Updated: 01 Jun 2011

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Introduction

You can get that really white, bright smile - or can you?

Whitening toothpastes, DIY bleaching products and treatments from your dentist may help bring back that white, bright smile. We check out the options and tell you about their pros and cons.

What causes staining?

There are two types of stain: surface and intrinsic (deep) staining.

Surface stains

These are mainly caused by over-indulgence in tea, coffee, red wine and cigarettes. The stains attach themselves to the pellicle (a thin layer of protein from saliva that forms on your teeth every day) or take hold in the pores of tooth enamel.

Intrinsic stains

These are changes in the structure of the tooth itself. There are four common causes:

• Ageing Wear and tear thins the outer enamel - the dentine layer below then begins to show through, making the teeth appear yellow.
  
  
• Fluorosis If children swallow too much fluoride toothpaste when their teeth are developing there's some risk they'll develop 'fluorosis' or surface mottling on the teeth.
  
  
• Antibiotics Tetracycline and other antibiotics can stain developing teeth blue-grey.
  
  
• Root canal work A single tooth can sometimes darken following this procedure.

Dentists use a shade guide (pictured above) to measure changes in tooth colour. One dental treatment claims to whiten your teeth by 8 shades.

Whitening toothpastes

Whitening toothpastes claim they contain additional abrasives and polishes to make the brushing action more effective. Some also have ingredients to remove staining material or to chemically alter stains so they're less able to stick to your teeth.

Australian and UK consumer organisations have conducted user trials of these products. After four weeks, half the Australian triallists and three-quarters of those in the UK felt their teeth were somewhat whiter. The UK report noted, however, that some of the positive results could be because the triallists brushed their teeth for longer - the full two minutes demanded by the trial.

Safety

The abrasive ingredients in whitening toothpastes aren't likely to damage tooth enamel.

The bottom line

Whitening toothpastes should remove some surface staining, but they won't lighten the natural colour of your teeth and they're usually more expensive than other toothpastes in the same range and pack size. Simply brushing your teeth for longer with an ordinary toothpaste may well achieve the same effect.

We tried them

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Ten Consumer staff members used whitening toothpastes (pictured above) for four weeks. They rated their teeth on a shade guide at the start of the trial and when the four weeks were up.

Six thought their teeth "maybe" looked a little whiter and five said they might consider buying the product they tried - not exactly a whole-hearted endorsement.

DIY bleaching

You can buy products to bleach your teeth whiter over the counter at a pharmacy or online. They use hydrogen peroxide (or carbamide peroxide, which breaks down to hydrogen peroxide) to bleach stains and the tooth itself.

• Paint-on gels: These are applied once or twice a day for up to two weeks. The taste is not unpleasant - but the gel may rub off if it hasn't dried before you close your mouth.
  
• Tray-based whiteners (pictured right): Gel is placed in a tray (mouthpiece) and worn for up to 15 minutes twice a day for two weeks. Over-the-counter trays are unlikely to fit properly and may irritate the gum if the whitening agent seeps out.
• Strips: These are worn on your teeth for 30 minutes twice daily for two weeks. They're more convenient than trays, but they don't provide full coverage (they leave your back teeth and maybe the areas next to your gums unbleached).
   

An overview of bleaching product user trials by Australia's Cochrane Collaboration found that these products work better than a placebo or no treatment. The trials covered tray, strips and paint-on-gels. 

Safety

Bleaching may cause gum irritation and sensitivity to heat or cold, although these side effects go away soon after you stop the treatment.

Bleach can also penetrate cracks or cavities in your teeth - and high concentrations can cause irreversible damage to the tooth pulp and enamel, as well as irritating the gums and lining of the mouth and weakening filling materials. 

• Make sure you have your teeth checked by a dentist before starting a DIY bleaching treatment. If you have cavities or failing dental work you're more likely to experience irritation and sensitivity.
• Don't be tempted to keep going with a DIY bleaching treatment for longer than 14 days. There's a point beyond which your teeth won't get any whiter - and continuous bleaching can damage tooth enamel. Wait at least three months between treatments.

The bottom line

These products are more effective at removing surface stains than "whitening" toothpastes. For any significant staining, it's better to see a dentist.

Professional whitening

Dentists use custom-made trays or in-surgery bleaching to whiten deeply stained teeth.

Your dentist should start by asking about your medical history to find out how your teeth became discoloured as different types of stains will respond differently to the treatment. Your teeth will be checked and any cavities or cracks will be repaired.

Is it worth it?

We asked members about their experiences of professional whitening.

Custom-made trays

Overall, people were pleased with the results from custom-made trays:

• "Found it very successful. Only needed five or so nights"
• "The effects lasted quite some time - many months"
• "Good results but sensitivity increases hugely".

Depending on the bleaching product used, you wear the trays either overnight or for a short period twice daily. The overnight option is more effective - but you're more likely to feel sensitisation (although the dentist can give you a desensitising gel to alleviate this). The treatment usually lasts 10 to 21 days.

You need to have a preliminary consultation to examine your teeth and take impressions for the trays.

In-surgery bleaching

Those who had had in-surgery bleaching were less satisfied. For this treatment the dentist cleans your teeth, paints a resin over your gums to protect them, and paints a concentrated gel on your teeth. An intense light is then shone on your teeth to activate the bleach. The session takes around 60 to 90 minutes.

Most felt it wasn't good value for the money they paid:

• "It was expensive, time-consuming, boring and not terribly effective"
• "My teeth went three to four shades lighter - but I would only do it if I had money to burn"
• "I wouldn't recommend it for a smoker like me".

Some dentists provide a take-home tray and gel.

Non-vital whitening

Non-vital whitening is used to treat a single tooth which has darkened after an accident or root canal work. The dentist drills into the tooth, places whitening agent inside and reseals it. One member found that the improvement was only temporary - a crown was the best solution.

Safety

Dentists can use higher concentrations of bleach because they can control your exposure to it and check the health of your teeth and gums.

Teethwhitening products that contain more than 12 percent hydrogen peroxide will be tightly controlled from June 2013. 

Only dentists and registered oral health practitioners supervised by a dentist will be allowed to sell these products and treatment must be carried out by a dentist or under a dentist's supervision.  

The bottom line

Bleaching at the dentist's gives the best results - it can lighten the colour of teeth by several shades. It's most likely to be successful where discoloration is light or evenly distributed (without dark bands or patches). It works well on yellow teeth and on brown stains, but blue-grey stains caused by tetracycline may not lighten as much as the surrounding enamel. This can make such staining appear worse than before. (See What causes staining? for more on types of stains.)

Bleaching won't work on tooth-coloured fillings, veneers, or crowns.

Our advice

To get rid of surface stains at home we recommend a 3-part approach:

• First, get your teeth checked and professionally cleaned by your dentist.
• Then use a whitening product (with no more than 7 percent hydrogen peroxide) for up to 14 days.
• Finally, reduce your intake of the substances that are causing the stains (cigarettes, red wine, coffee, tea). 

If you have deep stains or colour changes you'll need a dentist's help. Professional bleaching will not be a permanent solution - but if you avoid foods that stain, the effects may last for up to 3 years before you need another bleaching treatment.

For very deep staining you could consider veneers or bonding, or a crown for a single tooth.

More information

• Dental Council of New Zealand: www.dentalcouncil.org.nz
• Dental treatments - crowns, tooth whitening, veneers: www.nzda.org.nz
  
  

Report by Bev Frederikson