RU2054902C1 - Method for applying facing coating on the surface of metal dental prostheses - Google Patents

Abstract

FIELD: medicine. SUBSTANCE: method involves preparing tooth surface and applying in series retention and facing layers on the prosthesis surface. The retention layer is applied by means of microplasma spray-coating of powder in 0.1-0.15 mm thickness under condition of 40-45 A arc current, 25- 28 V voltage and 1.2-1.8 g/min inert gas consumption rate and 0.8-1.2 kg/h powder consumption rate. EFFECT: simplified method. 5 dwg, 3 tbl

Description

 The invention relates to medical equipment, in particular to dentistry, and is intended for prosthetics of teeth made of chromium-nickel stainless steel and cobalt-chrome alloys with powder coatings of the intermediate layer.

 Known methods in orthopedic dentistry for the manufacture of dentures in the following combinations: metal-plastic, metal-porcelain. The main disadvantage of the supporting facing crowns is the unreliable fastening of the facing material.

 A known method is that in a stamped crown, the plastic is fastened by cutting out the vestibular wall and creating retention notches along the periphery of the formed “window”.

 Experience in the manufacture of such crowns has shown their low efficiency, especially as a support for fixed prostheses. Cladding material, plastic, not withstanding the stresses arising in the prosthesis, exfoliates.

 A known method in which the plastic is attached by modeling a protective visor and a section of the crown at its cutting edge. To mask the color, the metal is coated with an emulsion of titanium dioxide, mixed with BF glue.

 In this crown, the plastic is held more securely, but it is rather difficult to stamp the visor, so it has not been widely used (Sverdlov E.Yu. Military Medical Journal, 1956, N 1, p. 76-78).

 A known method, which contains a two-lane mechanical fastening of the facing material by soldering to the crown of the protective visor and cutting it with special forceps near the gingival margin (Borodyuk ND Dentistry, 1967, N 4, p.104-105).

 The disadvantage of this method is the soldering of the protective visor with all the ensuing consequences of the use of solder.

 The closest in essence and the achieved result are methods of fastening the facing material to cast crowns using wax or plastic balls, which were obtained by spraying a wax mixture melted to 355-360 K. In air at 293-299 K with a free fall time of wax particles of 1.4-1.5 s, under the influence of surface tension, the wax particles acquire a spherical shape and in this form solidify on a lost wax model (Nazarov G.O. Kozlovskaya S.S. Shatunov V.P. and Kruglik Yu.N. Standard workpieces of recommended elements for facing crowns (Dentistry, 1984, No. 1, pp. 68-70).

 The disadvantage of this method is that after the conversion of wax models to silver-colored metal (stainless steel, KHS alloy), it is necessary to damp the natural color of the metal with a layer of muffler-muffler, since the plastic unevenly covers the prosthesis due to the diameter of the retention balls protruding to the surface, which reduces the adhesive properties of plastics and prosthesis material. In addition, the main disadvantage of this method is that the balls deposited on the surface of the wax reproduction, significantly worsen the quality of the cast crown, rinsed with metal when casting, forming blockages, underfill in casting.

 The purpose of the invention is to obtain a method for the manufacture of dentures by applying an intermediate retention layer-silencer with increased adhesive properties between the material of the denture and decorative plastic or porcelain, to improve the quality of dentures.

 The goal is achieved based on the design features of the denture, as the object of coating-retention is a small wall thickness (0.1-0.15 mm) and a small mass, which are not acceptable when performing known methods. In them, the creation of the retention layer and the fastening of the facing material is carried out by means of metalwork cutting out the “window” on the vestibular surface, applying notches along the periphery of the “window”, creating a protective visor and cutting it with a special tool, soldering the protective visor.

 Known methods of fixing plastic are laborious in technological execution, require special equipment, mechanical processing (sawing "windows") reduces the mechanical strength of the prosthesis itself and does not guarantee the adhesion of the plastic to the metal crown. The method of attaching the facing material by modeling wax or plastic balls according to the lost wax model also has several disadvantages that complicate the process, introduces additional operations of damping the natural color of the prosthesis metal, applying a coating, which reduces the adhesive properties of the facing material. Balls on the surface complicate the casting process of the denture, the quality of the cast crown is deteriorating.

 The proposed technical solution differs from the prototype in that a porous gas-flame coating with high adhesive properties is used as a retention layer on solid-cast, thin-walled dentures as an intermediate layer between the material of the denture and decorative plastic. This method allows you to save the thickness of the denture due to the insignificant thickness of 0.1-0.15 mm of the retention layer, to eliminate the additional operation of killing the natural color of the metal. Improves the mechanical strength of decorative plastic applied to the prosthesis.

 In FIG. 1 shows a cast metal crown of a tooth prepared for execution; figure 2 metal crown of the tooth with an applied intermediate layer; figure 3 metal crown of the tooth with an intermediate coating and decorative wear-resistant plastic; figure 4 diagram of the manufacture of a denture on a cast crown; figure 5 technological process for the manufacture of dentures.

To implement the method of applying an intermediate layer on thin-walled cast dentures, a microplasma apparatus with a compressed small-ampere arc of a concentrated heat source is used (Maksimovich B.I. Budzal B.P. Bogachek V.L. and Taranov A.I. Microplasma spraying. Kiev, 1985, p.2 Inf. letter of the Academy of Sciences of the Ukrainian SSR named after E.O.Paton N 30). An all-metal dental crown (prosthesis) with a thickness of 0.1-0.15 mm is made (Fig. 1). The front side of the prosthesis is subjected to abrasive blasting with electrocorundum with a particle size of 0.8-1.5 mm at a pressure of 0.6 MPa at a distance of 40-100 mm from the nozzle exit peskostruy to the surface to be processed, the angle of incidence of the incidence of particles relative to the surface of 80-90 ^about .

 For the manufacture of one-piece clasp prostheses, removable splinting devices and other designs, the KHS cobalt-chromium alloy (TU-64-2-162-77) is used. Based on the composition of the material of the denture, the sublayer is applied from the powder material of the same or similar composition. Powders of cobalt alloys, for example, PG10K-01 TU 48-4206-156-82, containing the elements shown in Table 1, are taken as the basis.

 The retention layer is sprayed onto the prepared face of the prosthesis (Fig. 1). A feature of a denture as an object of deposition is thin walls and low weight, which imposes special conditions on the technological modes of coating to prevent overheating and warping. The implementation of these requirements is achieved by the use of microplasma installations. Based on the results of a series of experiments, the spraying mode was selected to ensure optimal coating properties.

The spraying mode is as follows:
Plasma-forming gas argon, highest grade GOST 10157-79;
Arc current I _A 40 45 A;
Arc voltage U _V 25-28 V;
Consumption Ar V (2-3) · 10 ^-3 m ³ / s;
Powder consumption G 0.22-0.23 g / s;
The distance from the plasma torch to the surface is 60-100 mm.

Using these spraying modes, get a retention coating with an adhesion strength of 82-90 MPa and a porosity of 3-5% (figure 3)
The proposed method for the manufacture of dentures receive a design (Fig. 4, c), which consists of a solid metal base 1 (Fig. 4, a), retention adhesive layer 2 (Fig. 4, b), deposited with microplasma and coated with a facing material 3 (figure 4, c).

 The technological process of obtaining a denture of the proposed design (figure 5) is as follows.

 A powder is prepared that must comply with the certificate at the entrance control, the powder is dried at 303-323 K for 3-5 hours. For microplasma spraying, a powder of a certain fraction of 65-80, 80-100 microns is used. Why carry out the sieving of the powder on vibrating screens.

The surface of the cast prosthesis is subjected to abrasive blasting with electrocorundum with a particle size of 0.8-1.5 mm at a pressure of 0.6 MPa at a distance of 40-100 mm from the nozzle exit peskostruy to the surface to be machined with an incidence angle of incidence of particles relative to the surface of 80-90 ^about (figure 1). After abrasive blasting, the prosthesis is degreased with organic solvents.

After preparing the surface of the prosthesis and the powder, a technological operation is carried out to spray retentions using a microplasma apparatus. As a plasma-forming gas, argon is used in the following modes:
I 40-45 A; U 25-28 V; V _Ar (2-3) x
x10 ^-3 m ³ / s;
G 0.22-0.33 g / s; L 60-100 mm.

 On the front surface of the denture is applied a retention layer of the sprayed material in the form of a metal powder with a thickness of 0.1-0.15 mm (Fig. 2).

 After deposition of the retention layer on the surface of the denture, a facing material is applied (Fig. 3) according to generally accepted technologies (V.Yu. Kurlandinsky. Ceramic and solid cast fixed dentures. M. Medicine, 1978, pp. 96-98). The sprayed retention layer has a branched porous surface and provides the necessary adhesion between the base metal and the decorative plastic coating. This simplifies the manufacturing process of the denture, improves the quality and aesthetic appearance.

 For experimental verification of the proposed method, samples are prepared from KHS material and powder grade ПГ10К-01 with particle sizes of 63-80 microns, 80-100 microns in order to study the technological capabilities of the microplasma deposition process and determine the properties. The dimensions of the samples are 120 × 10 × 1.5 mm. Coating thickness 0.24-0.260 mm.

 The elastic modulus, ultimate deformation of the coating, its adhesion during shear testing according to the method developed at the Institute of Strength Problems of the Academy of Sciences of the Ukrainian SSR (Verenchuk V.S. and Kapochenko L.A., Deformed state of structural elements with a coating in the presence of plastic deformation are determined on the samples. Kiev, IPP AN USSR, 1986, N 12, p. 47-52). The density of the coating was determined by the method of nodal points (Saltykov V.A. Steriometric metallography. M. Metallurgy, 1976, p.270) and hydrostatic weighing (GOST 18898-73. Powder metallurgy, Products. Methods for determining the density and porosity. Introduced 01.04.74 g until July 1, 1990).

 From the data table. Figure 2 shows that at an arc current of 40-45 A and a voltage of 25-28 V there is a maximum strength properties of the microplasma coating with a minimum porosity of 3-5%. When the plasma torch power exceeds 1200 W, the sprayed material is intensively oxidized with a sharp deterioration in the strength properties of the sprayed layer.

 A specific example with a boundary value is given in Table 3.

As can be seen from table 3, which presents several options for the manufacture of solid cast dentures from the KHS alloy. Option 1 of Table 3 is a one-piece prosthesis with retention made in the form of metal balls in the manufacture of a wax model. The other four options are solid cast prostheses with a sprayed retention layer with a thickness of 0.08-0.1 mm of grade PG10K-01 powder (TU 48-4206-156-82) with various spraying modes (the arc current I and arc voltage U are variables) . The consumption of plasma-forming gas V (2-3) 10 ^-3 m ³ / s and powder G 0.22-0.33 g / s for all 4 options was constant.

Depending on the spraying conditions (I _A , U _B ), the porosity of the coating and its physicomechanical properties changed, which were compared with the base object, a prosthesis made using a one-piece method with metal balls.

 A one-piece prosthesis made of KHS alloy of the PG10K-0.1 powder significantly increases the physical and mechanical properties, especially the shear adhesion strength, which exceeds the base by more than 50% (60 MPa of the base object and 90 MPa for option 4).

 This method of manufacturing dentures allows to improve the quality, simplify the process due to the individual production of retention from metal balls when modeling a lost tooth prosthesis model, eliminating the application of a sublayer to damp the natural color of the metal with a layer of muffler coating, and to increase physical and mechanical properties.

Claims (1)

 METHOD FOR APPLYING FACING TO THE SURFACE OF METAL DENTISTS, which consists in preparing the surface of the denture and applying successively the retention and facing layers to the surface of the prosthesis, characterized in that, in order to increase the adhesion strength of the facing layer to the base and simplify the method, the retention layer is applied by means of microplasms spraying a powder, similar in composition to the material of the prosthesis, with a thickness of 0.1 - 0.15 mm, while spraying is carried out at an arc current of 40 - 45 A, voltage 25 - 28 V, inert gas course 1.2 - 1.8 g / min; and powder flow rate 0.8 - 1.2 kg / h.

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