JP4606539B2 - Manufacturing method of dental block - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a ceramic sintered body made of a ceramic material and a method for producing the same, and more particularly to a method for producing a dental block intended for use in cutting or grinding.
[0002]
[Prior art]
Generally, the ceramic sintered body made from ceramic materials contains air bubbles or pores for various reasons. Ceramic materials mainly include feldspar minerals, clay minerals, quartz, etc. As a feature of ceramic sintered bodies made using these materials, a glass phase is formed during sintering, and bubbles generated for various reasons are formed inside the sintered body. Often remains.
These residual bubbles or pores greatly impair the physical properties and transparency of the ceramic sintered body, for example.
Although the characteristics of these ceramics are often improved in various aspects when there are few bubbles or pores generated inside, there is a problem that the cost increase due to the improvement is too great.
[0003]
In particular, in recent years, the use of automatic measurement and automatic processing means such as CAD / CAM equipment has attracted attention as a method for producing high-precision ceramic processed products or decorative products by automatic processing of ceramics. Bubbles or pores existing inside the sintered body cause significant defects and defects in accuracy in processing and aesthetics after processing. One method of removing or reducing these bubbles is a vacuum firing method. However, the vacuum firing method cannot be said to be an inexpensive method for manufacturing ceramic products in terms of energy and production efficiency.
[0004]
In addition, for example, dental ceramics are required to have the same color tone and transparency as natural teeth, and have resistance to withstand occlusion in the oral cavity and hardness that does not wear the counter teeth. However, the prosthesis is required to be processed with high accuracy. In order to carry out cutting or grinding with high accuracy, it is extremely important to take measures against bubbles remaining inside. Furthermore, the presence of bubbles has the potential to become a source of plaque and calculus, and the presence of large bubbles on the surface after processing is also a serious problem.
[0005]
The presence of bubbles or pores is a cause of deterioration of quality for many ceramic sintered bodies, and there is a demand for an inexpensive and simple method that can improve the bubbles even a little.
[0006]
[Problems to be solved by the invention]
The present invention improves various properties of ceramic sintered bodies by reducing or reducing bubbles generated inside the sintered body without changing the material system and material characteristics of the ceramic sintered body using ceramic materials. It is a problem to establish a manufacturing method.
[0007]
The present invention is a ceramic sintered body having a denseness capable of being subjected to processing such as high-precision cutting and grinding, but can be formed by an easy process to such an extent that a known manufacturing method can be effectively used. The purpose is to provide ceramics.
[0008]
[Means for Solving the Problems]
The inventors have made various studies for the purpose of obtaining a ceramic sintered body having a residual bubble diameter of about 20 μm at the maximum by a known manufacturing process without using a vacuum firing method. As a result, it was found that the intended sintered body could be obtained with almost no change in the production method, and the present invention was completed.
[0009]
Furthermore, the inventor has found that the size of the bubbles generated inside the sintered body depends greatly on the amount of the phosphate, and the diameter of the bubbles is reduced only in a region where the amount of addition is very limited. I confirmed that there was nothing. As a result of the experiment, a sintered body having a maximum residual bubble diameter of about 20 μm can be obtained, and the manufacturing method requires almost no change from the conventional one, and there is no significant change in the color and physical properties of the material. As a result, the present invention was completed.
[0010]
Furthermore, in the above manufacturing method, the present invention can further reduce bubbles inside the sintered body even when a high purity phosphate, particularly hydroxyapatite, which is highly evaluated as a bioceramic, is used as the phosphate used. it can.
The phosphate in the present invention is calcium phosphate selected from hydroxyapatite , calcium pyrophosphate, tricalcium phosphate, tetracalcium phosphate, calcium hydrogen phosphate, and calcium dihydrogen phosphate.
The content in this case varies depending on the added phosphoric salt, but the following range is suitable for the time being. However, the content is not limited to this, and may be above or below this value.
[0011]
In the case of ceramic sintered bodies that require particularly high aesthetics, such as dental ceramics, a colorant composed of a metal oxide is added to a raw material composition composed of clay mineral, feldspar, quartz or the like. It is desirable to make it by adding.
[0012]
The raw material and the phosphate to be used are fine powder, and the fine powder is, for example, 100 mesh or less, preferably 200 mesh or less. The phosphate may be added as an aqueous solution by dissolving in water or acid. The phosphate used is preferably 0.5 to 5% by weight, more preferably 1 to 3% by weight.
[0013]
In the present invention, the material for ceramics refers to natural minerals such as clay minerals, feldspar, quartz, porcelain clay, mica, kaolin, and other artificially produced materials such as carbonates and oxides of various metals, glass, etc. It may be.
The material may be used alone or in combination of two or more materials. However, when an intraoral molded product such as an inlay or crown is manufactured by mechanically cutting or grinding, it is mainly composed of feldspar. The blending is preferable from the viewpoint of color tone. When the raw material is a natural mineral, there are some that generate hundreds of bubbles inside the sintered body due to the release of the contained gas, but the gas that causes these strong bubbles is It is more preferable to remove it by a treatment such as calcination.
It is also preferable to use it in a finely divided state in advance.
The finely powdered state is preferably adjusted to, for example, 200 mesh or less.
[0014]
Each of the above materials is used as the ceramic raw material of the present invention. Phosphate is added to the above-mentioned ceramic material, and after sufficient mixing, pressure molding is performed as necessary, followed by firing. The firing is preferably about 1100 to 1200 degrees and the time is preferably about 1 to 10 hours.
In the present invention, various known ceramic manufacturing techniques can be effectively utilized if the above-described steps and numerical adjustment are performed.
[0015]
The ceramic sintered body produced in this way is generated inside despite the fact that there is almost no change in aesthetics and physical properties compared to the ceramic sintered body produced without using phosphate. The diameter of the air bubbles or pores is the most common when no phosphate is used, and the diameter of the air bubbles or pores is 30 μ to 50 μ, and in some cases, bubbles of 100 μ or more may exist. The maximum size of the sintered body is about 20 μm.
[0016]
In addition, the sintered body of the present invention can be colored with a colorant such as a pigment, as in the case of using no phosphate, and build up ceramics and polymers on the surface of the sintered body. Things are also possible.
[0017]
[Action]
The present invention relates to a method for producing ceramics and ceramics by adding a small amount of phosphate to bubbles remaining inside ceramics during firing in ceramics sintered bodies produced using ceramic raw materials. Without changing the material system and material characteristics of the sintered body, it is possible to establish a manufacturing method that can reduce or reduce bubbles and make a block that can withstand machining such as cutting and grinding at low cost.
[0018]
【Example】
Examples will be shown below, and the present invention will be specifically described.
Example In this example, feldspar produced naturally as a raw material was used as a main raw material. As a result of firing this feldspar alone at about 1200 degrees, it was found that a large number of bubbles existed in the sintered body. First, in order to remove as much gas as possible from the feldspar, this feldspar was removed at 1200 degrees to 1300 degrees. Once heat-treated. This heating time was about 1 to 5 hours. Since the feldspar that has been heat-treated to such a temperature is melted, it is pulverized using a ball mill or the like. In the examples, feldspar powder that passed 325 mesh was used thereafter. Appropriate amounts of clay mineral and quartz mineral were further added to this material to obtain a raw material.
In order to perform coloring, a small amount of metal oxide was added, and 3% by weight of hydroxyapatite powder that passed 325 mesh was added and mixed well. The hydroxyapatite used in this example was synthesized by a synthesis method in which phosphoric acid was dropped into calcium hydroxide, and was pulverized and used after calcination at 750 to 800 degrees. In order to perform molding easily, an organic binder was added and granulated.
In this example, uniaxial press molding was performed, and thereafter, firing was performed at 1100 to 1150 degrees for 1 to 4 hours in the atmosphere.
The results are shown in FIG. 1 and 2 are SEM photographs.
The bending strength of the obtained sintered body was about 100 MPa, and as shown in FIG. 1, most of the internal bubbles were 10 to 20 μm.
In the conventional product, the strength of the sintered body is 90 to 100 MPa, and the average size of the bubbles is 30 to 40 μm as shown in FIG.
When these are compared, it can be seen that although the number of bubbles is not greatly changed, the size of each bubble is small, so that the whole is a dense sintered body.
Further, the appearance (transparency, color tone, etc.) of the obtained sintered body is hardly changed.
[0019]
【The invention's effect】
According to the present invention, in a ceramic sintered body produced using a ceramic raw material, the production of the ceramic is achieved by adding a small amount of phosphate to bubbles remaining in the ceramic sintered body during firing. Without changing the method and the material system and material characteristics of the ceramic sintered body, it is possible to produce a block that can reduce or reduce bubbles and withstand cutting work at low cost.
[Brief description of the drawings]
FIG. 1 is an explanatory view with a photograph for explaining an embodiment of the present invention.
FIG. 2 is an explanatory view by a photograph for explaining a conventional example.

Claims (5)

Heat-treated fine powder for ceramics contains 0.5-5% by weight of calcium phosphate selected from hydroxyapatite, calcium pyrophosphate, tricalcium phosphate, tetracalcium phosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate And a method for producing a dental block to be fired. The method for producing a dental block according to claim 1, wherein the calcium phosphate is hydroxyapatite. The method for producing a dental block according to claim 1, wherein the ceramic material is selected from clay mineral, feldspar, and quartz. The method for producing a dental block according to claim 1, wherein the firing temperature is 1100 to 1200 degrees and the firing time is 1 to 10 hours. The manufacturing method of the dental block of Claim 1 used in order to manufacture a dental prosthesis and a filler by cutting or grinding mechanically.

Images