Light up your smile

Tooth decay is one of the world's most prevalent diseases and the usual dental practise for dealing with it is a rather unpleasant remedy to a problem that has progressed too far, involving drilling and filling. If caught early enough, however, there are ways in which remineralisation can be encouraged in the tooth, thereby repairing the damage.

A dentist can detect tooth decay during a visual examination, however it can be hard to see the identifing characteristics, which are often no more than a white spot on a white background. The examination also involves a certain amount of scraping, which is not always condudive to the health of the tooth. An X-ray exam will reveal the small lesions in the tooth, however this method is not sufficiently sensitive and can only detect the erosion at a stage when a filling is already required.

Researchers are exploring various ways of detecting tooth decay in the early stages when something can be done to reverse the damage that's been caused. Many of these involve optical diagnostics, including fluorescence techniques that use a laser to illuminate the tooth and spectroscopic analysis to detect the identifying characteristics of decay in the reflected light, which are not always apparent during a visual inspection. Raman spectroscopy has been demonstrated to provide a more sensitive measure, by observing small shifts in the reflected light spectrum due to the structural changes in the tooth where decay has taken hold.

Researchers at the Institute of Photonics at Strathclyde University in the UK, have experimented with many of these techniques, as well as using conventional confocal microscopy coupled with fibre-optics, to obtain information on the depth of erosion, which they have further enhanced by using Optical Coherence Tomography. Imaging with multiphoton microscopy, whilst not a practical solution for dentists, has also been demonstrated by this team, allowing them to.visualise the tooth in three dimensions and, to a certain extent, inside of it.

The challenge for developers is to produce a portable device that is easy to operate and provides fast and reliable results. A commercial product would conceivably employ optical fibre to gain the necessary access to the patient's teeth and allow the dental practisioner to obtain instant results regarding the health of the teeth. Even if tooth decay can't be erradicated, at least we might then have a way of combatting it before it does the damage. The same advice applies: visit your dentist regularly.