A study on the ultrasonic-tomography of a vital tooth

当医生预备活髓牙时，了解预备面与髓腔壁的距离是非常重要的，现在我们已经研制出了超声诊断设备，它可以通过测量剩余牙本质的厚度来指示两个边界的接近程度，为了更准确地测量剩余牙本质的厚度并确定剩余牙本质的最薄点，B扫描超声断层成像是非常有用的。因此，我研究了活髓牙的超声断层成像指示方法。在实验中，在薄的人类牙本质板的一侧制备圆顶形或圆柱形的缺损。通过超声探头，在试样的另一侧扫描缺陷。结果表明，用超声反射波能量指示缺陷的形状时，圆顶状缺陷清晰，圆柱状缺陷不清晰，在该设备上，灰度表示法是最适合缺陷面积的表示方法，但在超声反射波能量指示缺陷的形状时，扫描方法的发展和灰度表示的区别是剩下的问题。

When a dentist prepares a vital tooth, it is very important to know the distance between the prepared surface and the pulp chamber wall, and now we have developed ultrasonic diagnostic equipment which can indicate the nearness of two boundaies by measuring the thickness of the remaining dentin.To measure the thickness more exactly and to confirm the thinnest point of the remaining dentin, the ultrasonic-tomography by B-scanning is very useful. So, I investigatid the method of indicating the ultrasonic-tomography of a vital tooth.Experimentally, a defect in the shape of a dome or a defect in the shape of a sylinder was prepared in a side of the thin human dentin plate. By the ultrasonic probe, the defect was scaned on the other side of the specimen. And, the figure of the defect was indicated on a CRT.As a result, when the figure of the defect was indicated by the energy of ultrasonic reflective wave, the dome shaped defect is clear, but the sylinder shaped defect is not clear.By this equipment, the grey scaling representation is the most suitable method to present the area of the defect.But, a development of the scanning method and a distinction of the grey scaling representation are remaining problems.