JPS6210939B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to crystallized glass useful as artificial bones and artificial tooth roots, and a method for producing the same. Conventionally, materials used for artificial bones and artificial tooth roots include corrosion-resistant alloys such as cobalt chromium alloys, stainless steel, and titanium alloys, and polymeric materials that are relatively stable in vivo, such as polymethyl methacrylate, silicone, and high-density polyethylene. I've been exposed to it. but,
These materials have drawbacks such as poor affinity with living tissues and the possibility that metal ions, monomers, etc. eluted from them may have a negative effect on the human body. On the other hand, ceramic materials generally have good biocompatibility, and there is little risk that components eluted from them will have a negative effect on the human body. In addition, alumina ceramics has excellent mechanical strength, so it has recently been attracting attention as a material for artificial bones and artificial tooth roots. However, alumina ceramics does not form a chemical bond with bone, so in order to fix it to the surrounding bone, it is necessary to drill holes or grooves in the ceramic and allow new bone to enter there. ,
If the shape of the ceramic is not appropriate, stress concentration will occur in the bone or a portion of the ceramic, which may lead to bone resorption or destruction of the ceramic. Therefore, ceramic materials that create chemical bonds with bones have been searched for, and so far Na ₂ O
-CaO-SiO ₂ -P ₂ O _5- based crystallized glass and apatite sintered bodies have become known. However, these have the disadvantage that they have low mechanical strength or are not easy to manufacture. The purpose of the present invention is to provide crystallized glass that has excellent biocompatibility as an artificial bone or artificial tooth root, forms a direct chemical bond with bone, and has excellent mechanical strength, and a method for easily producing the same. The crystallized glass of the present invention can be applied to artificial bones, artificial tooth roots, and the like. The crystallized glass for artificial bones of the present invention has at least
More than 90% is MgO1~7%, CaO42~53%,
It has a composition of 22 to 41% SiO ₂ and 10 to 27% P ₂ O ₅ , and is characterized by a structure in which a large number of apatite and wollastonite microcrystals are dispersed in the glass. In addition, the method for producing crystallized glass for artificial bone according to the present invention involves molding glass powder with a particle size of 200 mesh or less having the above composition, heating it in a glass powder sintering temperature range, and then heating it in an apatite and wollastonite crystal precipitation temperature range. It is characterized by heat treatment. Examples of the method for producing crystallized glass for artificial bone according to the present invention are as follows.

[Table] Prepare batches corresponding to the glass compositions of Examples 1 to 10 in the attached table using oxide, carbonate, hydrate, or fluoride raw materials, and place them in a platinum crucible in an electric furnace for 1400 to 1500 Melt for 2 hours at °C. Next, these melts are poured onto an iron plate to form sheet glass, which is then ground into powder having a particle size of 325 mesh (44 μm opening) or less. After pressure-molding these powders into a predetermined shape, they were heated in an electric furnace from room temperature to 1050°C at a rate of 5°C/min, held at 1050°C for 2 hours to sinter and crystallize, and then turned off the power source. Allow to cool naturally in the furnace. The crystallized glass produced by this method is a dense glass in which numerous microcrystals of apatite (Ca ₁₀ (PO ₄ ) ₆ O) and wollastonite (CaO SiO ₂ ) are precipitated in a continuous glass medium. It has a unique structure. The crystallized glass for artificial bones of the present invention contains a large amount of apatite and wollastonite crystals. Among these crystals, apatite crystals play an important role in creating a chemical bond between crystallized glass and bone. On the other hand, wollastonite crystals play an important role in increasing the mechanical strength of crystallized glass. When crystallized glass does not contain apatite crystals, chemical bonding is difficult to occur between crystallized glass and bone. On the other hand, if the crystallized glass does not contain wollite night crystals, its mechanical strength will not increase. More than 90% of the crystallized glass for artificial bones of the present invention is
MgO1~7%, CaO42~53%, _SiO2 22~41%,
It has a composition consisting of _10-27 % _P2O5 . This limited composition is suitable for making glass and for precipitating a large amount of both apatite and wollastonite crystals into the glass by heat treatment. If the MgO content is less than 1%, it is difficult for the melt to become glass, and if the MgO content is more than 7%, only a small amount of apatite and wollastonite crystals can be precipitated in the glass, which is not preferable. Therefore, MgO is 1
It was limited to ~7%. When CaO is less than 42%, the glass can precipitate only a small amount of apatite and wollastonite crystals, and when CaO is more than 53%, the melt is difficult to become glass. Therefore, CaO was limited to 42-53%. If SiO ₂ is less than 22%, the glass can only precipitate a small amount of wollastonite crystals and SiO ₂
If it is more than 41%, only a small amount of apatite crystals can be precipitated in the glass, which is not preferable. Therefore,
_SiO2 is limited to 22-41%. If P ₂ O ₅ is less than 10%, only a small amount of apatite crystals can be precipitated in the glass, and if P ₂ O ₅ is more than 27%, only a small amount of wollastonite crystals can be precipitated in the glass, which is undesirable. . Therefore P ₂ O ₅
was limited to 10-27%. The composition of crystallized glass is less than 10%
_Li2O , _Na2O , _K2O , SrO, _{B2O3 , Al2O3 ,}
It may contain additive components that are not harmful to the human body, such as TiO ₂ , ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and CaF ₂ . However, if the total amount of these additive components is more than 10%, only a small amount of apatite and wollastonite crystals can be precipitated in the glass. Therefore, the total amount of these additional components is limited to less than 10%, ie, the total amount of MgO, CaO, SiO ₂ and P ₂ O ₅ is limited to 90% or more. In the method for producing crystallized glass for artificial bone according to the present invention, glass is turned into powder with a particle size of 200 mesh or less, and then molded into a predetermined shape. The fact that the glass is a fine powder is an important condition in order to obtain, by heat treatment, a crystallized glass with few pores and in which apatite and wollastonite crystals are uniformly precipitated as fine particles. When the melt is directly formed into glass of a predetermined shape and then heat-treated,
Wollastonite crystals are precipitated only from the glass surface, and only crystallized glass with internal cracks and low mechanical strength can be obtained. Furthermore, when glass powder with a particle size larger than 200 mesh is used, only crystallized glass with high porosity and low mechanical strength can be obtained. Therefore, the particle size of the glass powder is limited to 200 mesh or less. Any method may be used to prepare the glass powder and the molded product thereof. In the method for producing crystallized glass for artificial bones of the present invention, a glass powder compact is heat-treated in a glass powder sintering temperature range and then in an apatite and wollastonite crystal precipitation temperature range. The former heat treatment is important for obtaining crystallized glass with low porosity and high mechanical strength, and the latter heat treatment is important for precipitating a large amount of apatite and wollastonite crystals from the glass. The glass powder sintering temperature range can be determined by heating a glass powder compact at a constant rate and measuring the thermal contraction during the heating. The glass powder sintering temperature range may be from the thermal contraction start temperature to the thermal contraction termination temperature. Further, the apatite and wollastonite crystal precipitation temperature range can be determined by heating glass powder at a constant rate and performing differential thermal analysis during the heating. The apatite and wollastonite crystal precipitation temperature range may be defined as the temperature range from the start temperature of heat generation due to the precipitation of apatite and wollastonite crystals to the temperature at which the heat generation ends. The heat treatment in these temperature ranges may be performed by keeping the temperature of the glass powder compact within these temperature ranges for a certain period of time, or by increasing the temperature of the glass powder compact at a constant rate during these temperature ranges. You may do so. Further, in addition to these temperature ranges, heat treatment may be performed in other temperature ranges. For example, as in the above embodiment, the glass powder compact may be heated continuously at a constant rate from room temperature to 1000° C., which is higher than the apatite and wollastonite crystal precipitation temperature range. However, the apatite crystals precipitated in the glass disappear at high temperatures and 3CaO・P ₂ O ₅ crystals precipitate in their place, so do not heat the glass powder compact to the temperature range where 3CaO・P ₂ O ₅ crystals precipitate. It won't happen. This 3CaO・
The P ₂ O ₅ crystal precipitation temperature range can also be determined from the position of the exothermic peak on the differential thermal analysis curve of the glass powder. When the crystallized glass for artificial bone of the present invention is inserted into a bone defect, it forms an extremely strong chemical bond with the surrounding bone without causing any harmful effects on the surrounding living tissue. For example, the crystallized glass prepared by the method of the above example having the composition of Examples 1 to 10 in the attached table,
When inserted into the defective part of the femur of a rabbit or rabbit, the crystallized glass did not show any harmful effects on the living tissue surrounding the crystallized glass even after 12 weeks, and after the same period it strongly bonded to the surrounding bone. It is confirmed that there is. This is because the crystallized glass for artificial bones of the present invention contains a large amount of apatite crystals. Furthermore, the crystallized glass for artificial bones of the present invention has extremely high mechanical strength. For example, Appendix 1~
As shown in the lower column of the attached table, the crystallized glass prepared by the method of the above specific example having a composition of No. 10 exhibits a high bending strength of 1200 to 1400 Kg/cm ² . This bending strength is compared to the previously known bending strength of crystallized glass for artificial bone, which creates a chemical bond with bone, which is less than 1000 kg/cm ² .
Quite expensive. The reason for this is that conventionally known crystallized glass for artificial bones contains only apatite crystals, whereas the crystallized glass for artificial bones of the present invention contains many fibrous wollastonite crystals in addition to apatite crystals. This is to include. That is, in the crystallized glass for artificial bones of the present invention, the fibrous wollastonite crystals play a role of reinforcing the crystallized glass in which apatite crystals are dispersed. The bending strength of the crystallized glass for artificial bone of the present invention is
The bending strength of apatite sintered bodies for artificial bones that create chemical bonds with bone that have been reported in Japan so far is 700~
This is high compared to 1200Kg/cm ² . The first apatite sintered body for artificial bone announced in the United States was 2000
Although it is reported that they exhibit a bending strength of Kg/cm ² or more, this is difficult to achieve in large products due to the complicated manufacturing process. In comparison, the crystallized glass for artificial bones of the present invention not only has excellent mechanical properties, but also has a simple manufacturing process according to the method of the present invention, and is an industrial scale that can be manufactured extremely easily up to large products. There is a certain effect.

Claims (1)

[Claims] 1. At least 90% of the crystallized glass is
MgO1~7%, CaO42~53%, _SiO2 22~41%,
Consisting of 10-27% P ₂ O ₅ , 0-10% Li ₂ O,
_Na2O , _K2O , _SrO , _B2O3 , _{Al2O3 , TiO2} ,
It has a composition consisting of one or more of ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and CaF ₂ and has a structure in which a large number of apatite and wollastonite microcrystals are dispersed in the glass. A crystallized glass for artificial bones characterized by: 2 At least 90% or more is MgO1-7%,
It consists of CaO42-53%, _SiO222-41 %, _P2O5 10-27%, _and 0-10% is _Li2O , _Na2O , _K2O , SrO,
_{B2O3 , Al2O3} , _{TiO2 , ZrO2 , Nb2O5 , Ta2O5} ,
Composition consisting of one or more types of CaF ₂
After molding glass powder with a particle size of 200 mesh or less,
1. A method for producing crystallized glass for artificial bones, which comprises heating in a glass powder sintering temperature range and then heat-treating in an apatite and wollastonite crystal precipitation temperature range.