JPH0136381B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a ceramic body for implants that has high strength, high toughness, and excellent compatibility with bone.

BACKGROUND ART Conventionally, as a method for producing ceramic bodies for implants, a method has been attracting attention in which a high-strength ceramic is used as a base and a covering layer made of a different type of ceramic having excellent affinity with bone is formed on the surface of the base. Typical base materials are dental porcelain, polycrystalline alumina, single crystal alumina, etc., and apatite is typically known as a coating layer. The method of printing with
This method is disclosed in Publication No. 53-118411, "Apatite-coated porcelain and its manufacturing method," but in this method, for example, partially stabilized zirconia, which has recently attracted attention as an implant material due to its high strength and high fracture toughness, is used as the base material. When using a sintered body, even if the apatite powder is baked at the general sintering temperature of apatite of 1,300°C or even higher at a temperature of about 1,500°C, the adhesive strength of apatite is such that it can be easily peeled off by rubbing it with your fingers. It was so weak that it would have caused it. Also, increase the baking temperature to 1600
When the temperature was raised to about .degree. C., the strength of the partially stabilized zirconia sintered body of the substrate significantly decreased.

The general sintering temperature of partially stabilized zirconia ceramics is 1500-1600℃, which is the sintering temperature of apatite.
It is considerably higher than 1300℃, making it difficult to form a good bonding layer with apatite, and reheating at a high temperature will cause significant grain growth, and cracks will occur as a result of volume changes due to phase transition, resulting in significant strength loss. It has been difficult to strongly bake apatite onto partially stabilized zirconia ceramics because it has properties that are different from conventional dental porcelain and alumina ceramics, such as causing deterioration.

The present invention has been made in view of the above situation, and its gist is to fill the pores near the surface of a porous body made by semi-sintering a ceramic molded body with powder of one or more types of tricalcium phosphate and apatite, or with powder of one or more of tricalcium phosphate and apatite. It is filled with a mixture of the above powder and a powder made of substantially the same material as the ceramic molded body, and fired at the sintering temperature of the ceramic molded body, and then the surface is coated with fine apatite powder or fine powder of apatite and calcium phosphate frit. A method for producing a ceramic body for an implant, characterized in that the ceramic body is coated with a mixture and baked at a temperature of 1350°C or less.

In the present invention, the porous body formed by semi-sintering the ceramic molded body is what ultimately constitutes the base of the ceramic body for implants manufactured by the present invention, and is usually a dense body with a porosity of several percent or less. A sinterable ceramic molded body with a porosity of 10 to 40% obtained by firing a sinterable ceramic molded body at a temperature approximately 200 to 400°C lower than the sintering temperature. Then, the pores near the surface of this porous body are filled with a powder of one or more of tricalcium phosphate and apatite, or a mixture of one or more powders and a powder of substantially the same material as the ceramic molded body, and It is sintered at the sintering temperature of the ceramic molded body to make it dense. Thus, near the surface of the sintered body, phosphates that can easily adhere to apatite are mixed together with the base material.
The surface is coated with apatite or a mixture of apatite and calcium phosphate frit by coating, dipping, spraying, or other known means, and these apatites are baked and bonded firmly at a low temperature of 1350°C or less without worrying about decomposition of the apatite. It becomes possible to do so. In addition, as mentioned above, the porous body that becomes the base material is sintered at the sintering temperature and becomes dense, so it has high mechanical strength, and if the main component is partially stabilized zirconia, it also has excellent toughness. It becomes.

Examples are shown below.

Example 1 A water-soluble binder was added to a powder containing 97 mol% of ZrO ₂ and ₃ mol% of Y ₂ O 3 obtained by mixing zirconium oxychloride and yttrium chloride as an aqueous solution, co-precipitating the mixture, and calcining it at 800°C. After adding and wet mixing, it is granulated by spray drying, rubber press molded at a pressure of 1500 kg/cm ² , the molded body is degreased and held in the air at a temperature of 1200°C for 1 hour to form a porous body, and the porous body is treated with phosphoric acid. It was immersed in a 5% tricalcium suspension, vacuum degassed for 5 minutes, taken out from the suspension, dried, and kept at atmospheric temperature.
A sintered body was obtained by firing at 1550°C for 1 hour. Separately, 5 parts by weight of CaO-P ₂ O ₅ -based frit with a Ca/P atomic ratio of 0.5, 95 parts by weight of apatite, and 1 part by weight of methylcellulose were wet-mixed to form a slurry, and this slurry was applied to the surface of the sintered body. ,
A ceramic body for an implant was manufactured by baking in the atmosphere at a temperature of 1300°C and a holding time of 1 hour.
A peel test was performed by hitting the baked part with a metal pin, and the bond was found to be good with no peeling.
The bending strength was approximately 80 Kg/mm ² .

Example 2 97% by weight of Al ₂ O ₃ powder with an average particle size of 1.5 μm, 2% by weight of CaO powder and 1% by weight of MgO powder were wet mixed, granulated by spray drying, and mold pressed at a pressure of 800 Kg/cm ² After molding and degreasing the molded body, the temperature in the atmosphere is 1150℃.
℃ for 1 hour to form a porous body, a 30% suspension of mixed powder of 5 parts by weight of apatite and 8 parts by weight of Al(OH) ₃ in water was applied to the porous body, and the temperature was kept in the air at 1600 ℃ for a holding time of 1. A sintered body was obtained by firing under the following conditions. Separately, 1 part by weight of methyl cellulose is added to 100 parts by weight of apatite powder, wet mixed to form a slurry, this slurry is applied to the surface of the sintered body, and baked at an atmospheric temperature of 1300°C for a holding time of 1 hour. A ceramic body for implants was manufactured using the following methods. A peel test was performed by hitting the baked part with a metal pin, and the bond was found to be good with no peeling. The bending strength was approximately 40 Kg/mm ² .

Claims (1)

[Scope of Claims] 1. Pores near the surface of a porous body made by semi-sintering a ceramic molded body are filled with a powder of one or more of tricalcium phosphate and apatite, or a powder of one or more of these and the ceramic molded body. Filled with a mixture of powder of the same material and fired at the sintering temperature of the ceramic molded body, the surface is then coated with fine apatite powder or a fine powder mixture of apatite and calcium phosphate frit, and the temperature is lower than 1350°C. A method for manufacturing a ceramic body for implants, which is characterized by baking. 2. The method for producing a ceramic body for an implant according to claim 1, wherein the ceramic molded body is a partially stabilized zirconia ceramic.