Two‐dimensional distribution of sound velocity in ground sections of dentin

Abstract

The longitudinal velocity of sound in a specific material depends, amongst others, on the material's density and elasticity (Young's Modulus). Ultrasound therefore may be used for indirect characterization of materials. In this paper a method is described which allows high resolution measurements on coplanar ground sections of human teeth. The results are presented in two-dimensional velocity profiles. There is evidence from the first images, that longitudinal sound velocity (LSV) in dentin varies depending on the location. The use of LSV may be another way to characterize hard dental tissues physically, and to monitor induced changes.

Diagnostic ultrasound tooth imaging using fractional fourier transform

“…The excitation method was also compared with a Gaussian pulse of the same bandwidth, which is widely used by researchers to measure the thickness of the tooth layers [2], [10], [3], [11], [33], [32], [34].…”

“…In order to facilitate the transmission of ultrasound waves into the sample, a coupling material must be used. Although various acoustic couplants are evaluated for tooth imaging [31], water is usually preferred as a coupling medium for non-contact ultrasound tooth measurements [1], [3], [10], [32]. However, the acoustical mismatch between the water, polystyrene delayline and enamel will interfere with echoes from target tissue and decrease the transmission efficiency.…”

“…In Figure 6 (top), the matched filter technique was used to compress the received ultrasound echoes. In Figure 6 (bottom), the received signals were transformed to the fractional Fourier domain where the rotation angle was calculated by Equation (10). The temporal information was recovered back by scaling the time axis according to Equation (11).…”

“…These were then used to compress the received signals. FrFT was performed at α = 1.7421 for the short LFM and at α = 1.3360 for the long LFM, where the rotation angle is calculated according to Equation (10). In phantom thickness measurements, both techniques were only used for compression.…”

“…SAM can be easily achieve sub-millimeter resolution, however it is not a practical diagnostic method for dentistry. Recently, the frequency range of [10][11][12][13][14][15][16][17][18][19][20] MHz is more commonly preferred by researchers due to the high attenuation in human tooth at higher frequencies [10], [3], [11], [12]. For this reason, a delay-line transducer with a 15 MHz center frequency is chosen in this study for the experiments.…”