A group of researchers in Australia and Taiwan led by Wang, Fleming, and their colleagues showed that they could analyze the health of extracted human teeth using lasers. This is done by measuring how the surface of a tooth responds to laser-generated ultrasound. This allows them to then valuate the mineral content of tooth enamel. Enamel is the hardest and most mineralized substance of the human body which engulfs teeth in a protective layer.
Enamel constantly undergoes a cycle of mineral loss and restoration, in which healthy teeth maintain a high mineral content. If the balance between mineral loss and gain is lost, teeth can develop areas of softened enamel which are precursors to cavities and damaged teeth.
This research could lead to the ability to assess oral health and predict emerging dental problems, such as tooth decay and cavities before they become severe and require treatment. However, using this technique on teeth alive in humans may still be many years off.
What Wang, Fleming, and their colleagues have developed a way to measure the elasticity of tooth enamel by adapting laser ultrasonic surface wave velocity dispersion. This is quite similar to how engineers evaluate the integrity of metals, thin films, and other materials.
The method uses short duration laser pulses to excite ultrasonic waves which propagate along the surface and emerge only slightly into the tooth. The velocity of these waves is influenced by the elastic properties of the enamel on a tooth. By detecting the ultrasonic waves with fiber optics at various points, it becomes possible to determine the enamel’s elasticity. The enamel’s elasticity can then be directly related to its mineralization. This method could be promising in years to come and help prevent cavities. But it is important to understand that proper dental hygiene and brushing can help prevent cavities and damaged teeth in the first place.
Based off the article “Laser Ultrasonic Surface Wave Dispersion Technique for Non-destructive Evaluation of Human Dental Enamel” by Hsiao-Chuan Wang et al.. which appeared in Optics Express, 2009.