Treatment handpiece for tooth root for dentistry

Abstract

To provide a treatment handpiece for a tooth root for dentistry which preferably maintains electrical connection of a conduction path of a root canal length measuring circuit, and facilitates exchange of a consumable supply without damaging appearance of the handpiece.SOLUTION: A head part 11 of a treatment handpiece 100 for a root canal for dentistry comprises: a contact piece 81 which contacts a base end side end face 15a of a dental treatment tool 15; a head cap 75 which has an inside space where the contact piece 81 is arranged; a first elastic member 83 which elastically energizes the contact piece 81 to the dental treatment tool side; an annular member 79 which faces the dental treatment tool side of the head cap 75; and a second elastic member 77 which is arranged in contact with both of the head cap 75 and the annular member 79, and elastically energizes the head cap 75. The annular member 79 is conducted to a signal conductor 51. The contact piece 81, the head cap 75, the second elastic member 77 and the annular member 79 respectively having conductivity form a conduction path 35 from the dental treatment tool 15 in this order.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a dental endodontia handpiece. [Background technology]

[0002] Dental root canal treatment handpieces used for cutting to enlarge the root canal of a tooth and for measuring the root canal length are disclosed in, for example, Patent Documents 1 and 2. The handpiece of Patent Document 1 uses a cutting tool such as a file as an electrode for measuring the root canal length, and can perform root canal treatment while measuring the root canal length. In this case, since the cutting tool is used as one electrode of the root canal length measurement circuit, it is necessary to send a measurement signal from the handpiece to the cutting tool. For this reason, a conductive path is provided that electrically connects a tool holding mechanism that holds the cutting tool to the root canal length measurement circuit.

[0003] 15 of Patent Document 1, a conductive path is formed that electrically connects a cutting tool 111 to a rotor part 113 that holds the cutting tool 111, an electrode piece 117 having a clip-shaped electrode piece (brush) 115 that contacts the rotor part 113, and a conductor 119 that is connected to the electrode piece 117. In addition, to ensure contact between the cutting tool 111 and the rotor part 113, a urging force is applied to the cutting tool 111 by a compression coil spring 121.

[0004] The handpiece of Patent Document 2 also has the above-mentioned conductive path. The handpiece of Patent Document 2 shown in Fig. 16 has a conductive path formed therein that electrically connects a cutting tool 111, a conductive spring 123 having one end in contact with a base end surface of the cutting tool 111, a presser cover (head cap) 125 with the other end of the conductive spring 123 in contact, a cover sheet 127 that supports the presser cover 125, and a head case (grip) 129 to which the cover sheet 127 is fixed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-213 A [Patent Document 2] China Patent Application Publication No. 112618062 Summary of the Invention [Problem to be solved by the invention]

[0006] In the handpiece of the cited document 1, if the electrode piece 117 comes into contact with tissue in the oral cavity, it will affect the circuit for measuring the root canal length, so a resin cover member 131 is attached to the outside to prevent contact with the tissue. However, the exposed cover member 131 deteriorates the appearance, and the electrode piece 117 and the like need to be replaced due to wear caused by use of the handpiece, which is a complicated and time-consuming task.

[0007] In the handpiece of the cited document 2, the conductive spring 123 is in direct contact with the cutting tool 111, so that the conductive spring 123 is easily displaced in the radial direction due to the rotation and vibration of the cutting tool. Therefore, the contact state between the cutting tool and the conductive spring 123 is easily unstable, which may affect the root canal length measurement circuit. In addition, if wear debris is generated due to wear of the conductive spring 123, the wear debris may cause a malfunction. When the conductive spring 123 becomes worn, it needs to be replaced, but this replacement work is time-consuming. Furthermore, since a measurement current flows through each of the members that come into contact with the human body, namely the presser cover 125, the cover sheet 127, and the head case 129, the surfaces of these members need to be electrically insulated to prevent noise from being superimposed on the measurement signal.

[0008] Therefore, an object of the present invention is to provide a dental root canal treatment handpiece that maintains good electrical connection of the conductive path of the root canal length measurement circuit while allowing consumables to be easily replaced without compromising the appearance of the handpiece. [Means for solving the problem]

[0009] The present invention comprises the following configurations. A dental root canal treatment handpiece comprising: a head portion having a tool holding mechanism for rotatably holding a dental treatment tool; and a grip portion connected to the head portion and having a signal line for transmitting a root canal length measurement signal therethrough, the grip portion being connected to the head portion and having a conductive path formed for electrically connecting the dental treatment tool held by the tool holding mechanism to the signal line, The head portion is a contactor that contacts a base end side end surface of the dental treatment tool held by the tool holding mechanism; a head cap having an inner space in which the contact is disposed so as to be movable in an axial direction of the dental treatment tool; a first elastic member disposed in the inner space and elastically biasing the contact toward the dental treatment tool; an annular member arranged to face the dental treatment tool side of the head cap; a second elastic member disposed between the head cap and the annular member in contact with both of them and elastically biases the head cap; Equipped with The annular member is electrically connected to the signal line, the contact, the head cap, the second elastic member, and the annular member, each of which is electrically conductive, form the conductive path from the dental treatment tool in this order; Dental root canal treatment handpiece. Effect of the Invention

[0010] According to the present invention, consumables can be easily replaced without impairing the appearance of the handpiece, while maintaining good electrical connection of the conductive path of the root canal length measuring circuit. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an overall view of a dental handpiece according to the present invention. [Diagram 2] FIG. 2 is a schematic block diagram of a dental-care device including the handpiece shown in FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing the internal structure of the handpiece. [Figure 4]FIG. 4 is an explanatory diagram showing a rotation drive mechanism of the dental treatment tool. [Diagram 5] FIG. 5 is a partial assembly view showing the cord, holder and leaf spring. [Figure 6] FIG. 6 is a cross-sectional view of a main part of the head portion of the handpiece. [Figure 7] 7 is a cross-sectional perspective view of the head portion shown in FIG. [Figure 8] FIG. 8 is an enlarged cross-sectional view of the upper part of the head portion. [Figure 9A] FIG. 9A is an explanatory diagram showing a chucking operation of a dental treatment tool by a tool holding mechanism in stages. [Figure 9B] FIG. 9B is an explanatory diagram showing a chucking operation of the dental treatment tool by the tool holding mechanism in stages. [Figure 9C] FIG. 9C is an explanatory diagram showing a chucking operation of the dental treatment tool by the tool holding mechanism in stages. [Figure 10] FIG. 10 is an explanatory diagram showing how an assembly including a head cap and a cap ring is detachably attached to a head portion. [Figure 11] FIG. 11 is a cross-sectional view taken along line XI-XI shown in FIG. [Figure 12] FIG. 12 is an exploded perspective view of the assembly. [Figure 13] FIG. 13 is a cross-sectional view showing the configuration of an assembly according to a modified example. [Figure 14] FIG. 14 is an exploded perspective view of the assembly shown in FIG. [Figure 15] FIG. 15 is a partial cross-sectional view showing the structure of a conventional handpiece. [Figure 16] FIG. 16 is a partial cross-sectional view showing the structure of another conventional handpiece. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a dental handpiece for root canal treatment according to the present invention will be described in detail with reference to the drawings. 1 is an overall view of a dental root canal treatment handpiece 100 according to the present invention. The dental root canal treatment handpiece 100 (hereinafter referred to as handpiece) includes a head portion 11, a grip portion 13 extending rearward from the head portion 11, and a motor portion 14. The head portion 11 includes a tool holding mechanism, the details of which will be described later, and a dental treatment tool 15 is detachably attached to the head portion 11. The dental treatment tool 15 attached to the tool holding mechanism is driven to rotate by a drive source such as a motor built into the motor portion 14. In this configuration, a file (reamer) for root canal treatment is used as the dental treatment tool 15, but the type of the dental treatment tool 15 is not limited to this.

[0013] Fig. 2 is a schematic block diagram of a dental medical device 200 including the handpiece 100 shown in Fig. 1. The dental medical device 200 includes the handpiece 100 having a built-in motor 21, a drive unit 23, an oral electrode 25, a root canal length measuring unit 27, a control unit 29, a setting unit 31, and a display unit 33.

[0014] The motor 21 rotates and drives the dental treatment tool 15 attached to the handpiece 100. Based on a command from the control unit 29, the drive unit 23 adjusts the voltage value to be applied to the motor 21, etc.

[0015] The oral electrode 25 is hung on the patient's lips and connected in an electrically conductive state to the root canal length measuring unit 27. The root canal length measuring unit 27 uses the dental treatment tool 15 as one electrode and the oral electrode 25 as the other electrode, applies a measurement voltage between both electrodes, and measures the impedance between the dental treatment tool 15 and the oral electrode 25. This notifies the control unit 29 of the tip position of the dental treatment tool 15 in the root canal. The handpiece 100 is provided with a conductive path 35 that constitutes a conductive path from the root canal length measuring unit 27 to the dental treatment tool 15, which is one of the electrodes.

[0016] The control unit 29 is responsible for storing the programs, the setting values ​​of the driving conditions, etc., and controlling each part according to the programs. The control unit 29 is composed of a computer equipped with a processor, a memory, a storage, an interface, etc., which controls the entire dental medical device 200.

[0017] The setting unit 31 is responsible for setting the driving conditions (rotation direction, rotation speed, rotation torque, etc.) of the motor 21, setting the control mode, etc. Examples of the control mode include a control mode in which the motor 21 is rotated in reverse when the driving torque of the motor 21 reaches a set torque in order to prevent the file, which is the dental treatment tool 15, from breaking, and a control mode in which the motor 21 is automatically stopped (or reversed) in rotation when the file reaches the root apex in order to prevent the root apex from penetrating through.

[0018] The display unit 33 displays various information such as the driving conditions of the motor 21, the rotation speed of the motor 21 during treatment, and the position of the tip of the file within the root canal.

[0019] FIG. 3 is a schematic cross-sectional view showing the internal structure of the handpiece 100. FIG. 4 is an explanatory diagram showing the rotation drive mechanism of the dental treatment tool 15. In the grip part 13 of the handpiece 100 shown in FIG. 3, a rotating shaft 37 to which a rotation force from the motor 21 (FIG. 2) is transmitted is rotatably supported by an insert member 39, although details are omitted. The rotation force is transmitted from a bevel gear 41 provided on the rotating shaft 37 to a tip rotating shaft 43 via a gear part 45 provided on one end of the tip rotating shaft 43. Also, as shown in FIG. 4, the rotation force transmitted to the tip rotating shaft 43 is transmitted to a gear part 49 supported coaxially with the dental treatment tool 15 via a bevel gear 47 provided on the other end of the tip rotating shaft 43. In this way, the dental treatment tool 15 is rotationally driven by the rotation force from the motor 21.

[0020] Inside the gripping part 13, a conductive path 35 is formed along the transmission path of the rotational force described above. As shown in Fig. 3, this conductive path 35 is arranged inside the gripping part housing 57, and includes a cord (signal line) 51 having one end connected to a metal insert member 39 that is in an electrically conductive state with the root canal length measuring part 27 (Fig. 2). The other end of the cord 51 is fixed to a holder 53 arranged near the head part 11, and is electrically conductive with the holder 53.

[0021] 5 is a partial assembly diagram showing the cord 51, the holder 53, and the leaf spring 55. The holder 53 is ring-shaped having a large diameter portion and a small diameter portion, and the cord 51 is fixed to a notch 53a formed in a part of the outer circumferential surface of the large diameter portion. A flat surface 53b is formed in a part of the outer circumferential surface of the small diameter portion, and a conductive leaf spring 55 is fixed to this flat surface 53b. The leaf spring 55 contacts a member on the head portion 11 side, which will be described later, and extends the conductive path 35 toward the dental treatment tool 15.

[0022] Next, the configuration of the head unit 11 will be described. Fig. 6 is a cross-sectional view of a main part of the head portion 11 of the handpiece 100. Fig. 7 is a cross-sectional perspective view of the head portion 11 shown in Fig. 6. In the following description, the direction in which the dental treatment tool 15 is inserted and removed when the dental treatment tool 15 is attached to the head portion 11 is also referred to as the "up-down direction" or "insertion direction", the front side of the insertion direction is also referred to as the "upper side" or "base end side", and the rear side of the insertion direction is also referred to as the "lower side" or "tip side".

[0023] The head portion 11 has a tool holding mechanism 61 that holds the dental treatment tool 15. The tool holding mechanism 61 has a hollow cylindrical rotor portion 63 into which the dental treatment tool 15 is inserted, a chuck mechanism 65 arranged above the rotor portion 63, and rolling bearings 67A, 67B that rotatably support the rotor portion 63. The rotor portion 63 is arranged concentrically with the axis of the gear portion 49 and rotates integrally with the gear portion 49. The chuck mechanism 65 has a lock piece 65a that is inserted into a locking recess 69 formed by recessing in the radial direction on the side surface on the base end side of the dental treatment tool 15, and a locking elastic member 65b such as a C-shaped retaining ring (C-ring) attached to the outer periphery of the lock piece 65a. The locking elastic member 65b elastically biases the lock piece 65a radially inward. The locking elastic member 65b is not limited to a C-shaped retaining ring, and may have other configurations, such as a coil spring arranged radially outside the locking piece 65a to bias the locking piece 65a radially inward. When the locking piece 65a is inserted into the locking recess 69, the locking piece 65a is locked in the locking recess 69, and the dental treatment tool 15 is prevented from coming off the rotor part 63. The rotor part 63 is supported by a pair of rolling bearings 67A, 67B spaced apart in the vertical direction of the dental treatment tool 15, and is rotatable with respect to a head housing 71 that covers the outer periphery of the head part 11.

[0024] The head housing 71 has an opening at the top, and a cap ring 73 is attached to this opening. The cap ring 73 integrally holds a head cap 75, a cap spring (second elastic member) 77, and an annular member 79 that receives the cap spring 77. The annular member 79 is disposed facing the dental treatment tool 15 side of the head cap 75. The head cap 75 has an inner space 76 that accommodates a contact 81, a contact spring (first elastic member) 83, and a cylindrical support portion 85, and is disposed to cover the cylindrical end of the cylindrical support portion 85 on the side opposite to the dental treatment tool 15. The cap spring 77 biases the cylindrical support portion 85 and the head cap 75 in the direction opposite to the dental treatment tool 15. The cap spring 77 and the contact spring 83 are preferably metallic coil springs, but may be other elastic members. In particular, the contact spring 83 is preferably a wave spring having a structure in which the load is uniformly received across the entire spring, which allows the upper and lower surfaces of the contact 81 in the thickness direction to be displaced with a high degree of parallelism, thereby improving the contact stability between the contact 81 and the dental treatment tool 15.

[0025] Fig. 8 is an enlarged cross-sectional view of the upper part of the head unit 11. In Fig. 8, only the members that form the aforementioned conductive path 35 are hatched. The chucking of the dental treatment tool 15 by the chuck mechanism 65 is released by pressing the head cap 75, the details of which will be described later. The head cap 75 is a circular release button in a plan view, and is hat-shaped in cross section in the vertical direction with the upper side being convex. An annular flange 75a protruding radially outward is formed at the bottom of the head cap 75. In addition, a small diameter step 73b protruding radially inward is formed at the upper part of the inner circumferential surface 73a of the cap ring 73. This allows the head cap 75 to move vertically along the inner circumferential surface 73a of the cap ring 73, and the flange 75a hits the small diameter step 73b to prevent it from coming off the cap ring 73.

[0026] The contact 81 is disposed in the internal space 76 formed in the head cap 75 so as to be movable in the axial direction of the dental treatment tool 15. The lower surface of the contact 81 abuts against the base end surface 15a of the dental treatment tool 15 held by the tool holding mechanism 61. The contact 81 is circular in plan view, and has a thick portion 81a at its center that protrudes toward the dental treatment tool 15. The lower surface of the thick portion 81a is a flat surface, but may be a convex curved surface that protrudes downward. The contact between the base end surface 15a of the dental treatment tool 15 and the contact 81 is a contact between a convex curved surface and a flat surface or a contact between two convex curved surfaces, so that the frictional resistance caused by the rotation of the dental treatment tool 15 can be reduced while ensuring conductivity.

[0027] The cylindrical support portion 85 is a cylindrical member with an inner peripheral surface thereof contacting the outer peripheral edge of the contactor 81. The cylindrical support portion 85 supports the contactor 81 movably in the axial direction of the dental treatment tool 15. A ring-shaped locking portion 85a protruding radially inward is provided at a lower cylindrical end of the cylindrical support portion 85, and prevents the contactor 81 from coming off the cylindrical support portion 85. A contactor spring 83 is disposed inside the cylindrical support portion 85, between the upper cylindrical end of the cylindrical support portion 85 and the contactor 81. One axial end of the contactor spring 83 abuts against the back surface of the head cap 75 on the inner space 76 side, elastically biasing the contactor 81 toward the dental treatment tool 15.

[0028] A fixing flange 85b protruding radially outward is provided on the outer periphery of the cylindrical support portion 85. The fixing flange 85b is fitted into a step portion 75c formed on the bottom portion of the head cap 75. A cap spring 77 is in contact with the lower surface of the fixing flange 85b. The cap spring 77 is disposed between the head cap 75 and the cylindrical support portion 85 and the annular member 79. The annular member 79 has a flat annular portion 79a having a predetermined radial width, and a cylindrical portion 79b extending downward from the outer peripheral edge of the annular portion 79a perpendicularly to the annular portion 79a. The cap spring 77 is pressed against the upper surface of the annular portion 79a of the annular member 79, and the lower surface of the annular portion 79a abuts against an end surface 87a of an outer ring 87 of the rolling bearing 67A. The cylindrical portion 79b is placed over the outer peripheral surface 87b of the outer ring 87.

[0029] The cap spring 77 elastically biases the head cap 75 upward via the fixing flange 85b of the cylindrical support portion 85. This cap spring 77 is compressed when the head cap 75 is pressed downward by the user, and generates an elastic force that presses the head cap 75 back upward in the opposite direction to the pressing direction.

[0030] The contact 81, the cylindrical support portion 85, the cap spring 77, and the annular member 79 are each electrically conductive. These members may be made of, for example, a metal material, or may be members having a conductive layer formed on the surface. The aforementioned leaf spring 55 is pressed against the lower end of the cylindrical portion 79b of the annular member 79, so that the annular member 79 and the leaf spring 55 are electrically conductive.

[0031] 9A to 9C are explanatory diagrams showing stepwise the chucking operation of the dental treatment tool 15 by the tool holding mechanism 61. As shown in FIG. 9A, when the dental treatment tool 15 is not chucked, the contact 81 is elastically biased downward by the contact spring 83 inside the cylindrical support part 85, and the outer periphery of the contact 81 is pressed against the annular locking part 85a. As a result, the contact 81 is locked at the lowest position of the movable range inside the cylindrical support part 85. In addition, the lock piece 65a of the chuck mechanism 65 is biased radially inward by the locking elastic member 65b, and is in a state of protruding radially inward from the inner circumferential surface of the rotor part 63.

[0032] In this state, when the dental treatment tool 15 is inserted from below the rotor unit 63, as shown in Fig. 9B, the base end surface 15a of the dental treatment tool 15 comes into contact with the lock piece 65a of the chuck mechanism 65. When the dental treatment tool 15 is further pushed up, the base end surface 15a and the lock piece 65a slide against each other, and the lock piece 65a moves radially outward.

[0033] 9C, when the dental treatment tool 15 is further pushed upward, the lock piece 65a moves radially inward and fits into the locking groove 15b of the dental treatment tool 15. The base end surface 15a of the dental treatment tool 15 comes into contact with the thick portion 81a of the contact 81, pushing up the contact 81. This operation of inserting the dental treatment tool 15 into the rotor part 63 continues until the step portion 15c recessed radially inward on the dental treatment tool 15 abuts against the protrusion 63a protruding radially inward on the rotor part 63.

[0034] As shown in Fig. 8, when the dental treatment tool 15 is held by the tool holding mechanism 61 of the head portion 11 in the above-mentioned procedure, a conductive path 35 is formed from the dental treatment tool 15 to the cord 51. That is, the base end surface 15a of the dental treatment tool 15 is conductively connected to the thick portion 81a of the contact 81 (arrow D1), and the outer periphery of the contact 81 is in contact with the inner periphery of the cylindrical support portion 85 for electrical conduction (arrow D2). The fixing flange 85b (or the annular locking portion 85a) of the cylindrical support portion 85 is in contact with the cap spring 77 for electrical conduction (arrow D3), and the cap spring 77 is in contact with the annular portion 79a of the annular member 79 for electrical conduction (arrow D4). The lower end of the cylindrical portion 79b of the annular member 79 is in contact with the leaf spring 55 for electrical conduction (arrow D5). The leaf spring 55 is electrically connected to the holder 53 (arrow D6) and to the cord 51 (arrow D7). As a result, the conductive path 35 from the dental treatment tool 15 to the cord 51 is formed.

[0035] The conductive path 35 described above is disposed inside the head cap 75, the cap ring 73, and the head housing 71, without being exposed on the outer surface of the head portion 11. In addition, the leaf spring 55, the holder 53, and the cord 51, which form the conductive path 35, are also disposed inside the grip portion housing 57, without being exposed on the outer surface of the grip portion 13.

[0036] Other members in contact with the above-mentioned conductive path 35, such as the head cap 75, the cap ring 73, the head housing 71, the grip housing 57, etc., are made of an electrically insulating resin material or have an insulating layer such as an insulating coating layer on their surfaces, so that disturbances such as superimposition of noise on the conductive path 35 are not generated. An annular member 79 abuts against an outer ring 87 of the rolling bearing 67A, but the annular member 79 is electrically insulated from an inner ring 88. In other words, a lubricant is applied between each of the rolling surfaces of the outer ring 87 and the inner ring 88 and the rolling elements (balls) 89, and the outer ring 87 and the inner ring 88 are insulated from each other by the lubricant.

[0037] In this way, the conductive path 35 inside the handpiece 100 is disposed in a state in which it is electrically insulated from the outside of the handpiece 100. As a result, when the handpiece 100 is in use, the conductive path 35 inside the handpiece 100 is not in direct conduction with the user and the patient, and does not affect the root canal length measuring circuit.

[0038] Fig. 10 is an explanatory diagram showing how an assembly 91 including a head cap 75 and a cap ring 73 is detachably attached to the head portion 11. Fig. 11 is a cross-sectional view taken along line XI-XI shown in Fig. 10. Fig. 12 is an exploded perspective view of the assembly 91.

[0039] As shown in Fig. 10, the assembly 91 can be attached to and detached from the head portion 11. The assembly 91 can be separated from the head portion 11 while remaining integral with itself, and the assembly 91 can be easily handled after removal. As shown in Figs. 11 and 12, the assembly 91 integrally includes a head cap 75, a cap spring 77, an annular member 79, and a cap ring 73. The contact 81, the contact spring 83, and the cylindrical support portion 85 are respectively housed in the inner space 76 of the head cap 75.

[0040] In this configuration, a male thread portion 73c is formed on the outer periphery of the lower end of the cap ring 73, and a female thread portion 71a is formed on the inner circumferential surface of the upper opening of the gripper housing 57. The assembly 91 is fixed to the head portion 11 by screwing the male thread portion 73c into the female thread portion 71a (see FIG. 8). The annular member 79 contacts the leaf spring 55 at the lower end of the cylindrical portion 79b, so that electrical continuity with the leaf spring 55 is ensured regardless of the rotation stop position of the assembly 91 when the assembly 91 is screwed to the head portion 11. The manner of fixing the assembly 91 to the head portion 11 is not limited to the above-mentioned screw fastening, and a well-known locking mechanism may be used.

[0041] As shown in Fig. 11, in this assembly 91, the contact 81 and the contact spring 83 are inserted in this order from an upper opening of the cylindrical support part 85 opposite to the annular locking part 85a. Then, the upper opening of the cylindrical support part 85 after insertion is covered with the head cap 75, so that the contact 81 and the contact spring 83 are accommodated in the inner space 76 of the head cap 75. The head cap 75 and the cap spring 77 are inserted from a lower opening of the cap ring 73. Furthermore, the annular member 79 is fitted from the annular part 79a, so that the head cap 75 is urged upward via the cylindrical support part 85 by the elastic force of the cap spring 77. As a result, the head cap 75 is supported so as to be capable of being pushed into the cap ring 73.

[0042] Each of the parts such as the contact 81, the contact spring 83, and the cap spring 77 that the dental treatment tool 15 comes into contact with while rotating is a consumable item that wears and deteriorates with the use of the handpiece 100, and needs to be replaced at a predetermined interval or timing. Conventionally, the replacement work was a complicated task of disassembling a part of the handpiece 100 to replace small consumable items, but with the handpiece 100 of the present configuration, replacement can be completed by a simple task of removing the assembly 91 in which the above-mentioned consumable items are integrated from the head part 11 and inserting a new assembly 91 into the head part 11. In addition, since the assembly 91 is replaced as a unit, the user can easily maintain the handpiece without the need to install small consumable items such as the contact 81 in a predetermined position.

[0043] Fig. 13 is a cross-sectional view showing the configuration of an assembly 91A of a modified example. Fig. 14 is an exploded perspective view of the assembly 91A shown in Fig. 13. In the assembly 91A of this modified example, an opening 75d is formed at the top of a head cap 75A, and a cover 93 is detachably attached to the opening 75d. The contact 81 is supported so as to be movable in the up and down direction along an inner circumferential surface 75e of the head cap 75A. The contact 81 is prevented from coming off by an annular locking portion 75f protruding radially inward from the lower end of the inner circumferential surface 75e.

[0044] The lid body 93 is fixed to the head cap 75A by screwing together a female thread formed on the inner peripheral surface of the opening hole 75d and a male thread formed on the outer peripheral surface 93a of the lid body 93. A groove 93b is formed on the top surface of the lid body 93, and the lid body 93 can be removed from the head cap 75A by inserting a tool such as a screwdriver into the groove 93b and rotating it. The lid body 93 may be fixed by a screw as described above, or may be fixed in another manner such as a snap-insertion mechanism.

[0045] According to the assembly 91A of this configuration, the contact 81 and the contact spring 83 can be easily replaced by removing the cover 93 from the head cap 75A, which further improves maintainability. Also, the above-mentioned cylindrical support portion 85 (see FIG. 11) can be omitted.

[0046] The aforementioned conductive path 35 in this assembly 91A is a path that is conductive when the base end face of the dental treatment tool (not shown) comes into contact with the contactor 81, the outer periphery of the contactor 81 comes into contact with the head cap 75A, and further comes into contact with the annular portion 79a of the annular member 79 via the cap spring 77. In this case, it is preferable to provide an insulating layer on the outer surface of the head cap 75 that the user touches.

[0047] The present invention is not limited to the above-described embodiment, and can be appropriately modified, improved, etc. In addition, the material, shape, size, numerical value, form, number, arrangement location, etc. of each component in the above-described embodiment are arbitrary as long as they can achieve the present invention, and are not limited.

[0048] As described above, the present specification discloses the following: (1) A dental handpiece for root canal treatment, comprising: a head portion having a tool holding mechanism for rotatably holding a dental treatment tool; and a grip portion connected to the head portion and having a signal line for transmitting a root canal length measurement signal therethrough, the grip portion having a conductive path formed to electrically connect the dental treatment tool held by the tool holding mechanism to the signal line, The head portion is a contactor that contacts a base end side end surface of the dental treatment tool held by the tool holding mechanism; a head cap having an inner space in which the contact is disposed so as to be movable in an axial direction of the dental treatment tool; a first elastic member disposed in the inner space and elastically biasing the contact toward the dental treatment tool; an annular member arranged to face the dental treatment tool side of the head cap; a second elastic member disposed between the head cap and the annular member in contact with both of them and elastically biases the head cap; Equipped with The annular member is electrically connected to the signal line, the contact, the head cap, the second elastic member, and the annular member, each of which is electrically conductive, form the conductive path from the dental treatment tool in this order; Dental root canal treatment handpiece. According to this dental root canal treatment handpiece, the dental treatment tool abuts against the contactor biased by the first elastic member, thereby preventing poor contact caused by vibrations accompanying the rotation of the dental treatment tool, and enabling a stable extraction of a root canal length measurement signal.

[0049] (2) The head cap has a cylindrical support portion that is disposed in the inner space and supports the contactor in a cylindrical manner so as to be in contact with the contactor within the cylindrical space and to form the conductive path; the first elastic member elastically biases the contact toward the dental treatment tool within the cylindrical support portion, The dental handpiece for root canal treatment according to (1), wherein the second elastic member is arranged in contact with the cylindrical support portion instead of the head cap. According to this dental handpiece for root canal treatment, the conductive path is connected to the signal line through the contactor arranged inside the head, the cylindrical support, the second elastic member, and the annular member, so that the conductive path is not exposed to the outside of the handpiece, and therefore external disturbances of electrical signals from the user or patient of the handpiece will not reach the conductive path.

[0050] (3) The tool holding mechanism comprises: a lock piece that is movable between an engagement position where the lock piece is inserted into a notch portion formed in a part of an outer periphery of the dental treatment tool and a disengagement position where the lock piece is removed from the notch portion; a locking elastic member that biases the lock piece from the disengaged position toward the engaged position; having The dental root canal treatment handpiece according to claim 1, wherein the engagement position is a position in which the base end face of the dental treatment tool pushes the contactor back in the axial direction, causing the contactor to retract. According to this dental handpiece for root canal treatment, when the dental treatment tool is engaged with the lock piece and chucked, the dental treatment tool and the contactor come into contact while being biased by the first elastic member, thereby ensuring reliable contact between the dental treatment tool and the contactor.

[0051] (4) A dental root canal treatment handpiece described in any one of (1) to (3), wherein the contact surface of the contactor that comes into contact with the base end face of the dental treatment tool is a flat surface or a convex curved surface that protrudes toward the base end face. According to this dental handpiece for root canal treatment, it is possible to reduce friction between the base end surface of the dental treatment tool and the contact.

[0052] (5) The dental root canal treatment handpiece according to any one of (1) to (4), wherein the first elastic member and the second elastic member are coil springs. According to this dental handpiece for root canal treatment, a wide range of elastic displacement can be stably obtained by expanding and contracting the coil spring, and a constant elastic force can be maintained even if wear occurs.

[0053] (6) The dental handpiece for root canal treatment according to any one of (1) to (5), wherein the first elastic member is a wave spring. According to this dental handpiece for root canal treatment, the parallelism of the contacts can be increased, and the contact stability between the contacts and the dental treatment tool can be improved.

[0054] (7) a holder provided on the gripping portion for holding the signal line; a leaf spring protruding from the holder toward the head portion; Equipped with The dental root canal treatment handpiece according to any one of (1) to (6), wherein the leaf spring is in elastically biased contact with the annular member. According to this dental handpiece for root canal treatment, the leaf spring is elastically biased against the annular member, thereby ensuring mutual contact and enabling a good conductive state to be stably maintained.

[0055] (8) A dental root canal treatment handpiece described in any one of (1) to (7), wherein the outermost surfaces of the head portion and the gripping portion are formed of an electrically insulating resin material or an electrically insulating layer. With this dental handpiece for root canal treatment, even if a user or patient of the handpiece touches the head or grip, the conductive path is not affected because the outermost surfaces of the head and grip are electrically insulating.

[0056] (9) The head portion is the head cap holding the contact and the first elastic member; The second elastic member; The annular member; a cap ring that holds the above together;

[0023] The assembly includes: The dental root canal treatment handpiece according to any one of (1) to (8), wherein the assembly is removably fixed to the head body excluding the assembly. According to this dental handpiece for root canal treatment, the consumables that need to be replaced are integrated into an assembly, so that the consumables can be easily replaced by replacing the assembly. In addition, there is no need to expose a cover for the consumables on the outer surface of the handpiece, so the appearance of the handpiece is not marred.

[0057] (10) The dental root canal treatment handpiece according to (9), wherein the assembly includes the cap ring fixed to the head body by screw fastening. According to this dental handpiece for root canal treatment, the cap ring and the head body are fastened together with a screw that can be easily attached and detached, so that the assembly can be easily fixed to and detached from the head body.

[0058] (11) The head cap has an opening formed at a top thereof, and a lid is detachably attached to the opening. 10. A dental endodontia treatment handpiece according to claim 9. According to this dental handpiece for root canal treatment, the contacts and the contact springs can be easily replaced by removing the cover from the head cap, thereby further improving maintainability. [Explanation of symbols]

[0059] 11 Head section 13 Grip part 14 Motor section 15 Dental treatment tools 15a Proximal end surface 15b Locking groove 15c Stepped section 21 Motor 23 Drive unit 25 Oral electrode 27 Root canal length measurement unit 29 Control Unit 31 Setting section 33 Display section 35 Conduction Path 37 Rotational Axis 39 Insert material 41 Bevel gear 43 Tip Rotating Shaft 45 Gear section 47 Bevel gear 49 Gear section 51 Code 53 Holder 55 Leaf spring 57 Grip housing 61 Tool holding mechanism 63 Rotor section 63a Protrusion 65 Chuck mechanism 65a Lock piece 65b Elastic member for locking 67A, 67B Rolling bearings 67a End face 69 Locking recess 71 Head housing 73 Cap ring 73a Inner surface 73b Small diameter stepped section 73c Male thread 75,75A Head Cap 75a flange 75b back 75c stepped section 75d opening hole 75e Inner surface 75f Circular locking part 76 Inner Space 75c stepped section 77 Cap spring (second elastic member) 79 Annular Members 79a Circular section 79b Cylindrical part 81 Contact 81a Thick wall part 83 Contact spring (first elastic member) 85 Cylindrical support 85a Circular locking part 85b Fixing flange 87 Outer Ring 87a End face 87b Outer surface 88 Inner Circle 89 Rolling elements 91,91A assembly 100 Dental Root Canal Treatment Handpiece

Claims

1. A dental root canal treatment handpiece comprising: a head portion having a tool holding mechanism for rotatably holding a dental treatment tool; and a grip portion connected to the head portion and having a signal line for transmitting a root canal length measurement signal therethrough, the grip portion being connected to the head portion and having a conductive path formed for electrically connecting the dental treatment tool held by the tool holding mechanism to the signal line, The head portion is a contactor that contacts a base end side end surface of the dental treatment tool held by the tool holding mechanism; a head cap having an inner space in which the contact is disposed so as to be movable in an axial direction of the dental treatment tool; a first elastic member disposed in the inner space and elastically biasing the contact toward the dental treatment tool; an annular member arranged to face the dental treatment tool side of the head cap; a second elastic member disposed between the head cap and the annular member in contact with both the head cap and the annular member and elastically biases the head cap; Equipped with The annular member is electrically connected to the signal line, the contact, the head cap, the second elastic member, and the annular member, each of which is electrically conductive, form the conductive path from the dental treatment tool in this order; Dental root canal treatment handpiece.

2. the head cap has a cylindrical support portion that is disposed in the inner space and supports the contactor so as to be movable in an axial direction of the dental treatment tool while being in contact with the contactor inside a cylinder, and forms the conductive path; the first elastic member elastically biases the contact toward the dental treatment tool within the cylindrical support portion, The second elastic member is disposed in contact with the cylindrical support portion instead of the head cap.

2. The dental endodontia treatment handpiece of claim 1.

3. The tool holding mechanism includes: a lock piece that is movable between an engagement position where the lock piece is inserted into a notch portion formed in a part of an outer periphery of the dental treatment tool and a disengagement position where the lock piece is removed from the notch portion; a locking elastic member that biases the lock piece from the disengaged position toward the engaged position; having The engagement position is a position where the base end surface of the dental treatment tool pushes back the contact in the axial direction and the contact is retracted.

2. The dental endodontia treatment handpiece of claim 1.

4. The contact surface of the contactor that comes into contact with the base end surface of the dental treatment tool is a flat surface or a convex curved surface that protrudes toward the base end surface.

2. The dental endodontia treatment handpiece of claim 1.

5. The first elastic member and the second elastic member are coil springs.

2. The dental endodontia treatment handpiece of claim 1.

6. The first elastic member is a wave spring.

2. The dental endodontia treatment handpiece of claim 1.

7. a holder provided on the gripping portion for holding the signal line; a leaf spring protruding from the holder toward the head portion; Equipped with The leaf spring is elastically biased and in contact with the annular member.

2. The dental endodontia treatment handpiece of claim 1.

8. The outermost surfaces of the head portion and the grip portion are formed of an electrically insulating resin material or an electrically insulating layer.

2. The dental endodontia treatment handpiece of claim 1.

9. The head portion is the head cap holding the contact and the first elastic member; The second elastic member; The annular member; a cap ring that holds the above together; [0023] The assembly includes: The assembly is detachably fixed to the head body excluding the assembly. A dental endodontia treatment handpiece according to any one of claims 1 to 8.

10. In the assembly, the cap ring is fixed to the head body by screw fastening.

10. A dental endodontia treatment handpiece according to claim 9.

11. The head cap has an opening formed at a top thereof, and a lid portion is detachably attached to the opening.

10. A dental endodontia treatment handpiece according to claim 9.

Images