JPH0135659B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the thickness of tooth dentin using ultrasonic waves.

Generally, the inside of a tooth is made up of a nerve and numerous tubes with an outer diameter of 1 to 2 microns that are supplied with nutrients from the nerve.

Currently, when treating cavities or the like, a certain amount of enamel and dentin on the surface of the tooth is removed, and after appropriate treatment, a crown is placed over the tooth.

However, conventional treatment methods have the following problems.

In other words, when the tooth is viewed from the front, as shown in Figure 1, the distance 6 between the surface of the dentin 2 and the nerve 1 can be seen by X-ray photography, but when the tooth is viewed from the side, as shown in Figure 2, the distance 6 between the surface of the dentin 2 and the nerve 1 is visible. Since there is no way to measure the distance 7 between the surface of 2 and the nerve 1, treatment has been based on ``experience and intuition.''

Therefore, cutting may be necessary to reach the nerve, which can cause anxiety and discomfort to the patient, and if the nerve is exposed and a crown is placed for treatment,
In the future, there was a possibility that bacteria would invade from the exposed parts and cause phlegm to form inside, which could lead to secondary illness. In order to prevent the patient from feeling anxious, it is possible to remove the nerve, but since removing the nerve has the disadvantage of making the tooth more brittle, it has become increasingly popular to treat the tooth without removing the nerve as much as possible. is required.

Therefore, in order to avoid cutting too much of the dentin and exposing the nerve, and to keep the thickness of the dentin constant,
The industry has been looking forward to a device that measures dentin thickness (the distance between the dentin surface and the nerve).

This invention was made as a means for improving dental treatment methods, and aims to provide a device for measuring the thickness of tooth dentin using ultrasonic waves.

This will be explained below using figures.

Figure 1 is a front view of a tooth with a crown placed on it, Figure 2 is a side view of a tooth with a portion of dentin removed and a crown placed on it, and Figure 3 is a side view of a tooth before a crown is placed on the tooth. show.

In the figure, 1 is the nerve, 2 is the dentin, and 3 is the crown used for treatment. 4 is the gum part, 5 is the enamel covering the surface of the dentin 2, and 6 is the distance from the dentin surface to the nerve (dentin thickness) when the tooth is viewed from the front.

When treating cavities, etc., dentists use a cutting tool to cut the enamel and then cut some of the dentin. This could be easily determined by taking X-rays, but the distance 7 from the dentin surface to the nerve shown in the side view of Figure 2 could be easily determined by X-rays from the side because the teeth are lined up. I was unable to photograph it and have not been able to measure it until today.

An embodiment of the present invention will be described below with reference to FIG.

In the figure, 8 is a tooth portion, 9a to 9c are couplants such as glycerin or water, and 10a to 10c are ultrasonic probes placed facing the dentin 2 of the tooth via the couplants 9a to 9c. It is a tentacle. These ultrasonic probes use a selector to select and set the transmission signal sent out from the transmission pulse generation circuit 14 which generates the transmission signal in synchronization with the signal from the synchronization section 13 which generates the timing signals necessary for each circuit. The ultrasonic signal is received via a transmission/reception selection switching circuit 11 which is automatically or manually selected and switched depending on the settings of 12, and generates an ultrasonic signal. 15
17 is a reception amplifier circuit which receives the ultrasonic signals generated from the probes 10a to 10c via the transmission/reception selection switching circuit 11 and amplifies them to the extent that the signals can be processed; and 17 is an ultrasonic echo from the reception amplifier circuit 15. 16 is a time axis unit that generates a signal for sweeping the time axis of the display 17 based on the timing signal from the synchronization unit 13. It is. Reference numeral 18 denotes a thickness measuring section, which includes a time measuring circuit 19 that measures the ultrasonic propagation time from the transmitted signal and the ultrasonic echo signal, and a time measuring circuit 19 that measures the ultrasonic propagation time using the pulses generated from the pulse generation circuit 21. It is composed of a propagation distance measuring circuit 20 that measures a sound wave propagation distance.

The thickness information of the dentin 2 obtained by the propagation distance measuring circuit 20 is digitally displayed on the display 23 as the distance between the cut dentin and the nerve (i.e., the thickness of the dentin is 6 or 7). Ru.

In addition, in the comparison/judgment circuit 24 that compares and decides the thickness information, that is, the value 22 of the propagation distance, with a reference thickness value preset by the setter 25,
In the process of cutting dentin 2, the above propagation distance value 2
2 becomes equal to or less than the reference thickness value, an alarm output 26 (for example, a buzzer sound or a lamp display) is sent out.

Although the above description has been made regarding the case of measuring the thickness of dentin, this invention allows for automatic or manual selection and switching of multiple ultrasonic probes.
Each tooth can be measured from each direction simultaneously, and the cross-sectional structure of the tooth can be estimated from these measurement data, which can be effectively used in the cutting process. It goes without saying that the above measurement data can be processed by an appropriate data processing device and output to a CRT display, printer, etc.

In addition, if several dental treatment instruments are installed, the ultrasonic probes 10a to 1 are installed for each treatment instrument.
0c can be provided and used in parallel with one thickness measuring device.

As described above, since the device according to the present invention has the above-mentioned functions, it is possible to maintain a constant distance between the dentin surface and the nerve part during the cutting process of dentin, and also to transmit ultrasonic echo signals. Since the tooth can be monitored from multiple directions using the display, cracks in the dentin, corrosion, etc. can also be determined to some extent. Therefore, the treatment can be carried out without causing any anxiety or discomfort to the patient, and also helps to prevent secondary illnesses caused by bacteria that invade from the nerves that are exposed due to excessive cutting, allowing the doctor to perform the treatment with peace of mind. be able to.

Although the above embodiment shows three probes facing the dentin of the tooth, the number of probes is not limited to three.

[Brief explanation of drawings]

Fig. 1 is a front view of a tooth with a crown placed on it, Fig. 2 is a side view of the tooth with a crown placed on it, Fig. 3 is a side view of the tooth with a crown placed on it, and Fig. 4 is a side view of the tooth with a crown placed on it. It is a figure showing an example. In the figure, 1 is the nerve, 2 is the dentin, 6 and 7 are the thickness of the dentin, 9a to 9c are the couplant, 10a to 10c are the ultrasound probes, 11 is the transmission/reception selection switching circuit, 18
19 is a thickness measuring section, 19 is a time measuring circuit, 20 is a propagation distance measuring circuit, 24 is a comparison judgment circuit, and 26 is an alarm output. In the drawings, the same or equivalent parts are designated by the same reference numerals.

Claims (1)

[Claims] 1. A transmission signal generation circuit that generates a transmission signal based on a signal from a synchronization section, and a circuit that is brought into contact with the dentin of the tooth via a couplant and generates an ultrasonic signal in response to the transmission signal. a plurality of ultrasonic probes, the above-mentioned transmission signals, a selection switching circuit for selectively switching the ultrasonic echo signals of tooth dentin obtained by the plurality of ultrasonic probes, and the above-mentioned a means for displaying an ultrasonic echo signal; a time measuring means for measuring the ultrasonic propagation time from the dentin surface of the tooth to the nerve; A thickness measuring means for measuring the propagation distance of the ultrasonic echo corresponding to the thickness from the surface to the nerve, a setting means for setting a reference thickness from the dentin of the tooth to the nerve, and measurement by the thickness measuring means. a comparison means for comparing the propagation distance of the ultrasonic echo and a reference thickness value set by the setting means, and an alarm means for generating an alarm output according to the comparison result of the comparison means. Ultrasonic tooth thickness measuring device.