JPH02156942A - Manufacture of artificial dental rod - Google Patents

Abstract

PURPOSE:To obtain an artificial dental rod which possesses the superior erosionproofness and strength by pouring a sol containing aluminium alcoxide as main constituent into a mold having a prescribed shape and solidifying and drying the gel at the stage where the foaming agent concentration in the sol generates a certain distribution and by heating the dry gel over the decomposition temperature of the foaming agent and then carrying out sintering. CONSTITUTION:Into a sol containing aluminium alcoxide as main constituent, a foaming agent having a specific gravity difference to the specific gravity of the sol is added and dispersed, and then said sol is poured into a mold having a prescribed shape, and solidification and drying are performed at the stage in which the foaming agent concentration in the sol is inclined by the specific gravity difference and a certain distribution is generated, and a dry gel is formed. Said dry gel is heated over the decomposition temperature of the foaming agent, and after the foaming agent is decomposed and removed, sintering is carried out. Therefore, the alumina sintered body for artificial dental rod which possesses porosity and fineness can be obtained. Therefore, the adaptability to living body of the artificial dental rod made of alumina can be improved, with the superior dynamic characteristic. Further, since the vacant efficiency distribution of the artificial dental rod can be determined arbitrarily by changing the production conditions, the manufacture of the artificial dental rod which possesses the vacant efficiency proper for the individual is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a porous alumina artificial tooth root used in dental treatment.

[Prior Art] There is a treatment method in which an artificial material is implanted into the alveolar bone after a tooth has fallen out, and the upper part of the material is made to function as a tooth. This artificial material is called an artificial tooth root, and research is progressing on various materials such as metals, ceramics, and polymers.

Two conditions are required for this artificial tooth root: 1) It must be smaller in shape than a natural tooth but have higher strength, and 2) It must be able to be firmly fixed in the bone for a long period of time. In order to satisfy this condition, the most research has been carried out in the past.
This is a metal artificial tooth root made mainly of titanium.

However, artificial tooth roots made of metal, including artificial tooth roots made of titanium, always have the problem of corrosion resistance, so research is currently underway on artificial tooth roots made of ceramics, which do not have to worry about corrosion resistance and have excellent strength. There is.

[Problems to be Solved by the Invention] Research is underway on two types of ceramic artificial tooth roots: biocompatible apatite and high-strength alumina.

Apatite has excellent biocompatibility and can be chemically bonded to bone tissue. For this reason, two months after apatite is embedded in bone tissue, a portion where the boundary line between the two is not clear appears. Although apatite has the property of blending well with the surrounding alveolar bone tissue, it has problems with its mechanical properties and cannot be used alone as an artificial tooth root. In order to compensate for this drawback of apatite, attempts have been made to make the core of the artificial tooth root metallic and the outer periphery made of apatite, but this has the problem of complicating the manufacturing process and increasing costs. .

Alumina has excellent mechanical properties and long-term stability, making it a promising material for artificial tooth roots. However, although alumina does not harm adjacent bone tissue, it has the problem that it does not blend in with the surrounding alveolar bone tissue because it cannot bind to bone at the molecular level. For this reason, a method has been considered in which the contact area of the alumina artificial tooth root with the bone tissue is made porous so that the living tissue can penetrate into this porosity and firmly connect the living body and the artificial tooth root. ing. However, there is also a problem in that porous alumina having both density and porosity cannot be produced using a normal sintering method.

The present invention is intended to solve these problems, and its purpose is to have both mechanical properties and biocompatible properties, so that the part that is implanted in a living body and comes into contact with bone tissue is porous. The purpose of the present invention is to provide a method for manufacturing an artificial tooth root made of alumina, the exposed part of which has high density and high strength.

[Means for Solving the Problems] The method for producing an artificial tooth root of the present invention uses a sol-gel method containing aluminum alkoxide as a main component, and includes the following steps: a) A blowing agent having a specific gravity different from that of the sol is added to the prepared sol. Adding and dispersing the sol, and b) injecting the sol into a mold with a predetermined shape, and solidifying and drying it to create a dry gel when the concentration of the blowing agent in the sol becomes gradient and has a certain distribution due to the difference in specific gravity. and C) heating the dry gel to a temperature higher than the decomposition temperature of the blowing agent to decompose and remove the blowing agent contained therein, followed by sintering.

[Function] According to the present invention, porous alumina, which is a material for artificial tooth roots and has a gradient in conversion rate, is made by adding and dispersing foaming agents with different specific gravity into the sol, and then foaming in the sol due to the difference in specific gravity. It can be obtained by solidifying, drying, foaming, and sintering at the stage where the concentration of the agent has become gradient.

[Example] (Example-1) Fig. 1 shows a process diagram of the manufacturing method of the present invention, and Fig. 3 shows an external view of an artificial tooth root created by the manufacturing method of the present invention.

Hydrolyzing aluminum isopropoxide under acidic conditions,
To this, Al with an average particle diameter of 0.05 to 0.1 (μm)
After adding 203 fine particles and further adding 0.05 (wt%) of azodicarbonamide as a foaming material, ammonia water was added to adjust the pH to 3.5 to prepare a sol. This sol is placed in a polypropylene container and stored in a sealed state to prevent gelation. Since the specific gravity of azodicarbonamide is smaller than the specific gravity of the sol, the concentration of azodicarbonamide in the sol is higher in the upper part of the container and lower in the lower part, resulting in a constant distribution.At this stage, aqueous ammonia is further added to the sol, Raise the pH value to 4°5-4.7. This change in pH value promotes the dehydration condensation reaction of the sol to produce a wet gel. Thereafter, the wet gel is taken out from the sealed container and dried for two weeks to produce a dry gel.

This dry gel was placed in a sintering furnace and heated at 20 ("C") in vacuum.
/ hour) to 200°C, and at the same temperature
The dry gel is further heated to 300''C at the same temperature increase rate and held at the same temperature for 5 hours to completely decompose the added azodicarbonamide and perform a desorption water treatment. Heated to 1280 °C at a heating rate of 30 ('C/hour) under nitrogen atmosphere, and heated to 24 °C at the same temperature.
Sintering is performed by holding for a certain period of time.

The obtained porous alumina sintered body is finally processed into the shape of an artificial tooth root, if necessary according to each application.

Porous alumina obtained by ordinary sintering methods generally has low mechanical strength, but porous alumina created by the present invention has
Fully sintered and exhibits excellent mechanical strength.

In this example, a cylindrical porous alumina sintered body of φ15×t20 (mm) was created, the sintered body was divided into 10 equal parts in the thickness direction, and the conversion efficiency at each position was measured. Changes in conversion efficiency in the thickness direction were measured. The result is the second
As shown in the figure.

As shown in Figure 2, the conversion rate of the sintered body changes almost continuously, with the high conversion rate part being the part of the molar that contacts the alveolar bone tissue, and the low conversion rate part being the crown part of the tooth that is exposed to the outside. Each can be used separately.

Since the shape of this sintered body changes greatly depending on the shape of the polypropylene container used when making the wet gel, it is also possible to create a sintered body with a shape close to the final shape.

Sintering is performed in a nitrogen atmosphere or in vacuum, but it is desirable to perform the foaming and degassing steps in vacuum until the foaming agent is completely decomposed and removed.

The blowing agents used are azo type such as azodicarbonamide,
Organic blowing agents represented by hydrazine type such as diphenylsulfone-3,3'disulfohydrazine, N-nitroso type such as N,N'-dinitrosopentamethylenetetramine, organic resin such as polystyrene polyethylene, and carbon, CaCo3 Any inorganic material may be used.

(Example-2) Among the manufacturing conditions of the artificial tooth root shown in Example-1,
By varying the amount of foaming agent and sintering temperature, we created porous alumina for artificial tooth roots with various conversion efficiency distributions. The table shows the amount of azodicarbonamide added and the sintering temperature used in this example.
Shown in 1.

The obtained porous alumina sintered body was divided into 10 equal parts in the thickness direction in the same manner as in Example-1, and the porosity of each part was measured. Figure 2 shows the relationship between the distance from the base and the conversion rate for each ceramic.

Table 1 By changing the manufacturing conditions, the porosity distribution can be changed. Similarly, it is also possible to control the pore size in the artificial tooth root, and in experiments, pores ranging from several tens (μm) to several hundred (μm) were obtained.

[Effects of the Invention] As described above, according to the present invention, the difference in specific gravity between the sol and the foaming agent is used to gel the sol with a well-distributed concentration of the foaming agent, and then foaming and sintering are performed. By doing so, it is possible to obtain an alumina sintered body for artificial tooth roots that has two contradictory properties: porosity and density. Therefore, it is possible to improve the biocompatibility of an alumina artificial tooth root with excellent mechanical properties.

Furthermore, by changing the manufacturing conditions, it is possible to arbitrarily determine the transformation rate distribution of the artificial tooth root, which has the effect of making it possible to manufacture an artificial tooth root with a transformation rate distribution suitable for each individual.

Furthermore, the present invention has the advantage that by taking advantage of the features of the sol-gel method for producing alumina, a sintered body having a complex shape close to the final shape of an artificial tooth root can be easily produced.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the method for manufacturing an artificial tooth root of the present invention. FIG. 2 is a diagram showing the air efficiency distribution of a porous alumina sintered body for artificial tooth roots produced by the manufacturing method of the present invention. FIG. 3 is a diagram showing the air efficiency distribution of porous alumina sintered bodies for artificial tooth roots produced under different manufacturing conditions. FIGS. 4(a) and 4(b) are diagrams showing an artificial tooth root produced by the manufacturing method of the present invention. (a) shows a longitudinal cross-sectional view of the processed artificial tooth root inserted into the alveolar bone, and (b) shows the shape of the cylindrical artificial tooth root prepared to measure the air efficiency distribution. The numbers 1 to 10 in the figure are the numbers of each sample when the sample is divided into 10 equal parts in the thickness direction. 101...Artificial tooth root 102...Vacancy 103...Gingiva 104...Alveolar bone and above Applicant: Seiko Epson Co., Ltd. Attorney Kizobe Tsuchi Suzuki (and 1 other person) Figure 3

Claims (1)

[Claims] A sol-gel method containing aluminum alkoxide as a main component includes: a) adding and dispersing a blowing agent having a specific gravity different from that of the sol into the prepared sol; and b) adding the sol to a predetermined value. and c) forming a dry gel by injecting the foaming agent into a mold with the shape of the foaming agent, and solidifying and drying the foaming agent at a stage where the concentration of the foaming agent in the sol has a gradient and a certain distribution due to the difference in specific gravity; A method for producing an artificial tooth root, comprising the steps of heating to the above temperature to decompose and remove the foaming agent contained therein, and then sintering.