JPS5814862B2 - low melting point magnetic alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dental alloy with a low melting point and excellent castability.
The present invention relates to dental magnetic alloys particularly suitable for use in combination with rare earth cobalt magnets.

The idea of using permanent magnets in the field of dentistry has been around for a long time, and attempts have been made to maintain and stabilize dentures using the attractive and repulsive force of magnets, but this has not been put into practical use.

However, in recent years, with the advent of extremely small and powerful rare earth cobalt magnets, this has become a reality for the first time.

A recent trend in denture technology is to utilize remaining teeth as much as possible.

Supplementary denture maintenance methods using permanent magnets are in line with this trend, and are being actively researched at various universities.

Clinical experiments at various universities have yielded good results to date, and there is a strong expectation that this technology will be perfected as a new method for dental prosthetics in the future, and that it will be used by general clinicians.

FIG. 1 shows the root plate force method, which is known as one of the basic methods of magnetic prosthesis.

When this method is applied to complete dentures, tooth loss can be prevented.
In addition to being comfortable to wear as it can be made palatal, compared to other attachments such as clasps and hooks, it does not put undue force on remaining teeth, reduces occlusal pressure, and is easier to clean. It has features such as preventing alveolar pyorrhea.

By the way, for example, in the above method, as shown in FIG. 1, a magnetic alloy 3 is used which is magnetized by a rare earth cobalt magnet 5 and has a sufficient attraction force between it and the magnet 5.

In addition to magnetic properties, the magnetic alloy used here must also have workability for dental casting, and must also have physical, mechanical, and chemical properties that are necessary for dental casting. It is preferable that the material is also excellent in properties.

As a dental soft magnetic alloy that meets the above requirements, Co
There are alloys whose main components are %Ni and Pd.

This alloy is a dental magnetic alloy with a melting temperature of 1350° C. or less, a saturation magnetic flux density of 2000 G or more, and excellent corrosion resistance.

However, the above-mentioned Co-Ni-Pd alloy has inferior castability compared to the commercially available Au-Ag-Pd alloy as a dental casting alloy, and dental technicians actually cast it with a centrifugal casting machine. When this process is performed, a slag-like thin film forms over the entire surface of the melt, making it difficult to determine the timing of casting.

An object of the present invention is to solve the above-mentioned problems, make it easier to determine the casting timing, and provide a novel dental magnetic alloy that has excellent castability.

In order to achieve the above object, the present invention provides a weight ratio of Co2
0 to 30%, Ni 20 to 40%, and Pd 30 to 70% as main components, Si exceeding 0.5% and having a coefficient of 5 or less
It is characterized by additionally containing.

In the present invention, the reason why Co is set at 20 to 35 is to keep the melting temperature below 1350°C, and also because by forming an alloy with Pd, a magnetic alloy with high corrosion resistance can be obtained. .

Ni has the effect of slightly improving corrosion resistance and hardness, and improving the Beauselen seizing property, but if it exceeds 40%, the magnetic flux density decreases significantly, so it was set at a ratio of 20 to 40%.

Furthermore, by adding Si, castability can be improved and blowholes can be significantly reduced.

Moreover, the effect is particularly remarkable when the content exceeds 0.51%.

On the other hand, if the amount of Si exceeds 5%, the material becomes extremely brittle, so the amount of Si added should be more than 0.5% and less than 5%.

Hereinafter, the present invention will be explained in detail based on Examples.

Alloys having the compositions shown in Table 1 were produced in an argon arc melting furnace.

In order to observe the pouring rate and cavities, 20X20XO
．． A wax pattern of 4 x 10 mm was prepared.

Cerabest was used as the investment material, and after dewaxing, the alloy was preheated to 800° C. and melted and cast using a high-frequency induction centrifugal casting machine.

In the same way, 4 3%Pd-2 7%Co-30
%Ni alloy and a commercially available Au-Ag-Pd alloy and compared the casting rate and cavity.

The results are shown in Table 2.

There was almost no difference in casting rate between the three types of alloys according to the present invention and the comparative material.

However, compared to the conventional material, the number of cavities in the alloy of the present invention to which Si was added was drastically reduced.

In addition, the alloy of the present invention containing Si has the effect of destroying the slag film coating the melt surface, and has the obvious advantage that the movement of the melt surface can be directly observed, making it easy to judge the casting timing. Ta.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a magnetic prosthesis method using a root plate method. 1... Gingival area, 2... Root area, 3...
...magnetic alloy, 4...denture, 5...
・Rare earth cobalt magnet.

Claims (1)

[Claims] 1 Weight ratio: Co 20-35, Ni 20-40,
Pd 30-70, and Si 0.5-5 (however, 0
．． 5%).