JP2016165361A - Block for dental cutting processing, and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a block for dental cutting processing capable of producing a prosthesis having any shape, while shortening a cutting processing time when producing the prosthesis by cutting the block for dental cutting processing.SOLUTION: A block 10 for dental cutting processing comprising a part 11 to be cut having a cylindrical shape having mutually-parallel same-shaped bottom surfaces 15, 17, and a fixture 13 mounted on one bottom surface 17 of the part 11 to be cut, has a constitution in which each shape of the bottom surfaces 15, 17 is a prescribed shape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a dental cutting block and a manufacturing method thereof. Specifically, the present invention relates to a dental cutting block for a dental CAD / CAM system and a manufacturing method thereof.

  In recent years, dental prostheses have been produced using CAD / CAM systems. By using a CAD / CAM system, the shape of a dental prosthesis that varies from case to case can be produced with a certain quality. The CAD / CAM system is based on the impression of the abutment, adjacent teeth, counter teeth, etc., and the shape of the dental prosthesis is designed using a computer, and the dental cutting made of resin, glass, ceramic, metal, etc. This is a system for producing a dental prosthesis having an intended shape by cutting a processing block.

  The dental cutting block usually has a basic shape such as a prism or cylinder. It takes a long time to cut the dental cutting block having these basic shapes to obtain the desired shape of the dental prosthesis, and the productivity is low.

  Patent Document 1-2 discloses a block for dental cutting, and it is disclosed that the block may have a ready-made shape that approximates a target shape. The cutting time can be shortened by approximating the dental cutting block to the target shape. However, Patent Document 1-2 does not describe a specific shape. The dental cutting block is required to be versatile so that prostheses of any shape can be produced. However, when the dental cutting block is approximated to a target shape, the versatility is lowered. Therefore, it is required to shorten the cutting time while maintaining versatility.

Japanese Patent Laid-Open No. 2001-19539 JP 2000-287997 A

  An object of the present invention is to provide a highly versatile dental cutting block that can reduce the cutting time when cutting a dental cutting block to produce a prosthesis.

  In order to solve the above-mentioned problems, the present inventor first examined the shape of a cut portion of a dental cutting block capable of producing various shapes of prostheses (for molars) in a short cutting time. . Furthermore, the attachment position of the fixture attached to this to-be-cut part was examined. As a result, the shape of the part to be cut of the dental cutting block is formed into a predetermined shape, and a prosthesis of any shape for molars is produced in a short time by attaching a fixture at a predetermined position. As a result, the present invention has been completed.

The present invention for solving the above problems is as described below. In the present specification, the columnar shape refers to a shape having bottom surfaces that are parallel to each other and have the same shape, and that all cross-sectional shapes parallel to the bottom surface have the same shape as the bottom surface.
Moreover, the vertex of a convex part means the upper end of a convex part, and when an upper end is a plane, it means the center part of this plane. Similarly, the valley bottom point of the concave portion refers to the lower end of the concave portion, and when the lower end is a plane, it refers to the center of the plane.

[1] A column-shaped workpiece having parallel bottoms and the same bottom surface;
A fixture attached to one bottom surface of the part to be cut;
A dental cutting block comprising:
The shape of the bottom surface has the following requirements (a) to (g):
(A) The length of the side AB and the side CD parallel to the X axis of the smallest rectangle (including a square), which includes the side AB, the side BC, the side CD, and the side DA and includes the shape of the bottom surface, is 9 to 15 mm and the length of the side BC and the side DA parallel to the Y axis is 7 to 15 mm;
(B) The shape of the bottom surface includes two convex portions each having a vertex (m) and a vertex (n) on the side AB side, and one concave portion having a valley point (o) between the two convex portions. And having two convex portions each having a vertex (p) and a vertex (q) on the side CD side, and one concave portion having a valley bottom point (r) between the two convex portions. , Having one convex portion having a vertex (s) on the side BC side and one convex portion having a vertex (t) on the side DA side;
(C) The separation distance in the X-axis direction between a line parallel to the side BC passing through the vertex (m) and intersecting the side AB and a line parallel to the side BC passing through the vertex (n) and intersecting the side AB is 30-80% of the length of side AB;
(D) The separation distance in the Y-axis direction between the line passing through the valley bottom point (o) and parallel to the side AB, and the line passing through the vertex (m) and parallel to the side AB, and the side AB passing through the valley bottom point (o) The distance in the Y-axis direction between the line parallel to the line and the line passing through the vertex (n) and parallel to the side AB is 5 to 40% of the length of the side BC;
(E) The distance in the X-axis direction between the line parallel to the side BC passing through the vertex (p) and intersecting the side CD and the line parallel to the side BC passing through the vertex (q) and intersecting the side CD is 50-95% of the length of the side CD;
(F) A separation distance in the Y-axis direction between a line passing through the valley bottom point (r) and parallel to the side CD, and a line passing through the apex (p) and parallel to the side CD, and
The separation distance in the Y-axis direction between the line passing through the valley point (r) and parallel to the side CD and the line passing through the vertex (q) and parallel to the side CD is 5 to 50% of the length of the side BC. is there;
(G) When an outer peripheral line of the bottom surface exists in an octagon formed by connecting each vertex and each valley bottom point, on the side AB connecting the outer peripheral line and the nearest side constituting the octagon The length of the parallel line segment is 15% or less of the length of the side AB, and the length of the line segment parallel to the side BC connecting the outer peripheral line and the nearest side forming the octagon is equal to the side Not more than 15% of the length of BC;
A dental cutting block characterized by satisfying

  [2] An angle formed between the line passing through the vertex (m) and the valley bottom point (o) and the side AB, and a line passing through the vertex (n) and the valley bottom point (o) and the side AB formed. The dental cutting block according to [1], wherein the angles are 5 to 40 °, respectively.

  [3] An angle formed by the line passing through the vertex (p) and the valley bottom point (r) and the side CD, and a line passing through the vertex (q) and the valley bottom point (r) and the side CD are formed. The block for dental cutting according to [1], wherein each angle is 10 to 50 °.

  [4] The dental cutting process according to [1], wherein the vertex (s) divides the side BC by 3: 7 to 7: 3 and the vertex (t) divides the side DA by 3: 7 to 7: 3. For block.

  [5] An angle formed by a line passing through the vertex (m) and the vertex (s), a line passing through the vertex (p) and the vertex (s), and passing through the vertex (n) and the vertex (t) The dental cutting block according to [1], wherein angles formed by the line and the line passing through the vertex (q) and the vertex (t) are each 100 to 170 °.

[6] Collecting projection images from a certain direction for a plurality of prosthetics of at least two sites;
Minimizing a superimposed image of a plurality of the projection images collected; and
Producing a column-shaped workpiece to be cut with the overlapped image having a minimized area as a bottom surface;
Attaching a fixture to one bottom surface of the part to be cut;
A method for producing a dental cutting block, comprising:

  The block for dental cutting according to the present invention has a predetermined shape for the part to be cut, so that the versatility of making prostheses of various shapes and shortening the cutting time when making the prosthesis It is possible to achieve both. Moreover, since the fixing tool is attached to the predetermined position, the dental cutting block of the present invention can further reduce the cutting time. Furthermore, the dental cutting block of the present invention can reduce the load on the workpiece in the cutting process because the cutting time is shortened. Therefore, the design range of the prosthesis can be expanded.

FIG. 1 is a front view showing the structure of the dental cutting block of the present invention. FIG. 2 is an explanatory view showing the shape of the cut portion of the dental cutting block of the present invention. FIG. 3 is an explanatory view showing the shape of the cut portion of the dental cutting block of the present invention. FIG. 4 is an explanatory view showing a state in which a prosthesis is formed on the dental cutting block of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

(1) Dental Cutting Block The dental cutting block of the present invention is composed of a portion to be cut on which a prosthesis is formed by cutting and a fixture for fixing the portion to be cut to a cutting machine. The FIG. 1 is an explanatory diagram showing a dental cutting block according to the present invention. In FIG. 1, 10 is a block for dental cutting according to the present invention, 11 is a part to be cut, and 13 is a fixture. Reference numerals 15 and 17 denote bottom surfaces of the part 11 to be cut. The bottom surface 15 and the bottom surface 17 are parallel to each other and have the same shape. The part 11 to be cut has a columnar shape. The shape of the cross section parallel to the bottom surfaces 15 and 17 of the workpiece 11 is the same as the shape of the bottom surfaces 15 and 17. A fixture 13 is attached to the bottom surface 17 of the part 11 to be cut. The axis of the fixture 13 is attached in parallel to the height direction (hereinafter also referred to as the Z-axis direction) of the part 11 to be cut having a columnar shape. In the dental cutting block of the present invention, the fixture 13 is fixed to a cutting machine (not shown) and is used for cutting.

(2) Cut part (block part)
FIG. 2 is a plan view showing the shape of the bottom surface 15 of the cut portion 11 of the dental cutting block of the present invention. In FIG. 2, the rectangle ABCD surrounding the bottom surface 15 is described for the sake of explanation and does not exist. This rectangle has four sides: side AB connecting point A and point B, side BC connecting point B and point C, side CD connecting point C and point D, and side DA connecting point D and point A. It is a rectangle with the smallest area that includes the shape of the bottom surface 15. Note that this rectangle includes a square shape. In the following description, the side AB direction and the side CD direction are set as the X-axis direction, the side BC direction and the side DA direction are set as the Y-axis direction, and the height direction of the workpiece 11 having a columnar shape (that is, the paper surface in FIG. 2). The direction perpendicular to the Z axis direction will be described. The size of the cut portion of the dental cutting block (hereinafter also referred to as block size) is represented by the length of the side AB × the length of the side BC × the height of the cut portion 11.

  The bottom surface 15 has a predetermined shape described below.

  The length of the side AB and the side CD of the rectangle ABCD that includes the bottom surface 15 is the same, 9 to 15 mm. The lengths of the side BC and the side DA are the same and are 7 to 15 mm. When it exceeds 15 mm, the time required for cutting becomes long. Moreover, when smaller than this length, the case where it is less than the magnitude | size of a prosthesis increases.

  On the bottom surface 15, a convex portion 21 having a vertex (m) and a convex portion 22 having a vertex (n) are formed on the side AB, and between the two convex portions 21 and 22, a valley bottom point ( One recess 23 having o) is formed. Similarly, a convex part 24 having a vertex (p) and a convex part 25 having a vertex (q) are formed on the side CD, and a valley point (r) is formed between the two convex parts 24 and 25. One concave portion 26 having the shape is formed. Preferably, one convex portion 27 having a vertex (s) is formed on the side BC side, and one convex portion 28 having a vertex (t) is preferably formed on the side DA side. .

  The vertex (m) is a portion corresponding to the buccal cusp or lingual cusp of the prosthesis after cutting, and the vertex (n) corresponds to the lingual cusp or buccal cusp of the prosthesis after cutting. Part. Moreover, the recessed part 23 is a part corresponded to the cleft of the prosthesis after cutting. The vertex (p) is a portion corresponding to the cheek side edge or the tongue side edge of the prosthesis after cutting, and the vertex (q) is the tongue side edge or the cheek side of the prosthesis after cutting. This is the part corresponding to the edge. The concave portion 26 is a portion corresponding to the tooth neck line after cutting.

  A line 30 passing through the vertex (m) and intersecting the side AB and parallel to the side BC and a line 31 passing through the vertex (n) and intersecting the side AB and parallel to the side BC are X A predetermined distance apart in the axial direction. The separation distance, that is, the distance indicated by 32 in the figure is 30 to 80% of the length of the side AB, and preferably 35 to 75%.

  A line 33 passing through the valley bottom point (o) and parallel to the side AB and a line passing through the apex (m) and parallel to the side AB are at a predetermined interval in the Y-axis direction, that is, in the drawing. , 35 apart from each other. Similarly, a line 33 passing through the valley point (o) and parallel to the side AB, and a line 36 passing through the apex (n) and parallel to the side AB are set at a predetermined interval in the Y-axis direction, That is, they are separated by a distance indicated by 37 in the drawing. The distances indicated by 35 and 37 are 5 to 40% of the length of the side BC, respectively, preferably 5 to 30%, and more preferably 5 to 20%.

  A line 40 passing through the vertex (p) and intersecting the side CD and parallel to the side BC, and a line passing through the vertex (q) and intersecting the side CD and parallel to the side BC are X A predetermined distance apart in the axial direction. The separation distance, that is, the distance indicated by 42 in the figure is 50 to 95% of the length of the side AB, preferably 55 to 90%, and more preferably 60 to 85%.

  A line 43 passing through the valley point (r) and parallel to the side CD and a line passing through the apex (p) and parallel to the side CD are at a predetermined interval in the Y-axis direction, that is, in the figure. , 45 apart. Similarly, a line 43 passing through the valley bottom point (r) and parallel to the side CD and a line 46 passing through the vertex (q) and parallel to the side CD are in a predetermined interval in the Y-axis direction, That is, they are separated by a distance indicated by 47 in the drawing. The distances indicated by 45 and 47 are 5 to 50% of the length of the side BC, respectively, preferably 8 to 45%, and more preferably 10 to 40%.

  FIG. 3 is a plan view showing the shape of the bottom surface 15 of the cut portion 11 of the dental cutting block of the present invention. FIG. 3 shows an octagon formed by connecting each vertex of the bottom surface 15 and each valley bottom point of the cut portion 11 of the dental cutting block of the present invention. When the outer peripheral line of the bottom surface 15 exists inside the octagon, the length of the line segment connecting the outer peripheral line of the bottom surface 15 and the nearest side constituting the octagon and parallel to the side AB. Is 15% or less of the length of the side AB, and preferably 10% or less. Similarly, the length of the line segment connecting the outer peripheral line of the bottom surface 15 and the nearest side constituting the octagon and parallel to the side BC is 15% or less of the length of the side BC. It is preferably 10% or less. When it exceeds 15%, the shape of the prosthesis that can be produced is limited, and the versatility is lowered. In addition, it can be determined whether these conditions are satisfy | filled by measuring the maximum value of the line segment which connects these outer peripheral lines and the nearest edge | side which comprises an octagon.

  An angle 52 formed between the line segment 50 connecting the vertex (m) and the valley bottom point (o) and the side AB, a line 51 passing through the vertex (n) and the valley bottom point (o), and the side AB Each of the formed angles 53 is preferably 5 to 40 °, and more preferably 10 to 35 °. An angle 54 formed by the line segment 50 connecting the vertex (m) and the valley bottom point (o) and the line 51 connecting the vertex (n) and the valley bottom point (o) is 100 to 170 °. Preferably, it is 110-160 degrees.

  An angle 57 formed by the line segment 55 connecting the vertex (p) and the valley bottom point (r) and the side CD, a line 56 passing through the vertex (q) and the valley bottom point (r), and the side CD are The formed angles 58 are each preferably 10 to 50 °, and more preferably 15 to 45 °. In addition, an angle 59 formed by the line segment 55 connecting the vertex (p) and the valley bottom point (r) and the line 56 passing through the vertex (q) and the valley bottom point (r) is 80 to 160 °. Preferably, it is 90-150 degrees.

  The vertex (s) is in contact with the side BC, and the vertex (s) is preferably divided from 3: 7 to 7: 3, more preferably from 4: 6 to 6: 4. That is, the distance between the point B and the vertex (s): The distance between the vertex (s) and the point C is preferably 3: 7 to 7: 3, and more preferably 4: 6 to 6: 4. . Similarly, the vertex (t) is in contact with the side DA, and the vertex (t) preferably divides the side DA by 3: 7 to 7: 3, more preferably by 4: 6 to 6: 4. preferable.

  The angle 64 formed by the line segment 60 connecting the vertex (m) and the vertex (s) and the line segment 61 connecting the vertex (p) and the vertex (s) is preferably 100 to 170 °. It is preferable that it is 110-160 degrees. Similarly, an angle 65 formed by the line segment 62 connecting the vertex (n) and the vertex (t) and the line segment 63 connecting the vertex (q) and the vertex (t) is 100 to 170 °. Is preferably 110 to 160 °.

  The area of the bottom surface 15 is preferably 50 to 95% of the area of the rectangular ABCD, more preferably 60 to 90%, and particularly preferably 65 to 85%.

  Although the length of the to-be-cut part 11 in the Z-axis direction is not particularly limited, it is generally 12 to 18 mm.

  As for the to-be-cut part 11 of the block for dental cutting, the XY surface has said predetermined shape. Depending on the size of the prosthesis to be manufactured, the workpiece 11 may be prepared in a plurality of similar sizes. For example, it is preferable to prepare different sizes for each part, such as for premolars and molars, because the cutting time can be further shortened. The dimension of the to-be-cut part 11 of the X-axis direction x Y-axis direction x Z-axis direction can be suitably selected within the range of 9-15 mm x 7-15 mm x 12-18 mm. For example, a plurality of sizes such as S size (10 × 12 × 15 mm), M size (11 × 12.5 × 17 mm), and L size (12 × 13 × 17 mm) can be considered.

  When the cut portion 11 having a plurality of sizes is manufactured as for premolars and molars, the cross-sectional shape of each size may be similar to the bottom surface 15. However, for example, the shape may be adjusted for each size by the following method.

  First, a prosthesis having a crown shape for each tooth is collected as much as possible (for example, 20 cases or more per site). Next, a projected image from a certain direction (for example, the mesial direction) is taken for each of these prosthetics. The obtained projection images are superimposed using image analysis software or the like, and the area of the superimposed image of the aggregate of projection images is minimized. There are several methods of minimization, and for example, a method of arranging the concave portions of the occlusal surface and the gingival surface of each projection image so as to overlap each other is mentioned. The superimposed image of the aggregate of projection images obtained by minimizing the area is adjusted so that the outer periphery thereof becomes a smooth curve. Thereby, the shape of the to-be-cut part 11 is optimized more. By creating a superimposed image for each tooth to create the shape of the cut portion 11, the shape of the cut portion 11 is optimized for each tooth. And versatility can be made high by creating a superimposed image and creating the shape of the to-be-cut part 11 about two or more different teeth (parts).

  The cross-sectional shape of the cut portion 11 of the dental cutting block of the present invention need not be a line object. Since the right and left sides of the natural tooth are almost the object, the design may be changed to match the shape of the part to be cut 11 according to the shape of the prosthesis to be manufactured.

  As a material of the cut portion 11 of the dental cutting block of the present invention, a conventionally known material can be used without limitation. For example, a composite resin (a product in which inorganic particles are blended in a proportion of 60% or more in a methacrylate resin), a resin type such as PMMA resin, PEEK resin; a glass type such as feldspar glass, lithium disilicate glass; Examples include ceramics such as zirconia and alumina; metals such as titanium and cobalt chrome.

  The present invention can be applied regardless of the material of the part 11 to be cut, but it is more effective when the hardness of the material is higher from the viewpoint of cutting time reduction efficiency, and is particularly effective when the material is a metal, ceramic, or composite resin. . Single crown repair with metal is not common. Further, since ceramic is too hard to be cut, a method of cutting an unsintered body has been conventionally employed. The present invention is particularly effective when a composite resin with a large amount of inorganic particles or a completely sintered ceramic is used as a material.

(3) Fixing tool The fixing tool 13 is used in order to fix the to-be-cut part 11 to a cutting machine (CAM). The fixture 13 is attached to one of the bottom surface 15 or 17 of the part 11 to be cut. A conventionally known fixture 13 can be used without limitation. Generally, it has a cylindrical fixed shaft. The material is generally a metal such as brass or aluminum.

  In general, natural teeth have smaller premolars and larger molars. The biggest difference between premolars and molars is the length of the mesial-distal direction. Therefore, by setting the length with the largest deflection width in the Z-axis direction, the cutting time of unnecessary parts can be shortened and not only can the wear of the cutting bar be suppressed, but also a wide variety of cases with one type of block Versatility can be acquired. In the dental cutting block of the present invention, a fixture is attached to the bottom surface 15 or 17 of the part 11 to be cut. That is, by attaching the fixing tool in the Z-axis direction, the cutting time of unnecessary portions can be shortened and the wear of the bar can be suppressed.

(4) Manufacturing method of block for dental cutting The conventionally well-known method can be used for the manufacturing method of the block for dental cutting of this invention without a restriction | limiting. For example, a method in which a molding composition containing an inorganic filler, an acrylic polymerizable monomer and a polymerization initiator is placed in a mold capable of molding the above-described shape and polymerized in the mold, or a larger bulk A method of punching or cutting the body so as to obtain the predetermined shape is mentioned. It can also be produced by producing a rod-like body having the predetermined cross-sectional shape and cutting the rod-like body.
As the polymerization method, a known method such as thermal polymerization or photopolymerization can be employed.
The blending amount of the inorganic particles is preferably 70 to 90% by mass. The present invention is particularly effective when the hardness of the obtained cut portion is high.
A fixture is attached to the obtained part to be cut by a conventionally known method. For example, a method using an adhesive or a screw can be used.

(5) Method of using dental cutting block A method for producing a prosthesis using the dental cutting block of the present invention will be described below.
First, a pedestal is formed in a patient's oral cavity by a dentist. For example, the abutment is formed by shaving teeth. Next, an impression of the abutment, adjacent teeth, counter teeth, etc. is taken by the dentist. The impression is taken using an alginate impression material, a silicone impression material, a digital impression device, or the like. Thereafter, a dental technician or dentist creates a gypsum model from the obtained impression, and the shape of the gypsum model is digitized using a scanning machine. Alternatively, a digital model is created from data obtained by a digital impression.

  Next, digital data of the prosthesis is created using design software based on the measurement data. Based on the digital data of the prosthesis, digital data for cutting with a cutting machine is created. At this time, it is confirmed on the software that the part to be cut of the present invention has a sufficient size for the prosthesis to be manufactured.

  Thereafter, the dental cutting block of the present invention is installed in a cutting machine, and cutting is performed. When the cutting by the cutting machine is completed, the sprue portion remaining in the dental cutting block is cut off. After the shape correction and polishing are performed, pretreatment of the inner surface of the prosthesis (roughening by sandblasting or the like) is performed. The prosthesis produced in this manner is pretreated on the inner surface (primer application or the like), and then adhered to a support in the patient's oral cavity using cement.

(6) Cutting of dental cutting block The above cutting is performed using a cutting machine (CAM, milling machine). It is preferable to use a commercially available dental cutting machine. To perform the cutting process, a cutting tool (bar) and a cutting process (CAM) software are required. The CAM software controls the movement of the cutting tool and the movement of the block fixed through the fixing tool, and typical parameters include position information, feed speed, and rotation speed. The cutting tool is preferably a general dental cutting bar. It is preferable that a coating such as a diamond coat is applied as a countermeasure against wear. Generally, a cutting bar is used in combination with a plurality of cutting bars according to the stage of cutting, such as for rough cutting, medium cutting, and fine cutting. For convenience, a rough crown shape is formed using rough cutting (for example, 2 mm diameter), and then the surface texture is smoothed using fine cutting (for example, 0.8 mm diameter), or a fine occlusal surface or the like. To express a simple structure.

  In cutting the dental cutting block, the prosthesis and the part to be cut need to be connected until the cutting by the cutting machine is completed. Therefore, a sprue is formed in the prosthesis formed by cutting, and the prosthesis is coupled to the part to be cut by the sprue. FIG. 4 is an explanatory view showing a state in which a prosthesis is cut into the dental cutting block of the present invention. In FIG. 4, reference numeral 12 denotes a prosthesis, and the prosthesis 12 is fixed to the cut portion 11 by a sprue 14. After cutting, the prosthesis 12 is separated from the cut portion 11 by cutting the sprue 14. Since a part of the sprue 14 remains in the prosthesis 12, the remaining sprue is removed by cutting or polishing.

  During cutting with a cutting machine, loads due to vibration during cutting concentrate on the sprue portion. Therefore, when a conventional cutting block is used, it is necessary to form the sprue thick (for example, with a diameter of 3.5 mm) so that the sprue does not break during the cutting process. If the sprue is formed thick, there is a problem that after the sprue is cut after the cutting process is finished, traces of the sprue remain, resulting in poor appearance and time-consuming post-processing. When the dental cutting block of the present invention is used, the cutting time can be shortened. Therefore, even if the sprue is formed thin (for example, with a diameter of 3.0 mm or less), the sprue is not easily broken during cutting. Therefore, the appearance and workability of post-processing are improved.

  The cutting time depends on the type of bar to be used, the rotation speed, and the cutting program of the CAM software (position information, feed speed, rotation speed, etc. are programmed). Moreover, it largely depends on the shape of the cut portion of the dental cutting block. In the CAM software, the shape information of the cut portion of the dental cutting block can be registered in advance, and the cutting is completed with the minimum movement of the cutting tool (bar) according to the shape of the cut portion. It is possible to improve efficiency.

  When the material to be cut is a hard material, the feed rate of the cutting tool may have to be set low in order to reduce the load on the apparatus. Even if the feed rate is the same, the cutting time may vary depending on the hardness of the material. This is a phenomenon that occurs because the traveling direction is blocked by the material and cannot keep up with the program feed rate, and such a time delay is called a delay time. Harder materials tend to have longer delay times. The dental cutting block of the present invention has the effect of minimizing such a delay time.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

(Production Example 1)
20 parts by mass of urethane dimethacrylate and 10 parts by mass of triethylene dimethacrylate, 0.2 parts by mass of benzoyl peroxide are mixed and dissolved, and 0.2 micron spherical silica zirconia is treated with γ-methacryloyloxypropyltrimethoxysilane. 70 parts by mass of the product was kneaded to obtain a heat polymerization type composite resin.

Example 1
Collecting 20 projection images of each of the 4th to 7th prosthesis, manually superimposing the superposed images of the collected projection images, and making the minimum area superposed image into a smooth curve The bottom shape was designed by preparing as above. A mold having a columnar structure having the bottom surface shape was prepared, and the heat polymerization type composite resin obtained in Production Example 1 was degassed and filled in the mold. Thereafter, heat polymerization was performed at 100 ° C. for 15 minutes, the mold was removed, and each was cut so that the length in the Z direction was 17 mm, thereby obtaining a cut portion of the dental cutting block. Thereafter, an aluminum pin as a fixture was adhered to one bottom surface of the part to be cut using a cyanoacrylate-based instantaneous adhesive to obtain a dental cutting block 1. The shape of the block 1 was as follows. AB and CD length (X axis): 13.0 mm, BC and DA length (Y axis): 12.0 mm, Z axis direction length: 17.0 mm, separation distance 32 (ratio): 7.2 mm (55%), separation distance 35 (ratio): 2.1 mm (17%), separation distance 37 (ratio): 1.7 mm (14%), separation distance 42 (ratio): 9.8 mm (75%), Separation distance 45 (ratio): 3.4 mm (28%), separation distance 47 (ratio): 2.4 mm (20%), side AB connecting the outer peripheral line existing inside and the nearest side constituting the octagon The length (ratio) of the line segment parallel to the line segment is 0.4 mm (3%) on the line segment 55, and the line segment parallel to the side BC connecting the outer peripheral line existing inside and the nearest side forming the octagon. Length (ratio): on line segment 55, 0.4 mm (4%), angle 52: 20 degrees, angle 53: 25 degrees, angle 54: 135 degrees, angle 57: 7 degrees, angle 58: 20 degrees, angle 59: 123 degrees, angle 64: 125 degrees, angle 65: 144 degrees, vertex (s) division point: 4.2 (Bs): 5.8 (sC), vertex The dividing point of (t): 6.0 (At): 4.0 (tD), the area of the bottom surface 15: 72% of the area of ABCD.

  CAD data and a cutting program for cutting a crown restoration prosthesis for the left lower jaw No. 4 were prepared. The crown shape was designed using CAD software based on the crown shape model tooth and the abutment formation model tooth for the jacket crown (both from Nissin). A cutting program was created using CAM software based on the created CAD data. The sprue was planted in the mesial plane, and the sprue diameter was 2.5 mm conical. The cutting program used was a LAVA Ultimate (3M-ESPE) cutting program, which is a resin material for dental cutting and a composite resin with an inorganic particle filling rate of 73 mass%. A dental cutting block was fixed to a cutting machine (DWX-50, manufactured by Roland), and cutting was performed. The cutting bar used was φ2.0 mm for rough cutting and φ0.8 mm for fine cutting (both from Yamahachi Teikoku Kogyo Co., Ltd.). The rotation speed of the cutting bar was 30000 rpm. The time during which the cutting bar was in contact with the block was counted as the cutting time, and the results are shown in Table 1.

(Examples 2 to 4)
The operation was performed in the same manner as in Example 1 except that the shape of the part to be cut and the shape of the target prosthesis were changed as shown in Table 1, and the results are shown in Table 1.

(Examples 5 to 8)
The shape of the part to be cut was changed, and a dental cutting block 2 was obtained in the same manner as in Example 1. The shape of the block 2 was as follows. AB and CD length (X axis): 12.0 mm, BC and DA length (Y axis): 10.0 mm, Z axis direction length: 15.0 mm, separation distance 32 (ratio): 7.6 mm (63%), separation distance 35 (ratio): 1.6 mm (17%), separation distance 37 (ratio): 1.2 mm (12%), separation distance 42 (ratio): 9.4 mm (78%), Separation distance 45 (ratio): 2.6 mm (26%), separation distance 47 (ratio): 1.4 mm (14%), side AB connecting the outer peripheral line existing inside and the nearest side constituting the octagon The length (ratio) of the line segment parallel to the line segment: 0.7 mm (6%) on the line segment 56, the line segment parallel to the side BC connecting the inner peripheral line and the nearest side forming the octagon. Length (ratio): 0.3 mm (3%) on line 56, angle 52:22 degrees, angle 53:20 degrees, angle 54: 138 degrees, angle 57: 6 degrees, angle 58:15 degrees, angle 59: 129 degrees, angle 64: 130 degrees, angle 65: 140 degrees, vertex (s) division point: 6.0 (Bs): 4.0 (sC), vertex The dividing point of (t): 6.0 (At): 4.0 (tD), the area of the bottom surface 15: 73% of the area of ABCD.

(Examples 6 to 8)
The operation was performed in the same manner as in Example 5 except that the shape of the part to be cut and the shape of the target prosthesis were changed as shown in Table 1, and the results are shown in Table 1.

(Comparative Examples 1-8)
A commercially available resin-based rectangular parallelepiped block for dental cutting (LAVA Ultimate 14L A3-LT, 3M-ESPE) was used. Moreover, except having changed the shape of the target prosthesis as described in Table 1, it operated similarly to Example 1, and the result was shown in Table 1.

(Comparative Example 9)
Cyanoacrylate-based instant adhesive using an aluminum pin as a fixture such that the BC side surface of the cut portion of the dental cutting block produced in Example 1 is bonded to the fixture Was adhered using. This was used as a dental cutting block 3. In creating the cutting program, sprue was planted on the buccal side. The operation was performed in the same manner as in Example 1 except that the shape of the target prosthesis was changed as described in Table 1, and the results are shown in Table 1. Although the comparative example 9 changed only the direction fixed to a fixing tool with respect to Example 1, since more cutting was needed for the X-axis direction, cutting time became long.

(Comparative Example 10)
The projection image of 20 prostheses of the lower jaw # 4 is collected, and the overlay image of the collected projection images is manually reduced to the minimum area, and the minimum area overlay image is corrected to have a smooth curve. By doing so, the bottom shape was designed. A columnar structure mold having this bottom shape was prepared, and a dental cutting block 4 was prepared in the same manner as in Example 1. The shape of the block 4 was as follows. AB and CD length (X axis): 11.0 mm, BC and DA length (Y axis): 12.0 mm, Z axis direction length: 17.0 mm, separation distance 32 (ratio): 3.6 mm (36%), separation distance 35 (ratio): 1.1 mm (10%), separation distance 37 (ratio): 0 mm (0%), separation distance 42 (ratio): 8.7 mm (87%), separation distance 45 (ratio): 2.1 mm (17%), separation distance 47 (ratio): 0.8 mm (7%).
The same operation as in Example 1 was performed except that the shape of the target prosthesis was changed as shown in Table 1. When a dental cutting block was prepared from a projection image of a premolar, the desired prosthesis could not be obtained because the shape was not sufficient for cutting a molar prosthesis.

DESCRIPTION OF SYMBOLS 10 ... Block for dental cutting 11 ... To-be-cut part 12 ... Prosthesis 14 ... Sprue 13 ... Fixing tool 15, 17 ... Bottom face of to-be-cut part 21, 22, 24, 25, 27, 28 ... convex part 23, 26 ... concave part m ... vertex of convex part 21 n ... vertex of convex part 22 o ... valley bottom point of concave part 23 p ... convex part Vertex 24: Vertex of convex part 25 r: Bottom point of convex part 26 s: Vertex of convex part 27 t: Vertex of convex part 28 30, 31, 33, 34, 36, 40, 41, 43, 44, 46, 51, 56 ... line 32, 35, 37, 42, 45, 47 ... separation distance 50, 55, 60, 61, 62, 63 ... line segment 52 ... An angle between line segment 50 and side AB 53 ... An angle between line 51 and side AB 54 ... An angle between line segment 50 and line 51 5 7 ... An angle between line segment 55 and side CD 58 ... An angle between line 56 and side CD 59 ... An angle between line segment 55 and line 56 64 ... Line segment 60 and line Angle formed by the minute 61... Angle formed by the line 62 and the line 63.

Claims (6)

Columnar-shaped parts to be cut that have parallel and identical bottom surfaces,
A fixture attached to one bottom surface of the part to be cut;
A dental cutting block comprising:
The shape of the bottom surface has the following requirements (a) to (g):
(A) The length of the side AB and the side CD parallel to the X axis of the smallest rectangle (including a square), which includes the side AB, the side BC, the side CD, and the side DA and includes the shape of the bottom surface, is 9 to 15 mm and the length of the side BC and the side DA parallel to the Y axis is 7 to 15 mm;
(B) The shape of the bottom surface includes two convex portions each having a vertex (m) and a vertex (n) on the side AB side, and one concave portion having a valley point (o) between the two convex portions. And having two convex portions each having a vertex (p) and a vertex (q) on the side CD side, and one concave portion having a valley bottom point (r) between the two convex portions. , Having one convex portion having a vertex (s) on the side BC side and one convex portion having a vertex (t) on the side DA side;
(C) The separation distance in the X-axis direction between a line parallel to the side BC passing through the vertex (m) and intersecting the side AB and a line parallel to the side BC passing through the vertex (n) and intersecting the side AB is 30-80% of the length of side AB;
(D) The separation distance in the Y-axis direction between the line passing through the valley bottom point (o) and parallel to the side AB, and the line passing through the vertex (m) and parallel to the side AB, and the side AB passing through the valley bottom point (o) The distance in the Y-axis direction between the line parallel to the line and the line passing through the vertex (n) and parallel to the side AB is 5 to 40% of the length of the side BC;
(E) The distance in the X-axis direction between the line parallel to the side BC passing through the vertex (p) and intersecting the side CD and the line parallel to the side BC passing through the vertex (q) and intersecting the side CD is 50-95% of the length of the side CD;
(F) A separation distance in the Y-axis direction between a line passing through the valley bottom point (r) and parallel to the side CD, and a line passing through the apex (p) and parallel to the side CD, and
The separation distance in the Y-axis direction between the line passing through the valley point (r) and parallel to the side CD and the line passing through the vertex (q) and parallel to the side CD is 5 to 50% of the length of the side BC. is there;
(G) When an outer peripheral line of the bottom surface exists in an octagon formed by connecting each vertex and each valley bottom point, on the side AB connecting the outer peripheral line and the nearest side constituting the octagon The length of the parallel line segment is 15% or less of the length of the side AB, and the length of the line segment parallel to the side BC connecting the outer peripheral line and the nearest side forming the octagon is equal to the side Not more than 15% of the length of BC;
A dental cutting block characterized by satisfying   The angle formed between the line passing through the vertex (m) and the valley bottom point (o) and the side AB, and the angle formed between the line passing through the vertex (n) and the valley bottom point (o) and the side AB. The dental cutting block according to claim 1, wherein each block is 5 to 40 °.   An angle formed between the line passing through the vertex (p) and the valley bottom point (r) and the side CD, and an angle formed between the line passing through the vertex (q) and the valley bottom point (r) and the side CD. The dental cutting block according to claim 1, wherein each block is 10 to 50 °.   The dental cutting block according to claim 1, wherein the vertex (s) divides the side BC by 3: 7 to 7: 3, and the vertex (t) divides the side DA by 3: 7 to 7: 3.   An angle formed by a line passing through the vertex (m) and the vertex (s), a line passing through the vertex (p) and the vertex (s), and a line passing through the vertex (n) and the vertex (t); The dental cutting block according to claim 1, wherein an angle formed by a line passing through the vertex (q) and the vertex (t) is 100 to 170 degrees. Collecting projection images from a certain direction for a plurality of prostheses of at least two sites;
Minimizing a superimposed image of a plurality of the projection images collected; and
Producing a column-shaped workpiece to be cut with the overlapped image having a minimized area as a bottom surface;
Attaching a fixture to one bottom surface of the part to be cut;
A method for producing a dental cutting block, comprising:

Images