CA1266868A - No alkali containing biocompatible glass ceramic with apatite, wollastonite and diopside crystals mixed - Google Patents
No alkali containing biocompatible glass ceramic with apatite, wollastonite and diopside crystals mixedInfo
- Publication number
- CA1266868A CA1266868A CA000533149A CA533149A CA1266868A CA 1266868 A CA1266868 A CA 1266868A CA 000533149 A CA000533149 A CA 000533149A CA 533149 A CA533149 A CA 533149A CA 1266868 A CA1266868 A CA 1266868A
- Authority
- CA
- Canada
- Prior art keywords
- glass ceramic
- glass
- sio2
- apatite
- cao
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/11—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen
- C03C3/112—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen containing fluorine
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/097—Glass compositions containing silica with 40% to 90% silica, by weight containing phosphorus, niobium or tantalum
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/11—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen
- C03C3/112—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen containing fluorine
- C03C3/115—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen containing fluorine containing boron
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C4/00—Compositions for glass with special properties
- C03C4/0007—Compositions for glass with special properties for biologically-compatible glass
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Molecular Biology (AREA)
- Materials For Medical Uses (AREA)
- Glass Compositions (AREA)
Abstract
Abstract of the Disclosures A biocompatible glass ceramic comprises, by weight, 7 - 16% MgO, 20 - 45% CaO, 41 - 50% SiO2, 8 -30% P2O5, 0 - 5% B2O3, 0 - 5% F2, and 0 - 10% Al2O3, and has a crystal structure where a number of fine crystals of apatite, wollastonite, and diopside are densely dispersed and interlace with one another in a glass phase. The glass ceramic is non-porous and has an increased mechanical strength of 2,000 Kg?f/cm2 without degradation of the chemical bonding with the bone of the living body. The glass ceramic contains no alkali and is chemically stable in the living body. The glass ceramic is useful for replacement materials of tooth roots and crowns as well as bones.
Description
~'~668~;13 NO ALKALI CONTAINING BIOCOMPATIBLE
GLASS CERAMIC ~ITH APATITE, WOLLASTONITE
AND DIOPSIDE CRYSTALS MIXED
Background of the Invention 1) Field of the Invention The present invention relates to crystallized glass or glass ceramics, and, in particular, to 5 biocompatible glass ceramics which are useful for artificial dental roots, artificial tooth crowns and others.
GLASS CERAMIC ~ITH APATITE, WOLLASTONITE
AND DIOPSIDE CRYSTALS MIXED
Background of the Invention 1) Field of the Invention The present invention relates to crystallized glass or glass ceramics, and, in particular, to 5 biocompatible glass ceramics which are useful for artificial dental roots, artificial tooth crowns and others.
2) Description of the Prior Art It is needless to say that the biocompatible 10 materials useful, for example, for tooth replacement materials, are required not to be harmful for living bodies such as human bodies and animal bodies. Among the other various requirements for those biocompatible materialR, a high mechanical strength and an excellent 15 biological affinity are also important.
Although alumina and sintered apatite are well known as typical and conventional biocompatible ; materials in the prior art, they have disadvantages.
Alumina cannot be chemically bonded to bones and teeth 20 of the living body, and therefore, any means is required to fixedly connect alumina to the living body. Sintered
Although alumina and sintered apatite are well known as typical and conventional biocompatible ; materials in the prior art, they have disadvantages.
Alumina cannot be chemically bonded to bones and teeth 20 of the living body, and therefore, any means is required to fixedly connect alumina to the living body. Sintered
3~
, 12~ 368 apatite has not a sufficient mechanical strength as replacements of the bones and the teeth.
In order to reduce the above-described disadvantages of alumina and sintered apatite, glass 5 ceramics are used for biocompatible materials in the prior art. U.S. patent No. 3,922,155 by Broemer assigned to ~rnst Leitz G.m.b.H. discloses a Na2O - K2O
- MgO - CaO - SiO2 - P2O3 glass ceramic as a bone replacement material. The glass ceramic includes 10 apatite crystals and has a good biological affinity.
However, since the glass ceramic contains Na2O and K2O, it is insufficient in the mechanical strength and has a low chemical resistance so that it is not maintained stable in the living body for a long time.
Also, MgO - CaO - SiO2 - P2O5 glass ceramics are disclosed for biocompatible materials in U.S. patent No.
, 12~ 368 apatite has not a sufficient mechanical strength as replacements of the bones and the teeth.
In order to reduce the above-described disadvantages of alumina and sintered apatite, glass 5 ceramics are used for biocompatible materials in the prior art. U.S. patent No. 3,922,155 by Broemer assigned to ~rnst Leitz G.m.b.H. discloses a Na2O - K2O
- MgO - CaO - SiO2 - P2O3 glass ceramic as a bone replacement material. The glass ceramic includes 10 apatite crystals and has a good biological affinity.
However, since the glass ceramic contains Na2O and K2O, it is insufficient in the mechanical strength and has a low chemical resistance so that it is not maintained stable in the living body for a long time.
Also, MgO - CaO - SiO2 - P2O5 glass ceramics are disclosed for biocompatible materials in U.S. patent No.
4,560,666 by Yoshida et al assigned to Hoya Corporation and Japanese patent application laid open with No.
191252/'82. The glass ceramics contain SiO2 which is 20 restricted to 41wt~ or less in amount so as to increase apatite crystals dispersed therein, so that the glass ceramics are excellent in chemical bonding with bone.
However, the glass ceramics are insufficient in the mechanical strength.
Japanese patent application laid open with No.
158841/'86 discloses another glass ceramic useful for a bone replacement material. The glass ceramic is a porous CaO - P2O5 - SiO2 glass ceramic having apatite crystals and diopside and/or wollastonite crystals. The glass ceramic is also insufficient in the mechanical strength.
Summary of the Invention It is an object of the present invention to provide a glass ceramic, as a biocompatible material, which has an improved excellent mechanical strength but with a good biological affinity similar to the Xnown glass ceramics in the prior art.
According to the present invention, a high-strength and no alkali containing biocompatible glass ceramic is obtained which has a composition consisting essentially, by weight, of 7 - 16% MgO, 20 -45% CaO, 41 - 50% SiO2, 8 - 30~ P2O5, 0 - 5% B2O3, 0 -15 5% F2, and 0 - 10% A12O3. A total content of MgO, CaO, SiO2 and P2O5 is 90~ or more. The glass ceramic is`
substantially non-porous and has a mechanical strength of 2,000 Xg f/cm2 or more and a crystal structure where a number of fine crystals are densely dispersed in a 20 glass phase.
A method for producinq a no alkali containing biocompatible glass ceramic according to the present invention comprises steps of; preparing a glass powder having a particle size of 200 mesh or less and having a 25 composition which consists essentially, by weight, of 7 - 16% MgO, 20 - 45% CaO, 41 - 50% SiO2, 8 - 30% P2O5, 0
191252/'82. The glass ceramics contain SiO2 which is 20 restricted to 41wt~ or less in amount so as to increase apatite crystals dispersed therein, so that the glass ceramics are excellent in chemical bonding with bone.
However, the glass ceramics are insufficient in the mechanical strength.
Japanese patent application laid open with No.
158841/'86 discloses another glass ceramic useful for a bone replacement material. The glass ceramic is a porous CaO - P2O5 - SiO2 glass ceramic having apatite crystals and diopside and/or wollastonite crystals. The glass ceramic is also insufficient in the mechanical strength.
Summary of the Invention It is an object of the present invention to provide a glass ceramic, as a biocompatible material, which has an improved excellent mechanical strength but with a good biological affinity similar to the Xnown glass ceramics in the prior art.
According to the present invention, a high-strength and no alkali containing biocompatible glass ceramic is obtained which has a composition consisting essentially, by weight, of 7 - 16% MgO, 20 -45% CaO, 41 - 50% SiO2, 8 - 30~ P2O5, 0 - 5% B2O3, 0 -15 5% F2, and 0 - 10% A12O3. A total content of MgO, CaO, SiO2 and P2O5 is 90~ or more. The glass ceramic is`
substantially non-porous and has a mechanical strength of 2,000 Xg f/cm2 or more and a crystal structure where a number of fine crystals are densely dispersed in a 20 glass phase.
A method for producinq a no alkali containing biocompatible glass ceramic according to the present invention comprises steps of; preparing a glass powder having a particle size of 200 mesh or less and having a 25 composition which consists essentially, by weight, of 7 - 16% MgO, 20 - 45% CaO, 41 - 50% SiO2, 8 - 30% P2O5, 0
- 5% Bz03, 0 - 5% F2, and 0 - 10% A12O3; press-forming the glass powder into a compact body of a predetermined ;lZ66;~368 shape; heating the compact body to obtain a sintered body at a temperature within a glass powder sintering temperature range; and heat-treating the sintered body at a temperature within a crystallizing temperature 5 range.
Preferably, the glass ceramic composition consists essentially, by weight, of 7.2 - 14% MgO, 25 -38% Cao, 41.5 - 50% SiO2, 8.2 - 25% P205, 0 - 4% B203, O - 3% F2, and 0 - 6% A12O3.
In the glass ceramic composition, a total content of B2O3 and F2 is preferably 0.05 - 5%.
Detailed Descri tion of the Invention p In the glass ceramic according to the present invention, the fine and dense crystals comprises apatite 15 crystals, wollastonite crystals, and diopside crystals which extend in respective particles of the powder inwardly from their outer surfaces and interlace in a complicated structure. The fine and dense crystals enhance the mechanical strength and the mechanical 20 machinability of the glass ceramic, so that the glass ceramic can be easily machined into a desired shape without any crack and chipping of the ceramic.
The wollastonite and diopside crystals serve to increase the mechanical strength of the glass ceramic.
25 The apatite crystals serve to make a good chemical bonding of the glass ceramic and the bone of the living body and enhance the biological affinity of the glass ceramic, as known in the prior art.
.
1~6~86~
Descriptioll will be made bel~w as to the reason why the amount of each component of the glass ceramic of the present invention is limited to the above-described range.
If MgO content is less than 7%, a resultant glass composition is devitrifiable so that the glass powder cannot hardly be prepared from a melt of the mixed raw materials. Further, an undesired small amount of the diopside crystals are only precipitated at 10 the crystallizing temperature heat treatment.
Therefore, the amount of MgO is 7% at minimum, or preferably 7.2% or more. The use of MgO more than 14%
decreases an amount of apatite crystals formed in the glass phase. Therefore, MgO content is 16% at maximum, 15 or preferably 14% or less.
When Cao amount is less than 25%, amounts of apatite and wollastonite crystals decrease. Therefore, CaO content must be preferably 25% or more, or 20% at minimum. If CaO content is more than 38%, a resultant 20 glass composition is devitrifiable so that the glass powder cannot hardly be prepared from a melt of the mixed raw materials. Therefore, CaO content is preferably 38% or less and is 45% at maximum.
When SiO2 content is less than 41%, amounts of 25 diopside and wollastonite cr~stals are reduced.
Therefore, SiO2 content is 41% at minimum and is preferably 41.5% or more. The use of SiO2 more than 50%
- increases viscosity of a melt of the resultant glass ~`
.
.
i2f~6~8 composition so that preparation of the glass powder is difficult. Further, a reduced amount of apatite crystals are only precipitated. Therefore, the amount of SiO2 must be 50% or less.
Considering that those glass ceramics in the above-described U.S. patent No. 4,560,666 and Japanese patent application No. 191252/'82 contain SiO2 which is restricted to 41wt~ or less to obtain an excellent chemical bonding with the bone, it is predicted that the 10 glass ceramic of the present invention has a reduced apatite and cannot be sufficiently chemically bonded to the bone because the SiO2 content is 41% or more.
However, as will be noted from examples which are demonstrated hereinafter, the glass ceramic of the 15 present invention has an astonished high mechanical strength without reduction of the chemical bonding strength with the bone in comparison with the known glass ceramic containing the SiO2 of 41% or less.
When P2O5 content is less than 8%, a resultant 20 glass composition has an increased devitrification so that the glass powder cannot be obtained. Further, an insufficient amount of apatite crystals can only be precipitated in the glass. Therefore, the content of P2O5 is 8% at minimum and preferably 8.2% or more. When 25 the amount exceeds 25~, the precipitated wollastonite crystals decrease in amount. Therefore, P2O5 content is preferably 25% or less and 30~ at maximum. Considering '~
' the mechanical strength of the resultant glass ceramic, it is recommended that P2O5 content is 10% or less.
B2O3, F2, and A12O3 are optional elements, and B2O3 and F2 are used for stably precipitating the 5 apatite crystals in the glass ceramic.
When the content of B2O3 exceeds 5%, it takes a long time period until the resultant glass ceramic forms a chemical bonding with the bone. Therefore, the content is limited up to 5% and preferably 4% or less.
When F2 is used more than 5%, a resultant glass composition has a high crystallization rate and is degraded for sintering. Therefore, the content is 5% at maximum and preferably 3% or less.
In order to form the apatite crystals reliably, 15 it is desired to use at least one of B2O3 and F2 by 0.05% or more. However, when the total content exceeds 5~, a resultant glass is apt to phase-separate and has a difficulty for glass shaping.
When A12O3 is more than 10%, a resultant glass 20 ceramic has a reduced biological affinity and cannot make the chemical bonding with the bone.
In a method for producing the glass ceramic of the present invention, the heat treatment at a temperature within the glass powder sintering 25 temperature range is important to obtain the glass ceramic which is substantially non-porous and has a high ; mechanical strength. While, the other heat treatment at a temperature within the crystallizins temperature range is important for precipitating a number of fine and dense crystals, that is, apatite, wollastonite, and diopside crystals in the glass.
The preparation of glass powder having particle 5 size of 200 mesh or less is important to obtain the glass ceramic by the heat treatments which is substantially non-porous and has a crystal structure wherein the apatite, wollastonite, and diopside crystals are fine and uniformly dispersed and interlace to one 10 another. If a glass body having a desired shape is formed directly from a molten glass without forming the glass powder and if the glass body is heat-treated for crystallization, the wollastonite and diopside crystals precipitate in only the surface of the glass body and 15 cracks or cavities are formed in the body, so that the resultant glass ceramic is low in the mechanical strength.
The term of "glass powder sintering temperature range" means a temperature range from a thermal 20 contraction starting temperature to a thermal contraction finishing temperature. The glass powder sintering temperature range is determined by observing the thermal contraction of the glass powder heated at a constant temperature elevating rate.
The term of "crystallizing temperature range"
means a temperature range from a temperature at which exothermic crystal precipitation is started to a temperature at which the exothermic crystal .~
126i6~
precipitation is finished. The crystallizing temperature range is determined by performing the differential thermal analysis of the glass powder heated at a constant temperature elevating rate.
Examples Table 1 demonstrates ingredients of various glass ceramics according to the present invention and their bending strength.
Each sample was produced as follows.
A glass batch comprising ingredients for each sample was prepared using oxides, carbonates, phosphates, fluorides and the like. The glass batch was inserted in a platinum crucible and was melted in an electric furnace at 1400 - 1500C for 4 hours. Then, 15 the molten glass was flowed between rolls cooled by water to form a glass ribbon. The ribbon was crushed down or milled to form a glass powder having particle size of 200 mesh or less. The powder was pressed to a compact body having a desired shape by use of a 20 hydraulic press. The compact body was heated in an electric furnace from the room temperature to an elevated temperature of 1050C at a temperature elevating rate o~ 30 - 60C/hour and was kept at 1050C
for 2 - 10 hours for sintering and crystallizing the 25 body. Then, the body was cooled to the room temperature at a rate of 30 - 120C/hour, and a glass ceramic was obtained.
36~
Each of the glass ceramic samples as thus produced had a number of apatite, wollastonite, and diopside crystals and a fine structure where those crystals int~rlace with one another and were dispersed 5 in the glass phase.
The porosity of each sample is only 0.3% or less and, therefore, the glass ceramic samples are substantially non-porous.
Further, each sample has a mechanical strength 10 (bending strength) of 2,000 Kg-ftcm2 or more which is quite high in comparison with any known glass ceramics.
The mechanical strength was measured as to a rod of 5 x 5 x 20mm of each glass ceramic sample by the three-point loading test.
Those samples have excellent biological affinity and make sufficient chemical bonding with bone similar to the known biocompatible glass ceramics.
A bonding strength to the bone was measured with respect to 10 x 10 x 2 mm size plate specimens of No. 6 20 sample in Table 1, a polycrystalline alumina, a sintered apatite, and a glass ceramic disclosed in the above-described Japanese patent application No. 191252/'82.
The measurement was carried out by inserting each plate specimen into a tibia condyle of a mature rabbit.
25 After 8 weeks, the plate specimen was extracted together with bone surrounding the plate specimen and it was pulled apart from the bone. A force required to f' pull the plate specimen apart from the bone was appreciated as the bonding strength.
Table 1 Samples _ _ In=~ 1 2 3 4 5 6 7 8 9 _ _ _ _ _ O (wt%) 13 7 5 8 11 14 11.2 13.0 12.9 9.7 CaO (wt%) 36 37.532.5 25 3035 33.4 25 5 28.5 SiO2 (wt%) 41 5 41.5 44.5 41.5 43 43.5 44.0 47.0 47.3 P2O5 (wt%) 8 5 9.5 14.0 21 5 12 4 8 2 9 2 12 6 13.0 B2O3 (wt%) 1.0 4.01.0 1.0 0.6 0.1 0.4 2.0 1.0 F2 (wt% ) = = = = = = = = =
A12O3 ~wt%) 2.0 0.5 Bending _ _ Strength 2300 22002200 2250 2200 2300 23002100 2000 (kg~ f/cm2) Sanples =
~ 10 11 12 13 14 15 16 17 Ingredients . _ _ _ _ O (wt%) 11 5 12.5 13 11.5 12.3 9 5 12.5 11.0 _ CaO (wt%) 30 0 33 5 31 4 27 0 25.1 25.034 3 35.0 SiO2 (wt%) 47.5 44.0 43.2 44.0 46.5 41.544.0 43.0 . _ _ _ P2O5 (wt%) 10.0 9.2 12.2 9.0 13.1 20.0 9.2 9.9 _ . _ _ B2O3 (wt% ) ~ 2.0 l F2 (wt% ) 1.0 0.8 0 2 2.5 1.0 1 5 1.1 A12O3 (wt%) -- 6 0 2.5 _ Bending Strength2200 2250 2250 2100 2200 2200 2300 2300 (kg f/cm2) - _ _ _ The measured bonding strength is shown in Table 2. It is noted from Table 2 that the specimen of No. 6 sample according to the present invention has a bonding strength which is equal to the specimen of the glass ceramic disclosed in Japanese patent application No.
191252/'82 but is higher than the polycrystalline alumina and the sintered apatite.
Table 2 Specimen by Specimen of Sintered Polycrystal-Specimens JPN PAT APPLN No. 6 of this apatite line alumina 191252/'82 invention _ p~nt of apatite in 35% 15 100 0 specimen . . . ... ... ...
. . _ Ingredients SiO2106 02wt% 44 2 CaO 47.7 34.3 ~0 6.1 12.5 Bending Strength21400 2300 lloo 4000 (kg~f/cm ) . . . . . .
Bending Strength . 6 0.2 Further, Table 2 teaches that the specimen according to the present invention has a high mechanical strength which is lower than the alumina specimen but is twice the other two specimens.
~Q~
Preferably, the glass ceramic composition consists essentially, by weight, of 7.2 - 14% MgO, 25 -38% Cao, 41.5 - 50% SiO2, 8.2 - 25% P205, 0 - 4% B203, O - 3% F2, and 0 - 6% A12O3.
In the glass ceramic composition, a total content of B2O3 and F2 is preferably 0.05 - 5%.
Detailed Descri tion of the Invention p In the glass ceramic according to the present invention, the fine and dense crystals comprises apatite 15 crystals, wollastonite crystals, and diopside crystals which extend in respective particles of the powder inwardly from their outer surfaces and interlace in a complicated structure. The fine and dense crystals enhance the mechanical strength and the mechanical 20 machinability of the glass ceramic, so that the glass ceramic can be easily machined into a desired shape without any crack and chipping of the ceramic.
The wollastonite and diopside crystals serve to increase the mechanical strength of the glass ceramic.
25 The apatite crystals serve to make a good chemical bonding of the glass ceramic and the bone of the living body and enhance the biological affinity of the glass ceramic, as known in the prior art.
.
1~6~86~
Descriptioll will be made bel~w as to the reason why the amount of each component of the glass ceramic of the present invention is limited to the above-described range.
If MgO content is less than 7%, a resultant glass composition is devitrifiable so that the glass powder cannot hardly be prepared from a melt of the mixed raw materials. Further, an undesired small amount of the diopside crystals are only precipitated at 10 the crystallizing temperature heat treatment.
Therefore, the amount of MgO is 7% at minimum, or preferably 7.2% or more. The use of MgO more than 14%
decreases an amount of apatite crystals formed in the glass phase. Therefore, MgO content is 16% at maximum, 15 or preferably 14% or less.
When Cao amount is less than 25%, amounts of apatite and wollastonite crystals decrease. Therefore, CaO content must be preferably 25% or more, or 20% at minimum. If CaO content is more than 38%, a resultant 20 glass composition is devitrifiable so that the glass powder cannot hardly be prepared from a melt of the mixed raw materials. Therefore, CaO content is preferably 38% or less and is 45% at maximum.
When SiO2 content is less than 41%, amounts of 25 diopside and wollastonite cr~stals are reduced.
Therefore, SiO2 content is 41% at minimum and is preferably 41.5% or more. The use of SiO2 more than 50%
- increases viscosity of a melt of the resultant glass ~`
.
.
i2f~6~8 composition so that preparation of the glass powder is difficult. Further, a reduced amount of apatite crystals are only precipitated. Therefore, the amount of SiO2 must be 50% or less.
Considering that those glass ceramics in the above-described U.S. patent No. 4,560,666 and Japanese patent application No. 191252/'82 contain SiO2 which is restricted to 41wt~ or less to obtain an excellent chemical bonding with the bone, it is predicted that the 10 glass ceramic of the present invention has a reduced apatite and cannot be sufficiently chemically bonded to the bone because the SiO2 content is 41% or more.
However, as will be noted from examples which are demonstrated hereinafter, the glass ceramic of the 15 present invention has an astonished high mechanical strength without reduction of the chemical bonding strength with the bone in comparison with the known glass ceramic containing the SiO2 of 41% or less.
When P2O5 content is less than 8%, a resultant 20 glass composition has an increased devitrification so that the glass powder cannot be obtained. Further, an insufficient amount of apatite crystals can only be precipitated in the glass. Therefore, the content of P2O5 is 8% at minimum and preferably 8.2% or more. When 25 the amount exceeds 25~, the precipitated wollastonite crystals decrease in amount. Therefore, P2O5 content is preferably 25% or less and 30~ at maximum. Considering '~
' the mechanical strength of the resultant glass ceramic, it is recommended that P2O5 content is 10% or less.
B2O3, F2, and A12O3 are optional elements, and B2O3 and F2 are used for stably precipitating the 5 apatite crystals in the glass ceramic.
When the content of B2O3 exceeds 5%, it takes a long time period until the resultant glass ceramic forms a chemical bonding with the bone. Therefore, the content is limited up to 5% and preferably 4% or less.
When F2 is used more than 5%, a resultant glass composition has a high crystallization rate and is degraded for sintering. Therefore, the content is 5% at maximum and preferably 3% or less.
In order to form the apatite crystals reliably, 15 it is desired to use at least one of B2O3 and F2 by 0.05% or more. However, when the total content exceeds 5~, a resultant glass is apt to phase-separate and has a difficulty for glass shaping.
When A12O3 is more than 10%, a resultant glass 20 ceramic has a reduced biological affinity and cannot make the chemical bonding with the bone.
In a method for producing the glass ceramic of the present invention, the heat treatment at a temperature within the glass powder sintering 25 temperature range is important to obtain the glass ceramic which is substantially non-porous and has a high ; mechanical strength. While, the other heat treatment at a temperature within the crystallizins temperature range is important for precipitating a number of fine and dense crystals, that is, apatite, wollastonite, and diopside crystals in the glass.
The preparation of glass powder having particle 5 size of 200 mesh or less is important to obtain the glass ceramic by the heat treatments which is substantially non-porous and has a crystal structure wherein the apatite, wollastonite, and diopside crystals are fine and uniformly dispersed and interlace to one 10 another. If a glass body having a desired shape is formed directly from a molten glass without forming the glass powder and if the glass body is heat-treated for crystallization, the wollastonite and diopside crystals precipitate in only the surface of the glass body and 15 cracks or cavities are formed in the body, so that the resultant glass ceramic is low in the mechanical strength.
The term of "glass powder sintering temperature range" means a temperature range from a thermal 20 contraction starting temperature to a thermal contraction finishing temperature. The glass powder sintering temperature range is determined by observing the thermal contraction of the glass powder heated at a constant temperature elevating rate.
The term of "crystallizing temperature range"
means a temperature range from a temperature at which exothermic crystal precipitation is started to a temperature at which the exothermic crystal .~
126i6~
precipitation is finished. The crystallizing temperature range is determined by performing the differential thermal analysis of the glass powder heated at a constant temperature elevating rate.
Examples Table 1 demonstrates ingredients of various glass ceramics according to the present invention and their bending strength.
Each sample was produced as follows.
A glass batch comprising ingredients for each sample was prepared using oxides, carbonates, phosphates, fluorides and the like. The glass batch was inserted in a platinum crucible and was melted in an electric furnace at 1400 - 1500C for 4 hours. Then, 15 the molten glass was flowed between rolls cooled by water to form a glass ribbon. The ribbon was crushed down or milled to form a glass powder having particle size of 200 mesh or less. The powder was pressed to a compact body having a desired shape by use of a 20 hydraulic press. The compact body was heated in an electric furnace from the room temperature to an elevated temperature of 1050C at a temperature elevating rate o~ 30 - 60C/hour and was kept at 1050C
for 2 - 10 hours for sintering and crystallizing the 25 body. Then, the body was cooled to the room temperature at a rate of 30 - 120C/hour, and a glass ceramic was obtained.
36~
Each of the glass ceramic samples as thus produced had a number of apatite, wollastonite, and diopside crystals and a fine structure where those crystals int~rlace with one another and were dispersed 5 in the glass phase.
The porosity of each sample is only 0.3% or less and, therefore, the glass ceramic samples are substantially non-porous.
Further, each sample has a mechanical strength 10 (bending strength) of 2,000 Kg-ftcm2 or more which is quite high in comparison with any known glass ceramics.
The mechanical strength was measured as to a rod of 5 x 5 x 20mm of each glass ceramic sample by the three-point loading test.
Those samples have excellent biological affinity and make sufficient chemical bonding with bone similar to the known biocompatible glass ceramics.
A bonding strength to the bone was measured with respect to 10 x 10 x 2 mm size plate specimens of No. 6 20 sample in Table 1, a polycrystalline alumina, a sintered apatite, and a glass ceramic disclosed in the above-described Japanese patent application No. 191252/'82.
The measurement was carried out by inserting each plate specimen into a tibia condyle of a mature rabbit.
25 After 8 weeks, the plate specimen was extracted together with bone surrounding the plate specimen and it was pulled apart from the bone. A force required to f' pull the plate specimen apart from the bone was appreciated as the bonding strength.
Table 1 Samples _ _ In=~ 1 2 3 4 5 6 7 8 9 _ _ _ _ _ O (wt%) 13 7 5 8 11 14 11.2 13.0 12.9 9.7 CaO (wt%) 36 37.532.5 25 3035 33.4 25 5 28.5 SiO2 (wt%) 41 5 41.5 44.5 41.5 43 43.5 44.0 47.0 47.3 P2O5 (wt%) 8 5 9.5 14.0 21 5 12 4 8 2 9 2 12 6 13.0 B2O3 (wt%) 1.0 4.01.0 1.0 0.6 0.1 0.4 2.0 1.0 F2 (wt% ) = = = = = = = = =
A12O3 ~wt%) 2.0 0.5 Bending _ _ Strength 2300 22002200 2250 2200 2300 23002100 2000 (kg~ f/cm2) Sanples =
~ 10 11 12 13 14 15 16 17 Ingredients . _ _ _ _ O (wt%) 11 5 12.5 13 11.5 12.3 9 5 12.5 11.0 _ CaO (wt%) 30 0 33 5 31 4 27 0 25.1 25.034 3 35.0 SiO2 (wt%) 47.5 44.0 43.2 44.0 46.5 41.544.0 43.0 . _ _ _ P2O5 (wt%) 10.0 9.2 12.2 9.0 13.1 20.0 9.2 9.9 _ . _ _ B2O3 (wt% ) ~ 2.0 l F2 (wt% ) 1.0 0.8 0 2 2.5 1.0 1 5 1.1 A12O3 (wt%) -- 6 0 2.5 _ Bending Strength2200 2250 2250 2100 2200 2200 2300 2300 (kg f/cm2) - _ _ _ The measured bonding strength is shown in Table 2. It is noted from Table 2 that the specimen of No. 6 sample according to the present invention has a bonding strength which is equal to the specimen of the glass ceramic disclosed in Japanese patent application No.
191252/'82 but is higher than the polycrystalline alumina and the sintered apatite.
Table 2 Specimen by Specimen of Sintered Polycrystal-Specimens JPN PAT APPLN No. 6 of this apatite line alumina 191252/'82 invention _ p~nt of apatite in 35% 15 100 0 specimen . . . ... ... ...
. . _ Ingredients SiO2106 02wt% 44 2 CaO 47.7 34.3 ~0 6.1 12.5 Bending Strength21400 2300 lloo 4000 (kg~f/cm ) . . . . . .
Bending Strength . 6 0.2 Further, Table 2 teaches that the specimen according to the present invention has a high mechanical strength which is lower than the alumina specimen but is twice the other two specimens.
~Q~
Claims (5)
1 A high-strength and no alkali containing biocompatible glass ceramic having a composition consisting essentially, by weight, of 7 - 16% MgO, 20 -45% CaO, 41 - 50% SiO2, 8 - 30% P2O5, 0 - 5% B2O3, 0 -5% F2, and 0 - 10% Al2O3, a total content of MgO, CaO, SiO2, and P2O5 being 90% or more, said glass ceramic being substantially non-porous and having a mechanical strength of 2,000 Kg?f/cm2 or more and a crystal structure where a number of fine crystals are densely dispersed in a glass phase.
2. A biocompatible glass ceramic as claimed in Claim 1, wherein said crystal structure comprises apatite, wollastonite, and diopside crystals extending to interlace with one another in a complicated form.
3. A biocompatible glass ceramic as claimed in Claim 1, having a composition which consists essentially, by weight, of 7.2 - 14% MgO, 25 - 38% CaO, 41.5 - 50% SiO2, 8.2 - 25% P2O5, 0 - 4% B2O3, 0 - 3% F2, and 0 - 6% Al2O3.
4. A biocompatible glass ceramic as claimed in one of Claims 1 and 2, wherein a total content of B2O3 and F2 is 0.05 - 5%.
5. A method for producing a high strength no alkali containing biocompatible glass ceramic comprising steps of;
(Claim 5 continued) preparing a glass powder having a particle size of 200 mesh or less and having composition which consists essentially, by weight, of 7 - 16% MgO, 20 -45% CaO, 41 - 50% SiO2, 8 - 30% P2O5, 0 - 5% B2O3, 0 -5% F2, and 0 - 10% Al2O3;
press-forming said glass powder into a compact body of a predetermined shape;
heating said compact body to obtain a sintered body at a temperature in a glass powder sintering temperature range; and heat-treating said sintered body at a temperature in a crystallizing temperature range.
(Claim 5 continued) preparing a glass powder having a particle size of 200 mesh or less and having composition which consists essentially, by weight, of 7 - 16% MgO, 20 -45% CaO, 41 - 50% SiO2, 8 - 30% P2O5, 0 - 5% B2O3, 0 -5% F2, and 0 - 10% Al2O3;
press-forming said glass powder into a compact body of a predetermined shape;
heating said compact body to obtain a sintered body at a temperature in a glass powder sintering temperature range; and heat-treating said sintered body at a temperature in a crystallizing temperature range.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000533149A CA1266868A (en) | 1987-03-27 | 1987-03-27 | No alkali containing biocompatible glass ceramic with apatite, wollastonite and diopside crystals mixed |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000533149A CA1266868A (en) | 1987-03-27 | 1987-03-27 | No alkali containing biocompatible glass ceramic with apatite, wollastonite and diopside crystals mixed |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1266868A true CA1266868A (en) | 1990-03-20 |
Family
ID=4135299
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000533149A Expired - Fee Related CA1266868A (en) | 1987-03-27 | 1987-03-27 | No alkali containing biocompatible glass ceramic with apatite, wollastonite and diopside crystals mixed |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1266868A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11236012B2 (en) | 2018-03-28 | 2022-02-01 | Corning Incorporated | Boron phosphate glass-ceramics with low dielectric loss |
-
1987
- 1987-03-27 CA CA000533149A patent/CA1266868A/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11236012B2 (en) | 2018-03-28 | 2022-02-01 | Corning Incorporated | Boron phosphate glass-ceramics with low dielectric loss |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4783429A (en) | No alkali containing biocompatible glass ceramic with apatite, wollastonite and diopside crystals mixed | |
| US3922155A (en) | Process of making biocompatible glass ceramic | |
| US4560666A (en) | High strength glass-ceramic containing apatite and alkaline earth metal silicate crystals and process for producing the same | |
| US4652534A (en) | High-strength glass ceramic containing apatite crystals and a large quantity of wollastonite crystals and process for producing same | |
| US4643982A (en) | High-strength glass-ceramic containing anorthite crystals and process for producing the same | |
| US4960733A (en) | Inorganic biomaterial and process for producing the same | |
| EP0641556A1 (en) | Canasite-apatite glass-ceramics | |
| GB2390848A (en) | Calcium silicate-based bioactive glass and sintered calcium phosphate glass containing it as sintering aid | |
| JP4477377B2 (en) | Bioactive rennite glass ceramic | |
| JPS6210939B2 (en) | ||
| GB2178422A (en) | Prosthesis | |
| JPH0436107B2 (en) | ||
| CA1266868A (en) | No alkali containing biocompatible glass ceramic with apatite, wollastonite and diopside crystals mixed | |
| JPS62231668A (en) | Inorganic bio-material and its production | |
| JPS62128947A (en) | Cao-al2o3-p2o5 crystallized glass | |
| KR920000150B1 (en) | Crystalized glass for human body and preparation method | |
| JPS62187142A (en) | Composite material for organism | |
| JPH0249260B2 (en) | ||
| JPS60137853A (en) | High-strength crystallized glass containing apatite crystal and its production | |
| KR940003461B1 (en) | Method for glass ceramic withused living body material | |
| JPH0191865A (en) | Inorganic biomaterial and its manufacture | |
| JPH01115360A (en) | Inorganic living body material and preparation thereof | |
| JPH0247417B2 (en) | ||
| JPS6382670A (en) | Inorganic vital material | |
| JPS62268561A (en) | Composite material for living body |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |