John Christoph
Biomedical Engineering Laboratory, Department of Conservative Dentistry, University of Tuebingen, Osianderstr 2-8, D-72076 Tuebingen, Germany.
J Acoust Soc Am. 2004 Jul;116(1):545-56. doi: 10.1121/1.1738454.
The speed of ultrasound at 20 MHz is measured for hard dental tissues inside human teeth. This includes the cementum, for which no data are available. The spatial distribution, extrema, and means of the longitudinal ultrasound velocity (LUV) are determined with an emphasis on the apical thirds and an extended spectrum. Tissue areas are investigated by optical means and by acoustical scanning, in order to compare apical regions-of-interest with the complete mineralized wet porous tissue that lies beneath the enamel cap. The maximal LUV in a single dentin specimen varies from 3903 m/s to 4226 m/s. The dentin's frequency distribution of LUV at 20 degrees C exhibits a predominant peak feature comprising several Voigt functions. Introducing standardized relative tooth width portions, the corono-apical decrease in LUV of 21 specimens is approximated by LUV=4224 - (257* ln(y)) along reduced distances in dentin. Abnormal teeth require a higher resolution and an approximate equation of the form LUV= (sigma(aiyi))/(1 + sigma(bi+1y(i+1. It can be used each time the corono-apical variation has to be quantified in each of the three tissues. Ten coefficients are numerically exemplified. An error evaluation is performed, which denotes errors of 0.2% +/- 1.3% (enamel), -0.1% +/- 1.6% (cementum), and acceptable residual errors for dentin.
对人类牙齿内部的硬牙组织测量了20兆赫兹时的超声速度。这包括牙骨质，目前尚无相关数据。确定了纵向超声速度（LUV）的空间分布、极值和平均值，重点关注根尖三分之一区域和扩展频谱。通过光学手段和声学扫描对组织区域进行研究，以便将根尖感兴趣区域与釉质帽下方完整的矿化湿多孔组织进行比较。单个牙本质标本中的最大LUV在3903米/秒至4226米/秒之间变化。20摄氏度时牙本质LUV的频率分布呈现出一个由几个沃伊特函数组成的主要峰值特征。引入标准化的相对牙宽部分，21个标本牙本质中LUV沿牙本质中减小的距离的冠根向降低情况可近似用LUV = 4224 - (257 * ln(y))来表示。异常牙齿需要更高的分辨率以及一个形式为LUV = (sigma(ai * yi)) / (1 + sigma(bi + 1 * y(i + 1))的近似方程。每次在三种组织中的每一种中对冠根向变化进行量化时都可以使用该方程。给出了十个系数的数值示例。进行了误差评估，结果表明釉质的误差为0.2% +/- 1.3%，牙骨质的误差为 -0.1% +/- 1.6%，牙本质的残余误差可接受。
