CN113197685A

CN113197685A - Dental root canal treatment instrument

Info

Publication number: CN113197685A
Application number: CN202110105945.XA
Authority: CN
Inventors: 松谷和彦; 村井秀行; 堀井真理; 村上悦男; 高野真弘
Original assignee: Mani Inc
Current assignee: Mani Inc
Priority date: 2020-01-31
Filing date: 2021-01-26
Publication date: 2021-08-03
Anticipated expiration: 2041-01-26
Also published as: CN113197685B

Abstract

The invention provides a dental root canal treatment instrument, which improves the flexibility, the cutting property and/or the fracture resistance of the dental root canal treatment instrument. In the dental root canal treatment instrument (100), the cross-sectional shape at a first longitudinal direction position on the distal end side is formed of an arc-shaped portion (111) and a first linear portion (112), and the number of linear portions forming the cross-sectional shape closer to the proximal end side than the distal end portion is increased.

Description

Dental root canal treatment instrument

Technical Field

The present invention relates to a root canal therapeutic device having a spiral cutting edge, which is used for enlarging, cleaning, or shaping a root canal during dental treatment.

Background

As a dental root canal cutting tool used for enlarging and cleaning a root canal in dental treatment, there are a drill and a file (for example, refer to patent document 1). The bur cuts primarily by rotation within the root canal, and the file cuts within the root canal by rotation or axial push-pull.

A general dental file includes a dental file used by holding a grip portion with a hand, and a dental file used by connecting the grip portion to a dental handpiece (hand). The dental file includes: a working part which is spiral and is tapered towards the tail end; a shaft connected to a rear end of the working unit; and a grip portion connected to a rear end of the shaft. The main performances required for such dental files include flexibility to follow a root canal having a complicated shape, cuttability to properly cut the root canal, and fracture resistance to prevent breakage during operation. The higher these properties are, the easier and faster the root canal formation is performed, and the burden on the operator and the patient can be reduced.

The end portion of the root canal of the tooth is extremely fine, and the root canal as a whole has a slightly curved shape. Moreover, the shape of the root canal varies greatly from individual to individual. The curved root canal wall is cut or ground to form a cone shape in endodontic treatment. Such root canal formation is performed using a root canal treatment instrument having a helical cutting edge called a file or drill.

That is, the surgeon performs the shaping of the root canal by performing a rotating operation or a pushing and pulling operation by pinching a selected file or drill with a fingertip. Recently, the selected endodontic instrument is held by a chuck of a rotary drive instrument called a handpiece and rotated in this state to perform the endodontic treatment, and the number of cases has increased.

An endodontic instrument is configured to have a handle and a cutting member fixed to the handle. The handle has an optimal shape corresponding to the holding operation of the doctor or the operation of holding the mobile phone. The cutting member has a shaft portion fixed to the handle and an operating portion continuous with the shaft portion, and the operating portion is formed in a tapered shape.

The root canal treatment instrument is required to have good performance of cutting the canal wall, good performance of discharging cutting debris, performance of following the root canal flexibly, and the like. Further, in the root canal treatment, there is also a demand for a performance of preventing the distal end portion of the root canal treatment instrument from penetrating into the distal end portion of the root canal and being difficult to handle and broken. In order to meet such a demand, root canal treatment instruments disclosed in patent documents 2 and 3 have been proposed.

The invention described in patent document 2 relates to a root canal treatment instrument such as a file or a drill, which does not exhibit the cutting performance during the pressing operation but exhibits the cutting performance only during the pulling operation. The root canal treatment instrument is configured such that the cross-sectional shape of the working section is a parallelogram having a length of 1.5 times or more the length of the short side of the long side, and an acute-angled blade of two blades that are adjacent in the longitudinal direction of the working section is disposed on the shaft side.

In the root canal treatment instrument described in patent document 2, the working portion is formed in a parallelogram in cross section, and therefore has flexibility and exhibits good following properties to a curved root canal. Further, since the cutting performance is exhibited when the doctor performs the pulling operation, the cutting debris can be easily discharged from the root canal.

The invention described in patent document 3 relates to a root canal treatment instrument such as a file or a drill, which is used to improve the flexibility of the root portion in the working portion. The root canal treatment instrument is formed such that the cross-sectional shape of the working section is a parallelogram, the length of the long side/short side in the cross-section of the root section on the shaft section side is greater than the length of the long side/short side in the cross-section of the tip section, and the torsion angle on the root section side is greater than the torsion angle on the tip section.

In the root canal treatment instrument described in patent document 3, the flexibility on the root side can be improved by changing the length of the long side/short side in the cross section of the parallelogram at the root and the distal end of the working portion. Therefore, the operability can be improved.

Patent document 1: japanese patent laid-open publication No. 2005-278945

Patent document 2: japanese patent No. 4214285 (Japanese patent laid-open No. Hei 11-358917)

Patent document 3: japanese patent No. 4214286 (Japanese patent laid-open No. 2000-000481)

In the root canal treatment instruments described in patent documents 2 and 3, since the blades each having a sharp angle are present on the circumference, the root canal treatment instruments have a characteristic of excellent cutting performance. However, since the cutting performance is excellent, there is a possibility that the cutting performance for the root canal wall is exerted preferentially at the distal end portion of the root canal to deviate from the intended treatment route, and that the operation is difficult because the cutting performance is deep into the root canal wall.

In addition, although a root canal treatment instrument having a substantially D-shape in which a cross section of a working portion is formed of one flat surface and an arc surface over the entire length is provided, the root canal treatment instrument has a problem that it is inflexible and suitable for treatment through a root canal, but has poor cutting performance.

Disclosure of Invention

In view of the above problems, an object of the present invention is to improve flexibility, cuttability and/or fracture resistance of a dental root canal treatment instrument.

Another object of the present invention is to provide a dental root canal treatment instrument which has the features of patent documents 2 and 3 and which can reliably follow the end portion of the root canal and prevent penetration into the canal wall.

In order to achieve the above object, a dental root canal treatment instrument according to the present invention includes a working portion formed in a spiral shape, wherein a first cross-sectional shape of a cross section perpendicular to a longitudinal direction at a first longitudinal direction position on a distal end portion side of the working portion includes an arc-shaped portion and a first linear portion, and the number of linear portions forming a cross-sectional shape closer to the proximal end portion side than the distal end portion is increased.

Thus, for example, by forming the linear portions one by one from the distal end portion of the dental root canal treatment instrument, the length of the arc-shaped portion is increased in the vicinity of the distal end portion, and thus, for example, the following ability in a root canal or the like bent in the vicinity of the apical end is easily improved. On the other hand, the flexibility is easily improved by improving, for example, the discharge performance up to the proximal end portion to prevent clogging, and both the machinability and the workability are easily achieved.

According to the present invention, the flexibility, the cuttability and/or the fracture resistance of the dental endodontic instrument can be improved.

In the dental root canal treatment instrument (hereinafter, simply referred to as "root canal treatment instrument") according to the present invention, even a root canal having a curved distal end portion can reliably follow the root canal, and penetration into the canal wall can be prevented.

That is, in the first tubular therapeutic device, the cross section near the shaft portion of the working portion is a parallelogram, and the cross section near the distal end portion is formed in a shape including one or two sides continuous with one of a pair of long sides and a pair of short sides facing each other and an arc, the long sides and the short sides constituting the cross section near the shaft portion of the working portion. The cross section from the vicinity of the tip portion to the vicinity of the shaft portion is formed such that a side continuous with any one of a pair of long sides and a pair of short sides facing each other in the cross section in the vicinity of the shaft portion constituting the working portion is formed in this order from the vicinity of the tip portion.

That is, since the cross section near the distal end portion of the working portion is formed by one or two sides and an arc, the number of blades contributing to cutting at the time of endodontic treatment is reduced. Therefore, the cutting performance in the vicinity of the distal end portion is reduced as compared with the cutting performance in the vicinity of the shaft portion, and penetration into the root canal wall can be prevented. Further, in the root canal treatment, the arc surface contacts the root canal wall and can be guided by the root canal wall surface to advance toward the apical end, and even a curved root canal can follow the curve.

In particular, the cross section from the vicinity of the distal end portion to the vicinity of the shaft portion is formed to shift from a parallelogram formed by one or two sides and an arc to a parallelogram formed by two or three sides and an arc, formed by four sides, and formed by four sides. Therefore, along with the change in the cross-sectional shape, improvement in cutting performance can be achieved. In addition, the cross-sectional shape can be changed from two sides to four sides.

In the second tube treatment instrument, the cross section from the vicinity of the distal end portion of the working portion to the vicinity of the shaft portion is a parallelogram including one side continuous with a pair of long sides or a pair of short sides opposed to the cross section in the vicinity of the shaft portion constituting the working portion, or two sides and an arc connecting the long sides and the short sides, two sides or three sides and an arc connecting the sides continuous with the one side or two sides, and three sides and an arc or four sides connecting the sides continuous with the two sides or three sides, and four sides.

Therefore, the cutting performance in the vicinity of the distal end portion is reduced as compared with the cutting performance in the vicinity of the shaft portion, and penetration into the root canal wall can be prevented. Further, in the root canal treatment, the arc surface contacts the root canal wall and can be guided by the root canal wall surface to advance toward the apical end, and even a curved root canal can follow the curve.

In the third tube treatment instrument, a cross section from the vicinity of the distal end portion of the working portion to the vicinity of the shaft portion includes one side or a pair of sides and an arc continuous with a pair of long sides or a pair of short sides which face the cross section in the vicinity of the shaft portion constituting the working portion, two sides or three sides and an arc continuous with the one side or the pair of short sides continuous with the pair of long sides or the pair of short sides are connected, and three sides and an arc or four sides continuous with the short sides are connected with the pair of sides, and a parallelogram is configured by four sides. In addition, the cross-sectional shape can also be changed from two sides to four sides.

Drawings

Fig. 1 is a plan view of a dental file according to embodiment 1.

Fig. 2 is a sectional view taken along line II-II of fig. 1.

Fig. 3 is a sectional view taken along line III-III of fig. 1.

Fig. 4 is a sectional view taken along line IV-IV of fig. 1.

Fig. 5 is a cross-sectional view taken along line V-V of fig. 1.

Fig. 6 is a top view of a dental file according to embodiment 2.

Fig. 7 is a sectional view taken along line II-II of fig. 6.

Fig. 8 is a sectional view taken along line III-III of fig. 6.

Fig. 9 is a sectional view taken along line IV-IV of fig. 6.

Fig. 10 is a cross-sectional view taken along line V-V of fig. 6.

Fig. 11 is a top view of a dental file according to embodiment 3.

Fig. 12 is a sectional view taken along line II-II of fig. 11.

Fig. 13 is a sectional view taken along line III-III of fig. 11.

Fig. 14 is a cross-sectional view taken along line V-V of fig. 11.

Fig. 15 is a side view of the endodontic instrument of the first embodiment.

Fig. 16 is an enlarged view illustrating the cross-sectional shape of the working section of the first embodiment.

Fig. 17 is an enlarged perspective view for explaining the working unit according to the first embodiment.

Fig. 18 is a side view of the endodontic instrument of the second embodiment.

Fig. 19 is an enlarged view illustrating the cross-sectional shape of the working section of the second embodiment.

Fig. 20 is a side view of the endodontic instrument of the third embodiment.

Fig. 21 is an enlarged view illustrating the cross-sectional shape of the working section of the third embodiment.

Fig. 22 is an enlarged perspective view for explaining the working unit according to the third embodiment.

Fig. 23 is a side view of the endodontic instrument of the fourth embodiment.

Fig. 24 is an enlarged view illustrating the cross-sectional shape of the working section of the fourth embodiment.

Description of the reference numerals

100 dental file

100a working part

100b shaft part

101 imaginary circle

111 arc part

111a, 111b arc-shaped part

112 first linear portion

113 second linear portion

114 third linear portion

115 fourth linear portion

121 connection point

122 connection point

123 connection point

124 connection point

A shaft part

B operation part

C handle

Near the axis of Ba

Near the terminal part of Bb

Bc. Bd position

1a long side

1b to 1d sides continuous from the long side 1a

2a short side

2 b-2 d from the short side 2a

3a long diagonal

4a short diagonal

5 a-5 d acute angle knife edge

Knife edge with obtuse angles of 6 a-6 d

7 arc of a circle

Detailed Description

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the following embodiments and modifications, the same reference numerals are given to components having the same functions, and descriptions thereof are omitted.

The root canal treatment instrument of the present invention will be described below. The root canal treatment instrument of the present invention has a shaft portion and a tapered working portion continuous to the shaft portion, and is used for shaping a root canal to be treated in a dental treatment into a tapered shape. In particular, the curved distal end portion of the root canal can be reliably followed, and penetration into the canal wall can be prevented.

(embodiment mode 1)

As shown in fig. 1, a dental file (dental root canal treatment instrument) 100 includes: a root canal cutting work section 100 a; a shaft portion 100b connected to a rear end of the working portion 100 a; and a grip portion, not shown, connected to the rear end of the shaft portion 100b and attached to the dental handpiece. As a material of the dental file 100, for example, highly elastic nickel titanium or the like suitable for treatment of a root canal having a complicated curvature is used.

The working portion 100a of the dental file 100 is configured such that the envelope surface of the outer surface has a tapered shape whose cross section is reduced toward the tip, and a cross section having a similar shape is formed in a spiral shape. More specifically, the cross-sectional shape of the working unit 100a in a cross section perpendicular to the longitudinal direction, for example, the cross-sectional view taken along line II-II to the cross-sectional view taken along line V-V of fig. 1, is as shown in fig. 2 to 5.

Namely, the cross-sectional shape includes: one arc-shaped portion 111 (margin portion); and one to three first to third linear portions 112 to 114 or four linear portions 112 to 115 which are sequentially increased from the distal end portion to the proximal end portion of the dental file 100 so as to be sequentially connected on the downstream side in the main rotational direction R, and the cross-sectional shape is set such that the diameter of a virtual circle 101 including the arc-shaped portion 111 decreases from the proximal end portion to the distal end portion of the working portion 100 a. Here, the main rotational direction R of the dental file 100 is a rotational direction in which chips in the working portion 100a are carried toward the base portion when the dental file 100 is normally used. Specifically, for example, when the spiral of the dental file 100 is a right-handed thread, the counterclockwise direction is the main rotational direction R when viewed from the distal end side. The direction of rotation of the dental file 100 is not limited to the R direction, and may be used in a mode including reverse rotation and a mode in which rotation is alternately changed. The linear portions 112 to 115 are not necessarily precise straight lines, and for example, even when they are slightly curved, the operational effects described below can be obtained. In fig. 2 to 5 and the following drawings, for the sake of easy understanding, the imaginary circles 101 are shown on a scale having the same diameter.

To describe more specifically the change in the cross-sectional shape of the dental file 100 from the distal end portion to the proximal end portion, first, the cross-sectional shape is formed such that the first linear portion 112 is connected to the connection points 121 and 122 at both ends of the arc-shaped portion 111 having a center angle of 180 ° or more at the line II-II cross-sectional position (fig. 2) in fig. 1. From the sectional position of the line II-II to the sectional position of the line III-III in fig. 1 (fig. 3), the second linear portion 113 oriented substantially at right angles to the first linear portion 112 is positioned gradually from the outer peripheral side of the imaginary circle 101 toward the center, and the connection point 122 generated between the second linear portion 113 and the first linear portion 112 is also positioned gradually inside the imaginary circle 101. Next, from the III-III line cross-sectional position to the IV-IV line cross-sectional position (fig. 4), the third linear portion 114, which is substantially perpendicular to the second linear portion 113, is positioned gradually from the outer peripheral side of the imaginary circle 101 toward the center, and the connection point 123 generated between the third linear portion 114 and the second linear portion 113 is also gradually positioned inside the imaginary circle 101. Then, from the IV-IV line cross-sectional position to the V-V line cross-sectional position (fig. 5), the fourth linear portion 115 substantially perpendicular to the third linear portion 114 is positioned from the outer peripheral side of the imaginary circle 101 toward the center, and after that, the fourth linear portion 115 corresponds to a position connecting both ends of the arc-shaped portion 111 in the IV-IV line cross-sectional position.

As described above, when the linear portions 112 to 115 are formed one by one from the distal end portion of the dental file 100, the arc-shaped portion 111 is long near the distal end portion, and therefore, it is easy to improve the following performance to a root canal or the like curved near the root apex. On the other hand, the discharge performance up to the proximal end portion is improved to prevent clogging, and the flexibility is also easily improved, so that both the machinability and the workability are easily achieved.

(embodiment mode 2)

The order of forming the linear portions 112 to 114 from the distal end portion of the dental file 100 toward the proximal end portion may be as shown in fig. 6 to 10, for example. That is, in the cross section at the line II-II position in fig. 6, as shown in fig. 7, the same cross sectional shape as that in fig. 2 is provided, but in the cross section at the line III-III position in fig. 6, as shown in fig. 8, the third linear portion 114 substantially parallel to the first linear portion 112 is formed, and the third linear portion 114 is located at a position corresponding to a chord of the arc-shaped portion 111 in fig. 7 which is separated from the first linear portion 112. Therefore, the cross-sectional shape of the rectangle surrounded by these

linear portions

112 and 114 and the two arc-shaped

portions

111a and 111b is formed. Subsequently, in the cross section at the IV-IV line position in fig. 6, as shown in fig. 9, the second linear portion 113 connecting the connection points 122, 123 is formed, for example, in the same cross-sectional shape as in fig. 4 of embodiment 1, and as shown in fig. 10, in the same cross-sectional shape as in fig. 5.

When the cross-sectional shape is formed as described above, particularly in the vicinity of the cross-sectional position shown in fig. 8, for example, when the rotation is performed in the main rotation direction R, the cutting action is generated by the two

connection points

121 and 123, and high cutting performance can be easily obtained.

The order of forming the linear portions 112 to 115 may be set in various ways, and for example, the fourth linear portion 115 may be formed earlier than the second linear portion 113 and/or the third linear portion 114. In the case of forming the following triangular sectional shape, the order of forming the linear portion may be set variously in the same manner.

(embodiment mode 3)

The dental file 100 is not limited to a rectangular cross-sectional shape in the vicinity of the proximal end portion, and may have a triangular cross-sectional shape as shown in fig. 11 to 14, for example. That is, in the cross section at the line II-II position in fig. 11, as shown in fig. 12, the same cross-sectional shape as that in fig. 2 is provided, but in the cross section at the line III-III position in fig. 11, as shown in fig. 13, the third linear portion 114 is formed continuously with the connection point 121, which is the upstream side end portion of the first linear portion 112 in the main rotational direction R of the dental file. Subsequently, in the cross section at the V-V line position in fig. 11, as shown in fig. 14, the second linear portion 113 connecting the connection points 122, 123 is formed, thereby forming a triangular cross sectional shape.

When the cross-sectional shape is formed as described above, particularly in the vicinity of the cross-sectional position shown in fig. 14, a cutting action is generated by the three connection points 121 to 123, and high cutting performance can be more easily obtained.

In addition, in the cross section at the line III-III position in FIG. 11, the second linear portion 113 may be formed instead of the third linear portion 114, and then the third linear portion 114 may be formed in the cross section at the line V-V position.

(other embodiments)

In the above embodiments, the cross-sectional shape of the distal end portion of the dental file 100 is formed by the one arc-shaped portion 111 and the one first linear portion 112, and the cross-sectional shape of the proximal end portion is formed by three or four linear portions, that is, the first to third linear portions or the first to fourth linear portions 112 to 115.

For example, the cross-sectional shape of the distal end portion side may be formed by one arc-shaped portion 111 and two or more linear portions 112 to 114, and the cross-sectional shape of the proximal end portion side may have the arc-shaped portion 111. More specifically, the cross-sectional shape of the distal end portion may be configured as shown in fig. 3, 4, 8, and 13, and the cross-sectional shape of the proximal end portion may be configured as shown in fig. 3, 4, 8, 9, and 13.

The linear portions are not limited to being increased one by one from the distal end portion side to the proximal end portion side, and two or more linear portions may be added. More specifically, the cross-sectional shape of the portion closer to the proximal end than the cross-sectional shape shown in fig. 2 and 12 may be configured as shown in fig. 4, 5, and 14, and the cross-sectional shape of the portion closer to the proximal end than the cross-sectional shape shown in fig. 3 and 8 may be configured as shown in fig. 5 and 10.

More specifically, for example, the cross-sectional shape from the distal end portion to the proximal end portion may be configured as follows.

FIGS. 2, 3, 4 and 5

FIGS. 2, 3 and 4

FIGS. 2 and 3

FIGS. 3, 4 and 5

FIGS. 3 and 4

FIGS. 4 and 5

FIGS. 2, 3 and 5

FIGS. 2, 4 and 5

FIGS. 2 and 4

FIGS. 3 and 5

FIGS. 2 and 5

FIGS. 7, 8, 9 and 10

FIGS. 7, 8 and 9

FIGS. 7 and 8

FIGS. 8, 9 and 10

FIGS. 8 and 9

FIGS. 7, 8 and 10

FIGS. 8 and 10

FIGS. 12, 13 and 14

FIGS. 12 and 13

FIGS. 12 and 14

FIGS. 13 and 14

(other items)

In the cross-sectional shape of the dental file 100 according to each of the above embodiments, the distances from the center of the imaginary circle 101 to two or more of the first to third linear portions 112 to 114 may be set equal to each other, or the linear portions 112 to 114 may be tangent to the same inscribed circle. Such a shape can be easily formed by making equal the cut amounts from the outer periphery of the virtual circle 101 to the linear portions 112 to 114, and for example, in a program for operating a grinding machine, a routine of a predetermined cut amount can be commonly used to easily perform grinding or the like.

The connection points 121 to 124 are not particularly limited to being located on the circumference of the virtual circle 101 or located inside the virtual circle 101, and may be set in various ways. For example, in fig. 13, instead of the third linear portion 114, a third linear portion 114 'indicated by a broken line may be formed to generate a connection point 121' located inside the imaginary circle 101. In fig. 14, instead of the second linear portion 113, a second linear portion 113 'indicated by a broken line may be formed to generate a connection point 123' located inside the imaginary circle 101. Further, the connection point 121 ' and the linear portions 114 ', 113 ' may be formed so that the connection point is located inside the imaginary circle 101. Similarly, in the cross-sectional shapes shown in fig. 5 and 10, instead of the fourth linear portion 115, fourth linear portions 115', 115 ″ corresponding to positions closer to the center of the imaginary circle 101 than the fourth linear portion 115 may be formed.

For example, the cross-sectional shapes shown in fig. 5, 10, and 14 may be rectangles, regular triangles, etc., or squares, rhombuses, parallelograms, trapezoids, isosceles triangles, right triangles, etc.

(examples)

Further, in the endodontic instrument of the present invention, the cross section from the vicinity of the distal end portion of the working portion to the shaft portion side is formed as follows: the parallelogram is formed from a substantially D-shape composed of one side and a circular arc, a shape composed of two sides and a circular arc, and a shape composed of three sides and a circular arc. Therefore, the flexibility can be improved from the vicinity of the distal end portion to the shaft portion side, and the cutting performance can be improved.

Further, by increasing the diameter of the inscribed circle of the parallelogram in the cross section near the tip end portion of the working portion, the torsional strength can be increased, and a large rotational force of the mobile phone can be transmitted.

The working portion is formed in a tapered shape that tapers from the shaft portion side to the distal end portion. The taper of the working portion is standardized in ISO as 2/100. However, the taper is not necessarily limited to the above, and an optimum taper is preferably set as appropriate in accordance with the treatment site. The thickness of the working portion is set in the range of 0.06mm to 1.40mm at the end portion of the working portion, and is standardized to a plurality of different sizes within the range. Further, the working portion is formed in a spiral shape, and the cutting chips can be discharged through the gap because the gap is formed between the adjacent blades at the time of endodontic treatment.

The endodontic instrument of the present invention is not limited to being held by a doctor or being attached to a handpiece for operation during treatment. Therefore, the endodontic instrument is configured to be held by a surgeon by integrally molding the shaft portion with a synthetic resin handle or by integrally molding the shaft portion with a metal stem so as to be held by a chuck of a handpiece in accordance with an operation method.

In the endodontic instrument of the present invention, the cross section in the vicinity of the shaft portion in the working portion is formed into a parallelogram having a pair of opposing long sides, a pair of opposing short sides, sharp cutting edges formed on the long diagonal, and obtuse cutting edges formed on the short diagonal.

Further, the cross section near the tip end portion of the working section is formed in a substantially D shape composed of one side and an arc continuous with any one of a pair of long sides and a pair of short sides constituting the cross section near the shaft portion, a deformed D shape or a drum shape composed of two sides and an arc. Therefore, in the vicinity of the tip end portion, the blade is formed by one side intersecting the arc.

As described above, the angle formed by the edge of the blade formed near the distal end portion of the working portion and the arc is larger than the angle formed by the long side and the short side of the blade formed on the long diagonal line near the shaft portion. Therefore, at the time of endodontic treatment, the cutting performance against the canal wall becomes poor, and it is possible to prevent penetration into the canal wall in the vicinity of the distal end portion. As a result, the treatment can be performed in a desired path by flexibly following the curve of the root canal.

Further, the cross-sectional area near the distal end portion of the working portion is larger than that in the case where the cross-sectional shape near the distal end portion is a parallelogram-like shape that constitutes the cross-sectional area near the shaft portion. Therefore, the risk of breakage during treatment can be prevented, and inflexibility (so-called stiffness) is increased, so that a favorable reaction force can be transmitted to a doctor during treatment, or the rotational force of a mobile phone can be transmitted reliably.

In the second tube treatment instrument according to the present invention, the length from the vicinity of the distal end portion to the position spaced apart by the predetermined dimension, that is, the "predetermined length range" is set in order, and in each of the predetermined length ranges, for one side of the substantially D-shaped cross section constituting the vicinity of the distal end portion of the working portion, two sides and an arc are added, which are connected to each other, from one pair of sides that are continuous from one pair of sides that constitute the parallelogram in the vicinity of the shaft portion, and the other side is added to the two sides to form three sides and an arc, and the three sides are added to the side that is continuous from one pair of sides to form the parallelogram in the four sides, so that the number of sides is increased in order. The method of increasing the number of sides is not limited to one-by-one increase, and may be, for example, increased from two sides to four sides.

In the third tube treatment instrument according to the present invention, the predetermined length ranges are set in order from the vicinity of the distal end portion, and in each of the predetermined length ranges, for one side of the substantially D-shaped cross section constituting the vicinity of the distal end portion of the working portion, two parallel sides and arcs formed by one side continuous from one pair of sides constituting the parallelogram in the vicinity of the shaft portion are added, one side continuous from the other pair of sides is added to the two sides to form three sides and an arc, and a parallelogram formed by four sides continuous from one pair of sides is added to the three sides, so that the number of sides is increased in order. The method of increasing the number of sides is not limited to one-by-one increase, and may be, for example, increased from two sides to four sides.

In the present invention, the dimensions of the vicinity of the distal end portion of the working unit and the predetermined length range from the vicinity of the distal end portion toward the axial portion side are not particularly limited, and are preferably set as appropriate in accordance with the intended use of the root canal treatment instrument and the thickness and length of the working unit.

From the viewpoint of the inventors of the present application, it is preferable that the vicinity of the distal end portion of the working portion is in a range of about 2.5% to 3% of the total length of the working portion from the tip end of the working portion, the predetermined length range from the vicinity of the distal end portion is 5% to 50% of the total length of the working portion from the tip end, and the predetermined length range further apart from the predetermined length range toward the shaft portion side is 15% to 75% of the total length of the working portion from the tip end, and within the range, the thickness of the target endodontic instrument and the total length (16mm, 20mm) of the working portion are set in consideration.

The vicinity of the shaft portion is a vicinity of a boundary portion between the working portion exhibiting good grinding performance and a transition portion formed between the working portion and the shaft portion and transitioning from the working portion to the shaft portion. However, the boundary portion is not necessarily required, and the length from the tip end necessary for performing the actual root canal treatment may be specified.

In the present invention, the material of the endodontic instrument is not limited, and austenitic stainless steel, martensitic stainless steel, titanium alloy having a shape memory function, or the like can be used selectively. Further, it is preferable to manufacture the target endodontic instrument by processing the selected material by an optimum processing method.

The working portion is formed by continuous cutting or grinding from the distal end side to the shaft portion side. Therefore, the cross-sectional shape of the working portion continuously changes from the vicinity of the distal end portion to the vicinity of the shaft portion. Therefore, in the following description, the cross-sectional shape at each position is shown by sequentially setting positions of a predetermined length range from the vicinity of the distal end portion, but the cross-sectional shape at each position is only a part of the shape of the working portion under change taken out, and is not necessarily limited to the shape shown in the drawings.

Next, the structure of the endodontic instrument of the first embodiment will be described with reference to fig. 15 to 17. The endodontic instrument of the present embodiment is configured to be attached to a handpiece and driven to rotate. Therefore, the root canal treatment instrument is configured to include: a shaft portion A; a working part B continuous with the shaft part A; and a handle C for fixing the shaft A and holding the shaft A by a chuck of a mobile phone.

The shaft portion a and the working portion B are continuously formed from one piece of material. The shaft portion a is formed in a shaft shape, one side is continuously formed with the working portion B, and the other side is connected to and integrated with the shank portion C.

The working portion B is formed in a tapered shape that tapers from the shaft portion a side to the tip portion, and a plurality of positions are set from the tip end to the vicinity of the shaft portion, corresponding to the entire length of the working portion B. That is, in the working section B, a shaft portion vicinity Ba (cross section IIBa), a tip portion vicinity Bb (cross section IIBb), a predetermined position Bc (cross section IIBc) within a predetermined length range from the tip portion vicinity, and a predetermined position Bd (cross section IIBd) within a predetermined length range from the predetermined position Bc are set, respectively.

The section IIBa near the shaft portion a and the section IIBb near the tip end portion Bb have different shapes. That is, as shown in fig. 16 (a), in the cross section IIBa in the vicinity of the shaft portion Ba, in the parallelogram formed by the pair of opposing long sides 1a and the pair of opposing short sides 2a, the acute-angled cutting edge 5a is formed on the long diagonal line 3a, and the obtuse-angled cutting edge 6a is formed on the short diagonal line 4 a.

As shown in fig. 16 (B), the cross section IIBb in the vicinity Bb of the distal end portion of the working portion B is formed in a substantially D shape including one side 1B and an arc 7, and the one side 1B is continuous with one of a pair of short sides 2a constituting the cross section IIBa in the vicinity of the shaft portion.

The intersection of the side 1b and the arc 7 in the cross section IIBb is configured as a cutting edge 5b, and the cutting edge 5b is continuous with the acute-angled cutting edge 5a in the cross section IIBa near the shaft portion. Since the angle of the blade 5b is larger than that of the blade 5a, cutting performance is reduced as compared with the vicinity of the shaft portion. Therefore, in the root canal treatment, penetration into the root canal wall can be prevented.

Further, the diameter of the inscribed circle (core) of the cross section IIBb is larger than, for example, the diameter of the inscribed circle when the similar shape of the cross section IIBa near the shaft portion Ba is set as the cross section near the tip end portion. That is, in the vicinity Bb of the tip end portion, the core has a large thickness, stiffness is increased, and torsional strength is increased, so that sufficient rotational force can be transmitted.

As shown in fig. 16 (c), the cross section IIBc set at the position Bc spaced apart from the vicinity Bb of the distal end portion of the working section by the predetermined length range is formed by a side 1c, which is continuous from one of the pair of short sides 2a constituting the cross section IIBa near the shaft portion Ba, a side 2c, which is continuous with the side 1c and is continuous from one of the pair of opposing long sides 1a constituting the cross section IIBa, and a circular arc 7. That is, the cross section IIBc has a shape in which the side 2c is connected to the side 1b in the cross section IIBb in the vicinity of the terminal portion Bb. The side 1c and the side 2c form an obtuse blade edge 6c continuous from the obtuse blade edge 6a in the cross section IIBa in the vicinity of the shaft portion Ba.

As shown in fig. 16 (d), the cross section IIBd set at the position Bd spaced apart from the position Bc by the predetermined length range is formed by a pair of sides 1d, a side 2d, and a circular arc 7, the pair of sides 1d being continuous from a pair of short sides 2a constituting the cross section IIBa in the vicinity Ba of the shaft portion, the side 2d being connected to the side 1d and being continuous from one of a pair of opposing long sides 1a constituting the cross section IIBa. That is, the cross section IIBd has a shape in which the side 1d is connected to the sides 1c and 2c in the cross section IIBc at the position Bc.

Further, the arc 7 is replaced with a side continuous with the pair of long sides 1a of the cross section IIBa constituting the shaft portion vicinity Ba, by connecting the side continuous with the pair of long sides 1d of the cross section IIBd constituting the shaft portion vicinity Ba to the shaft portion vicinity Ba from the position Bd, thereby shifting to the parallelogram of the cross section IIBa constituting the shaft portion vicinity Ba.

In the endodontic instrument of the first embodiment formed as described above, the stiffness can be changed from the vicinity Bb of the distal end portion to the position Bc and the position Bd, and a high rotational force can be transmitted.

The shape of the cross section IIBa to the cross sections IIBb, IIBc, and IIBd is changed as described above, and the feed amount of the cutting material or the grinding material during the cutting process may be adjusted according to the position of the working portion B in the longitudinal direction.

Next, the structure of the endodontic instrument according to the second embodiment will be described with reference to fig. 18 and 19. In the drawings, the same reference numerals are given to the same portions or portions having the same functions as those of the first embodiment, and the description thereof is omitted.

Fig. 18 and 19 show the shaft portion vicinity Ba and the cross section VBa, and the tip portion vicinity Bb and the cross section VBb. From the tip end portion vicinity Bb to the shaft portion vicinity Ba, a pair of long sides and a pair of short sides for constituting a parallelogram as a cross section VBa of the shaft portion vicinity Ba are formed in this order, as in the first embodiment described above.

In the present embodiment, as shown in fig. 19 (a), in the cross section VBa of the Ba in the vicinity of the shaft portion, in the parallelogram formed by the pair of opposing long sides 1a and the pair of opposing short sides 2a, the acute-angled blade edge 5a is formed on the long diagonal line 3a, and the obtuse-angled blade edge 6a is formed on the short diagonal line 4 a.

As shown in fig. 19 (b), the cross section VBb of the tip end portion vicinity Bb is formed into a shape including one side 1b, one side 2b, and a circular arc 7, the one side 1b being continuous with one of a pair of long sides 1a that constitute the cross section VBa of the shaft portion vicinity Ba, the one side 2b being continuous with the one side 1b and continuous with one of the pair of short sides 2 a.

As described above, in the present embodiment, the cross section VBb at the tip end portion vicinity Bb has the

sides

1b, 2b, which sides 1b, 2b are continuous with the long side 1a constituting the cross section VBa of the shaft portion vicinity Ba and the short side 2a connected to the long side 1a, respectively. Therefore, the shape of the cross section VBb is similar to the shape of the cross section IIBc at the position Bc in the first embodiment.

That is, in the present embodiment, the cross section VBb of the tip end portion vicinity Bb is constituted by the two

sides

1b, 2b and the arc 7 connected to each other, and the side continuous with the

side

1a or 1b is connected at a position spaced apart from the tip end portion vicinity Bb by a predetermined dimension. Further, the remaining sides are connected at positions spaced apart by a predetermined dimension to form a parallelogram having a shape similar to the cross-section Vba of Ba near the shaft portion. The method of increasing the number of sides is not limited to one-by-one increase, and may be, for example, increased from two sides to four sides.

Even in the root canal treatment instrument of the second embodiment configured as described above, the stiffness can be changed from the vicinity Bb of the distal end portion to the vicinity Ba of the shaft portion, and a high rotational force can be transmitted.

Next, the structure of the endodontic instrument according to the third embodiment will be described with reference to fig. 20 to 22. In the drawings, the same portions as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the present embodiment, the cross section VIIBb of the tip end portion vicinity Bb is the same as the corresponding cross section IIBb in the first embodiment described above, as shown in fig. 21 (b). In addition, as shown in fig. 21 (a), the cross section VIIBa of the shaft portion vicinity Ba is different from the corresponding cross section IIBa in the first embodiment, and the positional relationship between the short side and the long side is reversed.

As shown in fig. 21 (c), the cross section VIIBc set to the position Bc within the predetermined length range from the vicinity Bb of the distal end portion of the working unit is formed by a pair of opposing sides 1c and a pair of opposing arcs 7, the pair of opposing sides 1c being continuous with a pair of opposing long sides 1a of the cross section VIIBa constituting the vicinity Ba of the shaft portion, and the pair of arcs 7 connecting the pair of sides 1 c. That is, the cross section VIIBc has a shape in which the side 1c faces the side 1b in the cross section VIIBb in the tip end portion vicinity Bb.

As shown in fig. 21 (d), the cross section VIIBd set at the position Bd spaced apart from the position Bc by the predetermined length range is formed by a pair of sides 1d, a side 2d, and a circular arc 7, the pair of sides 1d being continuous from a pair of long sides 1a constituting the cross section VIIBa of the shaft portion vicinity Ba, the side 2d being connected to the side 1d and being continuous from one of a pair of opposing short sides 2a constituting the cross section VIIBa. That is, the cross section VIIBd has a shape in which a side 2d is connected to a pair of sides 1c in the cross section VIIBc at the position Bc described above.

Further, from the position Bd to the shaft portion vicinity Ba, a side continuous with the pair of short sides 2a of the cross section VIIBa constituting the shaft portion vicinity Ba is connected to the pair of sides 1d of the cross section VIIBa constituting the position Bd, whereby the arc 7 is replaced with the side, and the transition is made to a parallelogram of the cross section VIIBa constituting the shaft portion vicinity Ba.

In this embodiment, similarly to the first embodiment, the stiffness is increased in the vicinity Bb of the tip portion of the working portion B, and the stiffness can be continuously decreased from the vicinity Bb of the tip portion to the vicinity Ba of the shaft portion, and the rotational force of the cellular phone can be transmitted.

Next, the structure of the endodontic instrument according to the fourth embodiment will be described with reference to fig. 23 and 24. In the drawings, the same portions as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

Fig. 23 and 24 show the vicinity Ba of the shaft portion and the cross section XBa, and the vicinity Bb of the tip portion and the cross section XBb. A pair of long sides and a pair of short sides of a parallelogram constituting the cross section XBa of the shaft portion vicinity Ba are formed in this order from the tip portion vicinity Bb to the shaft portion vicinity Ba, similarly to the first embodiment. The method of increasing the number of sides is not limited to one-by-one increase, and may be, for example, increased from two sides to four sides.

In the present embodiment, as shown in fig. 24 (a), in the cross section XBa of the Ba in the vicinity of the shaft portion, an acute-angled cutting edge 5a is formed on the long diagonal line 3a and an obtuse-angled cutting edge 6a is formed on the short diagonal line 4a in a parallelogram formed by the pair of opposing long sides 1a and the pair of opposing short sides 2 a.

As shown in fig. 24 (b), the cross section XBb of the tip end portion vicinity Bb is formed in a shape including a pair of sides 1b and a circular arc 7, and the pair of sides 1b is continuous with both of a pair of long sides 1a constituting the cross section XBa of the shaft portion vicinity Ba. Thus, the shape of the cross section XBb is similar to the shape of the cross section VIIBc at the position Bc in the third embodiment.

In the present embodiment, the cross section XBb of the tip end portion vicinity Bb is formed by the pair of opposing sides 1b and the arc 7, and a side continuous with any one of the pair of opposing short sides 2a is connected at a position spaced apart from the tip end portion vicinity Bb by a predetermined dimension. Further, the remaining sides are connected at positions spaced apart from the positions by a predetermined dimension, forming a parallelogram having a shape similar to the cross section Xba of the Ba near the shaft portion.

Even in the root canal treatment instrument of the fourth embodiment configured as described above, the stiffness can be changed from the vicinity Bb of the distal end portion to the vicinity Ba of the shaft portion, and a high rotational force can be transmitted.

Industrial applicability

The root canal treatment instrument of the present invention can be used for root canal treatment in dental treatment.

Claims

1. A dental root canal treatment instrument having a working part formed in a spiral shape, characterized in that,

a first cross-sectional shape of a cross section perpendicular to the longitudinal direction at a first longitudinal direction position on the distal end portion side of the working portion includes an arc-shaped portion and a first linear portion, and

the number of linear portions forming a cross-sectional shape closer to the proximal end portion side than the distal end portion is increased.

2. The dental root canal treatment instrument according to claim 1, wherein a connection point between the added linear portion and a linear portion formed from a cross-sectional shape on a distal end portion side of the working portion with respect to the added linear portion is located on an inner side with respect to a circle including the arc-shaped portion.

3. The dental endodontic instrument according to claim 1 or 2,

a second cross-sectional shape and a third cross-sectional shape at a second longitudinal direction position and a third longitudinal direction position on the base end portion side in this order from the distal end portion, the second cross-sectional shape and the third cross-sectional shape having a shape in which the second linear portion and the third linear portion are sequentially increased,

the first to third linear portions are formed continuously in this order on the downstream side in the main rotational direction of the dental root canal treatment instrument.

4. The dental endodontic instrument according to claim 3, wherein a fourth cross-sectional shape at a fourth longitudinal direction position on a proximal end side of the third cross-sectional shape has a fourth linear portion corresponding to a position connecting both ends of the circular arc-shaped portion in the third cross-sectional shape or a position on a center side of a circle including the circular arc-shaped portion.

5. The dental endodontic instrument according to claim 1 or 2,

the second linear portion is formed at a position corresponding to a chord of the arc-shaped portion in the first cross-sectional shape that is apart from the first linear portion, and

the second linear portion and the third linear portion are formed on a downstream side of the first linear portion in a main rotational direction of the dental root canal treatment instrument.

6. The dental endodontic instrument according to claim 5, wherein a fourth cross-sectional shape at a fourth longitudinal direction position on a proximal end side of the third cross-sectional shape has a fourth linear portion corresponding to a position connecting both ends of the circular arc-shaped portion in the third cross-sectional shape or a position on a center side of a circle including the circular arc-shaped portion.

7. The dental endodontic instrument according to claim 1 or 2,

a second cross-sectional shape at a second longitudinal direction position on the base end portion side than the distal end portion has a shape that increases a second linear portion,

the second linear portion is formed to be continuous with an upstream end or a downstream end of the first linear portion in a main rotational direction of the dental root canal treatment instrument.

8. The dental endodontic instrument according to claim 7, wherein a third cross-sectional shape at a third longitudinal direction position on a proximal end side of the second cross-sectional shape has a third linear portion corresponding to a position connecting both end portions of the circular arc-shaped portion in the second cross-sectional shape or a position on a center side of a circle including the circular arc-shaped portion.

9. The dental endodontic instrument of claim 1,

further comprises a shaft part continuous with the working part,

the working portion is formed in a tapered shape tapering from the shaft portion to the tip portion,

the cross section near the shaft portion of the working portion is a parallelogram having a pair of opposing long sides, a pair of opposing short sides, an acute-angled blade formed on the long diagonal, and an obtuse-angled blade formed on the short diagonal,

the cross section near the distal end portion of the working portion is formed in a shape including one or two sides continuous with any one of a pair of long sides and a pair of short sides that are opposite to each other and constitute the cross section near the shaft portion of the working portion, and an arc, and the cross section from the distal end portion vicinity to the shaft portion vicinity is formed in a manner such that a side continuous with any one of the pair of long sides and the pair of short sides that are opposite to each other and constitute the cross section near the shaft portion of the working portion and not continuous with the side forming the cross section near the distal end portion is formed in this order from the distal end portion vicinity.

10. The dental endodontic instrument of claim 1,

further comprises a shaft part continuous with the working part,

a cross section in the vicinity of a distal end portion of the working portion is formed in a shape including one side continuous with one of a pair of long sides and a pair of short sides opposed to each other and constituting a cross section in the vicinity of a shaft portion of the working portion, or two sides continuous with the long sides and the short sides and connected to each other, and an arc, and a cross section at positions separated by a predetermined size from the vicinity of the distal end portion toward the vicinity of the shaft portion is formed in a shape including: one side continuous with any one of a pair of opposing long sides and a pair of short sides constituting a cross section near the shaft portion of the working portion or two sides continuous with the long sides and the short sides and connected to each other is connected to a side continuous with any one of a pair of opposing long sides and a pair of short sides constituting a cross section near the shaft portion and not continuous with a side forming a cross section near the tip portion, and an arc portion is reduced.

11. The dental endodontic instrument of claim 1,

further comprises a shaft part continuous with the working part,

the cross section of the working part near the shaft part is a parallelogram with a pair of opposite long sides, a pair of opposite short sides, an acute-angle cutting edge formed on one long diagonal and an obtuse-angle cutting edge formed on the other short diagonal,

the cross section near the distal end portion of the working portion is formed in a shape including one side continuous with one of a pair of opposing long sides and a pair of opposing short sides constituting the cross section near the shaft portion of the working portion, or a pair of opposing sides, and an arc, and the cross section from the proximal end portion toward the proximal shaft portion is formed in the following shape at predetermined positions: one side continuous to any one of a pair of opposing long sides and a pair of short sides constituting a cross section near the shaft portion of the working portion or a pair of opposing sides is connected to a side continuous to any one of the pair of opposing long sides and the pair of short sides constituting the cross section near the shaft portion and not continuous to a side forming the cross section near the tip portion, and the circular arc portion is reduced.