this treatment a light or laser is shone on the teeth to activate the chemical. The light speeds up the chemical reaction of the whitening product and the colour change can be achieved more quickly. Laser whitening can make teeth up to five or six shades lighter. This procedure usually takes about one hour.

 

What is 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;

1.A product can bleach a tooth, which means that it actually changes the natural tooth colour. Bleaching products contain peroxides that help remove deep internal (intrinsic) and surface (extrinsic) stains.

2.Non bleaching whitening products can be used which contain agents that work by chemical or physical action to help remove surface stains only.

How long has tooth whitening been used?

Tooth whitening has been practised 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 nightguard 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.

Interestingly enough, this system was initially discovered quite by accident by an orthodontist named William Klusmier. He instructed a patient to use an oral antiseptic containing 10% carbamide peroxide in an orthodontic positioner, which the patient wore at night, in an effort to facilitate tissue healing. The patient returned with improved tissue health and, after using the product for an extended period of time, his teeth were significantly lighter in colour. He began using this technique to lighten teeth. From 1970 to 1975, Klusmier presented his findings at several dental meetings. Haywood and Haymann attended one of these meetings and initiated their clinical and laboratory investigations on the technique as a result.

Why might I want my teeth whitened?

As with hair and skin colour, the colour of our teeth is genetically determined and therefore varies between individuals. Our 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 can also stain teeth. Acidic drinks and foods such as fizzy drinks, fruit juice and yoghurt can cause the teeth to appear more yellow as they cause erosion of the outer enamel layer allowing the underlying yellow dentine to shine through.

Discolouration can also be caused by illness or the use of tetracycline antibiotics while the teeth are forming. Minocycline, a tetracycline antibiotic, can cause staining in adult teeth.

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

In Surgery Technique

This technique involves using either light-activated units for 'power bleaching' or lasers while you sit in the dental chair.

The technician will apply a rubber dam or a gel to protect the soft tissues, and a bleaching agent, usually containing hydrogen peroxide, is then applied onto your teeth. A light or laser is then shone on the teeth to activate the chemical so that it acts more quickly on the discolouring molecules within the tooth. The actual tooth whitening procedure will take about one hour.

The success of these techniques is determined by the initial colour of the teeth. Generally, bleaching easily removes yellow with dark brown and grey stains being more resistant to the process.

What are the active ingredients in professional bleaching gels and how do they work?

Bleaching gels contain either hydrogen peroxide or one of its precursors, notably carbamide peroxide. Carbamide peroxide breaks down into hydrogen peroxide and urea, with hydrogen peroxide being the active ingredient.

The success of any bleaching treatment 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 discolouring molecules 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.

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 3 years. At this point you may chose 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.

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.

If you encounter any of these side effects you should consult your dentist.

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

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

Teeth should be dry and cleaned of debris before any bleaching agent is applied. 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 about whitening products bought 'over the counter'?

Although 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.

Can I whiten my teeth while I am pregnant?

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.