JPH09248311A - Root canal forming device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To enable automation of root canal forming work and improve safety and operability. SOLUTION: An automatic feeding mechanism 7 for moving a cutting tool (file) 2 in an axial direction is provided in a holder (handpiece) 4, and the holder 4 is fixed to a patient, so that the cutting tool 2
Was automatically inserted into and removed from the root canal 1a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a root canal forming device in the field of dental treatment, and more particularly to a root canal forming device capable of automating a root canal forming procedure.

[0002]

2. Description of the Related Art The treatment of root canal formation in dental practice is
A cutting tool such as a file or reamer is attached to the head of the handpiece, and it is inserted into the root canal while being driven by a motor or ultrasonic transducer. It is performed manually, and the insertion amount is determined by the operator's manual adjustment. In this way, root canal formation is a field where automation is delayed, and the operation requires skill and sufficient caution and requires a long working time, and the operator's fatigue after the root canal formation is extremely severe. It was

To help solve this problem, a root canal length measuring function is added to the root canal forming device to perform root canal formation while measuring the root canal length by using a cutting tool as a measuring needle as well. It is known that cutting is automatically stopped when the tip of the tool reaches a set position such as a root apex. However, even in these devices, the insertion of the cutting tool itself is a manual work, and it is far from the situation where the root canal formation is completely automated.

For example, Japanese Unexamined Patent Publication (Kokai) No. 8-38510 discloses a root canal forming device having such a root canal length measuring function, which comprises a measuring needle and an oral electrode placed in the oral cavity of a patient. A measurement voltage is applied between them, the tip position of the cutting tool is detected from the impedance change characteristics obtained between both electrodes, and the cutting tool is automatically stopped or reversed when the cutting tool reaches the set position. There is. In addition, there is another prior art that detects the point where the impedance change becomes the maximum by differentiating the output signal corresponding to the impedance, but even in this device, the cutting tool is manually inserted. Keeping the speed constant is difficult,
The output signal is not only the change in impedance but also the change in insertion speed superposed on it. Therefore, accurate measurement cannot be performed, and it is necessary to solve this problem for practical use.

[0005]

SUMMARY OF THE INVENTION The present invention has been made paying attention to these points, and an object thereof is to enable automation of work by a root canal forming device and to improve safety and operability.

[0006]

In order to achieve the above object, the root canal forming device of the present invention uses a cutting drive unit for a cutting tool that is attached to the tip of a holder and inserted into the root canal. In a root canal forming device that drives to form a root canal,
The automatic feed mechanism that automatically moves the reference position of the cutting tool with respect to the holder in the axial direction of the cutting tool is provided.

This device can be provided with means for sequentially detecting the load in order to control the automatic feed mechanism and the cutting drive unit according to the magnitude of the load applied to the cutting tool during operation. When the load when moving in the apex direction reaches a preset reference value, control is performed to stop movement by the automatic feed mechanism or reverse the movement direction, or to stop the cutting tool. Various controls are performed. In addition, it is possible to control the movement of the cutting tool in the apex direction and the movement in the crown direction automatically and repeatedly. In this case, the movement amount in the apex direction and the movement amount in the crown direction can be calculated. Each can be set independently. The moving direction of the cutting tool is appropriately displayed on the display as information for the operator or the like.

A pulse motor, for example, can be used as the cutting tool feed motor in this root canal forming device.

In the above apparatus, the cutting tool also serves as a measuring needle for measuring the root canal length, and the automatic feeding mechanism can be controlled according to the measurement data of the root canal length. That is, as is well known, since the tip position of the measuring needle and the measurement data obtained by the measurement have a substantially constant correspondence, for example, a value corresponding to a desired position such as a root apex is preset and automatically fed. When the measurement data of the root canal length when the cutting tool is moved in the direction of the root apex by the mechanism reaches the set value, the movement is stopped or the movement direction is reversed.

Further, the tip position of the measuring needle can be detected from the change in the measurement data of the root canal length accompanying the movement. Therefore, the root canal length measurement operation is automatically performed every time the cutting tool moves a preset distance in the direction of the root apex, and the tip position of the measuring needle is detected from the result to stop the feed as described above. And control such as inversion can be performed. Since the cutting tool can be moved at an arbitrary constant speed in the present invention, instead of measuring every time the set distance is moved, the cutting tool may be measured every predetermined time.

For the measurement accompanying this movement, the comparison data obtained by comparing the measurement data of the previous time and the measurement data of this time can be used. Furthermore, the measurement data of this time can also be used in addition to this comparison data. In the latter case, it is possible to improve the detection accuracy as much data is used.

Further, according to the present invention, the cutting drive unit can be controlled according to the measurement data of the root canal length. That is, similarly to the case of controlling the automatic feed mechanism with the above-mentioned measurement data of the root canal length, a value corresponding to a desired position such as a root apex is preset and the cutting tool is moved in the root apex direction. When the measured data of the root canal length at that time reaches the set value, the cutting is stopped by stopping the cutting tool, reducing the driving force, reversing the rotation direction, or the like.

Further, the measurement data of the root canal length can be used not only for the automatic control as described above but also appropriately displayed as information for the operator or the like.

Further, as the measurement data of the root canal length, one kind of measurement voltage is applied between the cutting tool which also functions as a measuring needle inserted into the root canal and the oral electrode placed in the oral cavity of the patient. The value obtained from the impedance response value in this case or the value obtained from the difference or ratio of the impedance response values when two types of measurement voltages are applied is used. Either or both of the automatic feeding mechanism and the cutting drive unit are controlled in accordance with any one of them or a combination thereof.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to illustrated examples. 1 is a block diagram showing the overall circuit configuration, FIG. 2 is a diagram showing an example of a motor controller circuit, FIG. 3 is a diagram showing an example of a root canal length measuring circuit, and FIG. 4 is a structure of a head having an automatic feeding mechanism. FIG. 5 is a flowchart showing an example of the control procedure.

In FIG. 1, 1 is a tooth, 1a, 1b and 1c are root canals, root apexes and crowns of the tooth 1, 2 is a file which serves as a cutting tool and a root canal length measuring needle, and 3 is a file. An oral electrode for measuring the root canal length, 4 is a handpiece, and 5 is a head at the tip of the handpiece. The handpiece 4 is provided with a cutting drive unit 6 including a cutting motor 6a and the like, as well as an automatic feeding mechanism 7 including a feeding motor 7a and the like. 8
Is a control device main body, 9 is a foot pedal, and the control device main body 8 is the same as that conventionally known, for example, a control unit 11 using a microcomputer, a motor controller 12, a root canal length measuring circuit 13, which will be described later. A setting unit 14, a display unit 15 for performing setting operations for various controls such as
The memory 16 and the like are provided.

The cutting motor 6a and the feed motor 7a are connected to the motor controller 12, one output terminal of the root canal length measuring circuit 13 is connected to the file 2 via the contact 13a, and the other output terminal is connected. It is used by connecting to the oral cavity voltage 3. Further, the foot switch 9 is connected to the control unit 11, and the cutting motor 6a and the feed motor 7a are driven by the operation of the foot pedal 9 as described later.
In addition, various operations such as measuring the root canal length are performed by the setting unit 14.
It is performed according to the setting contents in.

A DC motor is used as the cutting motor 6a of the cutting drive unit 6, a pulse motor is used as the feed motor 7a of the automatic feed mechanism 7, and a motor controller 12 is provided for the control unit 11. A DC output circuit that outputs a predetermined drive voltage to the cutting motor 6a based on a command and a pulse output circuit that outputs a predetermined drive voltage to the feed motor 7a are provided. Although the mechanism becomes complicated, it is possible to use one motor for both the cutting motor and the feed motor in some cases.

The motor controller 12 is a cutting motor 6
It has a function of detecting the load torque of a, and a circuit as exemplified in FIG. 2 is adopted as the DC output circuit for the cutting motor 6a. That is, the power transistor T1 is connected in series to the cutting motor 6a, and the motor current is adjusted by controlling the energized state of the power transistor T1 by the driver circuit D1, and the load torque during cutting flows through the resistor R1. It is detected from the magnitude of the motor current.

The root canal length can be measured by applying a measurement voltage between a measuring needle inserted into the root canal of a tooth and an oral electrode placed in the oral cavity, and measuring the impedance response value to obtain the root canal. It is known to calculate the length. For example, Japanese Examined Patent Publication (Kokoku) No. 62-25381 discloses a simple correspondence method for calculating the tip position of a measuring needle from an impedance response value with respect to a resistance value obtained by using one kind of measurement voltage.

Further, for example, in Japanese Examined Patent Publication No. 62-2817 or Japanese Patent Laid-Open No. 64-64354, at least two types of measurement voltages having different frequencies are used, and impedance response values obtained for each measurement voltage are compared. However, a comparison method is disclosed in which the tip position of the measuring needle is calculated from the value obtained from the difference or ratio. FIG. 3 shows a basic configuration of a root canal length measuring circuit according to the comparison method. Signals of frequencies f1 and f2 output from oscillators OS1 and OS2 are added by an adder A and applied to a measuring needle F. Then, the impedance response voltage generated in the resistor R is adjusted by the shaping circuit L1.
After being shaped by L2 and L2, the comparison circuit C compares them to obtain measured data.

Each of the above methods has its own characteristics. That is, for example, the simple correspondence method using only the measurement voltage of 400 Hz cannot perform accurate measurement when the inside of the root canal is wet, and the comparison method using the measurement voltage of 400 Hz and 8000 Hz has an impedance response value near the apex. Since it changes abruptly, it is effective to use both methods together to improve the measurement accuracy. Therefore, it is desirable to be able to select whether to use only the simple correspondence method, only the comparison method, or to use a combination thereof, and an operating unit for this selection is provided in the setting unit 14 of the control device body 8 to The person can select the required method.

Next, the structure of the head 5 will be described. FIG.
(A) is a plan view showing a part in section, (b) and (c) are side sectional views, (a) is a sectional view taken along the line AA of (b), and (b) is (a). Is a sectional view taken along line BB of FIG. In addition, (b) is file 2
Is moved in the crown direction, and (c) shows the file 2 moved in the apex direction.

The cutting drive unit 6 includes a cutting motor 6a located in the main body of the handpiece 4 and the motor 6a.
The rotary shaft 6b driven by a, a drive gear 6c provided at the tip thereof, a rotary gear 6e supported by a bearing 6d and meshing with the drive gear 6c, and the like. Further, the automatic feed mechanism 7 includes a feed motor 7a located at the main body of the handpiece 4 and a rotary shaft 7 driven by the motor 7a.
b, a pinion 7c provided at the tip thereof, a slide rack 7d slidably supported in the vertical direction and meshing with the pinion 7c, and the like.

Further, a pipe-shaped slide shaft 5a for holding the inserted file 2 is provided in the head 5, and is supported by a slide bearing 5b so as to be rotatable and vertically slidable. A coupling groove 5c is formed on the outer periphery of the slide shaft 5a in the axial direction. The coupling pin 6f of the rotary gear 6e is engaged with the coupling groove 5c, and the upper end of the slide rack 7d is engaged with the upper end of the slide shaft 5a. are doing.

The head 5 has such a structure. When the cutting motor 6a is driven, its rotation is transmitted to the slide shaft 5a via the rotary shaft 6b, the drive gear 6c and the rotary gear 6e, and the slide shaft 5a rotates. To do. Also, the feed motor 7
When a is driven, its rotation is the rotation shaft 7b and the pinion 7
The slide shaft 5a is transmitted to the slide shaft 5a through the slide rack 7d, and the slide shaft 5a slides up and down.
Therefore, like the conventional device, the file 2 inserted in the root canal 1a can be rotated to perform the root canal forming treatment for the root canal 1a. The insertion can be performed by the automatic feeding mechanism 7.

That is, when inserting the file 2 into the root canal 1a, first, as shown in FIG. 4 (b), the file 2 is moved in the crown direction most, and then the tip of the file 2 is moved to the root canal 1a. The head 5 is fixed so that it faces the tooth crown 1c at the upper end and the relative position of the head 5 to the tooth 1 is kept constant. This fixing can be easily realized, for example, by providing a fixing arm on a medical examination table or the like and holding the handpiece 4 by this arm. Thus head 5
When the feed motor 7a of the automatic feeding mechanism 7 is driven after fixing the slide shaft 5a, the slide shaft 5a moves downward and the file 2
Is automatically inserted into the root canal 1a while rotating and the apex 1b
Will be sent in the direction of.

There is a known root canal forming device that finely reciprocates a file in the axial direction, but this is, for example, a reciprocating motion with a constant stroke in conjunction with rotation, such as a handpiece. The reference position of the file with respect to the holder is unchanged. Therefore, in the present invention, this is completely different from the feeding operation for moving the cutting tool such as a file in the axial direction.

According to the apparatus of the present invention, not only the above-mentioned feeding to the apex side, but also the control of the insertion amount and the reverse feeding control to the crown side as described below are automatically performed. By doing so, complete automation of file operations is possible.

First, when the root canal is formed, the file 2 may bite into the root canal and may be broken. Therefore, the load torque is constantly detected from the magnitude of the motor current of the cutting motor 6a. Reaches the preset reference value, the direction of rotation of the feed motor 7a is reversed, and reverse feed to the crown portion 1c side is performed. This prevents the file 2 from being forcibly driven and prevents the occurrence of troubles such as biting into the root canal. In this case, the insertion in the direction of the apex 1b is not continuously performed, and the insertion amount is gradually increased while alternately repeating the feeding to the apex 1b side and the backward feeding to the crown portion 1c side. The setting unit 14 of the control device body 8 is provided with an operation unit that can independently and individually set the feed amounts in the apex direction and the crown direction.

Further, as described above, when the load torque reaches the reference value, the cutting drive unit 6 may be controlled to stop the cutting, which also prevents the file 2 from biting. The cutting may be stopped by, for example, stopping the cutting motor 6a, decelerating, reversing the rotation direction, or the like.

In the above example, the automatic feeding mechanism 7 is controlled according to the load, but in the illustrated apparatus, the automatic feeding mechanism 7 is also controlled by the root canal length measuring circuit 13 measuring the root canal length. It That is, in the root canal length measuring device, the measurement data obtained when the tip of the measuring needle is located near the apex is known in advance, so when the measurement data reaches the set value based on it, for example, the apex It is common to determine that This device also follows this idea, and when the measurement data when the file 2 is being sent in the direction of the apex 1b reaches a preset set value, the feed motor 7a is stopped or the rotation direction is reversed. The reverse feed to the crown portion 1c side is performed. Therefore, the mistake of penetrating the apex 1b and inserting the file 2 deeply is prevented automatically in advance.

As described above, the root canal length can be measured from the impedance change characteristic obtained between the measuring needle and the oral electrode. In this case, it is necessary to detect the impedance change state. Therefore, also in the apparatus of this example, the root canal length is measured each time the file 2 moves in the direction of the apex 1b by a preset distance to detect the impedance change state and detect the tip of the file 2. You can know the position of. Specifically, the impedance change status can be detected by comparing the measured data after the previous movement, that is, before the current movement and after the current movement, so the comparison data obtained from the comparison results in File 2
Is determined to have reached the apex 1b, and the feeding of the file 2 is stopped or reversed.

Note that, unlike the conventional manual file insertion, in this device, the movement when inserting the file 2 is performed by the feed motor 7a, so that the movement speed can be made constant. Therefore, the root canal length may be measured and the measurement data before and after may be compared each time a predetermined time elapses, instead of the method of measuring each time a fixed distance is moved as described above. Further, not only the comparison data obtained by comparing the measurement data before and after the movement in this way but also the measurement data after the movement itself indicates the position of the tip of the file 2, so that both the measurement data and the comparison data are used. More accurate detection is also possible.

Although various controls for the automatic feed mechanism 7 have been described above, in addition to these controls, the cutting drive unit 6 can also be controlled by the root canal length measurement data. The control for the cutting drive unit 6 is to stop the cutting by the file 2 when the measurement data when the file 2 is being sent in the direction of the apex 1b reaches a preset set value. This cutting is stopped, for example, by stopping or decelerating the cutting motor 6a, reversing the rotation direction, or the like. As a result, a mistake in which cutting is continued even when the file 2 reaches the apex 1b is automatically and automatically prevented.

The apparatus of this example rotates the file 2, but if the method is to cut by ultrasonic vibration, for example, stop the vibration or decrease the output of the ultrasonic vibrator. The cutting can be stopped.

As described above, the measurement data of the root canal length can be used for various controls, but the measurement data and the like are not only used for the automatic control but also displayed on the display unit 15. It is used to provide information to the surgeon. Therefore, the setting unit 14 of the control device body 8 is provided with an operation unit for designating or selecting these display contents.

As described above, the setting unit 14 is provided with an operation unit for independently and independently setting the feed amounts in the root apex direction and the crown direction, and for selecting a root canal length measuring method. Although an operation unit is provided, the rotation speed of the cutting motor 6a,
Reference value of cutting load when reversing the feed of file 2,
An operation unit for setting the setting values of root canal length measurement data when reversing the feed of File 2 and stopping cutting, an operation unit for selecting whether to perform these various controls, etc. are required It is provided according to.

Although the above description has individually described the content of each claim, these various controls are adopted individually or in an appropriate combination in an actual root canal forming device. The flow chart of FIG. 5 illustrates the control procedure of the root canal forming device in which typical control is combined, but this is an example, and it goes without saying that other procedures than those shown in the figure can be adopted.

First, a power switch (not shown) is turned on to turn on the power, and various setting conditions such as rotation speed, feed amount, cutting load reference value and root canal length setting value are set by the setting unit 14. Then, the tip of the file 2 is the crown portion 1c of the root canal 1a.
Fix the handpiece 4 with it slightly inserted in the
Depress the foot pedal 9 (step S1). In the next step 2, when it is confirmed that the file 2 is inserted in the root canal 1a from the impedance response value measured by the operation of the root canal length measuring circuit 13, the process proceeds to step S3 and the cutting motor 6a is operated. The feed motor 7a starts to rotate, and the file 2 is inserted into the root canal 1a at a constant speed while cutting by rotation.

When cutting is started, the load torque of the cutting motor 6a is detected in step S4. If the torque is within the reference value, the process proceeds to step S5, and if it exceeds the reference value, the process proceeds to step S11. . In step S11, the rotation direction of the feed motor 7a is reversed, and the torque detected while returning the file 2 to the direction of the crown portion 1c is compared with the second reference value. This second reference value is selected to be, for example, 1/2 of the reference value in step S4. If the torque falls within the second reference value, the feed direction is reversed and the feed is switched to the apex 1b again. And returns to step S4. As a result, the bite of the file 2 and the resulting breakage are prevented.

In this flow chart, the feeding to the apex 1b side and the feeding to the crown portion 1c side are switched by the detected load torque. For example, the movement amount is set to 0 in advance on the apex 1b side. 0.5 mm, 0 on the crown portion 1c side.
Set it to 3 mm, and advance 0.5 mm to 0.3 mm
It is also possible to perform control to automatically repeat the operation of returning. Further, instead of reversing the feeding direction in this way, it is also possible to adopt a control in which the feeding is temporarily stopped until the load torque falls within the reference value.

In step S5, it is determined whether or not a predetermined time set in advance has elapsed, and when the time elapses, the operation proceeds to step S6 and the root canal length measuring operation is performed.
Here, for example, the impedance response values obtained with respect to two types of measurement voltages having different frequencies are compared with each other, and the comparison method processing using the value obtained from the difference or ratio is performed to display the calculated measurement data. It is displayed on the container 15.
The operation from steps S4 to S6 is repeated until it is determined in the next step S7 that the measurement data has reached the set value.

This judgment can be made from the result of one measurement, but as described above, it can also be made from the change state of the measured data two times before and after, so from the second time, the result of this time and the last time. It is also possible to make a judgment using the comparison data obtained by comparing the above, or, if necessary, a judgment using this comparison data and the measurement data of this time.

When it is determined in step S7 that the measured data has reached the set value, the process proceeds to step S8, in which the feed motor 7a is rotated in the opposite direction to return the file 2 to the crown portion 1c and the cutting operation. Also, the measurement data of the final root canal length is displayed on the display device 15, for example. This cutting is stopped by stopping the cutting motor 6a, decreasing the rotation speed, or reversing. Then in step S9, the foot pedal 9
When is turned off, all the motors are stopped and the series of cutting operations is completed.

In addition to the measurement data of the root canal length, the moving direction, the rotation speed, the cutting torque, etc. of the file 2 are necessary information for the operator, so that the display 15 displays the above-mentioned step S6 or step S8. In addition to the display of the measurement data of 1., these data may be constantly displayed during a series of cutting operations.

Although FIG. 1 shows a control device main body 8 which is separate from the handpiece 4, a control unit 11, a motor controller 12, a root canal length measuring circuit 13 and the like are provided. All of these circuits and functions may be housed in the handpiece 4, or a part of them may be housed in a separate control device main body as required.

[0048]

As is apparent from the above description, in the root canal forming device of the present invention, the cutting tool that is attached to the tip of the holder and inserted into the root canal is driven by the cutting drive unit. A root canal forming device for forming a tube is provided with an automatic feeding mechanism for automatically moving a reference position of the cutting tool with respect to a holder in an axial direction of the cutting tool.

Therefore, it goes without saying that the cutting tool is automatically inserted into the root canal to reduce the burden on the operator during the formation of the root canal. Since the root canal can be kept constant, in the root canal forming device with the addition of the root canal length measurement function to perform cutting while measuring the root canal length, the fluctuation of the insertion speed due to manual work is superimposed on the measurement data. Since it is not performed, it becomes easy to accurately detect the tip position of the cutting tool that also serves as the measuring needle. Therefore, the problem that was a major obstacle to the automation of root canal forming work was solved, the root canal forming work was completely automated, and the burden on the operator was greatly reduced, and no high skill or attention was required. In addition, it is possible to reduce working time and fatigue.

Further, in the case where the automatic feed mechanism and the cutting drive unit are controlled according to the magnitude of the load applied to the cutting tool, it is possible to prevent the cutting tool from biting into the root canal and breaking due to this. it can.

Further, in the case where the automatic feed mechanism and the cutting drive unit are controlled according to the measurement data of the root canal length,
It is possible to prevent mistakes such as cutting being performed excessively beyond the apex.

Further, in measuring the root canal length, comparison data obtained by comparing the previous measurement data and the current measurement data obtained by sequentially measuring the cutting tool in the direction of the root apex, and the comparison data. In addition to this, the one that detects the position of the tip of the measuring needle by using the measured data this time also enables highly accurate detection because it uses a lot of data, and controls the automatic feed mechanism and the cutting drive unit. It can be done more appropriately.

Further, the measurement data obtained from the impedance response value when one kind of measurement voltage is applied between the cutting tool which also serves as the measuring needle and the oral electrode, and the respective cases when two kinds of measurement voltages are applied Even in the case where the position of the tip of the measuring needle is detected according to the combination with the measurement data obtained from the difference or ratio of the impedance response values, a large amount of data is used, which enables highly accurate detection,
The automatic feed mechanism and the cutting drive unit can be controlled more appropriately.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration in a root canal forming device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a motor controller circuit in the same apparatus.

FIG. 3 is a diagram showing an example of a root canal length measuring circuit in the device.

4A and 4B are views showing an example of a structure of a head in the same apparatus, FIG. 4A is a plan view showing a part of the head in section, and FIGS. 4B and 4C are side sectional views.

FIG. 5 is a flowchart showing an example of a control procedure of the device.

[Explanation of symbols]

 1 tooth 1a root canal 1b root apex 1c tooth crown 2 file (cutting tool and measuring needle) 4 handpiece 5 head 6 cutting drive unit 6a cutting motor 7 automatic feed mechanism 7a feed motor 8 controller main unit 11 control unit 12 Motor Controller 13 Root Canal Length Measuring Circuit 14 Setting Section 15 Display

Claims (20)

[Claims] 1. A root canal forming device for forming a root canal by driving a cutting tool, which is attached to a tip of a holder and inserted into a root canal, by a cutting drive unit, and a reference position of the cutting tool with respect to the holder. A root canal forming device comprising an automatic feeding mechanism for automatically moving the cutting tool in the axial direction of the cutting tool. 2. A means for sequentially detecting a load applied to the cutting tool, wherein the automatic feed mechanism and / or the cutting drive unit is controlled according to the magnitude of the detected load. The described root canal forming device. 3. When the cutting tool is moved in the direction of the apex, when the load reaches a preset reference value, the movement by the automatic feed mechanism is stopped or the movement direction is reversed. The root canal forming device according to claim 2. 4. The root canal according to claim 1, wherein the automatic feeding mechanism is controlled so as to automatically repeat the movement of the cutting tool in the root apex direction and the movement in the crown direction. Forming equipment. 5. The root canal forming device according to claim 4, wherein the movement amount in the root apex direction and the movement amount in the crown direction can be independently set. 6. The root canal forming device according to claim 1, wherein the root canal forming device is configured to display a moving direction of the cutting tool. 7. The root canal forming device according to claim 1, wherein a pulse motor is used as a feed motor of the automatic feed mechanism. 8. The cutting tool also serves as a measuring needle for measuring the root canal length, and the automatic feeding mechanism is controlled according to the measurement data of the root canal length. The root canal forming device according to claim 1. 9. The movement is stopped or the movement direction is reversed when the measurement data of the root canal length when the cutting tool is moved in the apex direction by the automatic feed mechanism reaches a preset set value. The root canal forming device according to claim 8, which is configured to perform. 10. The root canal forming device according to claim 8, wherein the root canal length measuring operation is automatically performed every time the cutting tool moves a preset distance in the root apex direction. . 11. The root canal length measurement data after the previous movement is compared with the root canal length measurement data after the current movement, and the automatic feed mechanism is controlled using the comparison data obtained by comparison. The root canal forming device according to claim 10, configured as described above. 12. Comparative data obtained by comparing the measurement data of the root canal length after the previous movement with the measurement data of the root canal length after the current movement, and the measurement of the root canal length after the current movement The root canal shaping device of claim 10, wherein the root canal forming device is configured to control the automatic feeding mechanism using both of the data. 13. The method according to claim 8, wherein the moving speed of the cutting tool by the automatic feed mechanism is constant, and the root canal length measuring operation is automatically performed every time a predetermined time elapses. Root canal forming device. 14. The root canal forming device according to claim 13, wherein the moving speed of the cutting tool by the automatic feeding mechanism can be arbitrarily set. 15. A structure for comparing the previous measurement data of the root canal length and the current measurement data of the root canal length during movement, and controlling the automatic feeding mechanism using the comparison data obtained by comparison. 15. The root canal forming device according to claim 13 or 14. 16. Use of both comparison data obtained by comparing the previous measurement data of the root canal length with the measurement data of the current root canal length during movement, and the measurement data of this root canal length 14. The structure of claim 13 configured to control an automatic feed mechanism.
Or the root canal forming device according to 14. 17. The cutting tool also serves as a measuring needle for measuring the root canal length, and the cutting drive unit is controlled according to the measurement data of the root canal length. The root canal forming device according to any one of claims. 18. When the measurement data of the root canal length while the cutting tool is being moved in the root apex direction by the automatic feed mechanism reaches a preset set value, the cutting drive unit drives the cutting tool. The root canal forming device according to claim 17, which is configured to stop, reduce a driving force, or reverse a rotation direction. 19. The root canal forming device according to claim 8, wherein the root canal forming device is configured to display measurement data of root canal length. 20. Between a cutting tool that also functions as a measuring needle inserted into a root canal and an oral electrode placed in the oral cavity of a patient,
The value obtained from the impedance response value when one type of measurement voltage is applied, and the value obtained from the difference or ratio of the impedance response values when two types of measurement voltage are applied are the root canal length measurement data. Used as an automatic feed mechanism or / or according to any or a combination of these measurement data.
And a cutting drive configured to control the cutting drive.
20. The root canal forming device according to any one of 19 to 19.