JPH06181938A - Root canal length measuring method and its device - Google Patents

Abstract

PURPOSE:To handily and accurately measure the root canal length regardless of the difference in conditions of the root canal by determining the gradient between two measurement frequencies at a root apex constriction section, comparing the gradients changed for the insertion of a measuring reamer into the root canal and pulpectomy, and measuring the distance between the measuring reamer and the root apex constriction section. CONSTITUTION:A measuring reamer 3 is inserted into a root canal 2 for pulpectomy, and pulse voltage is applied across the measuring reamer 3 at a root apex constriction section 4 and a connecting terminal 7 by an oscillation frequency selector switch 6. A synchronizing switch 11 is switched synchronously with it, pulse voltage is applied across a measured tooth 1 and gingiva at measurement frequencies of 500Hz and 2kHz, and the impedance to the root canal 2 is measured for the root canal length measurement. The data are calculated by an arithmetic circuit 26, the output voltage at 2kHz is inputted to the reference side of a logarithmic amplifier 9, and the other output voltage at 500Hz is connected to the input side of the logarithmic amplifier 9. The corrected logarithm is outputted, amplified by the second amplifier 14, and displayed on a display meter 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a root canal length measuring method and a device therefor for use in dental root canal treatment.

[0002]

2. Description of the Related Art Conventionally, in the case of tooth treatment such as caries, when the symptoms are severe, the pulp is removed and prostheses such as crowns and continuous teeth. In this root canal treatment, the pulp is accurately extracted to the apical constriction part. According to the current treatment method, it is desirable to accurately extract the bone up to 0.5 mm before the root. However, the shape of the tooth and its root canal varies greatly from person to person, and the root canal length is also disjointed, so that a high skill of the operator is required for accurate root canal treatment.

Therefore, at present, an ideal root canal treatment has come to be performed in which accurate measurement of the root canal length is performed simultaneously with the root canal treatment by making full use of the measurement technique. As a method thereof, for example, the tooth and periodontal tissue are regarded as C (capacitor) and R (resistor), regarded as a CR equivalent circuit, and the root canal length is measured using a CR low frequency oscillator. Also proposed are a method of measuring a root canal length by detecting a change in impedance between a measurement electrode and an oral electrode, a method of measuring a root canal length by measuring an impedance of a root canal, and the like. However, depending on the measuring method, it is difficult to measure the root canal length accurately because the wet condition is maintained in the root canal with saliva and other conductive liquids. In some cases, it was impossible to measure. In addition, depending on the method of processing the measurement data, the display changes greatly when it reaches the vicinity of the apical narrowing part, making it difficult to read (in other words, the display is small when it is far from the apex narrowing part, It is difficult to use because the display moves greatly near the squeezed part).

[0004]

The problems to be solved by the present invention are as follows.
Regardless of these differences in conditions within the root canal, the display is uniform even in the vicinity of the apical narrowed portion, and it is possible to easily and accurately measure the root canal length.

[0005]

Means for Solving the Problems The root canal length measuring method of the present invention was made in order to solve the above-mentioned problems, and it is referred to as “measurement reamer (3) on a root canal (2) of a tooth (1)”. In order to measure the root canal length by inserting and removing the root canal and measuring the root canal impedance, two measurement frequencies (M) are set apart from each other.
(N) is selected, and the measured frequency (M) (N) at the apical narrowing part (4)
The logarithm processed value (m) (n) of the output value corresponding to is determined to determine the slope between the measured frequencies (M) (N) at the apical narrowing part (4), and the root of the tooth (1). Characterized by measuring the distance from the apex squeezing part (4) of the measuring reamer (3) by comparing the inclination that changes with the insertion / extraction of the measuring reamer (3) into the tube (2) . This makes it possible to eliminate the error caused by the difference in the conditions inside the root canal (2) when measuring the root canal length by subtracting the logarithmically processed values (m) (n) from each other, making it easy and accurate You can take measurements. Further, since the logarithmically processed output value is used for display as described above, there is an advantage that the display in the vicinity of the apex narrowing part (4) does not change significantly and the usability is good.

Further, the root canal length measuring apparatus according to claim 2 is characterized in that "a reference oscillating unit (5) for outputting a pulse voltage at a plurality of measurement frequencies (M) (N) and an output of the reference oscillating unit (5). Oscillating frequency selector switch (6) for switching, and measuring reamer (3) that acts as a probe while being inserted into the root canal (2) for demyelination
A connection terminal (7) which is paired with the measurement reamer (3) and is held in contact with a part of the patient's body, a rectifier circuit (8) connected to the reamer (3) side, and a logarithmic amplifier. Control circuit including (9) (1
0), is connected between the rectifier circuit (8) and the control circuit (10),
It is composed of a synchronous switch (11) for switching in synchronization with the oscillation frequency changeover switch (6) and a display meter (12) for displaying the output of the control circuit (10). As a result, the method can be performed, and since the logarithmic amplifier (9) is used, the display in the vicinity of the apex narrowing part (4) does not change greatly as described above. There is an advantage that it is easy to use.

[0007]

The present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 is a block circuit diagram of a root canal length measuring apparatus (A) according to the present invention. (5) is a reference oscillator, (13) and (14) are first and second amplifiers, (8) is a rectifier circuit, and 10) is a logarithmic amplifier (9) and an arithmetic circuit (2
Control circuit including 6) and (16) alarm oscillator, (17) power supply, (12) indicator meter, (18) piezoelectric buzzer, (6) oscillation frequency selector switch, (11) synchronous switch,
(3) is a measurement reamer, and (7) is a connection terminal for locking to the lip.

The measuring reamer (3) has a sharp tip and is formed in a drilled shape, removes pulp in the root canal (2), and is connected to the measuring device (A) at the other end. The cord (24) is attached. The cord (24) is detachably connectable to the measuring reamer (3). Code (24)
The other end of is connected to the first amplifier (13) via the CR circuit (25), and the first amplifier (13) is connected to the rectifier circuit (8). The rectifier circuit (8) is further connected to the synchronous switch (11) and further connected to the control circuit (10) to perform a predetermined calculation.

The frequency changeover switches (6) are alternately turned on in synchronism in pairs of two. In the reference oscillating unit (5), 500 Hz and 2 kHz are oscillated in this embodiment, and one of the frequencies (M) (N) can be alternately output by the frequency changeover switch (6). It has become. Although the switching speed is 30 Hz in this embodiment, it is not limited to this. The measurement frequency is also an example, and is not limited to this.

The connection terminal (7) is connected to the other cord (24) derived from the measuring device (A), and the cord (2)
The other end of 4) is connected to the connection point of resistors (21) and (22) connected in series, one resistor (21) is grounded, and the other resistor (22) is the frequency selector switch (6). ) To the variable resistor (2
3) is connected via.

The output of the control circuit (10) is connected to the second amplifier (14) where it is branched and connected to the display meter (12) and the alarm oscillating unit (16). (1
6) is finally connected to the piezoelectric buzzer (18) and the reamer
When (3) reaches the vicinity of the apical narrowing part (4), an alarm sound is generated.

Next, the relationship between the apical narrowing part (4) and the root canal length measurement will be described. First, it is necessary to determine the meter display corresponding to the apical narrowing part (4). Therefore, first of all, after turning on the switch of the root canal length measuring device (A), lock the connection terminal (7) on the lip and insert the measurement reamer (3) into the root canal (2) while sharpening it. And then extract. A pulse voltage is alternately applied between the measurement reamer (3) and the connection terminal (7) by switching the oscillation frequency changeover switch (6) at a cycle of 30 Hz. And a sync switch (11)
Switches in synchronism with the oscillation frequency selector switch (6), and as described above, the measurement frequency of 500 Hz and 2 KH
The pulse voltage is measured at the measurement frequency of z and the measured tooth (1) and gingiva (1
The root canal length is measured by applying impedance to a) and measuring the impedance of the root canal (2).

The case of measuring the root canal impedance while extracting the pulp will be described in more detail.
A pulse voltage of z and 2 KHz is alternately applied to the tooth to be measured (1) and the gingiva (1a) at the switching frequency, and the connection terminal (7)
Through the first amplifier (13) to the rectification circuit (8). The synchronous switch (11) provided on the output side of the rectifier circuit (8) switches in synchronization with the frequency changeover switch (6) on the reference oscillator (5) side,
As a result, the output of the rectifier circuit (8) is synchronously rectified and input to the control circuit (10) as a measured voltage. Control circuit (1
The calculation circuit (26) of (0) calculates and is connected to the logarithmic amplifier (9). In the logarithmic amplifier (9), one output voltage (2 kHz in this embodiment) is input to the reference side of the logarithmic amplifier (9), and the other output voltage (500 Hz in this embodiment) is input to the logarithmic amplifier.
Connected to the input side of (9). The output outputs the logarithm corrected on the reference side, amplifies it by the second amplifier and displays the converted output on the display meter.

When the pulp extraction does not reach the apical narrowing part (4), the "output difference (unit = decibel)" is small and the apical narrowing part is small.
(4) Further, the "output difference" becomes larger as it passes through the apical narrowing part (4). Therefore, first use the test piece to check the "output difference" when it reaches the apical squeezing part (4), and when this "output difference" is displayed, display the display meter (12). Piezoelectric buzzer (18) at the same time as the apex position
Adjust the variable resistor (27) of the alarm oscillator (16) so that the alarm sounds.

2 to 5 are logarithmic graphs showing the relationship between the measured frequency and the corresponding output value (decibel). In the figure, the vertical axis represents the decibel (the output value of the control circuit), and the horizontal axis represents the frequency on a logarithmic scale. Fig. 2 shows a point about 3 to 4 mm in front of the apical narrowing part (4), Fig. 3 shows a point of 1 to 2 mm, and Fig. 4 shows that the pulp was extracted to the position of the apical narrowing part (4). FIG. 5 is a graph showing the state in which the measuring reamer (3) has penetrated the apical narrowing part (4).
The measurement principle is to determine the measurement frequency (M) (N) at two points, calculate the slope of the output (output difference) for each measurement frequency (M) (N), and then correspond to the apex position (output difference = 2 points). The inclination of the straight line that connects the two) is determined to determine the apex position. In the figure, measurement frequency (M) Hz
The positions of the measurement frequency (N) Hz are indicated by "▲" and "▼", respectively, and the difference is indicated by delta "DELTA". For example, FIG. 4 shows a case where the apex position is shown. Reference (REF) = (M) Hz →→→→ -11.
0 dB delta (→) → → → → → 6.
It is 9 dB (difference in output), and the difference in the root canal impedance between them is "6.9 dB".
Then, this is the (output difference) at the apex position.

On the other hand, in FIGS. 2 and 3 where the apex position has not been reached, the (output difference) is "2.4 dB" and "3.2 dB",
It is smaller than "6.9 dB" (output difference) corresponding to the apex position. On the contrary, FIG. 5 shows that the (output difference) is as large as "7.4 dB" and the reamer (3) penetrates the apical narrowing part (4). Of course, the “output difference” “6.9 dB” corresponding to the apex position is merely an example, and its value naturally changes by changing the measurement frequency. In the actual measurement of the root canal length, 0.5 mm before the apex squeezing part (4) is extracted, so the procedure should be completed at a point smaller than the output difference at the apex position. Become.

Next, a method of selecting the measurement frequency will be described. As can be seen from FIG. 4, the measurement frequency ranges from 0 to 10
Shows a gentle rising curve up to 10Hz
A rapid rising curve is shown up to around 500 Hz, and thereafter, a gentle curve is drawn. Also,
When it exceeds 10,000 Hz, the output value becomes unstable. The present invention is
"Output difference", that is, because the apex position is measured by comparing the slope with respect to the measurement frequency (M) (N), the stability of the output value with respect to the measurement frequency (M) (N) (curve Since the unevenness is small, if there is unevenness in the curve, it will cause a measurement error.)
The requirement is that the slope be as large as possible (that is, if the measurement frequencies are close to each other, the slope becomes small and the sensitivity deteriorates, and the circuit configuration becomes difficult accordingly). Therefore, the measurement frequency that meets the above requirements
As a result of studying (M) and (N), in this embodiment, (M) is 500H.
z and (N) were set to 2 KHz. In practice (M) is 500 Hz ±
10%, (N) will be used by selecting an appropriate value within the range of 2 KHz ± 10%.

It should be noted that if the measurement frequency (N) is set to 2 KHz or more, the sensitivity is slightly improved, but the performance of the amplifier must be correspondingly high, otherwise the waveform is not faithfully amplified and distorted. It will cause an error. Therefore, the practical range is 2 as described above.
An appropriate value will be selected and used within the range of KHz ± 10%.

Similarly, the measurement frequency (M) is 500 Hz.
In the following case, the capacitance of the capacitors in each circuit must be increased, and the time constant of the meter display becomes large, making it difficult to see. Therefore, an appropriate measurement frequency within the above range is selected.

[0020]

According to the root canal length measuring method of the present invention, two measurement frequencies separated from each other are selected, and logarithmic processed values of output values corresponding to the measurement frequencies at the apical narrowing portion are subtracted from each other. The reference slope between the measurement frequencies at the apical narrowing part is determined, and the slope that changes with the insertion / extraction of the measuring reamer into the tooth root canal is compared to determine the distance between the measuring reamer and the apical narrowing part. Although it is to be measured, it is necessary to eliminate the error caused by the difference in the conditions inside the root canal when measuring the root canal length, for example, when the root canal is filled with electrolyte liquid and when it is dry, by subtraction. This has the advantage that the root canal length can be measured easily and accurately. Further, since the logarithmically processed output values are subtracted from each other and displayed using this, there is an advantage that the display in the vicinity of the apical narrowing part does not change significantly and the usability is good.

The root canal length measuring apparatus according to a second aspect of the present invention includes a reference oscillating unit that outputs a pulse voltage at a plurality of measurement frequencies,
An oscillation frequency selector switch that switches the output of the reference oscillator, a measurement reamer that inserts into the root canal to perform myelination and acts as a probe, and a pair of the measurement reamer, which makes contact with a part of the patient's body Connection terminal to be held,
A rectifier circuit connected to the reamer side, a control circuit including a logarithmic amplifier, a synchronous switch connected between the rectifier circuit and the control circuit and switching in synchronization with the oscillation frequency changeover switch, and an output of the control circuit. It is composed of a display meter for displaying, but since the output voltage is arithmetically processed by the logarithmic amplifier, it is possible to compress and display the output value that changes significantly near the apex, and it is a very easy-to-read display. In addition to the above, there is an advantage that only one logarithmic amplifier is required and the circuit configuration can be simplified.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a root canal length measuring device of the present invention.

FIG. 2 is a logarithmic graph showing a relationship between a measurement frequency and a corresponding output value (decibel) in measuring the root canal length at a point about 3 to 4 mm before the apical narrowing part.

FIG. 3 is a logarithmic graph showing a relationship between a measurement frequency and a corresponding output value (decibel) in measuring the root canal length at a point about 1 to 2 mm before the apical narrowing part.

FIG. 4 is a logarithmic graph showing the relationship between the measurement frequency in root canal length measurement and the output value (decibel) corresponding to it at the apical narrowing point.

FIG. 5 is a logarithmic graph showing the relationship between the measured frequency and the corresponding output value (decibel) when the reamer crosses the apical narrowing point.

[Explanation of symbols]

 (1)… Tooth (2)… Root canal (3)… Measurement reamer (4)… Apex narrowing part (M) (N)… Measurement frequency (m) (n)… Logarithmic processed value

Claims (2)

[Claims] 1. A method for measuring the root canal length by inserting a measuring reamer into the root canal of a tooth to extract the root and measuring the root canal impedance, and selecting two measurement frequencies separated from each other, The logarithmic processed value of the output value corresponding to the measurement frequency at the apical constriction is subtracted to determine the slope between the measurement frequencies at the apical constriction, and the insertion and demyelination of the measurement reamer into the tooth root canal. A method of measuring a root canal length, which comprises measuring a distance between a reamer for measurement and a narrowed portion of an apex of a measuring reamer by comparing changing inclinations. 2. A reference oscillator that outputs a pulse voltage at a plurality of measurement frequencies, an oscillation frequency changeover switch that switches the output of the reference oscillator, and a measurement that acts as a probe while being inserted into the root canal for demyelination. For reamer,
Between the connection terminal that is paired with the measurement reamer and is held in contact with a part of the patient's body, a rectifier circuit connected to the reamer side, a control circuit including a logarithmic amplifier, and the rectifier circuit and the control circuit. A root canal length measuring apparatus comprising: a synchronous switch connected to the switch for switching in synchronization with the oscillation frequency changeover switch; and a display meter for displaying the output of the control circuit.