JP5205647B2 - Stainless steel bar - Google Patents

Description

  The present invention relates to a stainless steel bar used for cutting a carious portion of a tooth in dental caries treatment.

  Healthy teeth have enameled surfaces, dentine underneath, and pulp in the dentin. The tooth root is integrally formed in the dentin.

  Caries are generated by the propagation of caries fungi, but caries fungi usually adhere to the recesses on the surface of the enamel and begin to carve the enamel. As the enamel caries progress, the caries reach the dentin and soften. If left untreated, the caries will reach the pulp.

  When the caries portion is, for example, dentin, the treatment of caries is performed by scraping the carious portion from the teeth and filling a prosthesis in the hole.

  The cutting tool used for removing the carious portion is different depending on whether the target portion is enamel or dentin.

  The enamel is very hard with a hardness of Hv 270 to 300, so it is shaved with a dental bar. The dental bar is attached to a rotating instrument such as a handpiece, and a diamond bar, a tungsten carbide bar, or the like is used.

  In such a dental bar, even a hard enamel part can be easily scraped off, so that the dentin underneath can be cut more easily. However, if the carious portion of the dentin is cut with a dental bar, the cutting is easy, so that the peripheral portion other than the carious portion is cut too much, and the damage to the teeth increases.

  Therefore, conventionally, in a dental bar, only the carious portion of enamel is cut, and when it reaches dentin, it is cut with a steel bar. Since the steel bar has a lower hardness than the dental bar, it is possible to prevent the healthy dentin portion from being greatly cut.

  5A and 5B are views of a conventional steel bar, in which FIG. 5A is a front view and FIG. 5B is a cross-sectional view taken along line BB in FIG.

  The conventional steel bar 40 of FIG. 5 includes a base end side handle portion 41, a distal end working portion 42, a plurality of blades 42 a formed on the working portion 42, and the working portion 42 and the handle portion 41. And an intermediate portion 43 having a tapered shape.

  The handle part 41 has an attachment part 41a connected to the handpiece and a straight part 41b for the rotating implement to grip. The mounting portion 41a has an irregular shape in order to have a function of preventing rotation.

  There are the following problems in the cutting with the steel bar shown in FIG. The steel bar 40 is made of carbon steel, and the hardness exceeds Hv800 by heat treatment. On the other hand, the dentin caries have a hardness of about Hv20 and a healthy dentin has a hardness of Hv50-60. It is easy to cut carious parts of dentin with a steel bar with the above hardness, but even if you cut the healthy part of the dentin, it is not much different from cutting the carious part of the feel. So it is a problem that there is a possibility that the healthy dentin is greatly shaved. Sharp cutting to a healthy dentin causes a reduction in tooth quality and must be avoided.

In order to deal with such a problem, Patent Document 1 (Japanese Translation of PCT International Publication No. 2002-532133) proposes to use a cutting tool having a hardness lower than that of healthy dentin that is not caries. That is, a cutting tool having a hardness intermediate between the dentin caries hardness (about Hv20) and the healthy dentin hardness (Hv50-60) is used. When the cutting tool cuts the carious portion and reaches a healthy dentin, the cutting tool blade is worn out and cannot be cut, so there is no worry of cutting the healthy dentin.
Special table 2002-532133

  However, the boundary between the carious portion and the healthy dentin is only required to be a smooth surface. However, if there are fine irregularities, the cutting tool described in Patent Document 1 completely eliminates the carious portion in the fine concave portions. Can not be removed. If the caries part is not completely removed, it becomes a source of infection and is a factor that greatly hinders complete cure.

  The present invention has been conceived from such a situation, and it is possible to cut even a healthy dentin if necessary, such as a fine uneven part, but when cutting a healthy dentin, The object is to provide a steel bar that can be perceived by the surgeon.

  In order to achieve the above object, the steel bar of the present invention has a handle portion detachably coupled to the handpiece on the base end side, and a working portion with a blade for cutting teeth at the tip end. And a steel bar having an intermediate part between the working part and the handle part and having a tapered part in at least a part of the intermediate part, the steel bar is work hardened by wire drawing, It is characterized by being formed of austenitic stainless steel having a fiber-like structure, and having a narrow diameter portion and / or a hole in the middle portion side 1/3 and / or the middle portion of the handle portion.

  The narrow diameter portion may be configured to be formed in the tapered portion, or the narrow diameter portion may be configured to be formed near an end portion on the thickest diameter side of the tapered portion. The narrow diameter portion is preferably a narrow diameter portion (a U-shaped groove or the like) that does not provide a recess angle, but may be a V-shaped groove. Further, the number of small diameter portions is not limited to one, and a plurality of small diameter portions may be formed.

  Although the stainless steel bar of the present invention is made of austenitic stainless steel, it has a fibrous structure by wire drawing and has undergone work hardening, so it has sufficient hardness and strength to cut dentin. ing. And since the carious part of dentin is soft, it can cut without a problem. However, when cutting moves from a carious part to a hard and healthy dentin or enamel, the intermediate part 1/3 and / or the intermediate part of the handle part with the small diameter part bends and rotates by this. A vibration is generated in the stainless steel bar, which can inform the surgeon that healthy dentin is being ground. And it is possible to prevent overcutting by paying attention to the part being cut. In this way, even if the carious portion has irregularities, it can be smoothly cut and removed without leaving the carious portion.

Conventionally, in other dental bars (Peso reamer, Gates drill, etc.), for the purpose of identifying the product size, 1 to 6 narrow diameter portions have been formed on the handle (Japanese Patent No. 3375771). FIG. 1). However, in order to give appropriate mechanical performance (hard to break and rigid) as a bar for root canal cutting, the part that forms the small diameter part is the base end side (attachment to the handpiece) It was not assumed that the narrow-diameter portion is formed within the range of 1/3 of the intermediate portion side of the handle portion or in a thin and flexible portion such as the intermediate portion.

  In the present invention, a narrow-diameter portion and / or a hole is formed for a purpose different from the purpose in the prior art, and when a healthy dentin is cut (because the narrow-diameter portion is formed), the bar is bent. It is an object of the present invention to provide a steel bar that can completely remove carious portions of dentin and that does not cut sound dentin more than necessary.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1A and 1B are views of a stainless steel bar according to the present invention, in which FIG. 1A is a front view and FIG. Compared to the conventional example, the appearance is the same except that there is a small diameter portion 13a.

  Whereas the conventional steel bar 40 is made of steel, the stainless steel bar 10 of the present invention is made of austenitic stainless steel. Austenitic stainless steel wire is cold drawn once or more to obtain the desired thickness. The structure of austenitic stainless steel is drawn into fibers in the axial direction by wire drawing, and the bending strength is improved by undergoing work hardening, and it is possible to exhibit uniform strength without variation over the entire length. Become. Such a material has a concentric hardness distribution. That is, the hardness near the surface is the highest, and the hardness gradually decreases toward the center. Although there is a reduction in area that becomes the hardest by wire drawing, it is possible to obtain a material with the desired hardness and thickness by appropriately selecting the number of wire drawing and the reduction in area. Become. In addition, when the wire drawing is performed beyond the limit that makes it hardest, an annealing process may be provided between the wire drawing and the wire drawing to bring the fiber structure closer to the original granular structure. As described above, the stainless steel bar of the present invention formed from austenitic stainless steel is hardened by work hardening, so that the blade portion has a uniform hardness and more than the conventional steel bar. Softly, by providing a small-diameter portion to be described later, it becomes easy to bend between the working portion and the handle portion, so that there is a feature that the difference in feel when cutting a healthy dentin is conspicuous. On the other hand, since conventional steel bars are hardened by quenching, they tend to be as hard as the cutting edge, and even if healthy dentin is cut, it is difficult to recognize the difference in feel.

  The material manufactured as described above is cut into a predetermined length to form a spherical working part, a handle part coupled to the handpiece, a taper intermediate part between them, and a small diameter part. The stainless steel bar of the present invention is completed by forming a cutting blade in a spherical working portion.

  The stainless steel bar is now complete and can be used, but after this, it is further tempered to slightly harden the surface of the blade edge from the inside, and then remove burrs by etching, etc. You may make it dull.

  The stainless steel bar 10 in FIG. 1 includes a handle portion 11 on the base end side, a working portion 12 at the tip, a plurality of blades 12a formed on the working portion 12, and a gap between the working portion 12 and the handle portion 11. And a tapered intermediate portion 13.

  The handle part 11 has an attachment part 11a connected to the handpiece and a straight part 11b for the rotating implement to grip. The attachment portion 11a has an irregular shape in order to have a function of preventing rotation.

  The working unit 12 has a spherical shape, and a large number of arcuate blades 12a are formed around it. In the embodiment of the present invention, the hardness of the blade 12a is about Hv 600 to 700. This is the hardness that can cut enamel as well as dentin. The blade 12a is formed in the working unit 12 in a spiral shape.

  Although the intermediate portion 13 in this embodiment is tapered, a narrow diameter portion 13 a is formed in the vicinity of the connection portion with the thickest handle portion 11, and a narrow diameter portion 11 c is formed in the handle portion 11. The position of the narrow diameter portion 11c formed on the handle portion 11 is L2 when the length of the handle portion 11 is L1, and the length from the end portion on the intermediate portion 13 side of the handle portion 11 to the narrow diameter portion 11c is L2. <Within a range where the relationship of L1 / 3 is established. In other words, the small diameter portion 11 c is provided in the portion of the handle portion 11 on the middle portion 13 side 1/3. In the embodiment of FIG. 1, the small diameter portions 13a and 11c are both U-shaped grooves, but the present invention is not limited to this form. The shape, width, and depth of the groove are not particularly limited, and the bottom portion may be elongated in the axial direction, like a pot bottom, and may be V-shaped, but no concave angle is provided. When the groove is shaped like a letter, it is difficult for stress to concentrate, so that the structure can be made difficult to break. In the embodiment shown in FIG. 1, the number of the small-diameter portions 13a and 11c is two, but only one or three or more may be used. The position of the small-diameter portion 13a is not particularly limited, but is desirably formed between the center portion of the intermediate portion 13 and the connecting portion with the handle portion 11 in order to bend easily and not easily break.

  FIG. 2 is a diagram showing a state in which the carious portion 22a of the dentin 22 is being cut with the stainless steel bar 10 of FIG.

  The surface of the portion of the carious tooth 20 that protrudes from the gum is covered with enamel 21, and the dentin 22 is below it. There is a tooth follower 23 inside the dentin 22. 2 progresses from the enamel 21 portion to the middle of the dentin 22. When treating the caries 20, first, the carious portion 22 a of the enamel 21 is cut with a dental bar, and the caries of the dentin 22 is carved with the stainless steel bar 10 of FIG. 1 from the hole formed in the enamel 21. The part 22a is cut. The stainless steel bar 10 is attached to a handpiece (not shown) and rotates.

  While the working portion 12 of the stainless steel bar 10 is cutting the carious portion 22a, the intermediate portion 13 is not deformed, so that the operator performs cutting without feeling vibration.

  FIG. 3 is a diagram showing a state where the working unit 12 of the stainless steel bar 10 is cutting the healthy dentin 22. When the working unit 12 reaches the healthy dentin 22, the healthy dentin 22 is harder than the carious portion 22a, and also has the small diameter portions 11c and 13a. The part 13 is warped and vibrates. The surgeon can feel this vibration and recognize that the healthy dentin 22 is being cut. When the stainless steel bar 10 reaches a healthy dentin 22, it bends and vibrates, but it can be cut. Therefore, as shown in FIG. 2, even a carious portion 22a having irregularities and a thin concave portion can be completely removed by cutting together with the surrounding healthy dentin 22 as shown in FIG.

  FIG. 4 is a front view of a second embodiment of the stainless steel bar of the present invention. The stainless steel bar 30 shown in this figure includes a proximal handle portion 31, a distal working portion 32, a plurality of blades 32 a formed in the working portion 32, and the working portion 32 and the handle portion 31. Intermediate portion 33. The handle part 31 has an attachment part 31a connected to the handpiece and a straight part 31b for the rotating implement to grip. The intermediate portion 33 has a straight portion 33a on the working portion 32 side and a tapered portion 33b on the handle portion 31 side. Thus, a part of the intermediate part 33 may be a tapered part. A small diameter portion 33c is formed in the vicinity of the large diameter end of the taper portion 33b. In this way, when the narrow diameter portion 33c is formed in the vicinity of the large diameter end of the tapered portion 33b, in addition to the effect of making the bar difficult to break, even when the bar breaks, it is provided near the large diameter end of the tapered portion 33b. Since the stress concentrates on the small-diameter portion 33c and breaks, there is an advantage that the broken bar can be easily taken out (as compared with the case where the broken portion is broken on the working portion side). The small-diameter portion 33c in this embodiment is a V-shaped groove. In this embodiment, the handle portion 31 is provided with a hole 31c instead of a small diameter portion. The hole 31c may penetrate the handle 31 or may not penetrate. Even when the handle 31 is provided with a hole, it is possible to bend the bar in the same manner as when the narrow diameter portion is provided. The stainless steel bar 30 of the second embodiment can also be cut without bending when the carious portion 22a of the dentin 22 is cut, and when the healthy dentin 22 is cut, it is curved and vibration is generated. This is the same as the embodiment.

  Since the stainless steel bar 10 of the present invention uses austenitic stainless steel, it has a feature that it is not easily rusted. Steel bars are not disposable but are used repeatedly, but once used, they are sterilized by autoclaving before being used again. In the case of a steel bar made of steel, rusting occurs and the color changes to black by repeating the autoclave. On the other hand, since the thing of this invention is a product made from stainless steel, it can be used without rusting even if it repeats an autoclave many times.

  In addition, the conventional steel steel bar and the stainless steel bar 10 of the present invention are similar in appearance even though the materials are completely different, and may be wrong. However, like the stainless steel bar 10 of the present invention, by providing the small diameter portions 11c, 13a, 33c and the hole 31c, it is possible to make a clear difference in appearance and to prevent a mistake. . In addition, by changing the number of the small diameter portions 11c, 13a, 33c and the holes 31c, or coloring the small diameter portions 11c, 13a, 33c and the holes 31c with paint, the usage purpose and size of the stainless steel bars 10, 30 can be changed. You can also show the difference.

  In the present invention, the narrow diameter portions 11c, 13a, 33c and / or the hole 31c are formed in the intermediate portion side 1/3 portion of the handle portions 11, 31 and / or the intermediate portions 13, 33. Even when connected to the handpiece, the small diameter portions 11c, 13a, 33c and the hole 31c are exposed to the outside, and the small diameter portions 11c, 13a, 33c and the hole 31c can be easily seen.

  In the second embodiment, the case where the small diameter portion 33c is formed in the intermediate portion 33 and the hole 31c is formed in the handle portion 31 has been described. You may provide in the part of 1/3 of a part side, the hole 31c may be provided in both the intermediate part 33 and the handle | pattern part 31, or any one may be provided. When the narrow diameter portion and / or the hole is provided in the middle portion side 1/3 of the handle portions 11 and 31, the diameter of the narrow diameter portion is reduced and the size of the hole is smaller than that provided in the intermediate portions 13 and 33. It is preferable to increase the thickness. The reason for providing a narrow-diameter part and / or a hole in the middle part side 1/3 is that it is near the boundary with the middle part and is exposed from the handpiece when the stainless steel bar is gripped by the handpiece. It is easy to bend by making the hole thinner or making the hole larger, but if it is closer to the proximal side than 1/3, it is a part hidden in the handpiece, so even if you make the diameter narrower or make the hole larger It is because it is hard to bend.

It is a figure of the stainless steel bar of this invention, (a) is a front view, (b) is AA sectional drawing of (a). It is a figure which shows the state which is cutting the carious part of a decayed tooth with the stainless steel bar of FIG. It is a figure which shows the state which is cutting the healthy dentin with the stainless steel bar of FIG. It is a front view of 2nd Example of the stainless steel bar of this invention. It is a figure of the conventional steel bar, (a) is a front view, (b) is BB sectional drawing of (a).

Explanation of symbols

10, 30 Stainless steel bar 11, 31 Handle portion 11a, 31a Mounting portion 11b, 31b Straight portion 31c Hole 12, 32 Working portion 12a, 32a Blade 13, 33 Intermediate portion 11c, 13a, 33c Small diameter portion 20 Decay tooth 21 Enamel 22 Dentin 22a Caries 23 Tooth

Claims (3)

It has a handle part detachably coupled to the handpiece on the base end side, and has a spherical working part with a blade for cutting teeth at the tip, between the work part and the handle part. In a steel bar having a taper-shaped intermediate portion, the steel bar is formed by austenitic stainless steel, which is hardened by wire drawing and formed into a fiber-like structure. A small diameter part and / or a hole is formed in the part and / or the intermediate part, and when the working part cuts the dentin of the tooth, the tapered intermediate part is curved so that vibration occurs. Features a stainless steel bar.   The stainless steel bar according to claim 1, wherein the narrow diameter portion is formed in the tapered portion.   The stainless steel bar according to claim 1 or 2, wherein the small-diameter portion is a thin-diameter portion not provided with a dent angle.

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