JP2006081700A5 - - Google Patents

Description

Magnetic attachment

  The present invention relates to a magnetic attachment used for fixing a denture in the field of dentistry.

  A dental denture attachment is a medical device used to fix partial or full dentures in the oral cavity, and a keeper made of soft magnetic stainless steel is embedded directly in the abutment tooth of the jaw support or in the root plate. At the same time, a magnet structure that is attracted to the keeper by a magnetic attraction force is used by being embedded in an opposing position of the denture base. The magnetic attachment is not exposed like a clasp and has excellent aesthetics. It is easier to attach and detach than other attachments, can reduce the lateral force on the abutment tooth, and is easy to clean. It has excellent characteristics and has been widely used in recent years.

  There are several types of magnetic attachments, but due to the characteristics and ease of manufacturing methods, the so-called sandwich type (Patent Document 1) and cup yoke type (Patent Document 2) have become mainstream depending on the structure of the magnet structure. Yes. The shape of the suction surface is a rectangular shape in the sandwich type, and a disc shape is adopted in the cup yoke type.

Japanese Examined Patent Publication No. 7-32784 (3rd page, Fig. 2) Japanese Patent No. 3287531 (2nd page, FIG. 3)

  FIG. 7 schematically shows a sandwich-type magnetic attachment 70. 7A is a plan view, and FIG. 7B is a longitudinal sectional view of FIG. 7A taken along line A-A ′. The magnetic attachment 70 has a rectangular shape in which a yoke 72 made of a pair of soft magnetic stainless steels is sandwiched so as to be attracted to both poles of the permanent magnets 74 and the other surfaces of the permanent magnets 74 are covered with nonmagnetic stainless steels 77 and 78. It is a structure. The suction surface 77b is rectangular and has a shape close to the root form of the gingival margin of the front tooth, so that it is used for the front tooth. It is difficult to reduce the thickness of a sandwich-type magnetic circuit using a rectangular permanent magnet 74 and a yoke 72 by reducing the height dimension (= thickness c) without reducing the magnetic attractive force. For molars with a small intermaxillary distance, it is difficult to perform treatment according to the intermaxillary distance, so the sandwich type is not suitable for molars.

  FIG. 8 schematically shows a cup yoke type magnetic attachment 80. 8A is a plan view, and FIG. 8B is a longitudinal sectional view of FIG. 8A taken along line A-A ′. This magnetic attachment 80 has a cup yoke 82 provided with a circular opening on one surface of a soft magnetic stainless steel disk, and a permanent magnet 84 whose thickness direction is a magnetic pole is embedded in the opening. Further, a disk-shaped plate comprising a nonmagnetic ring 85 and a soft magnetic disk 86 is provided on the magnetic pole surface of the permanent magnet 84, and the cup yoke and the disk-shaped plate are sealed by welding. It is. The cup yoke type has a circular outer shape and is thinner than the sandwich type. Since the root form of the gingival marginal part is almost circular, it is used for a molar part having a small intermaxillary distance. However, in the cup yoke type, it is difficult to obtain a sufficient suction force for the front teeth. As described above, there is a problem that it is necessary to use sandwich type and cup yoke type magnetic attachments in accordance with the form and position of the tooth that will be the abutment tooth, and the technical operation becomes complicated.

  Accordingly, an object of the present invention is to provide a magnetic attachment that can be applied to both anterior teeth and molars.

In order to achieve the above object, a magnetic attachment of the present invention includes a cup yoke made of soft magnetic stainless steel having a cylindrical opening, and a disk-shaped magnet housed in the opening and magnetized in the thickness direction. a permanent magnet, wherein a shield ring of non-magnetic stainless steel which is secured to the outer periphery of the disc-shaped yoke and its made of a soft magnetic stainless steel which is provided on the permanent magnet, the surface of the yoke is the cup yoke and a disk-like plate which is attracted to the keeper having the same planar shape as the cup yoke together with the surface of the outer shape of the cup yoke has 6 or more corners that are chamfered and having two control axes with a line control polygon, in which the length along the one control shaft and said range near Rukoto of 1.1 to 1.5 times the other length along the control shaft .

According to the present invention, since it is a thin and rectangular magnetic attachment, it can be used for both molars and anterior teeth. Therefore, the technical operation at the time of forming a denture becomes easy. Furthermore, since the outer shape is a polygonal shape and the side surface has a large number of flat surfaces, the magnetic attachment can be fixed to the resin floor with high adhesion without rotating even when a force is applied.

Details of the present invention will be described below with reference to the accompanying drawings.
  1A and 1B show a magnetic attachment according to the present invention, in which FIG. 1A is a plan view and FIG. 1B is a longitudinal sectional view of FIG. 1A taken along line A-A ′. The magnetic attachment 10 includes an octagonal cup yoke 12, a disk-like permanent magnet 14 housed in a circular opening of the cup yoke 12, a shield ring 15 and a magnetic pole surface of the permanent magnet 14. A disk-like plate (outer diameter Dr) made of the disk yoke 16. The permanent magnet 14 was magnetized in the thickness direction of the disk, and one surface was an N pole and the other surface was an S pole. The cup yoke 12, the shield ring 15, and the disk yoke 16 were welded together with a laser and then ground for flattening the laser trace to form the suction surface 11. The area between the dotted lines in FIG. 1 (a) is a welded portion 19, and as shown in FIG. 1 (b), the cup yoke 12, shield ring 15 and disk yoke 16 are integrally welded at a predetermined depth. Equivalent to. The cup yoke 12 is formed by cutting magnetic stainless steel (SUS447J1) to form an opening and a pair of steps 12c formed on the side surface of the long axis a. The cup yoke 12 used as the magnetic path the portion having the thickness c and the portion having the thickness Tc, which is thin because the opening was formed. The octagonal corner of the cup yoke 12 was chamfered. The suction surface 11 is wide in the direction of the long axis a (longitudinal dimension) and narrow in the direction of the short axis b (width dimension). The disk-shaped plate made of the shield ring 15 and the disk yoke 16 has a concentric arrangement of magnetic stainless steel (SUS447J1) rods for disk yoke in a nonmagnetic stainless steel (SUS316L) cylinder for shield rings. Then, the cylinder and the round bar are clad-bonded by a drawing process, and then thinly cut along a plane perpendicular to the axial direction. As the permanent magnet 14, a sintered body of an NdFeB-based magnet was used.

  2A and 2B show a keeper 20 used as a pair with the magnetic attachment of FIG. 1, wherein FIG. 2A is a plan view and FIG. 2B is a longitudinal sectional view of FIG. This keeper 20 has a predetermined thickness after processing a rod of magnetic stainless steel (SUS447J1) so as to have the same octagonal cross section as the cup yoke 12, and forming a pair of step 20c and suction surface 20b on its end face. Cut to Tk. An adsorption surface 20b having the same shape as the adsorption surface 11 of the magnetic attachment was formed. The saturation magnetization Bs of this keeper 20 was set to 1.35T.

As is clear from FIG. 1A, the cup yoke 12 is a line-contrast polygon (octagon) having two reference axes (long and short axes), and has a length a and a short length along the long axis. By providing a ratio (a / b) of the length b along the axis of 1.1 to 1.5, a magnetic attachment having a cross section adapted to the root form of the gingival margin of the molar tooth from the front tooth part is provided. can do. If a / b is less than 1.1, it is difficult to use for anterior teeth. When a / b exceeds 1.5, it is difficult to use both for molars and for front teeth.

3A and 3B show another magnetic attachment of the present invention, in which FIG. 3A is a plan view and FIG. 3B is a longitudinal sectional view of FIG. 3A taken along line A-A ′. The magnetic attachment 30 includes a hexagonal cup yoke 32, a disk-like permanent magnet 34 housed in a circular opening of the cup yoke 32, a shield ring 35 and a magnetic pole surface of the permanent magnet 34. A disk-shaped plate consisting of a disk yoke 36 was disposed. The permanent magnet 34 was magnetized in the thickness direction of the disk, and one surface was an N pole and the other surface was an S pole. The cup yoke 32, the shield ring 35, and the disk yoke 36 were integrally welded with a laser, and then ground for flattening laser traces to form the suction surface 31. The area between the dotted lines in FIG. 3 (a) is a welded portion 39. As shown in FIG. 3 (b), the cup yoke 32, the shield ring 35, and the disk yoke 36 are integrally welded at a predetermined depth. Equivalent to. The cup yoke 32 is formed by cutting magnetic stainless steel (SUS447J1) to form an opening and a pair of cuts 33 formed on the side surface in the major axis a direction. For the cup yoke 32, a portion having a thickness c and a portion having a thickness Tc, which is thin because an opening is formed, were used as a magnetic path. The corner of the hexagon of the cup yoke 32 was rounded. The suction surface 31 is wide in the direction of the long axis a and narrow in the direction of the short axis b. The disk-shaped plate composed of the shield ring 35 and the disk yoke 36 is produced by the same material and method as in the first embodiment. As the permanent magnet 14, a sintered body of an NdFeB-based magnet was used.

  4A and 4B show the keeper 40 used as a pair with the magnetic attachment of FIG. 3, wherein FIG. 4A is a plan view and FIG. 4B is a longitudinal sectional view as seen in FIG. The keeper 40 is formed by machining a magnetic stainless steel (SUS447J1) rod to have the same hexagonal cross section as the cup yoke 32 and cutting it to a thickness Tk. An adsorption surface 40b having the same shape as the adsorption surface 31 of the magnetic attachment was formed. The saturation magnetization Bs of this keeper 40 was set to 1.35T.

  FIG. 5 is a perspective view showing a state in which handles 28 and 48 are provided in each of the keepers 20 and 40. The handles 28 and 48 were used as support portions when handling the keeper. The handles 28 and 48 were used when the keeper was embedded in the root plate, and the handles 28 and 48 were removed when the keeper was joined to the root plate. The handle 28 is joined after the keeper is manufactured. The handle 48 is formed by joining an elongated plate of the same composition to the side surface of a magnetic stainless steel rod when making the keeper, and cutting the rod and the plate together.

  FIG. 6 is a cross-sectional view of the entire dental magnetic attachment showing a state in which the magnetic attachment and the keeper are used in the oral cavity. Reference numeral 3 is a root plate of a non-magnetic material (SUS316L), and the keeper 20 of Example 2 is embedded in the end portion of the root plate 3 integrally with a caster. The root plate 3 in which the keeper was embedded was embedded in the tooth root 4 of the gum 8. Reference numeral 5b is a resin-made denture base, in which the denture 5a was implanted and the magnetic attachment 10 of Example 1 was embedded so as to face the root face plate 3. With the above configuration, a magnetic attractive force acts between the keeper 20 embedded in the root face plate 3 and the magnetic attachment 10 provided with the denture 5a and the denture base 5b. The denture 5a was supported in the oral cavity. 6 uses the magnetic attachment of FIG. 1 and the keeper of FIG. 2, the magnetic attachment 30 of FIG. 3 and the keeper 40 of FIG. 4 could also be used as dental magnetic attachments.

In the present invention, the following conditions are necessary in order to impart sufficient magnetic properties to the magnetic attachment having the above-described attracting surface. Permanent magnets are embedded in the circular recesses provided on the suction surface of the cup yoke, but the manufactured magnet structure has a sufficient attractive force, and in order to suppress the leakage magnetic flux density, the cup yoke is configured. Ratio (Bs × Sm) of the product (Bs × Sm) of the saturation magnetization Bs of soft magnetic stainless steel and the sectional area Sc of the attracting surface of the cup yoke (Bs × Sc), the residual magnetic flux density Br of permanent magnets, and the sectional area Sm of permanent magnets * Sc) / (Br * Sm) needs to be 0.8 to 1.2. If (Bs × Sc) / (Br × Sm) is smaller than 0.8, the magnetic flux density on the attracting surface of the cup yoke becomes small and sufficient attractive force cannot be obtained. Not only does the magnetic flux saturate but the leakage flux to the outside of the magnetic attachment increases but the attractive force does not increase, and if the permanent magnet used is small, the diameter of the circular recess provided on the suction surface of the cup yoke It is necessary to increase the strength of the magnet structure, and when the Br of the permanent magnet is large, the heat resistance of the magnet is impaired due to the decrease in the coercive force of the permanent magnet. Will be invited.

  The value (π × Dr × Tc) expressed by the distance between the diameter Dr of the circular recess provided on the cup yoke non-adsorption surface and the cup yoke adsorption surface and the bottom of the recess, ie, the thickness Tc on the non-adsorption surface The ratio (π × Dr × Tc) / Sc to the suction surface cross-sectional area Sc of the cup yoke needs to be 0.8 to 1.2. When (π × Dr × Tc) / Sc is smaller than 0.8, not only the amount of magnetic flux flowing on the suction surface of the cup yoke is reduced and the attractive force is reduced, but also the amount of leakage magnetic flux is increased. When (π × Dr × Tc) / Sc is greater than 1.2, the height of the magnet structure increases, and a sufficient intermaxillary distance cannot be obtained when this magnetic attachment is used for a molar portion.

A value (π × Dr × Tk) represented by the inner diameter Dr of the ring made of nonmagnetic stainless steel embedded in the concave portion of the attracting surface of the magnet structure and the thickness Tk of the keeper, and the attracting surface sectional area Sc of the cup yoke The ratio (π × Dr × Tk) / Sc needs to be 0.8 to 1.2. If (π × Dr × Tk) / Sc is smaller than 0.8, not only the amount of magnetic flux flowing on the suction surface of the cup yoke is reduced and the attractive force is reduced, but also the amount of leakage magnetic flux is increased. When (π × Dr × Tk) / (Br × Sc) is greater than 1.2, the keeper becomes thicker, so that a sufficient intermaxillary distance cannot be obtained when this magnetic attachment is used for a molar portion. Become.

The following examples further illustrate the present invention.

(Example 1)
In FIG. 1, the dimensions of the cup yoke 12 are as follows: long axis a = 3.1 mm, short axis b = 2.5 mm, long axis a / short axis b = 1.24, chamfering R = 0.93 mm on the long axis side, The chamfer R on the short axis side was 0.5 mm, the hole diameter of the opening was 2.1 mm , the height c was 1.45, and the thickness Tc was 0.65 mm . The dimensions of the shield ring 15 were an outer diameter Dr = 2.1 mm, an inner diameter = 1.7 mm, and a thickness = 0.2 mm. The dimensions of the disk yoke 16 were a diameter = 1.7 mm and a thickness = 0.2 mm. The cup yoke 12 and the disk yoke 16 have a saturation magnetization Bs = 1.35T. The permanent magnet 14 had a diameter = 2.05 mm, a height = 0.6 mm, a residual magnetic flux density Br = 1.4 T, and an energy product BHmax = 42 MGOe. Table 1 shows the obtained suction force and the like. That is, the suction force = 3.97 (N), the long axis / short axis = 1.24, and the applicability according to the site was good (◯). Further, (Bs × Sc) / (Br × Sm) = 0.98, (π × Dr × Tk) /Sc=1.03, (π × Dr × Tc) /Sc=1.03, and FIG. Sufficient adsorption force was obtained when used as a whole dental magnetic attachment. Here, the attractive force is an attractive force (N) when the magnetic attachment 10 and the keeper 20 are opposed to each other. This attractive force was measured by attaching the adsorbed magnetic attachment 10 and the keeper 20 to a tensile tester. Regarding the applicability depending on the part, the case where it can be used as both the magnetic attachment for the anterior teeth and the magnetic attachment for the molars was evaluated as good (◯), and the case where it could be used only for one was evaluated as inappropriate (×). Note that the saturation magnetization Bs and residual magnetic flux density Br of the material are measured by setting parts on a vibrating sample magnetometer (manufactured by Toei Kogyo Co., Ltd., VSM-3 type) and measuring the magnetization curve at room temperature. did.

(Examples 2 to 15)
About the magnetic attachment of Example 1, Examples 2-15 were obtained by changing dimensional conditions. That is, the major axis a (mm), the minor axis b (mm), the major axis a / minor axis b, and the height c (mm) are set as parameters for the cup yoke 12, and the thickness Tk (mm) is set as a parameter for the keeper 20. did. The resulting suction force or the like are also shown in Table 1. In Examples 2 to 15, the ratio of the major axis to the minor axis (a / b) is 1.24 to 1.31, and the applicability to both the front tooth use and the molar use is good (◯), which is sufficient Was able to obtain a strong suction force.

(Comparative Examples 1-3)
In Table 1, in Comparative Examples 1 to 3, the ratio of the major axis to the minor axis (a / b) is 1.57 to 1.60, and it is difficult to apply both the molar use and the front tooth application because it is too long horizontally. The applicability to both anterior and molar applications was unsuitable (x). Comparative Example 1 is not preferable in that the suction force is small as compared with Examples 1-15. Also, (Bs × Sc) / (Br × Sm) = 1.39 to 1.56, (π × Dr × Tk) /Sc=0.65 to 0.74, (π × Dr × Tc) / Sc = It was 0.65-0.70, and an appropriate value could not be obtained as a whole dental magnetic attachment of FIG.

(Conventional example 1)
A sandwich type magnetic attachment shown in FIG. 7 having a thickness of 2.2 mm was produced.

(Conventional example 2)
A cup yoke type magnetic attachment shown in FIG. 8 having a thickness of 1.5 mm was produced.

In Table 2, the first example, the conventional example 1 (sandwich type), and the conventional example 2 (cup yoke type) are compared. In the magnetic attachment of Example 1, the outer shape of the cup yoke was polygonal (octagonal), the opening and the permanent magnet housed therein were disk-shaped, and the cup yoke thickness was 1.45 mm. By using a disk-shaped permanent magnet, the thickness was reduced, and by securing the magnetic path of the magnetic circuit on the long axis side of the cup yoke, a high attractive force could be obtained. Therefore, it could be used for anterior teeth and molars, and the applicability depending on the site was good (◯). Not only in Example 1, but also in other examples of the present invention, a high attractive force could be obtained between the keeper and the magnetic attachment. This is because the magnetic path is ensured because the long axis side of the cup yoke is wide, and even if it is thin, the magnetic field lines coming out from the disk-shaped permanent magnet to the attracting surface side do not leak to the outside. This is probably because the magnetic resistance of the cup yoke does not increase with respect to the magnetic field of the plate-like permanent magnet.

On the other hand, since Conventional Example 1 and Conventional Example 2 cannot be used for both the front teeth and the molars, the applicability by the part was inappropriate (x). Magnetic attachment of the conventional example 1 (sandwich type), the external shape is a magnet shape polygon is a rectangle, the thickness of the whole became 2.2 mm. It is difficult to use it for molars because the distance between jaws does not match because of the thickness. An attempt to reduce the thickness is difficult because the magnetic pole surface of the permanent magnet becomes smaller and the attractive force becomes lower. Further, in the magnetic attachment of Conventional Example 2 (cup yoke type), the outer shape of the cup yoke was circular, the opening and the permanent magnet housed therein were disk-shaped, and the cup yoke thickness was 1.5 mm. However, the suction force has become smaller when used for anterior teeth.

It is the schematic of the magnetic attachment concerning embodiment of this invention. It is the schematic of the keeper used as a pair with the magnetic attachment of FIG. It is the schematic of the magnetic attachment concerning other embodiment of this invention. It is the schematic of the keeper used as a pair with the magnetic attachment of FIG. It is a perspective view which shows the form of a keeper. It is sectional drawing of the whole dental magnetic attachment. It is the schematic which shows an example of the conventional magnetic attachment. It is the schematic which shows another example of the conventional magnetic attachment.

Explanation of symbols

3: root plate, 4: gingiva, 5a: denture, 5b: denture base, 8: gingiva,
10: Magnetic attachment, 11: Suction surface, 12: Cup yoke,
12c: Step, 14: Permanent magnet, 15: Shield ring,
16: Disc yoke, 19: Welded part, 20: Keeper, 20b: Suction surface,
20c: Step, 28: Handle, 30: Magnetic attachment, 31: Adsorption surface,
32: cup yoke, 33: notch, 34: permanent magnet,
35: Shield ring, 36: Disc yoke, 39: Welded part,
40: keeper, 40b: suction surface, 48: handle

Claims (1)

A cup yoke made of soft magnetic stainless steel having a cylindrical opening, a disk-shaped permanent magnet magnetized in the thickness direction , housed in the opening , and a soft magnetic stainless steel provided on the permanent magnet a shield ring of non-magnetic stainless steel which is secured to the outer periphery of the disc-shaped yoke and its made of, adsorbed keeper surface of the yoke have the same planar shape as the cup yoke together with the surface of the cup yoke and a disk-like plate that is, the outer shape of the cup yoke has 6 or more corners that are chamfered and with a line control polygon having two control axes, along one of the control shaft magnetic attachment in length and wherein the range near Rukoto of 1.1 to 1.5 times the length along the other control axis is.