[The development of ultrasonic diagnostic equipment for dental use].

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 these two boundaries by measuring the thickness of the remaining dentin. This equipment can be used to measure the thickness of the remaining dentin between the prepared surface and the pulp chamber wall by means of a well-focused ultrasonic beam. 1. The measuring technique is very easy. The measuring method is as in the following. 1) The ultrasonic velocity in human dentin which differs according to the portions of tooth [e.g. crown: maxillary tooth 4,039 m/s, mandibular tooth 3,940 m/s, neck : 3,887 m/s, root : 3,743 m/s These are average values.-1985, MOROZUMI] is input to the microcomputer. 2) The probe which generates the ultrasonic wave is attached to the surface of the prepared tooth with the help of the existing water between the probe and the tooth's surface. 3) The reflected waves from the surface of the prepared tooth [S] and from the pulp chamber wall [B] can be observed on the CRT. The probe position must be adjusted so as to obtain the maximum amplitude of each reflections. 4) Keeping this probe position and pushing the measuring switch on the controller, the estimated thickness of the remaining dentin is indicated digitally after 0.3 seconds. 2. The ultrasonic wave which is generated from this equipment has no effect on the human body. 3. Accordingly, this equipment is useful for measuring the thickness of the remaining dentin under dental treatment.