JPH07241302A - Conus crown and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a conus crown by which accurate diagnosis becomes possible without causing turbulence of an MRI image. CONSTITUTION:A conus crown is composed of an inner crown 2 composed of a nonmagnetic material and an outer crown 3 having an external shape of a false tooth, and a permanent magnet member 5 is fixed to a bottom part of a recessed part 3a of the outer crown 3. A recessed 2a is formed on an upper end surface of the inner crown 2, and a holding plate 4 composed of a soft magnetic material is screw fitted to a screw part 2b situated in the center part of the recessed part 2a so as to be freely mounted and demounted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Cornus crown for holding and fixing a denture by utilizing a magnetic attraction force of a permanent magnet, and in particular, a soft magnetic holding plate can be easily attached and detached during MRI or the like. Conus Crown

[0002]

2. Description of the Related Art When fixing a denture in the oral cavity, various attempts have already been made to utilize the magnetic attraction force between a permanent magnet embedded in the denture and a soft magnetic alloy member fixed to the tooth root. , "Osseo Integrated
Application of Rare Earth Magnet Holding Member for Implant "
(TR Jackson, "Oral Maxiro Facial
Implant ", Vol. 1, No. 2, pp. 77-89 (1987
Year)), the example is described.

FIG. 4 shows a typical example of a denture fixing member utilizing the magnetic attractive force of a permanent magnet. A substantially disk-shaped holding plate 32 is fixed to the upper end surface of the main body 30 that fills the pores of the tooth root 1 and covers the exposed portion of the tooth root 1, and forms a root surface member 34. The main body 30 is formed of a corrosion-resistant non-magnetic material such as a palladium alloy, and the holding plate 32 is formed of a corrosion-resistant magnetic stainless steel such as SUS447J1. On the other hand, a denture 42 is implanted in the denture base 40, and a permanent magnet assembly 42 is embedded so as to be exposed at the bottom surface. The denture base 40 can be removably attached to the root member 34.

Since the denture fixing member having such a structure does not use a wire called a clasp, it can be freely attached and detached, there is little discomfort at the time of mounting, and there is little risk of damaging the denture fixing teeth. Have advantages. However, since the denture base 40 is provided, there is a problem in that a discomfort still remains when worn and the aesthetic appearance is poor.

By the way, a so-called Cornus crown is known as a means for fixing a denture which does not cause discomfort during mounting. As shown in FIG. 5, the Cornus crown is composed of an inner crown 2 that covers the trapezoidal protrusion 1a of the tooth root 1, and an outer crown 3 that closely fits the inner crown 2 and has the outer shape of a denture.
In order to prevent the detachable outer crown 3 from being detached during use, the fitting force generated by making the recess of the outer crown 3 slightly smaller than the outer periphery of the inner crown 2 is used.

[0006]

[Problems to be Solved by the Invention] However, the inner crown 2
It is very difficult to precisely cast the inner crown 2 and the outer crown 3 so that the fitting force between the outer crown 3 and the outer crown 3 is adjusted to the optimum value (about 500 g), and the fitting force gradually weakens as it is used for a long period of time. Therefore, there is a problem that it is easy to come off. Once the fitting force that holds the outer crown 3 is attenuated,
Cornus Crown must be rebuilt.

Therefore, when the cornus crown is used as the means for fixing the denture, it is preferable that the fitting force is not weakened even if it is used for a long period of time. Therefore, it is conceivable to use a permanent magnet as a means for fixing the outer crown 3 of the Cornus crown. In that case, it is necessary to fix the soft magnetic member to the inner crown as a means to be attracted to the permanent magnet, but this causes a problem that the magnetic field is disturbed during inspection such as MRI.

[0008] Therefore, an object of the present invention is to provide a conus crown and its manufacturing method which are not easily detachable even after long-term use and do not disturb the magnetic field during inspection such as MRI.

[0009]

As a result of earnest studies to achieve the above object, the present inventors have found that the permanent magnet member provided in the outer crown of the Cornus crown does not depend on the fitting force for fixing the outer crown. By using the magnetic force of, it is possible to attach and detach freely without lowering the fixing force (fitting force) of the outer crown permanently.
Moreover, it was discovered that if a soft magnetic holding plate for utilizing the magnetic force of a permanent magnet is detachably fixed to the inner crown with a screw or the like, it can be easily detached at the time of inspection such as MRI.
The present invention was conceived.

That is, the Cornus crown of the present invention is
It is composed of an inner crown made of a non-magnetic material and an outer crown having the outer shape of a denture, a permanent magnet member is fixed to the bottom surface of the concave portion of the outer crown, and the upper end surface of the inner crown is made of a soft magnetic material. The holding plate is detachably fixed.

Further, according to the present invention, an inner crown made of a non-magnetic material for detachably supporting a holding plate made of a soft magnetic material, and an outer crown having an outer shape of a denture and having a permanent magnet member fixed in a concave portion are provided. The method of manufacturing Cornus Crown is
(1) On the upper end surface of the wax pattern of the inner crown, the holding plate and the burnout screw member are fixed, and (2) by casting after removing the holding plate, while having a recess on the upper end surface. Form an inner crown having a threaded portion at its center, and (3) after mounting the holding plate on the cast inner crown, form a wax pattern on the outer crown to cast the outer crown. It is characterized by performing.

[0012]

As described above, since the fixing force of the outer crown is obtained by the magnetic force, the problem that the outer crown is easily detached when used for a long time does not occur. Moreover, by detachably fixing the soft magnetic holding plate to the inner crown, it is possible to prevent the problem that the magnetic field is disturbed during the inspection such as MRI and the accurate diagnosis cannot be performed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. [1] First Example of Cornus Crown FIG. 1 shows a Cornus crown according to the first embodiment of the present invention. This Cornus crown is a thin-walled inner crown 2 fixed to an exposed portion 1a of a tooth root 1 that is cut into a truncated cone shape, and an outer crown 3 that completely wraps the inner crown 2 and has a desired tooth appearance.
Consists of.

The inner cap 2 is made of a non-magnetic material such as a palladium alloy, and has a shallow recess 2a formed in its upper end surface, and a threaded portion 2b having the same height as the depth of the recess 2a is projected at the center thereof. . On the other hand, the outer crown 3 is made of a non-magnetic material such as a palladium alloy, and has a recess 3a having a shape that exactly covers the inner crown 2, and the permanent magnet member 5 is embedded in the bottom surface (the uppermost end in the figure) of the recess 3a. ing. Further, the outer crown 3 has a desired tooth shape, and may have the ceramic coating 3b from an aesthetic point of view. The permanent magnet member 5 is composed of a permanent magnet and a casing that seals the permanent magnet.

A holding plate 4 fixed in the recess 2a of the inner crown 2.
Is made of a soft magnetic material and has a screw hole 4a at its center. As the soft magnetic material for the holding plate 4, Mo2% and Cr are used.
Ultra low carbon ferritic stainless steel containing 30% and S
For example, US447J1 can be used. A groove (not shown) having a plus (+) or minus (−) shape for engaging a driver is provided on the upper surface of the holding plate 4.

In order to mount the above-mentioned Cornus crown, first, the inner crown 2 is permanently fixed to the truncated cone-shaped portion 1a of the tooth root 1 with cement or the like, and the screw portion 2b protruding from the concave portion 2a of the inner crown 2 is attached. Then, the holding plate 4 is screwed on using a tool such as a screwdriver. Next, the outer crown 3 is detachably attached to the inner crown 2.

Next, when undergoing an inspection such as MRI,
After removing the outer crown 3, the holding plate 4 is rotated in the opposite direction and removed. Since the magnetic field is not disturbed by removing the holding plate 4, accurate diagnosis is possible.

The shape shown in FIG. 1 is merely an example, and other shapes are possible. For example, when the tooth root has a hole after nerve removal, an inner crown having a protrusion that is shaped to fill the hole can be used.

[2] Second Example of Cornus Crown FIG. 2 shows a Cornus crown according to a second embodiment of the present invention. The inner crown 2 has a screw hole 2c on the upper end surface thereof, and a screw portion 4b having a shape complementary to the screw hole 2c is formed in the lower portion of the holding plate 4. Other parts may be the same as those in the embodiment of FIG. The attachment and detachment of the Cornus crown having this configuration and the attachment and detachment of the holding plate 4 can be performed in the same manner as in the embodiment of FIG.

[2] Method of Manufacturing Cornus Crown Since the methods of manufacturing the Cornus crowns of the first and second embodiments are almost the same, the manufacturing steps of the Cornus crown of the first embodiment shown in FIG. 3 are as follows. It will be explained in order.

(1) The exposed portion of the predetermined tooth 1 is ground into a truncated cone shape, and the wax pattern 20 of the crown is taken (see FIG. 3).
(1)).

(2) An inner crown wax pattern 22 fixed to the obtained truncated cone portion 1a is formed (FIG. 3 (2)).

(3) FIG. 3 (3) shows the wax pattern 22 for the inner crown.
The upper end part of is shown enlarged. A concave portion 24 is formed on the upper end surface of the inner crown wax pattern 22, and the holding plate 4 is formed therein.
(Or a dummy of the same shape as that) and a screw member 26 made of burnable material are installed, and then only the holding plate 4 is removed. As the burnout material for the screw portion 26, it is preferable to use plastic such as styrene. If a metal screw member is used instead of the burnout screw member, it can be cast as it is.

(4) Casting is performed after removing the holding plate 4 from the inner crown wax pattern 22, and has a recess 2a on the upper end surface.
An inner crown 2 having a shape in which a threaded portion 2b is projected at the center thereof is obtained.
After trimming the cast inner crown 2, the holding plate 34 is screwed again and the permanent magnet member 5 is installed on the upper end surface thereof. In this state, the outer crown wax pattern 28 is formed (FIG. 3).
(Four)).

(5) After removing the permanent magnet member 5 from the outer crown wax pattern 28, it is cast by a usual method. The permanent magnet member 5 is embedded in the recess of the recessed bottom surface of the obtained cast outer crown 3 (FIG. 3 (8)), and if necessary, ceramic coating is applied to complete the Cornus crown of the present invention.

[0026]

As described in detail above, the Cornus crown of the present invention fixes the soft magnetic holding plate to the inner crown and
Since the permanent magnet member is embedded in the outer crown, the outer crown can be firmly fixed to the inner crown by the action of the magnetic force, and the fixing force of the outer crown does not weaken even after long-term use. Moreover, since the soft magnetic holding plate is detachably fixed to the inner crown, the holding plate can be easily attached and detached at the time of MRI diagnosis, thereby enabling accurate diagnosis.

[Brief description of drawings]

FIG. 1 is a partially exploded sectional view showing a conus crown according to a first embodiment of the present invention.

FIG. 2 is a partially exploded sectional view showing a conus crown according to a second embodiment of the present invention.

FIG. 3 is a schematic view showing a manufacturing process of the Cornus crown of the first embodiment.

FIG. 4 is a partial cross-sectional view showing an example of conventional denture fixing means utilizing magnetic attraction.

FIG. 5 is a cross-sectional view showing a conventional Cornus crown.

[Explanation of symbols]

 1 ... Tooth root 2 ... Inner crown 2a .. Inner crown recess 2b .. Inner crown screw 3 ... Outer crown 3a .. Outer crown recess 3b .... Ceramic coating 4 ... Holding plate 4a ... Screw holes in holding plate 5 ... Permanent magnet member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirohide Yamada 5200 Sankejiri, Kumagaya City, Saitama Prefecture Hitachi Metals Co., Ltd.

Claims (3)

[Claims] 1. An inner crown made of a non-magnetic material and an outer crown having the outer shape of a denture. A permanent magnet member is fixed to the bottom surface of the recess of the outer crown, and an upper end surface of the inner crown is provided. A Cornus crown characterized in that a holding plate made of a soft magnetic material is detachably fixed. 2. The Cornus crown according to claim 1, wherein a recess is formed in an upper end surface of the inner crown, and the recess and the holding plate are provided with screwing means. Cornus Crown. 3. A Cornus crown comprising an inner crown made of a non-magnetic material for detachably supporting a holding plate made of a soft magnetic material, and an outer crown having an outer shape of a denture and having a permanent magnet member fixed in a recess. In the manufacturing method, (1) the upper end surface of the wax pattern of the inner crown, the holding plate and the burnout screw member is fixed, (2) by casting after removing the holding plate, the upper end surface Forming an inner crown having a concave portion and a threaded portion at the center thereof,
(3) A method of casting the outer crown by forming the wax pattern of the outer crown after mounting the holding plate on the cast inner crown.