JPH0669462B2 - Dental apex position detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a dentist that detects the position of the end (root apex) of the root canal by the impedance change between the reamer and one electrode in the root canal treatment of the tooth by the reamer. The present invention relates to a root apex position detection device.

[0002]

2. Description of the Related Art There are two means for electrically detecting the position of the root apex of a root canal in a root canal treatment by a dentist using a reamer, without directly measuring the position. The first means is that an electric current is passed between the reamer to be inserted into the root canal and the one electrode in contact with the oral mucosa of the patient, and the resistance decreases as the reamer approaches the apex. It is a means for detecting changes in current with a meter.

The second means is to pass alternating currents of two different frequencies between the reamer to be inserted into the root canal and the one electrode in contact with the oral mucosa so that the reamer approaches the apex. Accordingly, the impedance of each of the two types of frequency signals changes differently, and the difference between the impedance changes is detected to detect the position of the apex.

[0004]

The conventional means, in the above-mentioned first means, operates properly when the inside of the root canal into which the reamer is inserted is dry, so that the position of the apex can be detected. Although it is performed correctly, if the inside of the root canal is moistened by the remaining nerves and pus, a detection error will occur, so it is necessary to dry the inside of the root canal before treatment. , This operation has a problem.

Further, the second means detects the root apex position by the difference in impedance change between two different frequency signals. Therefore, even if the inside of the root canal is wet, There is an advantage that the position of the apex can be accurately detected even if nerves remain or pus is present.

[0006] However, since the inside of the root canal has a predetermined function due to the presence of water, the inside of the root canal does not function properly. Therefore, when the inside of the root canal is dry, It is necessary to inject liquid into the root canal to make it moist, which is a troublesome operation.

In addition, when the tooth to be treated is located on the side of the upper jaw, even if a solution for moistening the tooth is injected into the root canal, it flows out and keeps the water in the root canal. There is a difficult problem. Furthermore, if the tooth to be treated is a carious tooth, the water impregnated in the caries will cause an electric current to flow in a bypass shape, preventing it from functioning properly, so it may not be possible to use it even if the root canal is damp. is there. And in this case, dry the root canal,
The apex position must be detected by the above-mentioned first means.

Therefore, in order to adapt to the position of the tooth to be treated and the hospital, the dentist can detect the position of the dental apex by the above-mentioned first means which is applicable when the inside of the root canal of the tooth is dry. A device must be provided and used properly according to the condition and position of the tooth to be treated. From this, it can be said that one dental root apex position detection device is suitable for both cases where the inside of the root canal is dry or must be dried, and where the inside of the root canal is wet. It is desired to develop a means to make it possible.

The present invention has been made in order to meet this demand, and switches between a state where the root canal of a tooth to be treated is dry (dry mode) and a state where it is wet (wet mode). It is an object of the present invention to provide a dental apex position detection device that can be used as a dental device.

[0010]

SUMMARY OF THE INVENTION The present invention, however, has been completed based on the findings obtained through various studies for achieving the above-mentioned object. That is, as shown in FIG. 1, for example, between the reamer 2 to be inserted into the root canal 10 of the patient's tooth 1 and the single electrode 3 which is kept in contact with the oral mucosa such as the gum of the patient, for example, 6 kHz. Of the oscillator 40 for transmitting the frequency signal of 750 Hz and the oscillator 41 of the oscillator 41 for transmitting the frequency signal of 750 Hz, two kinds of alternating currents having different frequencies are combined and flowed by the mixing circuit 42, and thereby the one electrode 3 is supplied. The minute current that flows is amplified by the amplifier 43, and the bandpass filter 44
A voltage of 46 is returned to a current of a different frequency by 46, the current is converted to a direct current by the rectifiers 45 and 47, and is sent to a differential amplifier 48 that detects the difference in impedance between them, and the voltage output from the differential amplifier 48. The electric current having the difference ΔV of Δ is increased by the DC amplifier 49 and sent to the meter M, and the means for detecting the position of the root apex by the meter M is that there is blood pus in the root canal 10 of the tooth 1. , The root apex position can be detected accurately, but the root canal 1 of the tooth 1 to be treated
If the inside of 0 is dry, it will not function properly.

However, in this means, as shown in FIG. 2, a changeover switch such as a two-contact analog switch SW is provided between the differential amplifier 48 and the DC amplifier 49, and one rectifier is provided. The flow of the current output from 45 and flowing to the DC amplifier 49 via the differential amplifier 48 is blocked, and the current output from the other rectifier 47 directly flows to the DC amplifier 49 without passing through the differential amplifier 48. Then, it becomes the same as the first means for detecting the root apex position by changing the impedance of one kind of current.
The inside of 0 is dry, and it is converted into one that adapts to the dry state.

Further, the current flowing from the reamer 2 inserted into the root canal 10 to the one electrode 3 through the patient's body is in a dry state in the root canal 10 as shown in FIG. There is a reamer 2 inside the root canal 10 depending on whether the root canal 10 is wet (wet mode).
Since the flow rate is remarkably different from the beginning when the plug is inserted, as shown in FIG. 2 described above, the output value of the DC amplifier 49 is measured and the desired value is set. When a measurement current higher than the set value is detected, a determination circuit K that outputs the detection signal is connected, and the detection signal output from the determination circuit K causes the changeover switch SW to operate. If the barrel two-contact analog switch is controlled so as to perform a switching operation, when the reamer 2 is inserted into the root canal 10 and the inside of the root canal 10 is dry, currents of two kinds of frequencies are supplied. When one of the two is cut off to operate in the dry mode, and when the inside of the root canal 10 is wet, the changeover switch SW automatically performs the changeover operation to adapt to the wet mode. You Returns to the state, it has been found that would like to work in the state. With this configuration, it is possible to obtain the result that one dental root apex detection device can be used by switching between the dry mode and the wet mode.

Therefore, in the present invention, as means for achieving the above-mentioned object, two oscillators for generating two kinds of currents of different frequencies to flow between the reamer and the one electrode in contact with the human body of the patient. , A mixing circuit that mixes the currents sent from these oscillators and sends them to the reamer, a rectifier that returns the current that flows through one electrode via the human body of the patient to the currents of the two types of frequencies, and the change in the impedance of each of these currents In a dental apex position detecting device comprising a differential amplifier for detecting the difference ΔV of Δ, and a DC amplifier for amplifying the output of the differential amplifier and inputting it to a meter,
In the normal state, between the differential amplifier and the DC amplifier, the first contact of the first and second contacts on the input side and the contact on the output side are connected, and the input side of the input side is connected by the input of the signal current. A change-over switch for changing over to connect the second contact and the output-side contact is provided, and the input-side first contact of the change-over switch is connected to one of the rectifiers provided in the pair. A branch connection circuit branched from a connection circuit that connects the output side and the input side of the differential amplifier is connected, and the output side of the differential amplifier is connected to the second contact via the connection circuit. Between the DC amplifier and the meter, there is connected a judgment circuit for measuring the level of the current flowing between them and making a comparison with a set value which is set as desired, and the judgment circuit has a level higher than the set value. When you measure the current of the The output of the determination circuit, is to raise the dental apex position detecting device comprising brought connected to switching circuit of the two contact analog switch through a connection circuit including a latch circuit.

[0014]

Embodiments Next, embodiments will be described in detail with reference to the drawings. The same reference numerals are used for the constituent elements having the same effect as those of the conventional means.

FIG. 4 is a schematic explanatory view of the whole use state of the dental apex position detecting device A for carrying out the present invention. In FIG. 4, a is a body of the dental apex position detecting device A, and 1 is a body. Tooth of a patient to be treated, 2 is a reamer inserted in the root canal 10 of the tooth 1, 3 is a single electrode set on the lip of the patient, 4 is a reamer 2 and a pulse generator in the body a electrically. A holder for connecting, M is a meter for displaying the apex position provided on the body a, N is a display needle, b is a power switch, c is a battery check switch, d is an alarm on / off switch, "e" indicates an alarm volume adjusting screw.

FIG. 5 shows the dental root apex position detecting device A of the above.
In the block diagram of FIG. 1, 40 is an oscillator that emits a frequency signal of 6 kHz, 41 is an oscillator that emits a frequency signal of 750 Hz, and 42 is two types of waveforms emitted from the oscillators 40 and 41. Mixing circuit for synthesizing signals and sending to reamer 2 4
Reference numeral 3 designates an amplifier for increasing the minute current attenuated by flowing from the reamer 2 through the root canal 10 of the tooth 1 to the one electrode 3.
Is a bandpass filter for taking out only the current having a frequency of 6 kHz from the current amplified by the amplifier 43, 45 is a rectifier for converting the current passed through the filter 44 into direct current, and 46 is the current passing through the amplifier 43. My 7
A bandpass filter for extracting only a current having a frequency of 50 Hertz, 47 is a rectifier for converting the current passed through the filter 46 into a direct current, and 48 is a comparison between the voltages V1 and V2 of the two currents respectively output from the two rectifiers 45 and 47. A differential amplifier for outputting the difference ΔV between these voltages, 49 is a DC amplifier for increasing the current of the difference ΔV, and
M is the above-mentioned difference ΔV output from the DC amplifier 49.
It is a meter that displays the current of.

SW is a changeover switch provided between the above-mentioned differential amplifier 48 and DC amplifier 49, which is a two-contact analog switch and has two input-side first and second contacts S1 and S2. One of the second contacts S2 is connected to the output side of the differential amplifier 48 via the connection circuit 48a, and the output side contact S3 is connected to the input side of the DC amplifier 49.
It is connected via 8b. The other first contact S1 of the two input contacts S1 and S2 is connected to the output side of one of the two rectifiers 45 and 47 described above through a connection circuit 47a. ing.

When the power switch b is turned on and a current is passed through the circuit, the changeover switch SW has a first contact S of the first and second contacts S1 and S2 on the input side.
1 is maintained in a state of being connected to the contact S3 on the output side, and when the signal current is input, the second contact S2 on the input side is switched to a state of connecting to the contact S3 on the output side. is there.

K is the output side of the DC amplifier 49, which measures the current output thereto and compares it with a reference set value. When a current of a higher level than the set value is measured, K is a detection signal. In the determination circuit connected to output, the reference set value is, as shown in FIG.
The set value (b) is set to a level much higher than the level (a) of the current flowing from the reamer 2 through the patient's body to the one electrode 3 when the inside is dry.

The determination circuit K has a latch circuit connected to the output side for outputting the detection signal of the connection circuit k. When the judgment circuit K detects a judgment current of a level higher than a set value, the changeover switch SW is connected to a contact which receives a current. Two
The contact S2 is switched to the state in which it is connected to the contact S3 on the output side, and thereafter, the wet mode is used in which the apex position is detected by the difference in the impedances of the currents of two types of frequencies.

That is, when the reamer 2 is inserted into the root canal 10 of the tooth 1, the impedance difference between the two kinds of currents having different frequencies flowing from the reamer 2 to the one electrode 3 is set in the body a. The amount of movement of the needle N is displayed on the meter M.

By the way, a meter M for detecting this difference
At the time when the reamer 2 is inserted into the root canal 10 of the tooth 1, the current flowing from the reamer 2 to the one-sided electrode 3 is generated in the root canal 10 in the root canal 10 such as water, nerves, and blood pus existing in the root canal 10. By reading the conditions, the needle N is moved according to the conditions in the root canal 10. Therefore, when treating the inside of the root canal 10, at the time when the reamer 2 is inserted into the root canal 10 of the tooth 1, the needle N swung out according to the condition inside the root canal 10 is moved to the reference position. Although it is necessary to adjust them, there is no variable resistor operated by the operation of the dial D incorporated in the conventional means for this purpose, and this is omitted.

Then, in the operation of aligning the needle N of the meter M, which is shaken out by reading the condition in the root canal 10, with the reference position, the above-mentioned judgment circuit K detects a current of a level higher than the set value. Thus, the operation for outputting the detection signal is automatically performed.

Next, the structure will be described. In FIG. 5, reference numeral 50 is a one-shot (one-shot multivibrator) which operates so as to generate a pulse when it is turned on. Normally, a pulse is generated when a trigger is applied. The pulse output time is set to 1 second. The branch circuit 5 branched from the connection circuit k that outputs the detection signal of the determination circuit K is used as the trigger.
0a is connected, whereby the one-shot 50 is triggered at the same time when the determination circuit K outputs a detection signal for switching the changeover switch SW including a two-contact analog switch.

Reference numeral 51 is an analog switch which is turned on only during the time when a pulse is emitted from the one-shot 50.

Reference numeral 52 denotes a two-contact analog switch which is controlled to operate only while the analog switch 51 is on, and two contacts of which are operated to count up the binary up / down counter 53. It is connected to the contact to activate and the contact to activate to count down respectively. The analog switch 52 is an IC that performs an switching operation by selecting an analog value sent from the comparator 54. When the analog value sent from the comparator 54 is positive, the down side contact DOWN. When the analog value sent from the comparator 54 is negative, it operates so as to select the contact UP on the up side.

The comparator 54 has an input side connected between the DC amplifier 49 and the meter M so as to monitor the output of the DC amplifier 49. The reference of the comparator 54 is set to 0 volt, and when the output of the DC amplifier 49 is positive, the analog switch 52
Outputs a signal for selecting down (binary signal of H or L) to the analog switch 52.

Binary up / down counter 53
Operates by switching the input frequency between a countdown state and a countup state, and the switching of the operation is automatically controlled by the two-contact analog switch 52 described above. Then, the output side is connected to a D / A converter 55 for exchanging alternating current to direct current, whereby the analog value is exchanged. The output side of the D / A converter 55 is connected to the differential amplifier 48 so as to move the offset of the differential amplifier 48.

[0029]

The device of the embodiment thus constructed operates as follows. When the power supply switch b provided in the body a is turned on, the changeover switch SW, which is a two-contact analog switch provided in the circuit inside the body a, switches the two contacts S1 and S2 on the input side thereof. The first contact S1 and the output-side contact S3 are connected to each other, and only the current output from one rectifier 47 of the rectifiers 45 and 47 provided in the pair is the differential amplifier 48. DC without passing through
It will be input to the amplifier 49.

Therefore, in the dental apex position detecting device A, two kinds of currents having different frequencies flow between the reamer 2 and the one electrode 3, but one of the currents is cut off. , Only one kind of current flows through the DC amplifier 49 to the meter M, and the root canal 10 of the patient's tooth 1
The inside of the root canal 10 becomes dry when the dentist actually inserts the reamer 2 into the root canal 10 of the patient's tooth 1 when the inside is dry (dry mode). If so, the apex position can be accurately read by the swing of the needle N of the meter M.

Next, the patient's tooth 1 into which the reamer 2 is inserted
When the inside of the root canal 10 is in a wet state (wet mode), a high level current flows from the reamer 2 to the one electrode 3 from the beginning when the reamer 2 is inserted into the root canal 10. The determination circuit K connected to the OUT side of 49 detects this high level current,
The detection signal is sent to the changeover switch SW formed of a two-contact analog switch, and the changeover switch SW is changed to a state in which the second contact S2 on the input side thereof is connected to the contact S3 on the output side.

In this state, two kinds of currents having different frequencies output from the two rectifiers 45 and 47 enter the differential amplifier 48, the voltages of the currents are compared, and the difference ΔV between the voltages is output. Then, since it is in a state of flowing to the meter M through the DC amplifier 49, the position of the apex is detected by detecting the difference in impedance change between the two types of currents having different frequencies. It is a condition that adapts when wet.

Therefore, when the dentist inserts the reamer 2 into the root canal 10 of the tooth 1 to be treated, the root canal 1
If the inside of 0 is dry, the detection operation corresponding to it is performed. If the inside of the root canal 10 is wet, the detection operation corresponding to that state is automatically switched. Become.

The determination circuit K sends a detection signal to the changeover switch SW when the inside of the root canal 10 is wet, and the operation for switching to a state adapted to the detection operation of the root apex when the inside of the root canal 10 is wet. At the same time, the detection signal output from the determination circuit K flows to the trigger of the one-shot 50, and the one-shot 50 operates.

As a result, the analog switch 51 is closed for the time when a pulse is generated by the operation of the one-shot 50, and the current of 6 kHz frequency output from the oscillator 40 passes through the two-contact analog switch 52. It flows as the clock input of the binary up / down counter 53. At this time, if the output of the DC amplifier 49 is positive, the two-contact analog switch 52 operates to select the contact DOWN on the down side, and the binary up / down counter 53 counts down the input frequency to D /. It is sent to the A converter 55 and the offset of the differential amplifier 48 is moved. As a result, when the output of the differential amplifier 48 and the DC amplifier 49 reaches zero or exceeds zero and becomes negative, plus / minus vertical movement after this point is only one pit of the resolution of the D / A converter 55. (For a 12-bit D / A converter, the resolution is 1/4096 of the reference voltage applied to the D / A converter). At the same time, the comparator 54 inputs a signal for the two-contact analog switch 52 to select up to the two-contact analog switch 52, and the switch 52 performs an operation to select the up-side contact UP, and the binary up / down counter. The operation of counting up the input frequency of 53 is performed, and the offset of the differential amplifier 48 plus the DC amplifier 49 is moved toward the plus side. Then, this operation is repeated, and D
The output of the C amplifier 49 is brought close to zero.

Binary up / down counter 53
However, even if it is assumed that the worst count is from MSB to LSB, it is 4096 steps for 12 bits.
5 kHz binary up / down counter 53
If the clock of 4096/5000 seconds is given, the zero point is always reached. Therefore, one shot for 1 second is enough.

When the time of the pulse output from the one-shot 50 elapses, the analog switch 51 opens, whereby the binary up / down counter 5
3 stops operation. At this time, since the clock of the oscillator 40, which also serves as the clock of the binary up / down counter 53, is stopped by the opening of the analog switch 51, the binary up / down counter 53 holds the final value, and therefore, It keeps the stored state close to zero.

Therefore, when the reamer 2 is inserted into the root canal 10 of the tooth 1 and the inside of the root canal 10 is wet, when the operation for automatically switching to the wet mode is performed,
At the same time, the operation of calibrating the deflection of the needle N of the meter M almost instantaneously and adjusting it to the reference position is automatically performed.

[0039]

As described above, the dental apex position detecting apparatus according to the present invention has two oscillators 40 and 41 which generate currents of two different frequencies, and a difference in impedance change of the currents. A differential amplifier 48 and a meter M for detecting the signal are provided. However, when the power switch b is turned on, only one of the two currents flows to the meter M side across the differential amplifier 48, and the signal current The reamer 2 is provided with a changeover switch SW for changing over so that the two currents flow into the differential amplifier 48 by the input.
When the inside of the root canal 10 of the tooth 1 in which the
When the root apex position is detected by using only one of the three kinds of currents and the inside of the root canal 10 of the tooth 1 is wet, the root apex position is caused by the difference in impedance change between the two currents. Since it automatically switches to the state in which the detection operation is performed, the state in which the root canal 10 of the patient's tooth 1 is dry and the state in which the inside of the root canal 10 of the patient's tooth 1 is wet can be detected by one dental root apex position detector. And, both will be used automatically.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional dental apex position detecting device that performs an operation of detecting an apex position by two currents having different frequencies.

FIG. 2 is an explanatory view of a dental apex position detecting device according to the present invention.

FIG. 3 is a chart showing changes in measured current flowing through a reamer and one electrode when a reamer is sequentially inserted into the root canal when the tooth root canal is dry and wet. .

FIG. 4 is a perspective view of an apparatus according to an embodiment of the present invention.

FIG. 5 is a block diagram of a circuit of the same device.

FIG. 6 is an explanatory view of the operation of the above apparatus.

[Explanation of symbols]

A ... Dental apex position detector, SW ... Changeover switch, D
... dial, M ... meter, N ... needle, K ... judgment circuit, k
... Connection circuit, S1, S2, S3 ... Contact, a ... Body, b ...
Power switch, c ... Battery check switch, d ...
On / off switch, e ... Volume adjustment screw, 1 ... Tooth, 10
… Root canal, 2… Reamer, 3… One electrode, 4… Holder, 4
0 · 41 ... Oscillator, 42 ... Mixing circuit, 43 ... Amplifier, 44 ... Bandpass filter, 45 ... Rectifier, 46
... band pass filter, 47 ... rectifier, 47a ... connection circuit, 47b ... branch circuit, 48 ... differential amplifier, 48a.
48b ... Connection circuit, 49 ... DC amplifier, 50 ... One shot, 50a ... Branch circuit, 51 ... Analog switch, 5
2 ... Two-contact analog switch, 53 ... Binary up / down counter, 54 ... Comparator, 55 ... D /
A converter.

Claims (2)

[Claims] 1. Oscillators 40, 41 for generating two kinds of currents of different frequencies to flow between a reamer 2 and a single electrode 3 in contact with a human body of a patient, and the oscillators 40, 41.
A mixing circuit 42 which mixes the currents sent from the reamer 2 and sends the mixed currents to the reamer 2, and a rectifier 45.
7. A dental apex position having a differential amplifier 48 for detecting the difference .DELTA.V in the change in impedance of each of these currents, and a DC amplifier 49 for amplifying the output of the differential amplifier 48 and inputting it to the meter M. In the detection device, the differential amplifier 48
Between the DC amplifier 49 and the DC amplifier 49, the first contact S1 of the first and second contacts S1 and S2 on the input side and the contact S3 on the output side are normally connected to each other by inputting a signal current. A change-over switch SW for changing over to connect the second contact S2 on the input side and the contact S3 on the output side is provided.
A connection circuit 47a for connecting the output side of one of the rectifiers 45 and 47 provided in the pair and the input side of the differential amplifier 48 to the first contact S1 on the input side of the changeover switch SW. Is connected to the branch connection circuit 47b, and the output side of the differential amplifier 48 is connected to the second contact S2 via the connection circuit 48a.
A determination circuit K for measuring the level of the current flowing between them and making a comparison with a preset value set as desired is connected between 9 and the meter M, and the decision circuit K is based on the preset value. The output side of the determination circuit K, which outputs the signal current when a high level current is measured, is connected to the two-contact analog switch SW via a connection circuit k including a latch circuit.
Dental apex position detection device connected to the switching circuit. 2. An output side of the comparator 54 is connected to the output of the DC amplifier 49, and an output side of the comparator 54 is connected to the two-contact analog switch 52. A binary up / down counter 53, which switches between a state in which the input frequency is counted down and a state in which the frequency is counted up by the switching operation, is connected. The output of the binary up / down counter 53 is output to the differential amplifier 48 at the output thereof. Connect the input side of the D / A converter 55 that connects to move the offset of the dynamic amplifier,
A one-shot multivibrator 50 that causes a frequency signal transmitted from one of the oscillators 40 and 41 to be input to the input side of the two-contact analog switch 52 to flow into the binary up / down counter 53 via the two-contact analog switch 52. 2. The one-shot multivibrator 50 is connected so that it is controlled so as to be turned on by a signal current output when the determination circuit K measures a current having a value higher than a set value. The dental root apex position detection device described.