JPS5856741B2 - Metal mixed powder for mercury amalgam as dental filling material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method of dental care, in which a so-called amalgam is made by kneading metal powder with mercury (Hg), which is commonly used for the treatment of defects such as cavities. The present invention relates to an improvement in the metal material used in the method of filling defective parts with the metal material.

Conventionally, the metal materials used for this amalgam are Ag and Sn.
For one type of alloy powder mainly composed of
The method of adding and using it has been practiced for a long time, but when used in actual treatment, there are various drawbacks.

In other words, the edges of the amalgam filling are easily damaged,
It has drawbacks such as being easily corroded, and although various improvements have been made, it remains incomplete.

This will be explained using an example. In 1929, the United States established the following specifications for alloys mainly composed of Ag and Sn.

That is, Ag65 or more, 5n29% or less, Cu6%
Hereinafter, several 10% of Hg is added to an alloy powder prepared by melting Zn and these elements to obtain an amalgam.

Amalgam fillings made according to this standard have a weak compressive strength required for interlocking, and are susceptible to corrosion due to the precipitation of an intermetallic compound called the r2 phase.

In order to improve this, in Canada in 1963, a separate Ag-Cu binary alloy (60at%Ag) powder was made in addition to the above-mentioned American standard alloy powder, and this was
An amalgam material made by adding several tens of percent of Hg to a mixture of these two types of alloy powder and kneading it has been released and is in practical use. -Cu6S newly added to the surface of Cu alloy grains
It was found that an intermetallic compound called n5 was formed and this was a new cause of corrosion.

It was also found that the compressive strength of the amalgam made from this mixture was 10 times lower than that of the conventional amalgam made from a single type of alloy.

However, it is noteworthy that the precipitation of r2 phase disappeared.

The present invention has been made by studying the above historical development process in detail, and has completed an amalgam material that eliminates all the drawbacks of conventional amalgam alloys, has strong strength, and has excellent anti-axial properties.

An example of implementing this will be described.

Ag52%, Sn 27.5%, Cu 18.5%, Z
An alloy powder containing 1% N and 1% In was prepared, and 10% electrolytic Ag powder was mixed therein, and several 10% Hg was added to this mixed powder to form an amalgam.

When amalgam is made from the mixed powder thus produced, the reaction product not only forms rl phase (Ag2Hg5) and some Cu6Sn5 phase, but also newly forms β1 phase (Ag2Hg5).
It was found that a metal compound called gHg) can be formed.

This newly formed β1 phase could not be made to appear in any conventional amalgam;
Phase 1 (AgHg) has a close atomic ratio to phase r1 (Ag2Hg5), and r remains unreacted and forms the nucleus in the amalgam.
The phase (A g 3 S n ) and the crystal structure are extremely similar, and the two are easily combined in a primary manner, and have the property of binding particles dispersed in Hg, resulting in higher impact strength than those without the β1 phase. is significantly improved, and corrosion resistance is also significantly improved.

This fact is clear from the results of the following experiment.

Several dozen pieces of Hg were mixed into the above powder mixture, kneaded for 20 seconds, and then pressurized with 18 kg (ADA standard test method), diameter 4.772. A cylindrical specimen with a length of 8 mm was prepared.

The compressive strength after 1 hour after preparing the cylindrical sample was 1610 kg.
/ffl, 815.5 kg/crit of ADA standard
This shows a value that is approximately twice as strong.

4500 kg/C1 after 3 days of kneading? It was found to be extremely excellent.

In addition, when the creep value was determined by applying 60 kg of pressure, which is even more severe than the ADA standard 46.3-load pressurization test, it was 0.11%, which is less than 5φ required for 46.3 kg of pressurization. It turned out to be extremely good.

In the corrosion resistance test, increasing the amount of Ag powder caused Cu6Sn5
The green-blue corrosion color from the phase was reduced and could be completely inhibited with 10φAg.

In this way, the present invention has completed the ideal metal mixed powder for amalgam in terms of mechanical properties and corrosion resistance.
The composition ranges of each element described in the claims indicate the minimum and maximum allowable values of these mechanical and electrochemical properties.

In the present invention, In has the effect of refining alloy crystal grains.

In addition, when Zn is melted, the surface of the molten alloy selectively combined with oxygen is covered with a film of zinc oxide, and Ag, Sn
, prevents the oxidation of Cu, and these Ag, Sn.

This has the effect of preventing fluctuations in the Cu component ratio.

As described above, the present invention has completed an ideal metal mixed powder for amalgam, which has not been achieved in the past, and has extremely high industrial value.

Claims (1)

[Claims] 1. Alloy composition: Ag45φ~65%, 5n20%~
A metal for mercury amalgam as a dental filling material, which is prepared by preparing an alloy powder having a diameter of 30%, cu1o% to 25φ, and mixing pure Ag powder such as electrolytic Ag powder with 5φ to 25φ to this alloy powder. Mixed powder. 2 Alloy composition: Ag45%~65%, 5N20%~
30%, CulO% ~ 25%, Zn 2% or less, In 3%
Create an alloy powder composed of the following, and add 5% to pure Ag powder such as electrolytic Ag powder to this alloy powder.
A metal mixed powder for mercury amalgam as a dental filling material, which is made by mixing 25 pieces of powder.