Measurement of ultrasonic phase and group velocities in human dental hard tissue

Journal of Therapeutic Ultrasound

Ben A Scheven²  Michael McGrath³  Panagiotis Petrakis³  Sleiman R Ghorayeb¹ 

[1] Orthopaedics Research Lab - FIMR, North Shore Hospital, Manhassett NY, USA;School of Dentistry, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK;School of Engineering and Applied Sciences, Ultrasound Research Laboratory, Hofstra University, 104 Weed Hall, Hempstead, NY 11549, USA

关键词: Slowness curves;    Phase velocities;    Tooth repair;    Therapeutic ultrasound;    Dental ultrasound;   

Others  :  803014
DOI  :  10.1186/2050-5736-1-5

 received in 2012-11-07, accepted in 2013-02-18,  发布年份 2013

【 摘 要 】

Background

The development of ultrasound for use in dental tissues is hampered by the complex, multilayered nature of the teeth. The purpose of this preliminary study was to obtain the phase and group velocities associated with several directions of ultrasonic wave propagation in relation to the tooth structure, which would then lead to the determination of the elastic constants in dental hard tissue. Knowledge of these elastic constants can be used to feed back into numerical models (such as finite element) in order to simulate/predict ultrasonic wave propagation and behavior in the teeth. This will help to optimize ultrasonic protocols as potential noninvasive therapeutic tools for novel dental regenerative therapies.

Methods

An extracted human second molar was used to determine time-of-flight information from A-scan signatures obtained at various angles of inclination and rotation using a scanning acoustic microscope at 10 MHz. Phase and group velocities and associated slowness curves were calculated in order to determine the independent elastic constants in the human teeth.

Results

Results show that as the tooth was inclined at three azimuthal angles (Θ_in = 0°, 15°, and 30°) and rotated from Φ_in = 0° to 360° in order to cover the whole perimeter of the tooth, slowness curves constructed from the computed phase and group velocities versus angle of rotation confirm the inhomogeneous and anisotropic nature of the tooth as indicated by the nonuniform appearance of uneven circular shape patterns of the measurements when compared to those produced in a control isotropic fused quartz sample.

Conclusions

This study demonstrates that phase and group velocities of ultrasound as determined by acoustic microscopy change and are dependent on the direction of the tooth structure. Thus, these results confirm that the tooth is indeed a multilayered anisotropic structure underscoring that there is no single elastic constant sufficient to represent the complex structure of the tooth. The findings underline the importance to take into account these crucial characteristics in order to develop and optimize therapeutic as well as diagnostic applications of ultrasound in dental tissue repair, and further studies are warranted to analyze ultrasound transmission at various frequencies and intensities in different teeth to develop appropriate models for ultrasound biophysical behavior in dental tissues.

【 授权许可】

   
2013 Ghorayeb et al.; licensee BioMed Central Ltd.

【 图 表 】

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