A new technology that spots tooth decay almost as soon as it's begun promises to reduce the need for drilling and filling. Drilling is one of the top dental phobias and puts thousands of people off visiting their dentist every year.

The new technology, which may be available in dental surgeries in five years from now, is based on Raman spectroscopy most commonly used to distinguish between different chemicals by identifying each molecule's unique fingerprint. It detects decay simply and painlessly by pointing a tiny optical fibre at the tooth to check on its health.

A preliminary study at King's College London, where the technique is being developed, found that chemical changes in the tooth could be detected by analysing how light is scattered when a laser is fired at the tooth. Researchers were able to tell healthy teeth from carious teeth because bacteria, responsible for the decay, scatter light in a different way to healthy teeth.

Frances Downey, a PhD student working on developing the technique at King's College London, said: 'The earlier you spot decay the better as you can remineralise the area so there is no cavitation and therefore no need for a filling.'

Dr Frederic Festy, who is supervising the project, is planning a larger trial using more teeth samples and hopes to move onto human trials soon. The key to the technique is its simplicity, he explains.

Currently, decaying teeth are uncovered either by visual examination or the use of x-rays, but usually by then, the damage has been done and the decayed area must be drilled out. But Dr Steven Hogg, a microbiologist at Newcastle University's dental school, confirms that it is possible to repair teeth with a special mouthwash or fluoride varnish if dental decay is caught early enough.

The downside of developing the machines is the cost and the time it takes to do a scan - 30 seconds can be a long time for any patient to remain perfectly still.

The results were presented at Microscience 2008 and published in SCI's Chemistry & Industry (C&I) magazine.

Adapted from materials provided by Society of Chemical Industry, via AlphaGalileo.