JPH07246210A - Diagnostic device for dental purpose - Google Patents

Abstract

PURPOSE:To measure the length of a root canal without being affected by the contents of the root canal by passing a current between an electrode inserted into the root canal via a resistor and capacitor which are larger in both of resistance value and capacity than a living body and a dead electrode brought into contact with the oral mucosa from an oscillinator of several KHz and comparing the phases of the root canal electrodes. CONSTITUTION:An oscillator l oscillates AC of an oscillation frequency of several KHz and low voltage of about + or -500mV. The output of tf)g oscillator l is inputted to a parallel circuit 11 consisting of a shorted side path 9 and a load side path 10 consisting of a resistor 2 connected in series and capacitor 3. The resistor 2 and the capacitor 3 are regulated to the values sufficiently larger than the resistance and capacitance of the living body. The electrode 4 in the root canal is connected to the output of the side path consisting of the resistor 2 and the capacitor 3. A reamer 5 for treating the root canal which is connected to the electrode 4 in the root canal and detects the position of the apex 6 of the root canel is connected to the electrode 4 in the root canal. A mucosa membrane electrode 7 for passing the cifirrent between the electrodes 4 in the root canal and this electrode is grounded 8. The output of the parallel circuit 11 is inputted to a phase comparator 12 by which the phase difference of the potential generated in the electrode 4 in the root canal is detected. The current is then read by an ammeter 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the measurement of the root canal length of a tooth to be treated in dentistry.
The present invention relates to a dental diagnostic apparatus that is not affected by dental pulp, blood, exudate, drug solution, drying, etc., and enables measurement with a simple and clear circuit.

[0002]

2. Description of the Related Art In endodontic treatment, it is an essential condition to know the root canal length of the tooth to be treated, and an electrical diagnostic apparatus for that purpose has been proposed and patented. One of them is Japanese Patent No. 894037 (Japanese Patent Publication No. 52-23507).
As shown in the dental diagnostic device, a constant AC voltage is applied to the electrode in the root canal and the electrode of the oral mucosa, and the absolute value of the flowing current is known. In addition, Japanese Patent No. 1418544 (Japanese Patent Publication No. 62-25381) As shown in the dental diagnostic device, AC voltages of two different frequencies are applied, each frequency component of the flowing current is separated, and diagnosis is made by the ratio of the absolute values of the two. To do.

In the known device, in the former case, the measured value is greatly affected by the electrical conductivity of the root canal contents, and is unstable when bleeding or when a drug solution used for treatment is in the root canal. Also, in the latter case, the above-mentioned problems of the former are improved and the influence of the root canal contents is small, but the electric circuit of the device requires two oscillators and two filters, and further two rectification circuits and division circuits, and the circuit However, the structure is very complicated and the device is expensive.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above drawbacks all at once, and enables the measurement of the root canal length without being affected by the contents of the root canal by an electric circuit having a simple structure. The present invention intends to obtain a dental diagnostic device.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points of view, and an oscillator for oscillating an oscillation frequency of several KHz, a bypass for short-circuiting the output of the oscillator, and the oscillator. A parallel circuit in which a constant current conversion side path for converting the output of the device into a constant current is connected in parallel, a root canal inner electrode that loads the constant current conversion side path, and a root canal connected to the inner root canal electrode Reamer for root canal treatment for detecting the position of the root apex of the patient, an oral mucosa electrode for supplying an electric current between the intra-canal electrode, a phase comparator connected to the output side of the parallel circuit, and the phase comparison It is intended to provide a dental diagnostic device comprising an ammeter associated with a vessel.

In this case, the constant current conversion side path is connected in series with a resistor and a capacitor that are sufficiently larger than the resistance value and capacity of the living body.

The electrode for oral mucosa is a dead electrode having a relatively large area in order to reduce the contact resistance, and it is grounded.

[0008]

Next, the operation of the present invention will be described. Number KH
When a current is passed between the electrode inserted into the root canal and the dead electrode in contact with the oral mucosa via a resistor and a capacitor, both resistance and capacitance of which are larger than those of the living body by the oscillator of z, the current becomes almost constant. This current is 10 μA or less, which is safe for the living body. At this time, a voltage having an absolute value and a phase delay corresponding to the impedance is generated between the in-root electrode and the dead electrode. When the electrode in the root canal is inside the root canal and when it goes out of the apex, there is a large difference in the phase, so when the phase of the root canal electrode is applied to the comparator with the phase of the oscillator as the reference, This output changes greatly immediately before the intra-canal electrode passes through the apex to when it goes out of the apex. The position of the apex can be known by reading this change with an ammeter and showing the large change.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given below with reference to the drawings. FIG. 1 is an equivalent circuit configuration diagram showing an embodiment of the present invention. The oscillator 1 oscillates a low-voltage alternating current of about ± 500 mV with an oscillation frequency of several KHz. Bypass 9 with the output of the oscillator 1 shorted
And a parallel circuit 11 including a load side path 10 of a resistor 2 and a capacitor 3 connected in series. The resistor 2 and the capacitor 3 are for converting into a constant current, and they are sufficiently large values (hundreds of KΩ,
Several μF). A root canal treatment reamer that connects an electrode 4 inside the root canal to the output of the side path of the resistor 2 and the capacitor 3 and is connected to the electrode 4 inside the root canal to detect the position of the apex 6 of the root canal. Connect 5. The oral mucosa electrode 7 for supplying a current between the intra-root canal electrode 4 has a relatively large area in order to reduce the contact resistance and is grounded 8.

By inputting the respective outputs of the both paths 9 and 10 of the parallel circuit 11 into the phase comparator 12, the phase difference of the potential generated in the electrode 4 inside the root canal is detected with the output from the oscillator 1 as a reference. And an output proportional to that is obtained. This is read by the ammeter 13 associated with the phase comparator 12.

The output of the phase comparator 12 changes greatly immediately before the root canal treatment reamer 5 passes through the apex 6, so that the position of the apex is when the ammeter 13 changes greatly. become.

[0012]

As is apparent from the above description, according to the present invention, the position of the apex can be confirmed by reading the maximum phase change point.
The root canal length can be reliably measured without being affected by the root canal contents and conditions such as dental pulp, blood, exudate, drug solution, and drying.

[Brief description of drawings]

FIG. 1 is an equivalent circuit configuration diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Oscillator 2 Resistor 3 Capacitor 4 Root Canal Electrode 5 Root Canal Reamer 6 Root Canal Root Apex 7 Oral Mucosal Electrode 8 Grounding 9 Short Circuit Side Path 10 Load Side Path 11 Parallel Circuit 12 Phase Comparator 13 Ammeter

Claims (3)

[Claims] 1. A parallel circuit in which an oscillator for oscillating an oscillation frequency of several KHz, a bypass circuit for short-circuiting the output of the oscillator and a constant current conversion bypass circuit for converting the output of the oscillator into a constant current are connected in parallel, An inner root canal electrode to be loaded on the constant current conversion side path; a root canal treatment reamer connected to the inner root canal electrode to detect the position of the apex of the root canal; and the inner root canal electrode. A dental diagnostic device comprising: an oral mucosa electrode for passing a current therebetween; a phase comparator connected to the output side of the parallel circuit; and an ammeter associated with the phase comparator. 2. The dental diagnostic apparatus according to claim 1, wherein the constant current conversion bypass is formed by serially connecting a resistor and a capacitor that are sufficiently larger than a resistance value and a capacitance of a living body. 3. The dental diagnostic apparatus according to claim 1, wherein the oral mucosa electrode is a dead electrode having a relatively large area in order to reduce contact resistance, and the dead electrode is grounded.