JPH01203285A - Ceramic implant and production thereof - 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 (Industrial Application Field) The present invention provides a porous sintered body made of a mixture of tricalcium phosphate (hereinafter abbreviated as α-TCP) and zirconia on the surface of a zirconia sintered body. The present invention relates to a ceramic implant having a coating layer and a method for manufacturing the same.

(Conventional technology) As biological implant materials for hard tissues such as artificial tooth roots, metals such as stainless steel alloys and titanium alloys,
Ceramics such as single-crystal alumina, alumina sintered body, zirconia sintered body, and carbon are mainly used, and these are said to be bioinert implant materials because they do not bond directly to living tissue. On the other hand, hydroxyapatite (hereinafter abbreviated as HAP) sintered body, α-type tricalcium phosphate (hereinafter abbreviated as α-TCP) sintered body, β
The type tricalcium phosphate sintered body is a so-called bioactive implant material, and is attracting attention as a material that directly chemically bonds with living tissue. Furthermore, in recent years, attempts have been made to deposit bioactive substances onto the surface of bioinactive materials by plasma spraying.

(Problem to be solved by the invention) However, when the above-mentioned bioinert implant material is implanted in a living body, it does not bond directly to living tissue, so it tends to loosen over a long period of time. It will happen. On the other hand, bioactive implant materials do not cause loosening as mentioned above, but in terms of mechanical strength, materials in which a bioinactive material is deposited on the surface of a bioinactive material by plasma spraying have a plasma sprayed surface layer. The bond between the core material and the core material is weak (and easily peels off).

(Means for Solving the Problems) As a result of various studies in view of the above points, the present inventors added a coating layer of a porous sintered body made of a mixture of α-TCP and zirconia to the surface of a zirconia sintered body. Ceramic implants have high mechanical strength (do not break in vivo,
In addition, the present invention was achieved based on the knowledge that the bioactive surface porous layer that is firmly bonded to the core material bonds with living tissue in vivo, resulting in a material that can withstand long-term use.

That is, the gist of the present invention resides in a ceramic implant having a coating layer of a porous sintered body made of a mixture of α-TCP and zirconia on the surface of a zirconia sintered body, and a method for manufacturing the same, and furthermore, The present invention relates to a method for manufacturing a ceramic implant, which comprises depositing a mixed powder of hydroxyapatite and zirconia on the surface of a molded body made of oxidized zirconia, and then firing the mixture.

In the following, the present invention will be described in detail. Partially stabilized zirconia powder used in the present invention includes CaOlMgO, Y
It is a zirconia powder containing 2O3, Gd2O3, Ce 02, etc. as a solid solution as a stabilizer.

Molded bodies made of partially stabilized zirconia powder can be molded by various molding methods such as press molding, extrusion molding, cast molding, injection molding, and tape molding, but preferably molded bodies with complex shapes can be manufactured. It is preferable to use a cast molding method or an injection molding method.

Although there are various methods for providing a coating layer of α-TCP and zirconia sintered body on the surface of the zirconia sintered body, the most suitable method is to coat zirconia powder and HAP on the surface of the zirconia molded body before sintering. When the whole thing is fired, HAP
is changed to α-TCP, and zirconia is also sintered. In this case, it is applied to a zirconia molded body.

HAP powder is Ca+o-x (HPO4)X (PO
4) 6-x (OH)2-x ・nH2O (however, 0
The compound represented by the chemical formula (xx/) is used.

The zirconia powder to be mixed with HAP may be any powder containing zirconia as a main component, regardless of the presence or absence of a stabilizer.

The mixing ratio of HAP and zirconia is selected so that the weight ratio of zirconia to HAP is within the range of 0.0 & -20. More preferably, they are mixed so that the ratio is 0.7 to 2.3. If the weight ratio of zirconia to HAP is smaller than O,OS, the porosity of the coating layer of the obtained implant will be small and the bioactivity will be low, and the thermal expansion coefficient of the zirconia sintered body serving as the core material and the coating layer will be reduced. Due to the large difference in the temperature, many cracks occur on the surface of the coating layer and at the interface between the zirconia sintered body and the coating layer during cooling after firing. On the other hand, if the weight ratio of zirconia to HAP is larger than 20, the porosity of the coating layer of the obtained implant becomes small (and the content of α-TCP decreases, so the bioactivity becomes small).

As a method for applying a mixed powder of HAP and zirconia to the surface of a molded body made of partially stabilized zirconia, a method is selected in which the mixed powder is uniformly applied to the surface of the molded body. Specifically, a mixed powder of HAP and zirconia is uniformly dispersed in water to create a slurry, and a molded body made of partially stabilized zirconia is immersed in this slurry, so that the water in the slurry is absorbed into the molded body. A method is used in which the mixed powder is uniformly applied to the surface of the molded body at the same time as the molded body is coated.

A similar coating can also be achieved by spraying the slurry onto the molded body.

Firing is performed at a temperature range of /λ00°C to /S50°C. If the temperature is too low, the density and strength of the zirconia sintered body will be low (
turn into. On the other hand, if the temperature is too high, the porosity of the porous sintered body made of a mixture of α-TCP and zirconia will decrease, and the generated α-TCP will melt.

Furthermore, if the temperature is too high, the density and strength of the zirconia sintered body will decrease. In other words, by performing firing within an appropriate temperature range, the density and strength of the zirconia sintered body, which is the core material of the implant, can be increased (and at the same time, the porosity of the porous sintered body, which is the covering layer of the implant, can be increased). Thick (can be done)

In addition, α-TCP and zirconia, which are also produced as HAP by this firing, are strongly bonded while maintaining porosity, and
A strong bond can also be obtained between the zirconia sintered body and the porous sintered body, which are the core materials, but both of these are made of HA.
This is presumed to be due to the movement and diffusion of 2+ Ca ions in P to the zirconia powder and core zirconia.

EXAMPLES Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 211.6 g of distilled water and ammonium polyacrylate as a dispersant were added to a zirconia ball mill pot with an internal volume of ssomi! <7wt% aqueous solution 0.1. ．． After adding 3J and mixing, Ittria partial stabilization Sr. = 7
/ 2 A, 2 g/OHll 96 of zirconia ball IIoog was added. This was wet-pulverized using a vibrating ball mill and a rotary ball mill to obtain a zirconia slurry. To 1/3 liter of this slurry, @2wt% aqueous solution of binder a, bgg, and antifoaming agent 0.0 & 49 were added and briefly mixed for 30 minutes, and then defoamed under reduced pressure at 20 Torr for 20 minutes in a rotary evaporator. . This slurry was heated at room temperature of 2J℃/21nz91X/! r
Solid casting was carried out into a cylindrical shape of 0 mm. After drying this at 23°C day and night, use a platen to dry it '1. ! ; mx
A zirconia molded body was obtained by machining yf x and y o gIE into a cylindrical shape.

“Next, in an Oml alumina ball mill pot with an internal volume of 2!, 3 g of distilled water, A9 and a 0wt% aqueous solution of ammonium polyacrylate as a dispersant, 9
After mixing, add 36.0 g of hydroxyapatite powder and 2 g of ittria partially stabilized zirconia powder.
'1. Zirconia pole tioog of Og and 'CJ/Omtn915 was added. This was wet-pulverized using a vibrating ball mill and a rotating ball mill to obtain a mixed slurry of hydroxyapatite and zirconia. Add #Jwt% aqueous solution binder to 3g of this slurry. ,,?
fi, 0.02 r g of an antifoaming agent, and 273 g of distilled water were added and mixed for 30 minutes, followed by defoaming under reduced pressure at 20 Torr for 20 minutes in a rotary evaporator.

! ;0rnl-jj A mixed slurry of hydroxyapatite and zirconia is placed in a lath beaker, and the machined zirconia molded body is immersed in this slurry for 30 seconds for 15 minutes in the longitudinal direction to form hydroxyl on the surface of the zirconia molded body. A mixed powder of apatite and zirconia was deposited.

This is 2! After drying at 90° C. day and night, it was dried at 90° C. day and night. Further, this was roasted in an electric furnace.

℃ at a rate of 10℃/h, held at roo℃ for 1 hour to degrease, and then heated at a rate of 200℃/h/2! ;0℃
The mixture was baked for 2 hours.

In this way, α-TCP was applied to the surface of the zirconia sintered body.
A ceramic implant having a coating layer of a porous sintered body made of a mixture of zirconia and zirconia was obtained.

(Effects of the Invention) According to the method described above, it is possible to easily produce a ceramic implant having a bioactive surface porous layer that is not damaged in vivo due to its mechanical strength and is firmly bonded to the core material. Therefore, it can be suitably used as a material for biological implants such as artificial tooth roots, artificial joints, and artificial bones.

Claims (2)

[Claims] (1) A ceramic implant having a coating layer of a porous sintered body made of a mixture of α-type tricalcium phosphate and zirconia on the surface of the zirconia sintered body. (2) A method for manufacturing a ceramic implant, which comprises depositing a mixed powder of hydroxyapatite and zirconia on the surface of a molded body made of partially stabilized zirconia and then firing it.