Ultrasonic Dental Diagnostics Tool

Ultrasound, as a diagnostic tool, is widely used in different areas of contemporary medicine. However, until now it has not been used in dental diagnostics and had just a limited application in the experimental investigations of mineralized tissues. Dental application of ultrasound was restricted, firstly, by the complicated layered structure of the tooth, its curved surface, and its relatively small dimensions. The hardness and high density of enamel and dentine provide yet another challenge to ultrasound investigation of these tissues. Enamel and dentine have the highest values of sound velocity and acoustic impedance of all the tissues in the body.

Recently, the IDRI team has successfully executed a feasibility study of dental tissue characterization with high-frequency ultrasound. It was found that using a focused, ultrasonic beam it is possible to precisely measure the enamel thickness as well as the distance from the tooth surface to the pulp. It was also found that it is possible to observe bonding failures in the interface between restoration, dentine, and enamel and to detect hidden and secondary cavities.

The main objective of the project is the development of an affordable and portable Ultrasonic Dental Diagnostics Tool (UDDT).  The tool would be used to measure enamel thickness and to monitor the thickness of the remaining dentine layer as well as the distance to the pulp at the tooth processing point during prophylactic or restorative treatment. The proposed technology will offer multiple advantages over existing and emerging competitive approaches, such as much lower cost, portability, safety, ease of use, and general value to the dentist. The prototype of the dental device is envisioned as containing pulser-receiver electronics, a central control processor, and data acquisition software. The acquired data is displayed in a simplified and user-friendly form.

Due to poor acoustical contact with a curved surface of the tooth, most conventional medical ultrasound techniques using plane contact sensors fail to produce tractable results. Tooth slices also cannot be examined with a plane contact ultrasound sensor due to the heterogeneous properties of the tissue and the small size of the contact surface of the tooth slice. On the other hand, focused, short impulse ultrasound offers new opportunities in the investigation of tooth tissue because it does not require wide contact area between the transducer and a tooth surface. Proper positioning of such focused ultrasound probe can provide correct measurement and imaging of small areas below the surface. Design of a dedicated ultrasonic probe is therefore an essential part of the proposed work.

Further development of this new technology will include: design and practical realization of a portable, robust, FDA-approved hardware; reliable, commercial-grade software with sophisticated real-time signal processing and feature extraction algorithms; and, a database of dental material properties. In parallel with the equipment development effort, we will conduct additional research to better understand propagation of ultrasonic signals in dental structures and develop better sensors and analysis algorithms.