JPH0555150B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Industrial Application] The present invention relates to an inorganic biomaterial useful as an implant material for artificial bones, artificial tooth roots, etc. More specifically, the present _invention relates to a sintered crystallized glass containing CaO and _P2O5 . The present invention relates to a ceramic composite material in which zirconia ceramic is dispersed throughout the body, and a method for producing the same. [Conventional technology] Apatite sintered bodies and Na ₂ O ceramics that create chemical bonds with bones (bioactive)
_-K2O -MgO-CaO- _SiO2 - _{P2O5 -} based crystallized glass is known. Also, MgO−CaO−P ₂ O ₅ −
_SiO2 -based glass is crushed to 200 mesh or less, the resulting glass powder is molded, heat-treated in the sintering temperature range of glass powder, and then apatite crystal [ _Ca10 ( _PO4 ) ₆
(O _0.5′F ) ₂ ] and wollastonite crystals [CaO・
Crystallized glass that can be manufactured by heat treatment in the formation temperature range of SiO ₂ ] is also known. In this crystallized glass, apatite crystals contribute to biocompatibility, and wollastonite crystals contribute to mechanical strength. Therefore, in order to increase mechanical strength, it is desirable to increase the content of wollastonite crystals. Therefore, crystallized glass with an increased content of SiO ₂ and an increased amount of precipitated wollastonite crystals is also known. By the way, the bending strength of these ceramics is 1000 to 1400 Kg/cm ² for apatite sintered bodies.
Na ₂ O−K ₂ O−MgO−CaO−SiO ₂ −P ₂ O 1000 to 1500 Kg/cm ² for ₅ -based crystallized glass, MgO−CaO−
P ₂ O ₅ −SiO ₂ crystallized glass: 1200 to 1400 Kg/cm ²
That's about it. Furthermore, CaO−P ₂ O ₅ −SiO ₂ system with a large amount of wollastonite precipitated, or CaO
−P ₂ O ₅ −SiO ₂ −MgO, Y ₂ O ₃ -based crystallized glass is
It has a high bending strength of 1700-2300Kg/ ^cm2 . However, this value is not necessarily sufficiently satisfactory for artificial tooth roots or artificial bones.
There is a demand for materials with even higher strength. An object of the present invention is to provide an inorganic biomaterial that has excellent biocompatibility and even higher strength than conventional products, and a method for producing the same. [Means for solving the problems] The inorganic biomaterial of the present invention has a weight percentage of CaO 12-56 P ₂ O ₅ 1-27 SiO ₂ 22-50 MgO 0-34 Al ₂ O ₃ 0-25 K ₂ O 0-10 Li ₂ O 0-10 Na ₂ O 0-10 TiO ₂ 0-10 ZrO ₂ 0-10 SrO 0-10 Nb ₂ O ₅ 0-10 Ta ₂ O ₅ 0-10 B ₂ O ₃ 0- Contains the above components in the range of 10 F ₂ 0-5 Y ₂ O ₃ 0-5, including CaO, P ₂ O ₅ , SiO ₂ ,
A composite material of zirconia ceramic and crystallized glass having a composition in which the total content of MgO and Al ₂ O ₃ is 90% or more, wherein the zirconia ceramic is dispersed in the crystallized glass. It is a feature. The precipitated crystals of the crystallized glass include apatite crystals and one or more alkaline earth silicate crystals such as wollastonite, diopside, forsterite, okermanite, and anorsite, and further include β- Tricalcium phosphate crystal [β-Ca ₃
(PO ₄ ) ₂ ] may be included. The inorganic biomaterial of the present invention as described above has a weight percentage of CaO 12-56 P ₂ O ₅ 1-27 SiO ₂ 22-50 MgO 0-34 Al ₂ O ₃ 0-25 K ₂ O 0-10 Li ₂ O 0-10 Na ₂ O 0-10 TiO ₂ 0-10 ZrO ₂ 0-10 SrO 0-10 Nb ₂ O ₅ 0-10 Ta ₂ O ₅ 0-10 B ₂ O ₃ 0-10 F ₂ 0-5 Y ₂ O ₃ Contains the above components in the range of 0 to 5, including CaO, P ₂ O ₅ , SiO ₂ ,
Zirconia ceramic is uniformly mixed at a volume percentage of 5 to 50% into glass powder of 200 mesh or less with a composition in which the total content of MgO and Al ₂ O ₃ is 90% or more, and this mixture is molded into a predetermined shape. After that, this molded body is sintered, and apatite crystals, wollastonite, diopside,
It can be produced by heat treatment in a temperature range in which one or more types of alkaline earth silicate crystals selected from forsterite, okermanite, and anorsite are precipitated. Regarding the composition of the glass in the inorganic biomaterial according to the present invention, the reason for the quantitative limitation will be described below. If CaO is less than 12%, the sinterability of the glass powder becomes extremely poor, making it impossible to obtain high-strength crystallized glass. Moreover, when CaO exceeds 56%, the tendency of glass to devitrify becomes remarkable. Therefore, the content of CaO is limited to 12-56%. When P ₂ O ₅ is less than 1%,
The tendency of glass to devitrify is remarkable, and at 27% or more, wollastonite, diopside, forsterite,
Since the amount of alkaline earth silicate crystals such as okermanite and anorsite is reduced, P ₂ O ₅
The content of is limited to 1-27%. If SiO ₂ is less than 22%, the sinterability of the glass powder will be poor and the amount of alkaline earth silicate crystals precipitated will also be reduced.
Moreover, when SiO ₂ exceeds 50%, the glass tends to devitrify. Therefore, the content of _SiO2 is limited to 22-50%. MgO is not an essential component, but if it is included, the amount of apatite crystals produced will decrease if it is more than 34%, so it is limited to 34% or less. Similarly,
Al ₂ O ₃ is also not an essential component, but if it is included, the amount of apatite crystals produced will decrease if it is more than 25%, so it is limited to 25% or less. In addition to the five components mentioned above, the glass of the present invention contains K ₂ O, Li ₂ O, Na ₂ O, TiO ₂ , which are not harmful to the human body.
ZrO ₂ , SrO, Nb ₂ O ₅ , Ta ₂ O ₅ , B ₂ O ₃ , F ₂ , Y ₂ O ₃
One or more types can be contained within a range of 10% or less. The total of these optional components is 10%
If the amount is larger than this, the amount of apatite crystals and alkaline earth silicate crystals produced may decrease, so it is preferably 10% or less. However, if F ₂ is more than 5%, the glass tends to devitrify, and if Y ₂ O ₃ is more than 5%, the amount of apatite crystals and alkaline earth silicate crystals produced will decrease. ₂ and Y ₂ O ₃ are each limited to 5% or less. In producing the inorganic biomaterial according to the present invention, the mother glass (matrix glass) having the composition range limited above is first ground to a particle size of 200 mesh or less, mixed uniformly with zirconia ceramic, and then It is important to mold the mixed powder into a desired shape, then sinter the molded body, and then subject it to crystallization treatment. If the particle size of the mother glass is 200 mesh or more, pores tend to remain in the sintered body, making it impossible to obtain an inorganic biomaterial with high mechanical strength. In other words, in order to obtain a composite material in which zirconia ceramic is uniformly dispersed in crystallized glass with few pores and crystals uniformly precipitated from the glass, it is important to use fine mother glass powder with a particle size of 200 mesh or less. be. Furthermore, if the volume percentage of zirconia ceramic to be composited is less than 5%, no improvement in mechanical strength can be expected by the composite, and if it is more than 50%, sinterability will deteriorate, and no improvement in mechanical strength can be expected. The biocompatibility of crystallized glass cannot be fully utilized. Therefore, the amount of zirconia ceramic added is limited to 5 to 50% by volume of the base glass. According to the method of the present invention, a mother glass powder having a particle size of 200 mesh or less and zirconia ceramic are mixed by any known means, and further molded into a desired shape by a known means, and then the molded body is formed from the glass/zirconia ceramic. It is heat-treated in the sintering temperature range of the zirconia ceramic mixed powder, and then heat-treated in the temperature range where apatite crystals and alkaline earth silicate crystals precipitate. The former heat treatment is important for obtaining composite crystallized glass with low porosity and high mechanical strength, and the latter heat treatment is important for precipitating apatite crystals and alkaline earth silicate crystals from the glass. The sintering temperature range can be determined by heating a molded body of glass/zirconia ceramic mixed powder at a constant rate and measuring the thermal contraction during the heating.
The sintering temperature range is from the start temperature to the end temperature of thermal contraction. Further, the precipitation temperature range of apatite crystals and alkaline earth silicate crystals is determined by differential thermal analysis of a glass/zirconia ceramic mixture. X of glass/zirconia ceramic mixed powder heat treated at the temperature of the exothermic peak in the differential thermal analysis curve
By analyzing the line diffraction data, precipitated crystals corresponding to each exothermic peak are identified, and the range from the exothermic temperature to the end temperature of the exothermic peak is defined as the precipitation temperature range of each crystal. Any known heat treatment method may be used, including hot press and HIP (hot isostatic pressing).
When used, sintering is further promoted, pores are reduced, and a product with greater mechanical strength can be obtained. The zirconia ceramic mixed with the mother glass is
Either commercially available stabilized zirconia or partially stabilized zirconia may be used, or both may be used in combination. The reason why crystallized glass is strengthened by blending zirconia ceramics is that when stabilized zirconia is used, compressive stress is applied to crystallized glass due to the difference in thermal expansion coefficient between crystallized glass and stabilized zirconia particles. Therefore, it is desirable that the thermal expansion coefficient of the crystallized glass is comparable to or smaller than that of the stabilized zirconia. In the case of using partially stabilized zirconia, this is thought to be due to martensitic transformation of zirconia. Naturally, when both stabilized zirconia and partially stabilized zirconia are used together, the reinforcing effects of both are simultaneously expressed. The zirconia ceramic mixed with the mother glass is
It may be in the form of powder or fiber (including whiskers). When powdered zirconia ceramic is used, the crystallized glass is strengthened as described above, and when fiber-formed zirconia ceramic is used, in addition to the above-mentioned strengthened crystallized glass, the fibers bear the stress applied to the material. Therefore, further improvement in mechanical strength can be expected. Therefore, crystallized glass can be strengthened even when a mixture of powder and fiber zirconia ceramics is used. However, if the zirconia ceramic to be mixed is a powder, the particle size of the powder must be 200 mesh or less.
If the zirconia ceramic powder is larger than 200 meshes, pores tend to remain in the sintered body, making it impossible to obtain an inorganic biomaterial with high mechanical strength. In other words,
In order to obtain a composite material in which zirconia ceramic is uniformly dispersed in crystallized glass with few pores and crystals uniformly precipitated from the glass, fine glass powder with a particle size of 200 mesh or less and zirconia ceramic fine powder with a particle size of 200 mesh or less are used. It is important to use [Example] Using oxides, carbonates, phosphates, hydrates, fluorides, etc. as raw materials, a batch of glass corresponding to the composition shown in the following table was prepared, and this was placed in a platinum crucible and heated to 1450 ml. Melt at ~1550°C for 1 hour. Next, the melt was poured into water to be rapidly cooled, dried, and then placed in a ball mill and ground to a particle size of 20 μm or less. A commercially available powdered or fibrous zirconia ceramic was added to the mixture, followed by wet mixing using a ball mill for several hours and drying. The resulting mixture was placed in a graphite mold, heated from room temperature to 1150°C at a constant temperature increase rate of 3°C/min while applying a pressure of 300 kg/ ^cm2 , and held at 1150°C for 2 hours to sinter the molded product. The mixture was fused and crystallized. Thereafter, it was cooled to room temperature in a furnace to obtain a composite material. The fracture surface of each composite material manufactured in this way is
When observed with SEM, all had dense structures with few pores. Furthermore, these composite materials were crushed and the precipitated crystal phase was identified by powder X-ray diffraction. Furthermore, the composite material was processed into a round bar with a diameter of 3 to 5 mm using a No. 300 diamond grindstone, and a three-point bending strength test was conducted. The glass composition, the type of zirconia ceramic, the amount of zirconia ceramic blended (volume percentage relative to glass), the precipitated crystal phase, and the three-point bending strength are shown in the following table. As is clear from the table, the inorganic biomaterial of the present invention has a high bending strength of 2300 to 3300 Kg/cm ² .

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[Table] [Effects of the invention] The inorganic biomaterial of the present invention contains CaO and P ₂ O ₅ necessary for chemically bonding with bone, and moreover
Since it has a very high bending strength of 3300 Kg/cm ² , it is extremely useful as a biomaterial for artificial bones and artificial tooth roots.

Claims (1)

[Claims] 1 By weight percentage CaO 12-56 P ₂ O ₅ 1-27 SiO ₂ 22-50 MgO 0-34 Al ₂ O ₃ 0-25 K ₂ O 0-10 Li ₂ O 0-10 Na ₂ O 0 ~ 10 TiO _{2 0} ~ 10 ZrO _{2 0} ~ 10 SrO 0 ~ 10 Nb ₂ O ₅ 0 ~ 10 Ta ₂ O _{5 0} ~ 10 B ₂ O ₃ 0 ~ 10 F ₂ 0 ~ 5 Y ₂ O ₃ 0 Contains the above components in the range of 5 to 5, including CaO, P ₂ O ₅ , SiO ₂ ,
A composite material of zirconia ceramic and crystallized glass having a composition in which the total content of MgO and Al ₂ O ₃ is 90% or more, wherein the zirconia ceramic is dispersed in the crystallized glass. Characteristic inorganic biomaterials. 2. The crystallized glass according to claim 1 contains an apatite crystal and one or more alkaline earth silicate crystals selected from wollastonite, diopside, forsterite, okermanite, and anorsite. An inorganic biomaterial characterized by 3 In weight percentage CaO 12-56 P ₂ O ₅ 1-27 SiO ₂ 22-50 MgO 0-34 Al ₂ O ₃ 0-25 K ₂ O 0-10 Li ₂ O 0-10 Na ₂ O 0-10 TiO ₂ 0~10 ZrO _{2 0} ~10 SrO 0~10 Nb ₂ O ₅ 0~10 Ta ₂ O ₅ 0~10 B ₂ O ₃ 0~10 F ₂ 0~5 Y ₂ O ₃ Above in the range of 0~5 Contains components such as CaO, P ₂ O ₅ , SiO ₂ ,
Zirconia ceramic is uniformly mixed at a volume percentage of 5 to 50% into glass powder of 200 mesh or less with a composition in which the total content of MgO and Al ₂ O ₃ is 90% or more, and this mixture is molded into a predetermined shape. After that, this molded body is sintered, and apatite crystals, wollastonite, diopside,
1. A method for producing an inorganic biomaterial, characterized by heat treatment in a temperature range where one or more types of alkaline earth silicate crystals selected from forsterite, okermanite, and anorsite are precipitated. 4 The shape of zirconia ceramic is powder and/or
4. The method for producing an inorganic biomaterial according to claim 3, wherein the inorganic biomaterial is a fiber. 5 Claim 3, characterized in that the particle size of the zirconia ceramic is 200 mesh or less
The method for producing the inorganic biomaterial described in Section 1.