Having bad teeth can have a major impact on a person's self-esteem. With National Smile Week upon us, Barry Nelson sorts out the crowns from the veneers, and asks whether we should just take better care of what we have.

IT is impossible to open a magazine these days without being dazzled by the dental work of a smiley star. Tom Cruise, Julia Roberts, Britney Spears and Chancellor Gordon Brown are among a long list of famous names rumoured to have forked out for cosmetic dentistry in a bid to perfect their smile.

Yet designer teeth are no longer restricted to the rich and famous and even high street dentists are offering the latest cosmetic treatments nowadays. And with National Smile Week beginning on Monday May 12, what better time to splash out on a Hollywood smile?

Or - you could just brush up on your dental hygiene and take better care of the teeth than you have already.

Gill Roberts, a dentist from the NHS Zetland practice in Northallerton, North Yorkshire, says people can make the most of their teeth without the need for expensive cosmetic treatment by simply brushing thoroughly twice a day, using fluoride toothpaste, restricting sugary foods to meal times and visiting the dentist at least once a year.

One important thing to remember about dentists: not many people know that if you don't go to the dentist for more than 15 months you will no longer be on that practice's NHS list and you will have to contact the NHS Direct helpline (0845 4647) to find another NHS dentist willing to take you.

Peter Robinson, Professor of Dental Public Health at Sheffield University, says teeth are often at the root of a person's self-esteem.

''We are constantly fed images of people with nice teeth and film star smiles. People are very conscious about their appearance nowadays and teeth are one of the first things people notice about you.

''It can affect a person's self-confidence and their everyday life. People with bad teeth are reluctant to smile and sometimes don't even want to go out in public.''

A new study by Professor Robinson and a team of researchers showed that bad teeth can even have an adverse effect on the way others react to us.

The survey, which involved showing photographs to 200 people, found that people pictured smiling to show a set of healthy, sound teeth were perceived to be happier, more intelligent and better-educated.

However, when the photographs were computer-modified so that the same people appeared to have decayed and discoloured teeth, they were judged quite differently and reckoned to be less successful, to have poorer career prospects and lower self-esteem.

Robinson, a dental psychologist, adds: ''Imagine you are at a party and you meet the woman of your dreams - you smile and she walks away. There are situations when first impressions do count and this is where having bad teeth can affect you.''

One of the simplest and cheapest means of improving your fangs is bleaching. This can be done in the dental surgery but the most popular method allows the patient to apply the bleach at home.

The dentist makes a mould of your teeth and creates a mouthguard which you can fill with bleach gel and apply at your leisure. This allows you to control the intensity of the whitening.

Home bleaching costs £200 to £400 and the effects last about two years although the treatment can sometimes cause short-term gum and teeth sensitivity.

Bleaching is actually outlawed by EU regulations after scientists claimed the hydrogen peroxide bleach used in the procedure is too concentrated and could damage teeth or gums.

The British Dental Association (BDA) refutes this claim, and according to executive-director Armajit Gill the law is ''absolutely nonsensical''.

He adds: ''Bleaching is the safest, cheapest and least invasive way to brighten up teeth. I would use it on my brother. Every dentist I know is comfortable about bleaching and I don't know anyone who has stopped because of this regulation.''

For anyone happy to loosen the purse strings for the sake of something more long-lasting and guaranteed to resist the staining evils of nicotine, coffee and red wine, porcelain veneers are the answer.

Veneers fit onto the front of the tooth like a fingernail and can dramatically alter a smile by correcting any irregularities and making teeth as white as you want.

But while porcelain veneers can cost anything from £400 to £1,000 per tooth, Nottingham-based dentist Gill recommends the more straightforward option of composite plastic veneers, which cost just £50-£75 a tooth and are ideal for a quick fix.

''Composite veneers can be done in the practice there and then. It is painless, comfortable, quick and easy and they can be taken off and remodified. In the right patient they can last 10 to 15 years. Porcelain veneers take longer and have to be hand made. They last longer and are less likely to discolour but they can break.''

Whitening teeth is one matter, altering their alignment is quite another and orthodontic treatment is also a thriving area of cosmetic dentistry.

In 2001, around 25,000 adults had orthodontic braces fitted on the NHS - a rise of 36 per cent over ten years - and still more had braces fitted privately.

For those who want straight teeth without having to look like a metal-mouthed teenager a new 'invisible' brace has recently burst onto the market. Dubbed 'contact lenses for teeth' the Invisalign uses a series of clear, easily-removable acrylic 'aligners' to gradually straighten teeth without metal or wires.

At a cost of £2,000 to £3,000, orthodontic treatment is expensive but it can have a dramatic impact on a person's smile by altering the whole structure of their jaw.

The number of people seeking cosmetic treatment in the UK is growing so fast that the region's infamous association with poor dental hygiene seems a thing of the past. And that, at least, is something to smile about...