Laser technology could make visits to the dentist a pain-free experience if clinical trials at the University of London in the next two years are successful.

Gavin Pearson, coordinator of the project at the Eastman Dental Institute, says that the conventional dental drills have changed little in 100 years. They rely on an abrasive head which spins around at 2,000 to 300,000 rpm to grind away the tooth material. It is the combination of the vibration caused by the drill and the pressure on the tooth that causes pain.

Researchers are working with a team of scientists at Rutherford Appleton Laboratory to develop ultraviolet lasers operating at 248-193 nanometres wavelength for use in small, portable lasers that can be used by the dentist.

Dr Pearson says: "A small UV laser can produce high peak-power in bursts lasting less than one hundredth millionth of a second and the wavelength being used allows for an efficient drilling process, generating almost no heat."

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Conventional methods of drilling involve removing sound tissue before the decay is reached and removed. When it comes to repairing old fillings even more soft tissue is removed and the cavity increased.

"Just a few seconds of laser action can cut a perfect pyramid into the tooth only one fifth of a millimetre across with no damage to the surrounding tissue," says Dr Pearson.

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Experiments by the researchers on teeth freshly extracted from patients have shown that laser drilled surfaces are very clean and they believe that the level of accuracy could lead to "keyhole dentistry" to get at inner decay.

"Using lasers, a very small hole could be used to tunnel down to the decay in the tooth, leaving the bulk of the tooth undamaged and much stronger."

New ceramic fillings materials could also mean longer lasting and stronger fillings. Work by Michael Wilson at the institute suggests that technology could help to kill bacteria that cause dental decay. If the clinical trials are successful, routine laser dentistry could be a reality within the next five to ten years.