JPH0247419B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention relates to a high-strength crystallized glass useful as an implant material for artificial tooth roots and artificial bones, and more specifically, it relates to a high-strength crystallized glass containing β-tricalcium phosphate crystals and anorthite crystals. Concerning high-strength crystallized glass and its manufacturing method. [Prior art] Examples of crystallized glass for biological materials include
MgO−CaO−SiO ₂ − with MgO content of 7% by weight or less
P ₂ O ₅ glass is finely pulverized, the powder is molded and sintered, and then heat treated to precipitate apatite crystals [Ca ₁₀ (PO ₄ ) ₆ O] and wollastonite crystals [CaO・SiO ₂ ]. Crystallized glass is known. In addition, the MgO content is 8% by weight or more.
As crystallized glass obtained from MgO−CaO−SiO ₂ −P ₂ O ₅ series glass, apatite crystals and diopside [CaO・MgO・2SiO ₂ ],
Precipitated alkaline earth silicate crystals such as forsterite [2CaO·SiO ₂ ] and okermanite [2CaO·MgO·2SiO ₂ ] are known. These crystallized glasses have in common that they contain apatite crystals, which gives them biocompatibility. On the other hand, it is known that tricalcium phosphate crystals are absorbed in vivo and are a component that induces bone formation, and this sintered body arranged on the surface of polymethyl methacrylate can be used as an artificial tooth root. Porous sintered bodies of tricalcium phosphate crystals are used as bone replacement materials. [Problems to be Solved by the Invention] As mentioned above, tricalcium phosphate crystals have the property of being absorbed into the body and inducing bone formation. When actually used as an implant material,
There is a problem in that its shape must be designed taking into consideration the rate of absorption into the body and the rate of bone formation. This invention utilizes anorthite crystals [CaO・Al ₂ O ₃・2SiO ₂ ] that contribute to the mechanical speed of crystallized glass.
By coexisting with tricalcium phosphate crystals, the external shape of the crystallized glass can be maintained virtually unchanged even if the tricalcium phosphate crystals are absorbed into the living body, and this can also be used when designing implant materials. The object of the present invention is to provide crystallized glass and a method for producing the same that does not require consideration of the balance between absorption rate and bone formation rate of tricalcium phosphate crystals. [Means for solving the problem] The crystallized glass of the present invention has a weight percentage of
MgO 8~26%, CaO 18~43%, _SiO2 25~
40% _{, P2O5} 10-25%, _{Al2O3 10-25} %, _Li2O
0-10%, Na ₂ O 0-10%, K ₂ O 0-10
%, _{B2O3 0-10} %, _TiO2 0-10%, _ZrO2 0-10%, SrO 0-10%, _{Nb2O5 0-10} %,
Contains Ta ₂ O ₅ in the range of 0 to 10%, and the above
It has a composition in which the total content of MgO, CaO, SiO ₂ , P ₂ O ₅ and Al ₂ O ₃ is 90% or more, and 1 of each crystal of diopside, forsterite and okermanite.
It is characterized by containing a seed or two or more kinds, β-tricalcium phosphate crystal [β-Ca ₃ (PO ₄ ) ₂ ] and anorthite crystal. And, such crystallized glass contains 8-26% MgO, 18-43% CaO, and _SiO2 in weight percentage.
25-40% _{, P2O5} 10-25%, _{Al2O3 10-25} %,
Li ₂ O 0-10%, Na ₂ O 0-10%, K ₂ O 0-10%
10% _{, B2O3} 0-10%, _TiO2 0-10%, _ZrO2
0-10%, SrO 0-10%, Nb ₂ O ₅ 0-10
%, Ta ₂ O ₅ in the range of 0 to 10%, and the above-mentioned
A glass powder of 200 mesh or less with a composition in which the total content of MgO, CaO, SiO ₂ , P ₂ O ₅ and Al ₂ O ₃ is 90% or more is molded and then heat treated in the sintering temperature range of glass powder. , and then heat-treated in a temperature range that produces β-tricalcium phosphate crystals and anorthite crystals. In this case, one or more of diopside crystals, forsterite crystals, and okermanite crystals are precipitated in the crystallized glass of the present invention by heat treatment in the above-mentioned formation temperature range of both crystals. The reason for the quantitative limitation regarding the composition of the crystallized glass according to the present invention is as follows. When the MgO content is less than 8%, the sintering temperature range of the glass powder and the crystal formation temperature become close to each other, and crystallization occurs before the pores disappear due to sintering, making it impossible to obtain crystallized glass with a dense structure. Furthermore, if the MgO content is 26% or more, the amount of β-tricalcium phosphate crystals formed is undesirable. Therefore, the MgO content is limited to 8-26%. β when CaO is below 18%
- The content of CaO is limited to 18 to 43% because the amount of tricalcium phosphate crystals produced is small and the tendency of the glass to devitrify becomes significant above 43%.
If SiO ₂ is less than 25%, the glass tends to devitrify, and the amount of silicate crystals of aluminum, calcium, and magnesium produced also decreases, making it impossible to impart high strength to the crystallized glass. Moreover, if it exceeds 40%, the glass will undergo phase separation, making it impossible to obtain homogeneous glass. Therefore, the content of SiO ₂ is 25-40
limited to %. If the P ₂ O ₅ content is less than 10%, the amount of apatite crystals that are the precursor of β-tricalcium phosphate crystals will be small, and if it is more than 25%, the glass will undergo phase separation, so the P ₂ O ₅ content should be 10 to 25%. limited to %. If Al ₂ O ₃ is less than 10%, it is difficult to form anorthite crystals, and the desired strength cannot be achieved in crystallized glass, and if Al 2 O 3 is more than 25%, β-tricalcium phosphate crystals are formed. quantity decreases. Therefore, the content of Al ₂ O ₃ is limited to 10-25%. In addition to the above-mentioned five essential components, the crystallized glass of the present invention contains Li ₂ O, Na ₂ O, K ₂ O, which are not harmful to the human body.
One or more of SrO, B ₂ O ₃ , TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and ZrO ₂ can be contained within 10%. However, if the total content of these optional components exceeds 10% of the glass composition, the amount of β-tricalcium phosphate crystals and alkaline earth silicate crystals will decrease, so MgO, CaO, SiO ₂ , P ₂ O ₅
The total content of the five essential components of Al ₂ O ₃ must be 90% or more. In producing the crystallized glass according to the present invention, the parent glass in the composition range specified above is
After pulverization to a particle size of 200 mesh or less, it is important to mold the resulting glass powder into a desired shape, then sinter the molded body and then subject it to a crystallization treatment. By the way, if the above-mentioned parent glass is directly molded into the desired shape from the molten state without being crushed and then heat-treated, various alkaline earth silicate crystals such as anorthite, diopside, okermanite, and forsterite can be formed into glass. Since it precipitates from the surface and cracks occur inside, it is not possible to obtain crystallized glass with high strength. Further, even if the parent glass is crushed, if the particle size is 200 mesh or more, pores tend to remain in the crystallized glass, and in this case also, it is impossible to obtain a crystallized glass with high mechanical strength. In other words, in order to obtain a high-strength crystallized glass with few pores and uniformly precipitated fine particles of β-tricalcium phosphate crystals and silicate crystals such as anorthite, diopside, forsterite, and okermanite, the particle size must be
It is important to use fine parent glass powder of 200 mesh or less. According to the method of the present invention, parent glass powder with a particle size of 200 mesh or less is molded into a desired shape by any known means, and then the molded body is heat treated in the sintering temperature range of the glass powder, and then β - Heat treated in the temperature range for forming tricalcium phosphate crystals and anorthite crystals. Heat treatment in the sintering temperature range of glass powder is important to obtain crystallized glass with no pores and high mechanical strength. It can be determined by heating and measuring the thermal contraction caused by sintering of the compact. The sintering temperature range is from the start temperature to the end temperature of thermal contraction. Heat treatment in the formation temperature range of β-tricalcium phosphate crystals can induce β-tricalcium phosphate, which has the effect of inducing bone formation.
This is important for producing large amounts of tricalcium phosphate crystals. In addition, heat treatment in the anorthite crystal formation temperature range is important for precipitating a large amount of silicate crystals such as anorthite, diopside, okermanite, and forsterite, and increasing the mechanical strength of crystallized glass. be. The formation temperature range of each of these crystals is determined by differential thermal analysis of glass powder. By analyzing the X-ray diffraction data of glass powder heat-treated at the temperature of the exothermic peak in the differential thermal analysis curve, we can identify the precipitated crystals corresponding to each exothermic peak, and calculate the temperature from the exothermic start temperature to the exothermic end temperature. This is the temperature range in which each crystal forms. Generally, the temperature range for the formation of each crystal is in the range of 1000 to 1100°C. [Example] Using oxides, carbonates, phosphates, hydrates, 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 for 1400~
Melt at 1550°C for 30-60 minutes. Next, the molten glass was put into water to be rapidly cooled, and after drying, it was put into a pot mill and ground to a particle size of 300 mesh or less.
5 wt % paraffin was added as a binder to this glass powder, and the mixture was placed in a mold and pressure-molded at a pressure of 500 kg/cm ² . The obtained molded body was placed in an electric furnace and heated from room temperature to 1000°C.
Constant heating rate up to a constant temperature in the range of ~1100℃3
The molded body was heated at a rate of .degree. C./min and held at that constant temperature for 2 hours to sinter and crystallize the molded body. Thereafter, it was cooled to room temperature in a furnace to obtain crystallized glass. The fracture surface of each crystallized glass produced in this way is
When observed with SEM, all had dense structures with few pores. Furthermore, these crystallized glasses were crushed and precipitated crystals were identified by X-ray diffraction.
The results are shown in the table below along with the glass composition. In addition,
Some of the crystallized glass was processed into a round bar with a diameter of approximately 5 mm using a No. 300 diamond grindstone, and its bending strength was measured. The results are also listed in the table below. As is clear from the table, the crystallized glass of the present invention is
It has a high bending strength of 1700-2300Kg/ ^cm2 .

【table】

【table】

[Table] [Effects of the invention] The crystallized glass of the present invention has β-
Contains a large amount of tricalcium phosphate crystals, and
Since it has a very high bending strength of 1700 to 2300 Kg/cm ² , it is extremely useful as a biomaterial for artificial bones and artificial tooth roots.

Claims (1)

[Claims] 1. MgO in weight percentage of 8 to 26% and CaO in weight percentage of 18 to 26%.
43%, 25-40% _SiO2 , _10-25 % _{P2O5 , Al2O3}
10-25%, Li ₂ O 0-10%, Na ₂ O 0-10
%, _K2O 0-10%, _{B2O3 0-10} %, _TiO2 0-10%, _ZrO2 0-10%, SrO 0-10%,
Contains Nb ₂ O ₅ in a range of 0 to 10%, Ta ₂ O ₅ in a range of 0 to 10%, and contains the above-mentioned MgO, CaO, SiO ₂ , P ₂ O ₅ , and
It has a composition in which the total content of Al ₂ O ₃ is 90% or more,
A high-strength crystallized glass characterized by containing one or more of diopside, forsterite, and okermanite crystals, β-tricalcium phosphate crystals, and anorthite crystals. 2 MgO 8-26%, CaO 18-26% by weight
43%, 25-40% _SiO2 , _10-25 % _{P2O5 , Al2O3}
10-25%, Li ₂ O 0-10%, Na ₂ O 0-10
%, _K2O 0-10%, _{B2O3 0-10} %, _TiO2 0-10%, _ZrO2 0-10%, SrO 0-10%,
Contains Nb ₂ O ₅ in a range of 0 to 10%, Ta ₂ O ₅ in a range of 0 to 10%, and contains the above-mentioned MgO, CaO, SiO ₂ , P ₂ O ₅ and
Has a composition in which the total content of Al ₂ O ₃ is 90% or more
Glass powder of 200 mesh or less is formed, heat-treated in the sintering temperature range of glass powder, and then β-
A method for producing high-strength crystallized glass, characterized by heat treatment in a temperature range for forming tricalcium phosphate crystals and anorthite crystals.