A new technology that spots tooth decay almost as soon as it has begun promises to reduce the need for drilling and filling.

The technology, which may be available in dental surgery in 5 years, is based on Raman spectroscopy, which is most commonly used to distinguish between different chemicals by identifying each molecule’s unique fingerprint. It detects decay simply by pointing a tiny optical fiber 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 analyzing how light is scattered when a laser is fired at the tooth. Researchers were able to tell healthy teeth from carious teeth because the bacteria responsible for the decay scatter light in a different way than healthy teeth do.

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. 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 machine 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.