JPH0136382B2 - - 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 a ceramic body for an implant, 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 a loss. 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 apatite sintering temperature.
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 impregnate the pores of a porous body made by semi-sintering a ceramic molded body with a calcium ion-containing liquid and a phosphate ion-containing liquid, A method for producing a ceramic body for an implant, characterized in that the ceramic body is fired at the sintering temperature of the molded body, the surface is then coated with apatite or a mixture of apatite and calcium phosphate frit, and the ceramic body is fired at a temperature of 1350° C. or lower.

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 is fired at a temperature approximately 200 to 400°C lower than the sintering temperature to create a large number of pores that allow liquids containing calcium ions or phosphate ions to penetrate into the molded body. It refers to an aggregate of primary particles that are bonded to such an extent that they do not lose their shape even when immersed in the liquid. Then, this porous body was immersed in a calcium ion-containing liquid to allow the calcium ion-containing liquid to be contained in the pores of the porous body, dried, and then immersed in a phosphate ion-containing liquid and the same operation was performed. , the ceramic molded body is sintered at the sintering temperature to make it dense. Here, since the calcium ion-containing liquid and the phosphate ion-containing liquid are infiltrated into the pores near the surface of the porous body, even if the porous body is sintered and densified, at least near the surface of the sintered body The base material contains calcium compounds and phosphates that can easily adhere to apatite. Thus, the surface of the sintered body is coated with apatite or a mixture of apatite and calcium phosphate frit by a known method such as coating, dipping, spraying, etc.
It is possible to bond firmly by baking at low temperatures below 1350℃ without worrying about apatite decomposition. In addition, as mentioned above, the porous body that serves as the base 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 something. Note that the order of impregnating the pores with the calcium ion-containing liquid and the phosphate ion-containing liquid is not limited to the above, and the same effect can be obtained even if the phosphate ions are impregnated first or both ions are impregnated simultaneously.

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, coprecipitating the mixture, and calcining it at 800°C. After 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, which is saturated with calcium hydroxide. Immersed in an aqueous solution, vacuum defoamed for 10 minutes, then taken out from the solution and dried, then immersed in a 1% orthophosphoric acid aqueous solution, vacuum defoamed and dried in the same way, at an atmospheric temperature of 1550°C, holding time 1. A sintered body was obtained by firing under the following conditions. Separately, a suspension of fine apatite powder was applied to the surface of the sintered body and baked at a temperature of 1300° C. for 1 hour to produce a ceramic body for an implant. 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 70 kg/mm ² .

Example 2 99 mol% Al ₂ O ₃ powder with an average particle size of 1.5 μm and
Wet-mixing 1 mol% of MgO powder, press-molding the granulated powder with a mold at a pressure of 800 kg/cm ² , degreasing the molded body, and holding it in the air at a temperature of 1200°C for 1 hour to form a porous body. A ceramic body for an implant was manufactured under the same conditions as in Example 1 except that the firing conditions for obtaining a sintered body were a temperature of 1630° C. and a holding time of 2 hours. A peel test was conducted in the same manner as in Example 1, and the bonding was good without peeling. The bending strength was approximately 40 kg/mm ² .

Claims (1)

[Scope of Claims] 1 A calcium ion-containing liquid and a phosphate ion-containing liquid are impregnated into the pores near the surface of a porous body obtained by semi-sintering a ceramic molded body, and the porous body is heated at the sintering temperature of the ceramic molded body. 1. A method for producing a ceramic body for implants, which comprises firing, then coating the surface with fine apatite powder or a fine powder mixture of apatite and calcium phosphate frit, and baking at a temperature of 1350°C or less. 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.