JP4368343B2 - Silver palladium alloy for dental porcelain baking - Google Patents

Description

  The present invention relates to a porcelain baking alloy used for dental treatment.

  In dental treatment, the crown defect part and tooth defect part are prosthetic by casting crown, bridge and denture, but as one of the methods satisfying aesthetics and functionality, it was made with a casting alloy for porcelain baking Porcelain-baked crown bridges are used in which the tooth shape is restored by baking ceramic called porcelain on the surface of the metal frame.

  The basic conditions necessary for porcelain alloys are that the porcelain alloys are excellent in castability, have a strong bond with porcelain, and have a thermal expansion coefficient compatible with porcelain. It is done. Conventional precious metal alloys for baking porcelain that have been developed so far are roughly classified into alloy systems mainly containing Au and alloy systems not containing Au.

As a representative of the latter precious metal alloy not containing Au, there is a silver palladium alloy. Since these do not contain gold, they have advantages such as low cost, light weight in the oral cavity, and sufficient mechanical properties. However, conventional silver-palladium alloy products have many problems such as discoloration of porcelain, cracking and peeling of porcelain, and generation of bubbles in porcelain when baking porcelain. One reason for the cracking and peeling of porcelain is that the silver-palladium alloy has a higher thermal expansion coefficient than other alloys. In consideration of compatibility with commercially available porcelain, the thermal expansion coefficient of the alloy is preferably about 13.8 to 14.8 × 10 ⁻⁶ K ⁻¹ .

In Patent Document 1, a porcelain baking alloy composed of an Ag—Pd—Fe group and an additive element is disclosed. However, although this technique has mechanical properties as a dental alloy, its thermal expansion coefficient is as high as 15.0 × 10 ⁻⁶ K ⁻¹ or more. In addition, since 5 to 10% by weight of Fe is added as a component element, the oxide film color tone of the alloy is black, and a black line appears at the interface between the porcelain and the alloy after the porcelain build-up, and can be easily removed. Detract from aesthetics. From the above, it cannot be said that the technique required for the porcelain baking alloy is sufficient.
JP 54-132426 A

In Patent Document 2, as silver-palladium alloy for porcelain baking, Claim 1 includes Ag: 7 to 45 wt%, Pd: 45 to 80 wt%, Ru: up to 1 wt%, Ga: up to 7 wt%, Co: Silver palladium alloys comprising up to 5% by weight and Ge: up to 3% by weight are disclosed. Claim 5 discloses a silver-palladium alloy comprising the range of the components of claim 1 with Au: up to 5 wt%, In: up to 5 wt%, Sn: up to 5 wt%, and Cu: up to 2 wt%. ing. However, the development goal of this alloy is focused on suppressing discoloration during firing of porcelain, and the coefficient of thermal expansion required for the porcelain baking alloy is high, and there are many uneasy aspects of porcelain seizure. Even when viewed from the examples, the thermal expansion coefficient is as high as 14.9 to 15.8 × 10 ⁻⁶ K ⁻¹ , so it cannot be said that the conventional problem has been solved.
Japanese Patent No. 2851295

The object of the present invention is to provide a technical problem to the negative point of the silver-palladium dental porcelain alloy described above. Specifically, the thermal expansion coefficient that affects the porcelain seizure property is 14.8 × 10. ^It provides a silver palladium alloy for baking dental porcelain at ^-6 K ^-1 or less and without cracking or peeling of the porcelain.

  The present invention is a dental alloy for producing a dental prosthesis by casting, Ag: 20-30% by weight, Pd: 60-70% by weight, In: 6-8% by weight, Ga: 3-5% by weight , Sn: a silver-palladium alloy for baking dental porcelain, characterized by comprising 0.1 to 6% by weight.

The present invention also comprises Ag: 20-30% by weight, Pd: 60-70% by weight, In: 6-8% by weight, Ga: 3-5% by weight, Sn: 0.1-6% by weight, A silver-palladium alloy for dental porcelain baking, having an expansion coefficient of 14.8 × 10 ⁻⁶ K ⁻¹ or less.

The present invention further includes Ag: 20-30 wt%, Pd: 60-70 wt%, In: 6-8 wt%, Ga: 3-5 wt%, Sn: 0.1-6 wt%, and Au , Pt, Rh selected from at least one element selected from 0.1 to 1% by weight, Ge, Zn, Sb, Si selected from one element selected from 0.1% to 1% by weight, Ir, It comprises an element selected from one of Ru, W, and Re up to 0.1 to 1% by weight, and has a thermal expansion coefficient of 14.8 × 10 ⁻⁶ K ⁻¹ or less. A silver-palladium alloy for dental porcelain baking.

  Next, the constitution of the silver-palladium alloy for baking porcelain in this invention and the reason for limiting the components will be described.

[Ag, Pd]
First, regarding Ag and Pd, changing the component ratio in the binary alloy of AgPd affects the melting point and thermal expansion of the alloy. That is, when the Ag content is increased (Pd content is decreased), the thermal expansion coefficient is high and the melting point is low. On the other hand, the opposite is true when the Ag content is low. By adding an element having a low melting point other than Ag and Pd, the melting point of the alloy is lowered, but the thermal expansion coefficient is increased. Therefore, in the present invention, paying attention to the ratio of Ag / Pd, the ratio is set in the range of Ag30 or less, the melting point is high, the thermal expansion coefficient is low, and the melting point is adjusted by adjusting the addition amount of other elements. The combination of components satisfying a low thermal expansion coefficient of 14.8 × 10 ⁻⁶ K ⁻¹ or less was found.

When the component element Ag is less than 20% by weight, the thermal expansion coefficient of the alloy is low, but even if other elements are added, the melting point cannot be lowered, and the melting and castability deteriorate. On the other hand, if it exceeds 30%, the melting point of the alloy becomes low, but the thermal expansion coefficient becomes high. In addition, by adding an element having a low melting point, the thermal expansion coefficient increases and greatly exceeds 14.8 × 10 ⁻⁶ K ⁻¹ . From the above results, it was set to 20 to 30% by weight.

  If the component element Pd is less than 60% by weight, the melting point of the alloy is lowered, but the coefficient of thermal expansion is increased, and the addition of other elements further increases the coefficient of thermal expansion. On the other hand, if it exceeds 70% by weight, the coefficient of thermal expansion becomes low, but even if other elements are added, the melting point cannot be lowered and the melting and casting properties are deteriorated. From the above results, it was set to 60 to 70% by weight.

[In]
The component element In lowers the melting point of the silver-palladium alloy, improves the melting and casting properties, and affects the thermal expansion coefficient. When combined with other component element Ga, if the addition amount is less than 6% by weight, the coefficient of thermal expansion is lower than 14.8 × 10 ⁻⁶ K ⁻¹ , but the melting point increases, so melting and castability are poor. It will be enough. On the other hand, if it exceeds 8% by weight, the thermal expansion coefficient becomes higher than 14.8 × 10 ⁻⁶ K ⁻¹ . From the above, it was set to 6 to 8% by weight.

[Ga]
The component element Ga lowers the melting point of the silver-palladium alloy and improves the melting and casting properties, and contributes to the improvement of mechanical properties and the strength of bonding with porcelain. When combined with the other component element In, the effect is seen from the addition of 3% by weight or more, and when it exceeds 5% by weight, the alloy becomes brittle and the workability is lowered. From the above, it was set to 3 to 5% by weight.

[Sn]
The component element Sn lowers the melting point of the silver-palladium alloy, improves melting and casting properties, and improves mechanical properties. When added in combination with other elements Ga, 0.1% by weight or more has a sufficient effect on mechanical properties. On the other hand, addition exceeding 6% by weight causes the alloy to become brittle. From the above, it was set to 0.1 to 6% by weight.

[Au, Pt, Rh]
The component element Au contributes to the reduction of the thermal expansion coefficient by a slight addition, and also contributes to the improvement of mechanical properties and corrosion resistance. However, if it exceeds 1% by weight, the melting point of the alloy increases, so 0.1 to 1% by weight was included. The component elements Pt and Rh also have the same effect up to 0.1 to 1% by weight.

[Ge, Zn, Sb, Si]
The component element Ge has an effect of lowering the melting point of the AgPd alloy while maintaining a thermal expansion coefficient of 14.8 × 10 ⁻⁶ K ⁻¹ or less. In addition, it contributes to strengthening the bonding strength between the alloy and porcelain, improving the color tone of the oxide film, and improving the mechanical properties. However, if it exceeds 1% by weight, the increase in the thermal expansion coefficient of the alloy is significantly affected. It was decided to contain up to 1-1% by weight. The component elements Zn, Sb, and Si have the same effect up to 0.1 to 1% by weight.

[Ir, Ru, Re, W]
The component element Ir contributes to the reduction of the thermal expansion coefficient by a slight addition, and also contributes to the refinement of crystal grains and the improvement of mechanical properties of the alloy. However, if it exceeds 1% by weight, the melting point of the alloy may be increased or segregation in the alloy may be caused. The component elements Ru, Re and W have the same effect up to 0.1 to 1% by weight.

  By limiting the component range as described above, it is possible to provide a silver-palladium alloy for dental porcelain baking that has excellent castability and good seizure characteristics.

  The components and properties of the examples of the present invention are shown in Table 1 below.

  For each sample, each pure metal was weighed, melted in a high-frequency heating melting furnace, and processed into a predetermined shape. Samples shown in Table 1 were cast by a mechanical casting machine, and predetermined test pieces were produced by the lost wax method. The contents of each test are as follows.

(1) Casting test Each sample was cast into a predetermined shape, and the presence or absence of a cast hole was observed.

(2) Melting temperature A test piece was cut out from each sample, and the points at which the melting and melting of the alloy started and ended were measured with a differential thermal analyzer.

(3) Hardness test Using a micro Vickers hardness tester, the hardness was measured under conditions of a load of 200 g and a load application time of 10 seconds.

(4) Thermal expansion test In accordance with JIS T 6120, the test method was prepared as a test piece with a size of about φ4 mm × L20 mm, heated to 550 ° C. at a temperature rising rate of 5 ° C./min with a thermomechanical analyzer, The average coefficient of thermal expansion up to 500 ° C was calculated.

(5) Porcelain discoloration confirmation test The presence or absence of discoloration of the porcelain after baking the porcelain on each test piece was observed.

(6) Porcelain seizure test In accordance with JIS T 6118, the porcelain is baked on each test piece, and then a metal rod with a diameter of 10.0 mm is pressed against the back of the baked surface until the porcelain is broken. Bend it. Furthermore, the test piece was straightened, and the state of the porcelain adhered to the baking surface after breaking was observed.

  Table 2 shows the test results of the above (1) to (6).

As can be seen from the results shown in Table 2, within the scope of the present invention, there is no cast hole, a thermal expansion coefficient of 14.8 × 10 ⁻⁶ K ⁻¹ or less is satisfied, there is no discoloration of the porcelain, and the porcelain after bending Sufficiently remained. Therefore, it was confirmed that by limiting the component range as described above, it is possible to provide a silver-palladium alloy for dental porcelain baking that has excellent castability and good seizure characteristics.

Claims (3)

  Silver palladium for baking dental porcelain consisting of Ag: 20-30 wt%, Pd: 60-70 wt%, In: 6-8 wt%, Ga: 3-5 wt%, Sn: 0.1-6 wt% alloy. Ag: 20-30% by weight, Pd: 60-70% by weight, In: 6-8% by weight, Ga: 3-5% by weight, Sn: 0.1-6% by weight. A silver-palladium alloy for baking dental porcelain, characterized by being 8 × 10 ⁻⁶ K ⁻¹ or less. Ag: 20-30% by weight, Pd: 60-70% by weight, In: 6-8% by weight, Ga: 3-5% by weight, Sn: 0.1-6% by weight, in addition to Au, Pt, Rh Of these, at least one element selected from 0.1 to 1% by weight, and at least one element selected from Ge, Zn, Sb, and Si from 0.1 to 1% by weight, Ir, Ru, W, Dental porcelain comprising at least one element selected from Re in an amount of 0.1 to 1% by weight and having a thermal expansion coefficient of 14.8 × 10 ⁻⁶ K ⁻¹ or less Silver palladium alloy for baking.