Experimental determination of ultrasonic phase velocities in human teeth along arbitrary symmetry directions

Ultrasound has been used extensively in medicine such as obstetrics and ophthalmology, and in the nondestructive testing of engineered materials such as isotropic and anisotropic composite structures. One area where ultrasound has found a new place for its application is dentistry. Several laboratory studies have shown great promise for this newly developed application. However, all of the inquiries assumed that the tooth is isotropic and homogeneous. The purpose of this project is to account for the multilayering and anisotropy nature of teeth by determining the phase velocities associated with several directions and orientations of ultrasonic wave propagation. Time-of-flight (TOF) information from A-scan signatures obtained at various angles of inclination and rotation are used in order to calculate the phase velocities. Slowness curves that would eventually lead to the determination of the independent elastic constants in human teeth are generated and reported in this paper.