JP2000254149A - Dental root canal forming and root canal length measuring handpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dental handpiece usable as the dental root canal forming and root canal length measuring which eliminates the restriction conditions of the conventional dental handpiece used when a dentist carries out root canal expansion and cleaning after the dental pulp extraction of the patient's teeth. SOLUTION: A contact lever 3 made of conductive material which is formed with a notch 3a in a direction perpendicular to the longitudinal direction of a shape to abut against a metallic needle handle part 5c of a root canal forming implement 5 on the flank at one end in the longitudinal direction and is formed with a connecting/positioning part 3b for electrically conducting a dental root canal length measuring instrument to the other end, is formed of a structure obtained by mounting the connecting/positioning part 3b freely rotatably around a fulcrum 4 in the approximate central position of a contact lever 3 on the lower side of the neck part 2 of the dental handpiece in the position where the this part is positioned to the dental handpiece. This fulcrum 4 is preferably fixed to a sleeve member 2 constituted freely attachable and detachable to and from the neck part 1 of the dental handpiece.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handpiece for dental root canal formation and root canal length measurement which is used by a dentist for root canal enlargement and cleaning after dental pulping in a patient's mouth. It is about.

[0002]

2. Description of the Related Art In general, when a patient visits a dental clinic for complaining of tooth pain, the caries are not simply invaded, but the caries have developed before pulpitis occurs. Is the majority. When the inflammation of the pulpitis has spread to most areas of the pulp chamber or has spread to the pulp in the root canal, immediate pulpal removal is necessary. The reason is that if this inflammation is left untreated, the inflammation spreads to the entire dental pulp tissue, causing gangrene, and further adversely affects the apical periodontal tissue to form a lesion. In addition, for a reason such as a broken tooth, a healthy pulp may be subjected to a pulpotomy procedure for convenience because of the necessity of a prosthetic procedure.

[0003] After the local anesthesia is performed and the pulpotomy is performed, the length of the target tooth to the physiological apical hole (generally referred to as the working length or root canal length) is determined. In addition to the measurement, root canal treatment is performed using a device such as a canal cleanser (pulp removal needle), a reamer, and a file as a dental root canal forming tool to remove the root pulp, enlarge and clean the root canal.

[0004] In order to completely perform such a root canal treatment, it is very important to accurately measure the length to the physiological apex (hereinafter sometimes simply referred to as a root canal length) as described above. Element. This can result in inflammation or dissemination of the inflamed root canal contents from the apical foramen into surrounding tissue, resulting in apical foci if the tissue surrounding the apex is inadvertently damaged. Because of this, the root canal treatment must be performed only within the physiological apical length.

[0005] Therefore, as a method of measuring the root canal length, for example, a thin reamer or a file such as a file is inserted into the root canal after the removal of the spinal cord by relying on the operator's finger sensation (experienced intuition). In addition, there is a method of sensing a change in a sense of resistance received when reaching the apical stenosis. However, this method not only requires considerable skill, but also has large variations among humans and lacks reliability. As another method, there is a method using an X-ray photograph. This is done by taking an X-ray photograph with a root canal forming tool such as a reamer or file inserted into the root canal, comparing the used root canal forming tool with the X-ray photograph, and determining the actual insertion rate from the inserted ratio. This is a method to determine the root canal length. However, since the X-ray photography increases the exposure of the patient to X-rays which are harmful to the patient, it has recently become less common.

[0006] The reason that the above-mentioned method based on X-ray photography is not carried out is also because a method capable of measuring the root canal length more accurately and easily has been developed. It is a method based on changes in electrical resistance. This is done by inserting the root canal forming tool into the root canal, and when the tip of the root canal forming tool reaches the apical foramen, it is common to use an electrode applied to other parts of the body (using a salivary duct). This method focuses on the fact that the electric resistance value existing between the root canal forming tool and the root canal forming device is substantially constant irrespective of the size, type, age, and gender of the teeth.

[0007] Devices used for such purposes are sold as root canal length measuring devices by companies such as "End Dontech Meter" and "Root Canal Meter". In each case, the change in resistance value is indicated by a meter or the like, and when the meter is at a predetermined position, it indicates that the tip of the root canal forming tool has reached the apical foramen. It is. The general configuration of these root canal length measuring machines is configured to include a main body having the above-described meter and connecting tools respectively connected to two conductive wires extending from the main body.

[0008] One of the connecting devices is connected to a root canal forming device, and the other is connected to a metal part such as a salivary duct in contact with the oral mucosa. Since such a connection is made, both of the above-mentioned connecting devices are alligator grips, or one is a crocodile grip and the other is a key-shaped clamp so as to be easily connected to the metal needle handle of the root canal forming device. Generally, it is composed.

[0009] The root canal enlargement and cleaning using a root canal forming tool such as a reamer or a file is performed by hand of a dentist (generally referred to as hand reaming), and therefore, a treatment that adds a considerable burden. Therefore, recently, it is performed using an electrically driven dental handpiece (hereinafter, may be simply referred to as a handpiece) having a built-in electric motor that has a torque even at a low speed and easily controls the rotation speed. It is becoming.

[0010] In the case of hand reaming, a rough feeling is grasped from the resistance to the fingers, and the operation is stopped at a certain point. One of the connecting devices of the root canal length measuring machine is connected to the root canal forming device and the other is connected to the root canal forming device. For example, it is possible to check the root canal length with a meter by connecting to a metal part such as a salivary duct in contact with the oral mucosa. However, when using a handpiece, there is almost no sense of resistance to the fingers, so the tip of the root canal prosthesis may protrude from the apical hole or may not reach the apical hole. is there.

As a result, if the tip of the root canal prosthesis protrudes from the apical foramen, the tissue surrounding the apex is inadvertently damaged as described above, so that inflammation or inflammation occurs. The resulting root canal contents may diffuse from the apical foramen into the surrounding tissue and cause apical lesions, and the tip of the root canal forming tool did not reach the apical foramen In this case, the root canal is not sufficiently cleaned, and pathogenic bacteria in the inflamed pulp tissue will remain, which may cause dead space at the time of filling the root canal and recurrence of inflammation. There is.

In order to prevent such a situation, the use of the handpiece has the advantage that the burden on the root canal treatment is reduced. However, the drive of the handpiece is stopped several times during the treatment to form the root canal. The inconvenience of having to perform the work intermittently while checking the insertion depth of the tip of the tool into the root canal remains. When confirming the insertion depth of the tip of the root canal forming tool into the root canal, care must be taken so that the position of the tip of the root canal forming tool does not deviate from that position.

There have been some attempts to improve the focus on such points. It makes use of the fact that the neck of the handpiece is made of metal, and also makes the gripping handle of the root canal forming tool a metal, so that all these are electrically connected, and the neck of the handpiece is A metal ring, etc., and connect one of the connecting devices of the root canal length measuring device to this ring, so that the work can be performed accurately without stopping and checking the position of the tip of the root canal forming tool. Thus, the tip of the root canal forming tool can be guided to the apical position.

However, there are too many restrictions in the above-described configuration. That is, when the handpiece is a latch-type chuck, the latch fitting portion of the root canal forming tool must be made of metal so that there is electrical conduction with the needle portion of the root canal forming tool. Is a push button type chuck, a nylon chuck cannot be used as the push button type chuck, and the gripping handle must be made of metal as a root canal forming tool, so that the root canal forming tool becomes expensive. , And so on.

[0015]

SUMMARY OF THE INVENTION According to the present invention, there is provided a gripping handle for a root canal forming tool which eliminates the above-mentioned restriction conditions when a root canal forming tool is mounted and held on a handpiece to perform root canal enlargement and cleaning. There is no limitation on the material used for the part, and the method of chucking the handpiece does not matter, and it is preferably used for dental root canal formation and root canal length measurement which can be easily changed even with a conventional handpiece. It is an object of the present invention to provide a handpiece that can perform the above-described operations.

[0016]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have applied a metal needle handle of a dental root canal forming tool to one side in the longitudinal direction. A conductive material in which a notch in a direction perpendicular to the longitudinal direction of the contacting shape is formed, and a connecting portion and a positioning portion for electrically connecting to a dental root canal length measuring device are formed at the other end. A contact lever made of metal is mounted below the neck of the handpiece at a position where the connection / positioning portion is positioned on the dental handpiece so as to be rotatable about a fulcrum at a substantially central position of the contact lever. We figured out what to do with the configuration.

In the above-described configuration, the fulcrum may be fixed directly to the neck of the handpiece or fixed to a sleeve member detachably attached to the neck of the handpiece. It is preferable that the connecting portion and the positioning portion are engaged with the positioning portion provided on the neck of the handpiece and positioned. In this case, the positioning portion provided on the neck of the handpiece is connected to the contact lever. If it is a mode made of a conductive material that electrically connects the handpiece neck and the contact lever when engaged with the part / positioning part, only when the gripping handle part of the conventional root canal forming tool is metal A handpiece that can be used for root canal treatment can be used even when the grip handle of the root canal forming tool is made of non-conductive resin. To be able to be of was also investigated more preferable.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a handpiece for forming a root canal and measuring a root canal length according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective explanatory view illustrating a state in which a dental root canal forming tool is attached to a handpiece according to the present invention as viewed obliquely from below, and FIG. 2 is a perspective view of the handpiece illustrated in FIG. 1 as viewed obliquely from above. FIG. 3 is a perspective explanatory view illustrating a state, FIG. 3 is an enlarged perspective explanatory view illustrating an embodiment of a contact lever with a sleeve member mounted on a handpiece according to the present invention, and FIG. FIG. 5 is an explanatory view showing one embodiment of the shape of a contact lever in contact with a positioning portion provided on a neck of a handpiece, FIG.
Is an explanatory view of another embodiment corresponding to FIG. 4, and FIG. 6 is an explanatory view of still another embodiment corresponding to FIG.

In the drawings, reference numeral 1 denotes a handpiece neck detachably attached to a handpiece body (not shown),
Inside the handpiece head 1a at the tip thereof, a gripping handle 5a opposite to the blade 5b of the dental root canal forming tool 5 such as a dental cutting tool such as a diamond bar or a reamer or a file to be mounted and held is provided. The chuck 1b to be gripped is supported by bearings on both upper and lower sides so as to be rotatable.

As a configuration of the chuck 1b, that is, a configuration for mounting and holding a dental root canal forming tool 5 such as a dental cutting tool, a reamer, and a file, there are different types such as a push button type chuck and a latch type chuck. It is widely known. Although the handpiece shown in FIG. 1 is assumed to have a push button type chuck, it goes without saying that the present invention is not limited to this.

Reference numeral 2 denotes a sleeve member which is attached or fixed to the lower side of the handpiece neck 1.
For example, there is a method in which the sleeve member 2 is fixed with an adhesive or a method in which the cross section of the sleeve member 2 is formed in a C-shape having one open side, and the sleeve member 2 is externally fitted to the neck portion 1 of the handpiece. With the latter configuration, the sleeve member 2 becomes detachable from the neck portion 1 of the handpiece, so that the sleeve member 2 can be attached as needed according to the type and progress of the treatment. Therefore, the sleeve member 2 becomes an obstacle except when the root canal is enlarged and the cleaning procedure is performed.
It is possible to respond to the demands of dentists that it is preferable to have none. Note that the sleeve member 2 may not be used in the present invention.

Numeral 3 is made of a conductive material such as copper, and has a longitudinal end portion having a shape contacting a metal needle handle 5c of the dental root canal forming tool 5 on one side in the longitudinal direction. A notch 3a is formed in a direction perpendicular to the longitudinal direction, and a connection portion / positioning portion 3b for electrically conducting with a dental root canal length measuring device is formed at the other end portion. The contact lever is rotatable about a fulcrum 4 fixed to the handpiece neck 1 or the sleeve member 2 at a substantially central position, and is mounted at a position where the connecting portion and positioning portion 3b is positioned on the handpiece.

The contact lever 3 is attached to the chuck 1 in the handpiece head 1a at the tip of the handpiece neck 1.
b) Metal needle handle 5 of dental root canal forming tool 5 gripped by b
c is a member for electrically connecting the dental root canal length measuring device to the dental root canal length measuring device, and the connecting portion and positioning portion 3b may be connected to a conducting wire connected to the dental root canal length measuring device. The description of each of the embodiments is as follows. A metal ring or the like is attached to the handpiece neck 1, one of the connecting tools of the root canal length measuring machine is connected to the ring, and a conductive positioning portion provided on the handpiece neck 1 is described. 1c will be described.

As described above, the contact lever 3 must be kept in constant contact with the metallic needle handle 5c of the dental root canal forming tool 5 when performing a root canal enlargement and cleaning procedure. At least one end in which a notch 3a in a direction perpendicular to the longitudinal direction is formed is plate-like, and the width of the opening of the notch 3a is a metal needle handle of the dental root canal forming tool 5. As shown in FIG. 4, the width of the opening is narrower than the thickness of the portion 5c, and the width of the opening is formed to have the same diameter as the thickness of the metal needle handle 5c of the dental root canal forming tool 5. In the case of the form, the contact lever 3 is rotated about the fulcrum 4 and the opening of the notch 3a is formed by the elasticity of the material so that the metal needle handle of the dental root canal forming tool 5 is formed. 5c expand or twist to expand the dental root canal The metal needle handle 5c of the fixture 5 is accommodated in the innermost part of the notch 3a, and the notch provided in the connecting part / positioning part 3b is protruded from the handpiece neck 1. The notch 3a is connected to the protrusion made of a conductive member, which is the positioning portion 1c, and positioned, so that the metal needle handle 5 of the dental root canal forming tool 5 is formed.
c can be maintained in a state of being always in contact with c.

Another aspect of the contact lever 3 is that a side surface of one end in the longitudinal direction is perpendicular to the longitudinal direction of the shape which is in contact with the metal needle handle 5c of the dental root canal forming tool 5. U-shaped notch 3a is formed in
As shown in FIG. 5, a connecting portion / positioning portion 3 b for electrically conducting with the dental root canal length measuring device at the other end is provided with a slightly U-shaped recess parallel to the longitudinal direction. If it is shaped, rotate it around the fulcrum 4 and cut it out.
a metal needle handle 5c of the dental root canal forming tool 5
When one side of the concave portion of the connecting portion / positioning portion 3b is slightly deformed by elasticity, the projection made of a conductive member serving as the positioning portion 1c protruding from the handpiece neck 1 serves as the connecting portion. The notch 3a formed on the side surface of one end portion in the longitudinal direction when enlarging and cleaning the root canal is made to fit into the concave portion of the positioning portion 3b so that the metal of the dental root canal forming tool 5 can be formed. A state in which it is always in contact with the needle handle 5c made of a metal can be maintained.

Further, as another mode of the contact lever 3, a side surface of one end in the longitudinal direction is perpendicular to the longitudinal direction of the shape contacting the metal needle handle 5 c of the dental root canal forming tool 5. U-shaped notch 3a is formed in
The connection / positioning portion 3b for electrically conducting with the dental root canal length measuring device at the other end has a dish shape projecting downward, as shown in FIGS. If
It is rotated about the fulcrum 4 so that the metal needle handle 5c of the dental root canal forming tool 5 can be accommodated in the innermost part of the notch 3a, and the dish-shaped part is elastically movable so that the handpiece neck 1 is formed. Immediately after climbing over the projection made of a conductive member, which is the positioning portion 1c, which is protruded from the projection, the projection is engaged with the top of the projection so that the root canal is enlarged and cleaned. The notch 3a formed on the side surface of one end in the longitudinal direction can always be kept in contact with the metal needle handle 5c of the dental root canal forming tool 5.

Further, as another mode of the contact lever 3, a side surface of one end in the longitudinal direction is perpendicular to the longitudinal direction of the shape contacting the metallic needle handle 5 c of the dental root canal forming tool 5. U-shaped notch 3a is formed in
The U-shaped cutout 3 is provided with a connecting portion / positioning portion 3b for electrically connecting with the dental root canal length measuring device at the other end.
The notch opened in the same direction as a and a portion extending from a fulcrum 4 to be described later to the connecting portion and positioning portion 3b and / or a portion extending from the fulcrum 4 to the U-shaped notch 3a is a wire-like material. With the configuration shown in FIG. 6 having an elasticity capable of bending in the direction of rotation of the contact lever 3 about the fulcrum 4, the dental lever is rotated about the fulcrum 4 and the deepest part of the notch 3 a is An operation for fitting the metal needle handle 5c of the root canal forming tool 5 and a connection and positioning part 3b
The elasticity of at least one of the operations of making the projection formed of the conductive member, which is the positioning portion 1c protruding from the handpiece neck 1, fit into the innermost part of the notch. A notch 3a formed on the side surface of one end in the longitudinal direction when performing a root canal enlargement and cleaning procedure.
Can always be kept in contact with the metal needle handle 5c of the dental root canal forming tool 5.

Next, the method of using these components will be described. First, a fulcrum 4 is fixed to a sleeve member 2 which is detachably attached to the neck portion 1 of the handpiece. When the sleeve member 2 is not attached to a predetermined position of the neck 1, the sleeve member 2 is attached to a predetermined position of the handpiece neck 1. Then
By rotating the contact lever 3 about the fulcrum 4, the notch 3 a is located at a position away from the chuck 1 b of the handpiece neck 1.

Next, a dental root canal forming tool 5 (for example, a reamer having an appropriate thickness according to the thickness of the root canal of the patient) is selected and the handpiece head 1 at the tip of the handpiece neck 1 is selected.
The grip handle 5a is gripped and attached to the chuck 1b provided in the inside of the a. At this time, it goes without saying that the grip handle 5a of the dental root canal forming tool 5 may be made of metal or synthetic resin (plastic), regardless of its material. This is because, in the present invention, the grip handle 5a of the dental root canal forming tool 5 is not an element for root canal length measurement. And the blade part 5b of the dental root canal forming tool 5
On the side of the needle handle 5c, a rubber stopper 6 for displaying the length when reaching the apex is provided in advance.

When the preparation described above is completed, the contact lever 3 is rotated about the fulcrum 4 so that the innermost part of the notch 3a is brought into contact with the needle handle 5c of the dental root canal forming tool 5. At the same time, the connecting part / positioning part 3b is connected and positioned to a projection part which is a positioning part 1c protruding from the handpiece neck part 1. An operation for bringing the deepest part of the notch 3a into contact with the needle handle 5c of the dental root canal forming tool 5 and a positioning part 1c protruding from the handpiece neck 1 and the like as a connecting part and positioning part 3b. The operation of connecting to and positioning the protrusions differs depending on the mode of the contact lever 3 as described above.

When the innermost portion of the notch 3a of the contact lever 3 is in contact with the needle handle 5c of the dental root canal forming tool 5, the needle handle 5c of the dental root canal forming tool 5 has a root. Since it is a round bar having no blade such as the blade portion 5b for forming a tube, the notch 3a is not damaged even if the dental root canal forming tool 5 is rotationally driven. As described above, the notch 3a of the contact lever 3 holds the needle handle 5c of the dental root canal forming tool 5 or the needle handle of the dental root canal forming tool 5 due to the elasticity of the contact lever 3. Since the dental root canal forming tool 5 is slightly vibrated during rotation, it can follow the movement of the dental root canal forming tool 5 because the dental root canal forming tool 5 is kept in contact with 5c. Therefore, the dental root canal forming tool 5 and the notch 3a of the contact lever 3 can always be kept in contact with each other.

If the handpiece is not equipped with a metal ring or the like and one of the connecting devices of the root canal length measuring machine is connected to this ring, the handpiece neck 1
The lead wire connected to the root canal length measuring device (not shown) is connected to the connection part / positioning part 3b which is connected and positioned to the protrusion which is the positioning part 1c protruding from the base. When such preparations are completed, the other cord (electrode) of the root canal length measuring machine (not shown) contacts the patient's body by using the saliva drainage tube or by holding it in the patient's hand. Let it.

Then, the dental root canal forming tool 5 is inserted into the root canal of the target tooth of the patient from the side of the blade portion 1b, and the handpiece is rotated at a relatively low speed of about 200 to 2000 rpm, and the root canal is rotated. The dental root canal forming tool 5 is gradually inserted deeply while checking the indicated value of the meter of the length measuring machine, and the position where the tip of the blade portion 5b of the dental root canal forming tool 5 reaches the position of the apex. When it is confirmed by the meter (some devices emit a warning sound), the rotation of the dental root canal forming tool 5 is stopped, and the rubber stopper 6 is lowered until it comes into contact with the tooth.

Next, the dental root canal forming tool 5 is pulled out as it is, and the dental root canal forming tool 5 is removed from the handpiece.
And remove the rubber stopper 6 from the tip of the blade 5b.
Measure the length up to the lower surface with a ruler or the like. This means that the length of the root canal of the tooth has been determined. The rubber stopper 6 may be positioned so that the dental root canal forming tool 5 used thereafter has the same length.

[0035]

As described above, the dental root canal forming and root canal length measuring handpiece according to the present invention forms a portion for attaching a fulcrum to an existing handpiece and rotates the contact lever by the fulcrum. In the case of using a sleeve member that can be simply modified to be freely mounted, or when a sleeve member that can be retrofitted is used, no modification is required at all, so that it can be manufactured at low cost, and the grip handle portion is made of inexpensive plastic. The angioplasty tool can also be used for root canal treatment. In addition, since it is configured to directly contact the metal needle handle of the dental root canal forming tool, the type of chuck of the handpiece used does not matter. In use, the contact lever is rotated about a fulcrum at a substantially central position thereof, and a notch in a direction perpendicular to the longitudinal direction formed on a side surface of one end in the longitudinal direction is formed in the dental root canal. The dental tool can be used immediately by simply performing the operation of abutting the metal needle handle of the shaping tool and positioning the connecting and positioning portion formed at the other end in the longitudinal direction on the dental handpiece. There is almost no need for a doctor. In the case where the fulcrum for rotatably mounting the contact lever at a substantially central position thereof is fixed to a sleeve member which is configured to be detachable from the neck of the dental handpiece, the dental root canal according to the present invention is provided. The handpiece for forming and measuring the length of the root canal can be used properly when the root canal treatment is performed or not. As described above, the value of the handpiece for forming a root canal and measuring the length of the root canal according to the present invention which contributes to a dental treatment institution is very large.

[Brief description of the drawings]

FIG. 1 is a perspective explanatory view illustrating a state in which a dental root canal forming tool is attached to a handpiece according to the present invention, as viewed obliquely from below.

FIG. 2 is an explanatory perspective view illustrating a state in which the handpiece shown in FIG. 1 is viewed obliquely from above.

FIG. 3 is an enlarged perspective explanatory view showing one embodiment of a contact lever with a sleeve member mounted on the handpiece according to the present invention.

FIG. 4 is an explanatory view showing one embodiment of the shape of a contact lever abutting on a grip handle portion of a dental root canal forming tool and a positioning portion provided on a neck portion of a handpiece.

FIG. 5 is an explanatory diagram of another embodiment corresponding to FIG. 4;

FIG. 6 is an explanatory diagram of still another embodiment corresponding to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Handpiece neck 1a Handpiece head 1b Chuck 1c Positioning part 2 Sleeve member 3 Contact lever 3a Notch 3b Connecting part and positioning part 4 Supporting point 5 Dental root canal forming tool 5a Grip handle 5b Blade 5c Needle handle 6 Rubber stopper

Claims (5)

[Claims] 1. A notch (3a) in a direction perpendicular to the longitudinal direction of a shape contacting a metal needle handle (5c) of a dental root canal forming tool (5) on a side surface of one end in a longitudinal direction. ) Is formed, and a contact lever (3) made of a conductive material having a connecting portion and a positioning portion (3b) formed at the other end for electrically conducting with a dental root canal length measuring device, Under the neck portion (1) of the dental handpiece, the connecting portion and the positioning portion (3b) are rotatable about a fulcrum (4) at a substantially central position of the contact lever (3), and the connecting and positioning portion (3b) is attached to the dental handpiece. A dental root canal forming and root canal length measuring handpiece, which is mounted at a position to be positioned. 2. A fulcrum (4) having a neck portion (1) for a dental handpiece.
The dental root canal forming and root canal length measuring handpiece according to claim 1, which is directly fixed to the base. 3. The fulcrum (4) is a dental handpiece neck (1).
The dental root canal forming and root canal length measuring handpiece according to claim 1, wherein the handpiece is fixed to a sleeve member (2) which is configured to be detachable from the body. 4. The positioning part (3c) provided on the neck part (1) of the dental handpiece by positioning the connecting part / positioning part (3b) of the contact lever (3). 4. The handpiece for dental root canal formation and root canal length measurement according to any one of the items up to 3. 5. When the positioning part (1c) provided on the dental handpiece engages with the connecting part and positioning part (3b) of the contact lever (3), the dental handpiece and the contact lever (3) are connected. 5. The handpiece for dental root canal formation and root canal length measurement according to claim 4, wherein the handpiece is formed of a conductive material that is electrically conducted.