RU2241410C2 - Method for treating dental prostheses - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: method involves coating base with gold alloy by dipping it in electrolyte containing potassium salt of univalent gold and additives, holding therein exposed to electric current of given intensity and temperature under continuous stirring conditions. Then, washing and drying is applied. Solution containing various potassium salts taken in known proportions. The process is carried out under temperature of 65-75°C, current intensity of 0.2-1.0 A/dm² and voltage of 0.7-1.0 V. Holding time is selected depending on coating thickness to be produced.

EFFECT: high quality of coating; low labor consumption level.

5 cl

Description

The invention relates to the field of medicine, namely dentistry, and more particularly to the field of manufacture of dentures from corrosion-resistant alloys with a gold coating, as well as the creation of a sublayer for applying ceramic to a denture.

A known method of processing dentures [RF patent No. 2036622, IPC A 61 C 31/02, 1995] by applying gold alloys to a corrosion-resistant alloy, comprising sequentially immersing the prosthesis in gilding electrolytes of two compositions, keeping them at a given voltage, washing and drying. In this case, as the electrolyte of the first composition, a solution containing a salt of trivalent gold, cobalt chloride, citric acid, amines, hydrochloric acid, taken in the following proportions, wt.%:

Trivalent Gold Salt 0.25

Cobalt Chloride 0.03

Citric Acid 8.0

Amines 0.2

Hydrochloric acid Rest to pH 1

As the electrolyte of the second composition, a solution is used containing potassium dicyanoaurate, nickel sulfamic acid, nitrilotriacetic acid, potassium citrate, formic acid, brightening agents and water, taken in the following proportions, wt.%:

Potassium Dicyanoaurate 0.5

Nickel sulfamic acid 0.4

Nitrilotriacetic acid 1.7

Potassium Citrate 6.0

Formic Acid 1.2

Boric Acid 2.0

Brightening additives 0.1

Water Else

In this case, the exposure time in the electrolyte of the first solution is 3-6 minutes, at a voltage of 4-5 V, and in the second solution 30-50 minutes at a voltage of 2-4 V, at room temperature.

The disadvantages of this method of processing dentures are its potential carcinogenicity and allergy due to the presence of nickel in it, the complexity of the execution due to the complex composition of the electrolyte of the first solution, as well as insufficient wear resistance, in particular, there was a need to restore the coating 24 months after the manufacture of the prosthesis.

There is also known a method of processing dentures [RF patent No. 2158564, IPC A 61 C 13/02, 2000] by applying a gold alloy to a corrosion-resistant alloy, comprising sequentially immersing the prosthesis in electrolytes of two compositions, keeping them at a given current value and temperature and constant stirring, washing and drying, while a solution containing monovalent gold salt, citric acid, water taken in the following proportions, wt.%:

Potassium Dicyanoaurate 0.15

Citric Acid 8.0

Water Else, pH 1-1.5

The exposure time in an electrolyte of composition No. 1 is 8-10 minutes at a current density of 0.3-0.5 A / dm ² and room temperature, and as the electrolyte of composition No. 2, a solution containing a monovalent gold salt, cobalt sulfate, trilon A, citric acid, potassium trichloride, zirconium oxide, brightening additive, surfactant, water, taken in the following proportions, wt.%:

Potassium Dicyanoaurate 1.0

Cobalt sulfate 0.1

Trilon A 0.25

Citric Acid 3.0

Potassium citrate trisubstituted 6.0

Zirconium oxide 0.5

Brightening Additive 0.008

Surfactant 0.008

Water Else

The exposure time in the electrolyte of composition No. 2 is 2-2.5 hours at a current density of 0.8-1 A / dm ² and room temperature with constant stirring due to the reciprocating motion of the cathode rod.

A common disadvantage of the known methods is the insufficient wear resistance of the coating, as well as the presence of micropores through which the base metal diffuses over time, changing the color of the prosthesis, which is completely unacceptable, in particular, for ceramic prostheses. This disadvantage is not eliminated by increasing the thickness of the coating due to the longer deposition process.

In addition, a common disadvantage of the known methods is the complexity of the coating due to the use of several formulations.

The objective of the invention is to improve the quality of the coating while reducing the complexity of the coating.

The problem is solved by the method of processing dentures by applying a gold alloy to the base, including immersing the base in an electrolyte containing potassium salt of monovalent gold and additives, keeping it there at given current and temperature and stirring, washing and drying, characterized in that as an electrolyte use a solution containing various potassium salts, taken in the following ratios, g / l:

Potassium sulfate K ₂ SO ₄ 9.2-9.6

Potassium hydroxide KOH 11.6-11.8

Potassium hyposulfite K ₂ S ₂ O ₃ 9.8-10.2

Potassium bisulfite K ₂ S ₂ O ₅ 29-31

Potassium Dicyanoaurate K [Au (CN) ₂ ] 15-21

Potassium Sulfonated

polyunsaturated fatty acids

as a brightener

additives 0.05-0.1

Water 1 L

The process is carried out at a temperature of 65-75 ° C, a current density of 0.2-1.0 A / dm ² and a voltage of 0.7-1.0 V, and the holding time is selected depending on the thickness of the coating that needs to be obtained.

When implementing the method as a basis, you can use:

- frame made of corrosion-resistant alloy;

- a working model on which a layer of copper is preliminarily chemically applied.

When implementing the method, it is recommended to use potassium salts of sulfonated polyunsaturated fatty acids linoleic or linolenic.

Improving the quality of the coating, namely, increasing its hardness and reducing porosity, occurs due to the formation of a precipitate having a crystalline structure with a reduced grain size and the inclusion of a phase containing potassium, which in turn is achieved by the proposed combination of electrolyte ingredients. In this case, the potassium salt of a sulfonated polyunsaturated fatty acid, for example linolenic, additionally plays the role of a brightening additive. Adequate hardness of the coating and the absence of micropores provide a high quality coating and make it possible to manufacture gold crowns in a galvanic manner.

This method in the manufacture of gold crowns can successfully compete with casting, surpassing it in accuracy and efficiency.

Case Studies

Example 1. A bridge was made using cermet based on a nickel-chromium alloy framework. The prosthesis was carefully polished, degreased, etched in a 25% hydrochloric acid solution for 1 minute, washed in water and hung in an electrolyte of the composition, g / l: potassium sulfate K ₂ SO ₄ - 9.2; potassium hydroxide KOH - 11.6; potassium hyposulfite K ₂ S ₂ About ₃ - 9.8; potassium bisulfite K ₂ S ₂ O ₅ - 29; potassium dicyanoaurate K [Au (CN) ₂ ] - 15; potassium salt of linoleic acid - 0.05; water - 1 l. The process was carried out for 1 hour, at a temperature of T = 75 ° C, voltage U = 0.9 V and current density J = 0.5 A / dm ² .

The method was carried out with constant stirring of the electrolyte, by reciprocating the cathode rod, on which the frame was fixed, to prevent depletion of the near-cathode layer.

As a result, a framework coating of 0.02 mm thickness was obtained, on which a ceramic layer could be further applied.

Example 2. A layer of copper was chemically applied to a polymer copy of the working model (column), after which the product was hung in a bath. The electrolyte composition, g / l: potassium sulfate K ₂ SO ₄ - 9.6; potassium hydroxide KOH - 11.8; potassium hyposulfite K ₂ S ₂ About ₃ - 10.2; potassium bisulfite K ₂ S ₂ O ₅ - 31; potassium dicyanoaurate K [Au (CN) ₂ ] - 21; potassium salt of sulfonated polyunsaturated fatty acid - linolenic - 0.1; water - 1 l.

As a result, a crown frame of the required thickness of 0.3-0.4 mm from chemically pure gold was obtained, on which a ceramic layer can be further applied. The process was carried out for 20 hours, at a temperature of T = 65 ° C, voltage U = 0.9 V and current density J = 0.8 A / dm ² . The method was carried out with constant stirring of the electrolyte, by reciprocating the cathode rod, on which the model was mounted, to prevent depletion of the near-cathode layer.

To determine the quality of the obtained gold coating, the prosthesis was placed in an electric furnace and heated to a temperature of 960-1000 ° C. In this case, the gold layer characteristic of thin gold (porous) coatings did not disappear.

Claims (5)

1. A method of processing dentures by applying a gold alloy to a base, comprising immersing the prosthesis in an electrolyte containing potassium salt, monovalent gold and additives, keeping it at a given current and temperature and constant stirring, rinsing and drying, characterized in that the electrolyte used is a solution containing various potassium salts, taken in the following ratios, g / l: potassium sulfate K ₂ SO ₄ 9.2-9.6, potassium hydroxide KOH 11.6-11.8, potassium hyposulfite K ₂ SO ₃ 9,8-10,2, potassium bisulfite, ₁ K S ₂ O ₅ 29,0-31,0, ditsianoau atm potassium K [Au (CN) _2] 15,0-21,0, potassium salt of sulphonated 0.05-0.1 polyunsaturated fatty acid as a brightening additive, water 1 liter, the process is carried out at a temperature of 65-75 ° C, current densities of 0.2-1.0 A / dm ² and voltages of 0.7-1.0 V, and the holding time is selected depending on the thickness of the coating that you want to get. 2. The method of processing dentures according to claim 1, characterized in that as a basis use a frame made of a corrosion-resistant alloy. 3. The method of processing dentures according to claim 1, characterized in that as a basis use a model on which a layer of copper is preliminarily applied. 4. The method of processing dentures according to claim 1, characterized in that the potassium salt of linoleic acid is used as the brightening additive. 5. The method of processing dentures according to claim 1, characterized in that the potassium salt of linolenic acid is used as a brightening agent.