JP2009261847A - Dental cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dental cutting tool where a cutting amount is large since an edge blunts little with increase of a used time. <P>SOLUTION: In the dental cutting tool where a plurality of cutting edges 22a are arranged at nearly regular intervals around a rotary shaft O, the heights of adjacent cutting edges from the rotary shaft are made to be different from each other. Namely, the eight cutting edges 22a are arranged at equal intervals of 45&deg; with respect to the rotary shaft O. A cutting edge 22a1 and a cutting edge 22a1' are positioned symmetrically with respect to the rotary shaft O. Similarly, a cutting edge 22a2 and a cutting edge 22a2' are positioned symmetrically with respect to the rotary shaft O, a cutting edge 22a3 and a cutting edge 22a3' are positioned symmetrically with respect to the rotary shaft O, and a cutting edge 22a4 and a cutting edge 22a4' are positioned symmetrically with respect to the rotary shaft O. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a dental cutting tool for cutting tooth enamel, metal, dentin, nerves, and the like, and particularly relates to a dental cutting tool that is hard to lose sharpness and can improve the cutting amount.

  In general, when treating a tooth, a dentist cuts the tooth using a cutting tool such as a reamer or file having a blade, a peso reamer, a gates drill, or a carbide bar. These cutting tools have a spiral blade, and this blade portion is applied to an affected part of a tooth or inserted into a root canal, and is cut by push-pull or rotary cutting. Then, the cutting tool is repeatedly exchanged as necessary, and formed into a desired shape while changing the size. There are a method of cutting by hand while holding a handle portion of the cutting tool, and a method of driving by using rotational power from an engine such as a motor by connecting to a handpiece.

  The reamer has a large spiral pitch and is a loose spiral, and is mainly used for rotary cutting. Since the file has a smaller pitch than the reamer, the reamer is mainly used for push-pull cutting like a file. Further, drills that drill holes in teeth such as Peasorima, Gates drills, and carbide bars have a spiral blade, and this blade has a shape that can be cut at the tip of a cutting tool.

  As a material for the dental cutting tool, general tool steel may be used, but stainless steel is often used because it is resistant to rust. Moreover, since the enamel part of the tooth is hard, cutting with stainless steel is difficult. Therefore, diamond or tungsten carbide may be used as a dental cutting tool for punching teeth. For dentin, a steel bar made of general tool steel or a stainless steel bar made of stainless steel may be used.

  FIG. 6 is a front view of a carbide bar in one of the conventional dental cutting tools. FIG. 7 is an enlarged cross-sectional view taken along line CC of FIG.

  The carbide bar 10 shown in FIG. 6 includes a proximal handle portion 11, a distal working portion 12, a plurality of blades 12 a formed on the working portion 12, and a taper between the working portion 12 and the handle portion 11. And an intermediate portion 13 having a shape.

  Among these, the working part 12 at the tip is made of tungsten carbide, and the handle part 11 and the intermediate part 13 are made of stainless steel.

  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 handle portion 11 and the intermediate portion 13 are made of stainless steel.

  A tungsten carbide lump is connected to the tip of the intermediate portion 13, and the working portion 12 having a spherical shape and a large number of spiral blades 12a is formed by grinding. Since the working unit 12 is made of tungsten carbide, the blade 12a is hard, and the hard enamel on the tooth surface can be easily cut.

  As shown in FIG. 7, there are eight blades 12a of the working unit 12 at equal intervals. Each blade 12a has the same blade edge angle, rake angle, clearance angle, and lead angle, and the height of the blade 12a. The same is true. Therefore, the tips of the blades 12a are arranged on the same circle 12b.

  However, when the tip heights of the plurality of conventional blades 12a are all equal, there is a problem that as the cutting time increases, the blades 12a are evenly worn and the sharpness rapidly decreases. It was.

  The present invention has been made to solve such problems, and it is an object of the present invention to provide a dental cutting tool that has a reduced feeling of sharpness due to an increase in use time and an improved usability.

  In order to achieve the above object, the dental cutting tool of the present invention is a dental cutting tool in which a plurality of cutting blades are arranged at substantially equal intervals around a rotating shaft, and the height of the adjacent cutting blade from the rotating shaft is high. It is characterized by the difference.

  Arbitrary one of the cutting blades has a blade having the same height at a position symmetrical with respect to the rotation axis, and a pair of blades are formed by the two blades at the symmetrical position. It can be set as the structure arrange | positioned at an equal angle with respect to the said rotating shaft.

  Alternatively, in a dental cutting tool in which a plurality of cutting blades are arranged at approximately equal intervals around the rotation axis, the blade angles of adjacent cutting blades are different.

  According to the dental cutting tool of the present invention, in the plurality of cutting blades formed on the dental cutting tool, the adjacent cutting blades have different heights. Since the state which does not change and does not change continues for a long time, the cutting amount is increased as compared with the conventional dental cutting tool, and it is possible to shorten the cutting time and reduce the burden on the patient.

  If the blade angle is changed instead of the height of the cutting blade, the progress of wear is also different. And since it wears first from the one with a small blade angle, and the state where the sharpness does not deteriorate and does not change continues for a long time, the amount of cutting increases as compared with the conventional dental cutting tool, and the cutting time There is a special effect that can be shortened. The same effect can be obtained when both the height of the adjacent cutting blade and the blade angle are changed.

  A pair of blades are formed by two blades at symmetrical positions, and a plurality of pairs of blades are arranged at an equal angle with respect to the rotating shaft, so that vibration does not occur during use, and stable cutting is achieved. It can be performed.

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

  FIG. 1 is a front view of a dental cutting tool of the present invention. The dental cutting tool of the present invention has a configuration similar in appearance to the conventional carbide bar 10 described in FIG. That is, the proximal end side handle portion 21, the distal end working portion 22, a plurality of cutting blades 22 a formed in the working portion 22, and a tapered intermediate portion 23 between the working portion 22 and the handle portion 21. And have. Among these, the working part 22 at the tip is made of tungsten carbide, and the handle part 21 and the intermediate part 23 are made of stainless steel.

  The handle part 21 has an attachment part 21a connected to the handpiece and a straight part 21b for the rotating implement to grip. The attachment portion 21a has a deformed shape in order to have a function of preventing rotation.

  FIG. 2 is an enlarged cross-sectional view taken along line AA in FIG. The working portion 22 is formed with eight cutting blades 22a (representation of 22a1, 22a2, 22a3, 22a4, 22a1 ', 22a2', 22a3 ', 22a4') in a spiral shape. However, in the dental cutting tool 20 of the present invention, the eight cutting blades 22a are not the same height.

  The eight cutting blades 22a are arranged at equal intervals of 45 ° with respect to the rotation axis O, and the cutting blade 22a1 and the cutting blade 22a1 ′ are symmetrical with respect to the rotation axis O, that is, 180.゜ It is in a different position. Similarly, the cutting blade 22a2 and the cutting blade 22a2 ′ are in a symmetric position with respect to the rotational axis O, and the cutting blade 22a3 and the cutting blade 22a3 ′ are in a symmetric position with respect to the rotational axis O. The blade 22a2 and the cutting blade 22a2 ′ are in positions symmetrical with respect to the rotation axis O. Each cutting blade is in a symmetrical position and is in a position that is 180 ° different, but it may not be exactly 180 °, and there may be a variation of about ± 10 °.

  The cutting blade 22a1 and the cutting blade 22a1 'are paired, are inscribed in the circle 25, and have the same height (= distance) from the rotation axis O. The cutting blade 22a2 and the cutting blade 22a2 ′ are inscribed in the circle 26, the cutting blade 22a3 and the cutting blade 22a3 ′ are inscribed in the circle 27, and the cutting blade 22a4 and the cutting blade 22a4 ′ are inscribed in the circle 28. , Each is paired. The circles 25, 26, 27, and 28 are increased by 0.05 mm in diameter in this embodiment. The shape of each cutting blade 22a is the same, and the rake angle, the blade angle, and the clearance angle are also the same angle.

  The dental cutting tool 20 rotates in the direction of the arrow in FIG. 2 to perform cutting. The rake angle S is a negative rake angle, but there is no problem even if it is a positive rake angle.

  This dental cutting tool 20 is attached to a handpiece and used at a high speed rotation of 100,000 to 300,000 times / minute. Although the heights of the cutting blades 22a are not uniform, they can be used in the same manner as a normal dental cutting tool without feeling strong vibration because they rotate at high speed. In particular, since the height from the rotation axis O of the paired cutting blades 22a provided at the symmetrical position is the same, vibration can be suppressed. Although the heights of the paired cutting blades 22a are the same, some variation is allowed, and a desired effect can be obtained if the variation is about ± 10 μm.

  In addition, although the dental cutting tool of the said Example is rotated and used at high speed, the dental cutting tool of this invention is applicable also to the file, reamer, etc. which are used for root canal treatment. In the case of a dental cutting tool used by turning with these hands, vibration is not a problem.

The dental cutting tool 20 is sequentially subjected to cutting from a cutting blade having a high height. When the highest cutting blade is worn, the cutting blade having the next height is used for cutting, and the cutting blade is sequentially reduced to a lower cutting blade. Since almost the same sharpness can be maintained, the cutting amount is increased and the cutting time can be shortened as compared with the conventional dental cutting tool. That is, when SUS304 plate material and melamine resin plate material were used as the work material and an experiment was conducted to examine the change in the cut amount by cutting into 10 times, the initial cut amount (weight of the cut face per unit time) and The ratio of the cutting amount after 10 times of use is improved by about 34% when the work material is SUS304, and by about 51% when the work material is melamine resin, compared with a conventional dental cutting blade of uniform height. did. Cutting test conditions when using SUS304 plate material were model number 1557, workpiece angle 0 °, cutting depth 3.0 mm, air pressure 2.7 Kg / cm ² , cutting load 23 g, cutting time 1 min / time, melamine resin Cutting test conditions when using the plate material are melamine model number 5, workpiece angle 0 °, cutting depth 0.5 mm, air pressure 2.7 kg / cm ² , cutting load 23 g, cutting time 0.5 sec / time. In addition, the amount of cutting after 10 times of use (the weight of the faceted material cut per unit time) increased by an average of about 10% from that of conventional cutting blades having the same height.

  In the above embodiment, the heights of the two cutting blades at the symmetrical positions are the same, but the present invention is not limited to this configuration. For example, the height may be changed for all eight blades. Moreover, although the difference of the height of an adjacent blade is made small, this is not limited to an Example. Furthermore, the working unit 22 is not limited to tungsten carbide, and steel, austenitic stainless steel drawn into a fiber structure, various ceramics, or the like can be used.

  FIG. 3 is a front view of the second embodiment of the present invention, and FIG. 4 is an enlarged sectional view taken along line BB of FIG. In this embodiment, the number of cutting blades is six.

  The dental cutting tool 30 includes a proximal handle portion 31, a distal working portion 32, a plurality of blades 32 a formed on the working portion 32, and a tapered intermediate portion 33. The front working portion 32 is made of tungsten carbide, and the handle portion 31 and the intermediate portion 33 are made of stainless steel. The handle portion 31 includes an odd-shaped attachment portion 31a connected to the handpiece, and a straight portion 31b for gripping the rotating device.

  The six cutting blades 32a (representation of 32a1, 32a2, 32a3, 32a1 ′, 32a2 ′, 32a3 ′) are equally arranged at 60 ° intervals with respect to the rotation axis O, and the cutting blades 32a1 And the cutting blade 32a1 ′ are symmetrical with respect to the rotation axis O, that is, at positions different by 180 ° and have the same height. Similarly, the cutting blade 32a2 and the cutting blade 32a2 ′ are symmetrically positioned with respect to the rotation axis O and have the same height, and the cutting blade 32a3 and the cutting blade 32a3 ′ are symmetrical with respect to the rotation axis O. At the same height. In this embodiment, three pairs of cutting blades are provided.

  The cutting blade 32a1 and the cutting blade 32a1 ′ are inscribed in the circle 35, the cutting blade 32a2 and the cutting blade 32a2 ′ are inscribed in the circle 36, and the cutting blade 32a3 and the cutting blade 32a3 ′ are inscribed in the circle 37. ing. The circles 35, 36, and 37 are increased in diameter by 0.05 mm in this embodiment. The shape of each cutting blade 32a is the same, and the rake angle, the blade angle, and the clearance angle are also the same angle.

  The dental cutting tool 30 rotates in the direction of the arrow in FIG. 2 to perform cutting. The rake angle is approximately 0 °.

  The dental cutting tool 30 is attached to a handpiece and used at a high speed rotation of 100,000 to 300,000 times / minute in the same manner as described above. Although the heights of the cutting blades 32a are not uniform, they can be used in the same manner as normal dental cutting tools without feeling strong vibrations because they rotate at high speed. In particular, the pair of cutting blades at symmetrical positions have the same height, so that the balance is good and vibration can be suppressed.

  In addition, the cutting blades with the highest height are used for cutting, but when the highest cutting blade wears, the cutting blade with the next height is used for cutting, and the cutting blades with the same height are almost the same. Since the sharpness can be maintained, the cutting amount is increased as compared with the conventional dental cutting tool, and the cutting time can be shortened. Thus, compared with the conventional dental cutting blade of uniform height, it is difficult to reduce the sharpness and the amount of cutting is increased, so that the feeling of use can be improved.

  FIG. 5 is an enlarged cross-sectional view of the working unit 42 according to the third embodiment of the present invention. In the first and second embodiments, the heights of the adjacent cutting blades are changed, but here the blade angles are made different by changing the rake angle of the adjacent cutting blades.

  The overall configuration of the dental cutting tool is the same as that of the dental cutting tool 20 of the embodiment shown in FIG. The working unit 42 corresponds to the working unit 22 in the embodiment of FIG.

  The working unit 42 is formed with eight cutting blades 42a in a spiral shape. However, the rake angle and the cutter angle of the eight cutting blades 42a are not the same.

  Eight cutting blades 42 a 1, 42 a 2, 42 a 3, 42 a 4, 42 a 1 ′, 42 a 2 ′, 42 a 3 ′, and 42 a 4 ′ are arranged at an equal interval of 45 ° with respect to the rotation axis O. Therefore, four sets of cutting blades facing the rotation axis O with a difference of 180 ° are configured. The rake angle between the cutting blade 42a1 and the cutting blade 42a1 ′ is S1, and similarly, the rake angle between the cutting blade 42a2 and the cutting blade 42a2 ′ is S2, and the rake angle between the cutting blade 42a3 and the cutting blade 42a3 ′ is S3. The rake angle of the cutting blade 42a4 and the cutting blade 42a4 ′ is S4. The rake angle is increased by 5 ° from the rake angle S1 to S4.

  The clearance angle between the cutting blade 42a1 and the cutting blade 42a1 ′ is N1, and similarly, the clearance angle between the cutting blade 42a2 and the cutting blade 42a2 ′ is N2, and the clearance angle between the cutting blade 42a3 and the cutting blade 42a3 ′ is N3. The clearance angle between the cutting blade 42a4 and the cutting blade 42a4 ′ is N4. Then, if the cutter angle = the rake angle + the clearance angle, in the embodiment of FIG. 5, the rake angles S1 to S4 are changed, and the clearance angles N1 to N4 are also changed to change the cutter angles of the cutting blades. I am letting. However, when the rake angles S1 to S4 are changed, the cutter angle can be changed even if the clearance angles N1 to N4 are the same angle. When the rake angle is large, the blade angle is large, and when the rake angle is small, the blade angle is small.

  In the illustrated example, the blade angles of the cutting blades 42a1 and 42a1 ′ are equal, the blade angles of the cutting blades 42a2 and 42a2 ′ are equal, the blade angles of the cutting blades 42a3 and 42a3 ′ are equal, and the blades of the cutting blades 42a4 and 42a4 ′. The corners are equal. These four sets have different blade angles for each set. Although not shown in the figure, the same can be said when the rake angle is the same and the clearance angles are different, contrary to the present embodiment. That is, when the clearance angle is large, the blade angle is large, and when the clearance angle is small, the blade angle is small.

  This dental cutting tool rotates in the direction of the arrow in FIG. 2 to perform cutting. Since the four pairs of cutting blades have different rake angles and cutting tool angles, the cutting blades 42a1 and 42a1 ′ of S1 having a small rake angle and cutting tool angle wear quickly, and the cutting blades 42a4 of S4 having a large rake angle and cutting tool angle, The wear of 42a4 'is delayed. Therefore, the cutting blade 42a does not wear out uniformly, so the life is extended.

  With such a configuration, cutting with each cutting blade is different due to the difference in blade angle, the amount of cutting is increased, the cutting time is shortened, and the burden on the patient can be reduced.

  Although not shown, it is also possible to combine the above-described embodiments, to make the heights of adjacent cutting blades different and to make the blade angle different, and the same effects as described above can be obtained.

FIG. 1 is a front view of a dental cutting tool of the present invention. It is an AA line expanded sectional view of FIG. It is a front view of 2nd Example of this invention. FIG. 4 is an enlarged sectional view taken along line B-B in FIG. 3. It is a figure of 3rd Example of this invention, and is sectional drawing to which the working part was expanded. It is a front view of a carbide bar in one of the conventional dental cutting tools. It is an expanded sectional view of the CC line of FIG.

Explanation of symbols

20 Dental cutting tool 21 Handle portion 21a Mounting portion 21b Straight portion 22 Working portion 22a Cutting blade 23 Intermediate portion 30 Dental cutting tool 31 Handle portion 31a Mounting portion 31b Straight portion 32 Working portion 32a Cutting blade 33 Intermediate portion 34 yen 35 yen 36 yen 37 yen 42 working part 42a cutting blade

Claims (3)

  A dental cutting tool in which a plurality of cutting blades are arranged at substantially equal intervals around a rotating shaft, wherein the heights of the adjacent cutting blades from the rotating shaft are different.   Arbitrary one of the cutting blades has a blade having the same height at a position symmetrical with respect to the rotation axis, and a pair of blades are formed by these two symmetrical blades. The dental cutting tool according to claim 1, wherein the dental cutting tool is disposed at an equal angle with respect to the shaft.   A dental cutting tool in which a plurality of cutting blades are arranged at substantially equal intervals around a rotating shaft, and the cutting tool angles of adjacent cutting blades are made different from each other.

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