JPH0595965A - Permanent magnet assembly for stabilizing denture - Google Patents

Abstract

PURPOSE:To provide a permanent magnet assembly for stabilizing a denture which allows the increasing of a holding force with a denture base without decreasing a magnetic attraction force. CONSTITUTION:This permanent magnet assembly for stabilizing a denture comprises a case 2 with a U-shaped cross section made of an anticorrosive magnetic material, a permanent magnet 1 which is magnetized axially while being housed into the case 2, a sealing plate 13 which is made of an anticorrosive material and fastened at an open end of the case 2 to seal up the inside of the case 2. A surrounding groove 12 with the depth thereof of 0.05-0.3mm is provided on the outer circumferential surface of the case 2 at the position 0.3-1.0mm from the bottom surface thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet assembly for stabilizing a denture for use in a prosthetic method for holding a denture by utilizing a magnetic attraction force of a permanent magnet.

[0002]

2. Description of the Related Art Various attempts have been made in the past to utilize a magnetic attraction force acting between a permanent magnet and a soft magnetic alloy when fixing a denture in the oral cavity, for example, "TR Jackson." : Application of Rare Earth Magnet Sustainer for Osseo Integrated Implants, Oral Maxiro Facial Implant, Vol. 1 (1987), No. 2, 77-89 "
Variously described in.

In order to put this kind of denture into practical use, the permanent magnet must be completely sealed in a case made of a material that has been proved to be harmless to the human body, and the leakage magnetic flux to the outside. Is required, and a permanent magnet assembly having a structure as shown in FIG. 2, for example, has been used. In FIG. 2, (a) is a perspective view showing the external appearance, and (b) is a longitudinal sectional view. As shown in FIG. 2, for example, a permanent magnet 1 formed in a columnar shape from a rare earth cobalt-based material and magnetized in the axial direction indicated by an arrow is formed of stainless steel having excellent corrosion resistance and magnetism in a longitudinal sectional shape. Are housed in a U-shaped case 2 and are sealed by a cover plate 3 formed in the shape of a thin disk made of non-magnetic stainless steel having excellent corrosion resistance. Bonding is performed to form a permanent magnet assembly 10 having a closed structure.

FIG. 3 is a longitudinal sectional view of a main part showing an example of a denture fixing means using a conventional permanent magnet assembly. In FIG. 3, reference numeral 7 denotes a root member, which is made of a soft magnetic alloy, for example, has a T-shaped longitudinal section and is embedded in the tooth root 9. Reference numeral 8 denotes a denture base, and the permanent magnet assembly 10 shown in FIG. 2 is embedded in the denture base 8 such that the lid plate 3 side faces the root member 7. With the above configuration, a magnetic attraction force acts between the permanent magnet assembly 10 and the root member 7, and the denture base 8 is pressed against the root 9 by this magnetic attraction force, so that the denture 11 is placed in the oral cavity. It can be stabilized.

In this case, since the magnetic flux emitted from the permanent magnet 1 passes through the magnetic path consisting of the permanent magnet 1, the root member 7, the case 2 and the permanent magnet 1, the leakage flux to the outside is extremely small. Further, since both the case 2 and the cover plate 3 are made of stainless steel, the corrosion resistance and the wear resistance against the meshing force of the denture 11 are practically sufficient, and the adhesive 4
It is also said that the adhesive strength, the sealing property when used in the oral cavity, the chemical stability, etc. are sufficiently practical.

[0006]

However, the permanent magnet assembly 10 having the above structure has the following problems.
That is, the permanent magnet assembly 10 is only held by the resin material forming the denture base 8, and the frictional force between the outer peripheral surface of the case 2 forming the permanent magnet assembly 1 and the resin material. Is only held by.
On the other hand, since the resin material forming the denture base 8 is an organic compound, there is concern about maintaining chemical stability for a long time and holding power of the permanent magnet assembly 10. Further, due to the meshing force applied to the denture 11, the denture base 8 and the permanent magnet assembly 1
Since the action of promoting relative movement in the axial direction with respect to 0 is also added, relative movement occurs between the denture base 8 and the permanent magnet assembly 10 during use, and in extreme cases, the permanent magnet assembly 10 There is a problem that 10 may separate from the denture base 8.

In order to solve the above problems, a circumferential groove is formed on the outer peripheral surface of the case 2 constituting the permanent magnet assembly 10 to increase the holding force of the denture base 8 with respect to the permanent magnet assembly 10. Attempts have been made to make it happen. However, the case 2 is a member that forms the magnetic path of the permanent magnet 1, and the outer peripheral wall thickness is usually very small. On the other hand, in order to increase the holding force, it is sufficient to increase the depth of the circumferential groove. However, increasing the depth of the circumferential groove reduces the cross-sectional area of the magnetic path and prevents leakage. There is a problem that the magnetic flux increases and the magnetic attraction force decreases.
In addition, depending on the position where the circumferential groove is provided, the effective magnetic flux to be applied from the permanent magnet 1 to the root surface member 7 is reduced, and the magnetic attraction force is also reduced.

The present invention solves the above problems existing in the prior art and provides a denture stabilizing permanent magnet assembly capable of increasing the holding force of the denture base without reducing the magnetic attraction force. To aim.

[0009]

In order to achieve the above object, according to the present invention, a case having a U-shaped longitudinal cross-section made of a corrosion-resistant magnetic material, and a case magnetized in the axial direction and housed in the case are provided. A permanent magnet assembly for stabilizing a denture, which comprises a permanent magnet and a seal plate made of a corrosion-resistant material and fixed to the opening end of the case so as to seal the inside of the case. A technical means was adopted in which a circumferential groove having a depth of 0.05 to 0.3 mm was provided at a position of 1.0 mm.

In the present invention, it is not preferable that the position where the circumferential groove is provided is less than 0.3 mm from the bottom surface of the case because the circumferential groove that is sufficient to secure the holding force cannot be provided. On the other hand, if the above position exceeds 1.0 mm from the bottom surface of the case, the magnetic flux to be applied from the permanent magnet to the root member is disturbed or reduced, and as a result, the magnetic attraction force is reduced, which is inconvenient.

Next, if the depth of the circumferential groove is less than 0.05 mm, the holding force or pull-out resistance cannot be secured, which is not preferable. On the other hand, if the depth of the circumferential groove exceeds 0.3 mm,
As a result of the decrease in the cross-sectional area of the case where the magnetic path is to be formed, the magnetic path is saturated, the leakage magnetic flux increases, and the magnetic attractive force decreases, which is inconvenient.

Further, the permanent magnet used in the present invention is required to be small in size and to obtain a magnetic flux as strong as possible. Therefore, the SmCo type magnet or Nd is used.
Rare earth magnets such as Fe magnets are used. The shape thereof depends on the part to be used, but a cylindrical or columnar shape is usually used. Therefore, as the case, a hollow cylinder having a bottom is often used.

[0013]

With the above construction, it is possible to increase the holding force or pull-out resistance of the denture base to the permanent magnet assembly without reducing or disturbing the effective magnetic flux that should contribute to the magnetic attraction force.

[0014]

1 is a longitudinal sectional view showing an embodiment of the present invention, in which the same parts are designated by the same reference numerals as in FIG. Figure 1
Reference numeral 12 denotes a circumferential groove, which is circumferentially provided on the outer peripheral surface of the case 2 formed in the shape of a hollow cylinder with a bottom. Note that L is the distance from the bottom surface 2a of the case 2 to the middle portion of the circumferential groove 12, and t is the depth dimension of the circumferential groove 12. The longitudinal cross-sectional shape of the circumferential groove 12 is, for example, an isosceles right triangle. Therefore, the width of the circumferential groove 12 in the axial direction is 2t. Next, 13 is a seal plate, in which the seal ring 14 and the seal disc 15 are integrally formed by seam welding 16. The seal plate 13 and the case 2 are integrally fixed by seam welding 16.

In this case, the case 2 is made of ferritic stainless steel (magnetic), for example, SUS447J, and has an outer diameter of 4.
4 mm, inner diameter 3.4 mm, height 2.1 mm, depth 1.5 mm
(Thickness of bottom and side wall is 0.6mm)
O system permanent magnet 1 (H22A made by Hitachi Metals) outer diameter 3.2m
m and height 1.4 mm, and fixed in the case 2. The seal plate 13 is made of SUS447J and has an outer diameter of 2.6.
mm, the thickness of the sealing disk 15 is 0.25 mm, and austenitic stainless steel (non-magnetic), for example SUS
316, outer diameter 3.4 mm, inner diameter 2.6 mm, thickness 0.
The seal ring 14 formed to 25 mm was formed by seam welding and fixed to the open end of the case 2 to hermetically seal the permanent magnet 1.

Table 1 is a table showing the values of the magnetic attraction force and the pull-out withstanding force when the distance L and the depth dimension t of the circumferential groove 12 in FIG. 1 are changed. As a comparative example, the result for the conventional one shown in FIG. 2 is also shown as No. 26.

[0017]

[Table 1]

As is clear from Table 1, the comparative example N
At o.26, although magnetic attraction is secured,
The value of pull-out resistance is extremely small. On the other hand, No. 1-
In No. 25, the pulling resistance is larger than that of the comparative example, and the effect of providing the circumferential groove 12 shown in FIG. 1 is shown. It should be noted that as the depth of the circumferential groove 12 becomes smaller, the pull-out resistance tends to decrease, and it is presumed that those having a depth of less than 0.05 mm are equivalent to those of the comparative example. On the other hand, when the depth of the circumferential groove 12 becomes large, the pull-out resistance is improved, but the magnetic attraction force tends to be decreased. When the depth dimension is 0.4 mm, the magnetic attraction force is lower than that of the comparative example. It is also understood that the magnetic attraction force decreases as the distance from the bottom surface 2a of the circumferential groove 12 (see FIG. 1) increases. Especially in the case of 1.5 mm, the degree of this decrease is large. This is because the magnetic flux to be applied to the root surface member 7 (see FIG. 3) from the permanent magnet 1 shown in FIG. 1 is disturbed or reduced as the distance increases.

The depth of the circumferential groove 12 was made the same, and the width in the axial direction was changed, and the evaluation was made. The results are the same as in Table 1. This is because the magnetic path formed by the case 2 depends on the magnetic saturation state depending on the cross-sectional area.
It is considered that the pulling-out resistance is caused by the fact that it changes depending on the depth dimension of the circumferential groove 12. In addition, the results of evaluation of the embedded permanent magnet assembly 10 after soaking in hot water at 37 ° C. for 30 days also show that
It was confirmed that the same tendency as in Table 1 was exhibited.

[0020]

EFFECTS OF THE INVENTION Since the present invention has the structure and operation described above, the holding force for the permanent magnet assembly by the denture base and the magnetic attraction force by the permanent magnets housed in the case are not reduced. This has the effect of significantly increasing the pull-out resistance.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a conventional permanent magnet assembly,
(A) is a perspective view showing an external appearance, and (b) is a longitudinal sectional view.

FIG. 3 is a longitudinal sectional view of an essential part showing an example of artificial tooth fixing means using a conventional permanent magnet assembly.

[Explanation of symbols]

 1 Permanent magnet 2 Case 12 Circumferential groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Okuno 2-3-10 Kanda Surugadai, Chiyoda-ku, Tokyo Inside the Medical Equipment Laboratory, Tokyo Medical and Dental University (72) Satoru Mizutani 1-5 Yushima, Bunkyo-ku, Tokyo 45 Tokyo Medical and Dental University Faculty of Dentistry (72) Inventor Shin Ishikawa 1-5-45 Yushima, Bunkyo-ku, Tokyo Tokyo Medical and Dental University Faculty of Dentistry

Claims (2)

[Claims] 1. A case having a U-shaped longitudinal section formed of a corrosion-resistant magnetic material, a permanent magnet axially magnetized and housed in the case, and a case made of a corrosion-resistant material for sealing the case. A permanent magnet assembly for stabilizing a denture, which comprises a seal plate fixed to the open end of
On the outer peripheral surface of the case, at a position of 0.3 to 1.0 mm from the bottom surface,
A permanent magnet assembly for stabilizing a denture, comprising a circumferential groove having a depth of 0.05 to 0.3 mm. 2. The permanent magnet assembly for stabilizing artificial teeth according to claim 1, wherein the permanent magnet and the case have a circular cross-sectional shape.