JP7198191B2 - dental file - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dental file used for enlarging and cleaning root canals in dental treatment.

Reamers and files are known as dental root canal cutting tools used for enlarging and cleaning root canals in dental treatment (see, for example, Patent Document 1). The reamer cuts the inside of the root canal by rotating it, and the file cuts the inside of the root canal by rotating it or pushing and pulling it in the axial direction.

Common dental files include those that are used by holding the grip portion by hand and those that are used by connecting the grip portion to a dental handpiece. A dental file has a spiral working portion tapered toward the tip, a shaft connected to the rear end of the working portion, and a gripping portion connected to the rear end of the shaft. The main performance requirements for such dental files are flexibility to follow complex shaped root canals, machinability to properly cut root canals, and fracture resistance to prevent breakage during work. etc. The higher these performances are, the easier and faster root canal formation can be performed, and the burden on the operator and the patient can be reduced.

JP 2005-278945 A

SUMMARY OF THE INVENTION In view of the circumstances as described above, an object of the present invention is to improve the flexibility, cuttability, and/or breakage resistance of a dental file.

In order to achieve the above objects, the present invention
A dental file having a helically formed working portion, comprising:
The cross-sectional shape of the cross section perpendicular to the longitudinal direction is composed of one arc-shaped portion and three first to third linear portions sequentially continuing from the arc-shaped portion, and the base end to the tip end. The diameter of the virtual circle containing the arc-shaped portion is set small over
A connection point between the first linear portion and the second linear portion and a connection point between the second linear portion and the third linear portion are positioned inside the virtual circle. is set and
A diameter passing through a connection point between the arcuate portion and the first linear portion and an angle formed by the first linear portion are set to be large from the base end portion to the distal end portion. .

Thereby, for example, when the dental file rotates in the direction from the arcuate portion to the first linear portion, cutting is performed mainly in the arcuate portion and the first linear portion while the arcuate portion follows the inner surface of the cutting hole. The angle formed by the first linear portion and the diameter passing through the connection point between the arc-shaped portion and the first linear portion is determined from the proximal end to the distal end. By setting the diameter to be large, for example, it is possible to improve cutting performance, ejection performance, and flexibility toward the base end while suppressing the cutting force near the tip.

According to the present invention, the flexibility, cuttability and/or breakage resistance of dental files can be increased.

1 is a plan view of the dental file of Embodiment 1. FIG. FIG. 2 is a sectional view taken along the line II-II of FIG. 1; FIG. 2 is a cross-sectional view taken along line III-III of FIG. 1; FIG. 2 is a cross-sectional view corresponding to the III-III line in FIG. 1 in Embodiment 2;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In addition, in the following embodiments and modifications, constituent elements having similar functions are denoted by the same reference numerals, and descriptions thereof are omitted.

(Embodiment 1)
As shown in FIG. 1, the dental file 100 includes a working portion 100a for cutting a root canal, a shaft 100b connected to the rear end of the working portion 100a, and a dental handpiece connected to the rear end of the shaft 100b. and a gripping portion (not shown). As the material of the dental file 100, for example, highly elastic nickel titanium suitable for treating a complicatedly curved root canal is often used, but not limited to this, stainless steel, various alloys, plastics, etc. etc. may also be applied.

The working portion 100a of the dental file 100 has a tapered outer enveloping surface with a cross section that decreases toward the tip, and has a spiral cross section with a similar shape. More specifically, the cross-sectional shape of the working portion 100a perpendicular to the longitudinal direction is formed, for example, as shown in FIG. 2 or FIG. there is That is, the cross-sectional shape is composed of one arc-shaped portion 111 (land portion) and three linear portions 112 to 114, first to third, successively continuing from the arc-shaped portion 111. The diameter of an imaginary circle 101 including the arc-shaped portion 111 and centered at O is set to decrease from the base end portion to the tip end portion of the portion 100a. The linear portions 112 to 114 do not necessarily have to be straight lines. For example, even if they are slightly curved, the effects described below can be obtained. Here, in FIGS. 2 and 3, for the sake of convenience, the virtual circles 101 are drawn on a reduced scale such that the diameters are equal.

A connection point 122 between the first linear portion 112 and the second linear portion 113 and a connection point 123 between the second linear portion 113 and the third linear portion 114 are the virtual circle 101. It is set to be positioned inside the Also, although not particularly limited, for example, the first linear portion 112 and the third linear portion 114 are formed parallel to each other. As a result, it is easy to facilitate blade groove grinding and improve blade groove grinding accuracy.

Here, when the dental file 100 is normally used, the main rotation direction R is the rotation direction in which cutting waste in the working part 100a is carried toward the base. Specifically, for example, When the spiral of the dental file 100 is a right-handed screw, if the rotation direction R is mainly counterclockwise when viewed from the tip side, when rotating in such a direction of R, the arc-shaped portion 111 and The connection point 121 with the first linear portion 112 will produce a cutting action as the dental file 100 rotates. The rotation direction of the dental file 100 is not limited to the R direction, and may be used in a mode including reverse rotation or a mode in which the rotation direction alternates.

Also, the angles A11 and A12 formed by the first linear portion 112 and the diameter of the virtual circle 101 passing through the connecting point 121 between the arc-shaped portion 111 and the first linear portion 112 are the angles ( For example, A11) is set to be larger than the angle at the proximal end (eg, A12). Although the absolute angles A11 and A12 are not particularly limited, they are set in the range of 10° to 40°, for example.

The setting of the angles A11 and A12 as described above is such that, for example, the relative distance (distance ratio) from the center O of the virtual circle 101 to the diameter of the virtual circle 101 to the first linear portion 112 is This can be done by setting the distance L11 at the base end to be longer than the distance L21 at the proximal end.

Also, although not equivalent to the setting as described above, in practice, the ratio of the distances L21 and L22 between the first linear portion 112 and the third linear portion 114 to the diameter of the virtual circle 101 is defined. It can also be set by That is, for example, the cross-sectional shape of the dental file 100 is symmetrical with respect to a straight line passing through the center O of the virtual circle 101, and the first linear portion 112 and the third linear portion 114 are formed in parallel. In this case, the ratio of the distances L21 and L22 between the first linear portion 112 and the third linear portion 114 to the diameter of the virtual circle 101 is from the proximal end to the distal end of the dental file 100 You may make it set large. Also, the central angles A21 and A22 corresponding to the arcuate portion 111 may be set to be large from the proximal end to the distal end of the dental file 100 .

These make it easy to exhibit the effect of improving followability in a stage where cutting force near the tip is to be slightly suppressed (initial stage of root canal formation, etc.), or in a root canal where the vicinity of the root is curved. In addition, cutting performance and discharge performance are improved in the shank portion, and flexibility is also improved in the shank portion, so that both machinability and operability can be achieved. Furthermore, there is a so-called "elasticity" in the vicinity of the tip, which makes it easy to improve the rotation transmission force.

(Embodiment 2)
The same angular relationship as the angles A11 and A12 between the distal end and the proximal end of the dental file 100 as described above can also be set by forming the cross-sectional shape at the proximal end as shown in FIG. . That is, the angle (the angle on the side of the arcuate portion 111) formed by the perpendicular drawn from the center O of the arcuate portion 111 to the first linear portion 112 and the perpendicular drawn to the third linear portion 114 is the tip The angle A31 at the base end is set to be smaller than the angle A33 at the base end. As a result, the angles A11 and A13 formed by the first linear portion 112 and the diameter of the virtual circle 101 passing through the connection point 121 between the arc-shaped portion 111 and the first linear portion 112 are the angles at the tip portion. (eg, A11) can be set to be larger than the angle at the proximal end (eg, A13).

As a result, not only can moderate cutting performance be obtained at the stage where cutting force near the tip should be slightly reduced (initial stage of root canal formation, etc.), but also at the finishing stage and in cases where the overall cutting force is required. It becomes easier to perform. In addition, it is possible to increase the cutting force toward the shank while providing high followability to curved root canals. In addition, cutting performance and discharge performance are improved in the shank portion, and flexibility is also improved in the shank portion, making it possible to achieve both cutting performance and operability.

(Other Matters)
In the cross-sectional shape of the dental file 100 as described above, the distances from the center O of the virtual circle 101 to two or more of the first to third linear portions 112 to 114 are set equal to each other, or these lines The shaped portions 112 to 114 may contact the same inscribed circle having the same center as the center O of the virtual circle 101 . Such a shape can be easily formed by equalizing the amount of cutting from the outer circumference of the virtual circle 101 to each of the linear portions 112 to 114. For example, in a program for operating a grinding machine, a predetermined amount of cutting It is possible to easily perform grinding using the same routine.

REFERENCE SIGNS LIST 100 dental file 100a working part 100b shaft 101 imaginary circle 111 arc-shaped part 112 first linear part 113 second linear part 114 third linear part 121 connection point 122 connection point 123 connection point

Claims (6)

A dental file having a helically formed working portion, comprising:
The cross-sectional shape of the cross section perpendicular to the longitudinal direction is composed of one arc-shaped portion and three first to third linear portions sequentially continuing from the arc-shaped portion, and the base end to the tip end. The diameter of the virtual circle containing the arc-shaped portion is set small over
A connection point between the first linear portion and the second linear portion and a connection point between the second linear portion and the third linear portion are positioned inside the virtual circle. is set and
A diameter passing through a connection point between the arcuate portion and the first linear portion and an angle formed by the first linear portion are set to be large from the base end portion to the distal end portion. dental file. The dental file of claim 1, comprising:
A dental file, wherein a ratio of the distance from the center of the virtual circle to the first linear portion with respect to the diameter of the virtual circle is set large from the proximal end to the distal end. The dental file of claim 2, wherein
The first linear portion and the third linear portion are formed in parallel, and the distance between the first linear portion and the third linear portion with respect to the diameter of the virtual circle A dental file, characterized in that the ratio is set to be large from the proximal end to the distal end. The dental file of claim 2, wherein
a perpendicular drawn from the center of the virtual circle to the first linear portion;
A dental file characterized in that the angle formed by the arc-shaped portion side formed by a perpendicular drawn from the center of the virtual circle to the third linear portion is set small from the base end portion to the tip end portion. . The dental file of claim 1, comprising:
A dental file, wherein a central angle corresponding to the arc-shaped portion is set to be large from the proximal end to the distal end.
The dental file of claim 1, comprising:
A dental file, wherein distances from the center of the virtual circle to the first to third linear portions are set equal to each other.

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