JPS6214846A - Producion of artificial tooth and bone - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing ceramic artificial teeth and bones. Specifically, a core portion of a bio-harmless and high-strength ceramic-based dense sintered body is formed, and then a surface layer of a bio-harmless ceramic-based open-pore sintered body is formed around the core portion.

Concerning the manufacturing method of biocompatible artificial teeth and bones.

Conventional Techniques and Problems Conventionally 2 Metals, alumina, and the like are usually used as artificial tooth/bone materials. However, metals have the disadvantage that their components elute into the human body and have an adverse effect on the human body. Conventional alumina sintered bodies are inert in the body, but because they are not bonded to living organisms, they have been bonded to living tissues using cement or mechanically.

Therefore, stress concentrates on the connected biological parts.

There was a risk of damaging the surrounding area. It has been proposed that apatite sintered bodies be used in artificial bones and teeth as biocompatible teeth and bones. However, the bending strength is comparable to that of a human bone (for example, 1
In order to obtain an apatite sintered body having a value close to 000 to 2000 Kpf/square CIr1), the sintered body must be made as dense as possible. However, dense apatite sintered bodies have difficulty in invading and assimilating bone cells, and do not have sufficient biocompatibility. On the other hand, porous apatite is easy for bone cells to invade, but it has 2 strength.

In particular, the bending strength is extremely low. In particular, since bending strength is important for artificial teeth and bones, problems arose in the practical application of porous apatite sintered bodies to artificial teeth.

The same applies to the porous tricalcium phosphate sintered body.
Furthermore, even if these porous sintered bodies are reinforced with mineral fibers or the like, there may be problems with the strength of the porous bodies (IJ socks).

Therefore, the main object of the present invention is to provide a method for manufacturing artificial teeth and bones that have bending strength comparable to that of teeth and bones and have excellent biocompatibility.

Another main object of the present invention is to provide a method for manufacturing an artificial tooth/bone having a structure that can be bonded to a living body even when the material itself is made of a material that does not have biocompatibility.

Means for Solving the Problems The present inventor formed the core part of the artificial tooth/bone using a high-strength ceramic sintered body, and the surface layer part was made of a ceramic porous sintered body having continuous pores of a desired pore size. It has been found that artificial teeth and bones having both sufficient strength and biointegrity can be obtained by forming them in the body. Furthermore, the core portion and the surface layer portion are formed by a method including a first sintering step for forming the core portion and a second sintering step for forming the porous surface layer in the presence of a specific additive. The present invention was based on the discovery that it is possible to manufacture artificial teeth and bones having the above-mentioned properties in which these are integrated. That is, the first sintering step is a condition for obtaining a high-strength and dense ceramic yarn core, and the second sintering step is a condition for obtaining a biocompatible open-pore ceramic surface layer.
The above problems were advantageously solved by the combination of sintering steps.

Therefore, according to the present invention, a core portion made of a ceramic sintered body having sufficient strength is formed by sintering a ceramic material that is harmless to living organisms;
After being covered with a bio-harmless ceramic material containing one selected from fine particles of pyrolyzable and/or solvent-soluble substances and mixtures thereof, the whole is sintered to form a material around the core. It is characterized by the formation of a thin outer layer of bonded open-pored ceramic sintered body.

A method for manufacturing a biocompatible artificial tooth/bone is provided.

Examples of bio-harmless ceramic materials forming the core of the artificial tooth/bone mentioned above include apatite/calcium phosphate (preferably tricalcium phosphate (TCP)), a mixture of the two, and bioglass.

Ceramics such as crystallized glass, alumina (A12o3), zirconia (Zr02), silicon tinide (SI3N4) r carbon can be used as window materials. Al
2O5, ZrO2・Si3N4. When a window material such as carbon is used, it is preferable to roughen the optical surface of the core portion by a blast treatment or the like in order to improve bonding with the porous outer layer. Mineral materials that do not change through firing (e.g. carbon, silicon carbide) are added to the above ceramic materials.

Alumina, mullite, silicon titanide, coated metal fibers, etc.) short fibers or whiskers are mixed in and sintered.

Of course, reinforcement is also possible. As the above-mentioned apatite, apatite proposed as a material for artificial teeth and bones can be used. Typically, the basic composition has the general formula: C
a+a (PO4)6Zm・”(1) (here 2 is O
Selected from H, co, , F, CI, essentially O
An example is an apatite represented by H and/or Co, and m is a number that substantially satisfies the valence (for example, 1 or 2). However, 2 (1) middle.

The ca/p ratio does not necessarily have to be stoichiometric (5/3), and typically the ca/p ratio is between about 1.33 and about 1.8.
7.

Non-stoichiometric amounts may be present, preferably ranging from about 1.45 to about 1.67. Generally, apatite (hereinafter referred to as hydroxyapatite) in which all of 2 is an OH group, or the majority is an OH group and the remainder is a Co3 group is preferred.

As the ceramic material harmless to the human body for forming the porous ceramic outer layer, the ceramic materials mentioned above as the material for the core portion can be used.

Among these, the above-mentioned apatite (% hydroxyapatite), calcium phosphate (@KTCP, d!-'r
c p ) or mixtures thereof are preferred.

If the material for the core portion and the material for the outer layer are materials containing substantially the same components, the core portion and the outer layer will have good bonding properties and an artificial tooth/bone that is appropriately integrated can be obtained. A particularly preferred combination of core material and outer layer material is a combination of hydroxyapatite (preferably reinforced with mineral fibers) and hydroxyapatite (optionally reinforced with mineral fibers).

In the firing process of the ceramic material that will become the core,
Known techniques of firing or sintering may be employed.

For example, a hot press method, a sealed pressure firing method, a compression heating method such as a HIP method, etc. can be advantageously used. pressure.

The firing temperature and time vary depending on the ceramic material used, and the pressure, temperature and time that form a dense sintered body are selected. Additionally, if the material consists essentially of apatite (alone or reinforced with mineral fibers), the powder or preform may be placed in a substantially inert, pressure-deformable container (e.g., platinum, gold, silver, etc.).

When using a method (HIP method) of enclosing the material in a tube of aluminum or the like and firing it under isopressure compression (HIP method), a sintered body with significantly increased various strengths, especially bending strength, can be obtained. The usual sintering conditions in the HIP method for apatite are a pressure of about 500 to about 5 ooo Kp/m2.

The temperature is about 1000°C or less, preferably about 800°C or less.

In particular, the temperature is about 600° C. or lower (if mineral fibers are mixed with apatite, the temperature is about 1000° C. or lower, which is less than the temperature at which the fibers are denatured), and the firing time is usually about 0.5 hours or more. Generally, by pressure sintering, a dense ceramic sintered body having a ratio of relative density=actual density/true density (theoretical density) of about 80 or more can be obtained.

One method is to cover the above-mentioned ceramic sintered body, which serves as the core, with a ceramic material that is harmless to living organisms.

The following three methods are exemplified.

(1) Dry method: The sintered body is wrapped with ceramic powder and CRP (cold isostatic press) is performed.

Press using the isostatic non-thermal compression method. Usually, in order to effectively form continuous pores, fine particles of thermally decomposable and/or solvent-soluble substances such as organic substances (for example fibers or powders) are mixed into the ceramic powder.

(2) Wet method: The sintered body is surrounded by a slurry of ceramic powder and a liquid such as water, and then dried.

Usually, in order to effectively form continuous pores, fine particles (fibers or powders) of thermally decomposable and/or solvent-soluble substances such as organic substances or blowing agents such as hydrogen peroxide are mixed into the material. .

Examples of the organic fibers include acrylic, nylon, polyvinyl alcohol, and polyester fibers, and examples of the organic powder include paraffin wax and polyethylene wax. The fibers and powder usually have an average diameter in the range of tens to hundreds of microns and are usually incorporated into the ceramic powder in a proportion of about 5 to about 30 volumes of the total porous outer layer material. The above hydrogen peroxide blowing agent may also be used in a dilute aqueous solution (for example, about 111 H,...
02 aqueous solution).

After covering the core with ceramic powder using a dry or wet method, the whole is heated to sinter the ceramic powder around the core to form a porous outer layer with open pores. For example, when the ceramic powder is apatite, the pressure is about 50 to 2000 Kp/cdt and the temperature is soo C.
It is recommended to cure for about 1 hour or more in the following steam atmosphere. Furthermore, when organic fibers or powder are mixed into the ceramic powder, if water vapor is present in the system, the organic matter decomposes and dissolves into the water vapor, forming large continuous pores. If decomposed organic matter remains in the outer layer after firing.

If washed in a solvent, the solution will come out and continuous pores will be formed as well. A blowing agent such as H2O2 may also be present.

Firing generates gas and forms continuous pores in the outer layer.

When using 7-TCP powder for the outer layer, it can also be sintered and hardened with consideration of hydrolysis at low temperatures.

From the viewpoint of maintaining the bending strength of the core portion above a predetermined value and providing sufficient biobondability, the porous outer layer is usually a thin layer with a thickness of about 0.5 to 5 W. The porosity of the outer layer is about 3 to 50 vol. h, preferably about 5 to 30 vol. h. The average pore size is about 1 to about 500 microns, and about 50 microns or more when the material itself is made of a non-biocompatible ceramic material.

Preferably it is about 100 j1 or more. Thus, even if a bioincompatible material such as alumina is used for the porous outer layer, sufficient biocompatibility may not be achieved if the tatoo layer harbors open pores of about 50 microns or more, preferably about 100 microns or more. can get.

EXAMPLES The present invention will be specifically explained below using examples and drawings.

Example 1 cl Ca5 (PO4)2 powder was arp-molded into a cylindrical shape and fired at 11150°C for 3 hours. The bending strength of the obtained cl Ca3(PO4)2 sintered body 2 was set at 1520 and 9 f/all. Next, 80 volumes of powder (ca/p ratio: 95/60) and 20 volumes of paraffin wax powder with an average particle size of 100 μm were mixed homogeneously, and the mixture was filled so as to cover the sintered body. , CIP molded. After heating this above the melting point of paraffin wax to melt the wax,
It was cured in an autoclave at 800° C. in a hydrothermal atmosphere of 400 KP/cII for 3 hours. A porous apatite outer layer 3 (about 2 mm thick) having continuous pores with an average pore diameter of 100 μm was formed around the calcium phosphate sintered body 2 . The bending strength of the artificial tooth/bone sintered body 1 thus obtained was 1450 KPf/'C1l.

Example 2 The surface of an alumina sintered body having a porosity of substantially O was roughened. An alumina slurry containing an Ic 14 H2O2 aqueous solution and 15% by volume of polyvinyl alcohol fibers was poured around it, and the temperature was slowly raised to 80''C and dried. Then, it was fired at 1500°C for 3 hours.

This was thoroughly washed with a solvent. The obtained alumina sintered body had continuous pores only in two surface layers (thickness approximately 3+o+),
Its pore diameter is 0.2~0.5m (200~500μ)
I failed.

Note that the pore size is approximately 200 to 700μ (average pore size approximately 400μ).
The compressive strength of an alumina sintered body with a porosity of 50 μ) is approximately 10
It is known that it is 00Kp/d or more. Therefore,
It can be seen that the above double-structured alumina sintered body has sufficient strength to be used as artificial teeth and bones.

Operation and Effects The first sintering step of the ceramic material under pressure forms a core portion of dense sintered body.

Next, by covering the obtained core with ceramic powder containing a foaming agent such as H2O2 and/or organic fiber or powder, etc., and subjecting it to a second sintering process, the average pore diameter is approximately 1 to 500μ. A porous surface layer having continuous pores, preferably about 100 A or more, is formed integrally with the core portion. In addition, the surface of the obtained double-structured ceramic sintered body has an average pore diameter of about 1 to 500μ, and a percentage of about Zoo
Because it is a porous material with ~500 continuous pores 2 When used as an artificial tooth or bone 2 Osteocytes easily invade the porous outer layer of the surface, and after invasion, the surface area in contact with bone cells is Fully bond with living organisms. For example, if the outer layer material is a biocompatible material such as apatite,
Even if the average pore size is less than about 1 to 100 μ, it will bond with the living body, and especially if the pore size is about 100 μ or more, new bone will penetrate more easily and bond more quickly. Even in the case of a material that does not have biocompatibility, such as a porous body having continuous pores with an average pore diameter of about 100 j or more, new bone can invade and bond with the porous outer layer. On the other hand, since the core part has a dense structure, it has high strength, and gives the above-mentioned ceramic sintered body the strength to be used as an artificial tooth or bone.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a cylindrical artificial tooth/bone obtained by the present invention. 1...Artificial tooth/bone, 2...core portion, 3...porous outer layer. Patent applicant Inax Co., Ltd. Figure 1 1: Artificial bone/bone 2, core valve 3: Porous outer layer

Claims (2)

[Claims] (1) Sintering a ceramic material that is harmless to living organisms to form a core made of a ceramic sintered body with sufficient strength; and surrounding the core with a foaming agent, thermally decomposable and/or solvent soluble. A continuous porosity ceramic sintered material is coated with a bio-harmless ceramic material containing fine particles of substances of Biocompatible artificial teeth, characterized by forming a thin outer layer consisting of the body.
Bone manufacturing method. (2) The method according to claim 1, wherein the ceramic material of the continuous porous outer layer is selected from biohazardous apatite, calcium phosphate, and mixtures thereof.