Ultrasound to make dental patients smile

When David Hsiao-Chuan Wang accepted the challenge of a University of Sydney scholarship proposal of ‘using optics for dental health’ he had no idea he would make a pioneering breakthrough in the area of painless analysis of tooth density.

Wang, a postgraduate student in the Institute of Photonic and Optical Science(IPOS), has developed an Ultrasonic Evaluation Technique using laser-generated ultrasound to measure the elasticity of the surface of teeth. Normally a needle or probe is used for such evaluations and this can be painful and cause unnecessary damage.

Wang’s painless technique uses a short laser pulse to generate ultrasonic surface acoustic wave on the surface of the tooth enamel. This ultrasound pulse propagates across the area of interest on the enamel, while probing some distance under the surface, and is detected for analysis. The calculated propagation velocity of the ultrasound then reveals the elasticity of the tooth, from which the early stages of decay can be diagnosed.

"There are many things that made the measurements difficult, such as the small dimensions of the tooth area and the surface conditions," explains Wang. "The use of optical fibre is important for our work because it allows us to make precise measurements on the small dimension samples without being in contact."

After eighteen months of optics research Wang, supervised by Professor Simon Fleming and working in collaboration with dental researchers at the University of Sydney, needed someone who understood ultrasonic methods. Enter Professor Yung-Chun Lee from the National Cheng Kung University in Tainan City, Taiwan, who worked with Wang for a further fourteen months researching and adapting equipment.

The first successful measurement on teeth was carried out in mid-2008. "It was a mixture of relief and excitement as we had a good result. Actually, after more than three years of work it was very exciting," grins Wang.

Wang hopes to develop the dental ultrasound evaluation technique further by making it a hand-held dental tool. "We still have a long way to go and it’s important to get funding otherwise we cannot do any more research and development. It’s a great chance for the dental industry to become more involved." We all hope this is one opportunity dentists will want to sink their teeth into.

David Hsiao-Chuan Wang is the lead author of the paper "Laser Ultrasonic Surface Wave Dispersion Technique for Non-Destructive Evaluation of Human Dental Enamel", recently published in Optics Express.

(Source: University of Sydney: Optics Express: September 2009)