Source: Optical Society of America

By measuring how the surface of a tooth responds to laser-generated ultrasound, the mineral content of tooth enamel can be evaluated, according to a group of researchers in Australia and Taiwan whose work was published in the latest issue of Optics Express, the Optical Society of America's (OSA) open-access journal. This is the first time anyone has been able to non-destructively measure the elasticity of teeth, creating a method that can be used to assess oral health and predict caries risk.

"The ultimate goal is to come up with a quick, efficient, cost-effective, and non-destructive way to evaluate the mineralization of human dental enamel," says David Hsiao-Chuan Wang, a graduate student at the University of Sydney in Australia and first author on the paper in Optics Express. Wang and his advisor Simon Fleming, a physics professor at the University of Sydney's Institute of Photonics and Optical Science, collaborated on the study with dental researchers at the University of Sydney and ultrasonic evaluation researchers at National Cheng Kung University in Tainan City, Taiwan.

The method uses short duration laser pulses to excite ultrasonic waves that propagate along the surface and penetrate only a small distance into a tooth. The velocity of these waves is influenced by the elastic properties of the enamel on a tooth, and by detecting the ultrasonic waves with fiber optics at various points, they can determine the enamel's elasticity, which is directly related to its mineralization.

In their Optics Express article, Wang, Fleming, and their colleagues showed that they could use this technique on extracted human teeth. They have not yet tested the technique on a living person's teeth, and it will likely take several years before any eventual device is ready for use in practice.

This work was funded by the Australian Government and Bio-Dental Technology Pty. Ltd.

Paper: "Laser Ultrasonic Surface Wave Dispersion Technique for Non-destructive Evaluation of Human Dental Enamel," Hsiao-Chuan Wang et al., Optics Express.