JP2000254220A - Organism active cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organism active cement composition having a mechanical strength. SOLUTION: This organism active cement comprises an organism active filler powder, a methacrylate type polymer powder, a methacrylate type monomer, a polymerization initiator and a polymerization accelerator. The organism active filler powder is spherical and a weight average molecular weight of the methacrylate type polymer powder is 150,000 or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bioactivity used for adhesive fixation of implant materials used in the fields of orthopedics and oral surgery, filling of bone defects, reconstruction of cranial defects in neurosurgery, and the like. The present invention relates to a cement composition.

[0002]

2. Description of the Related Art Conventionally, natural bone is used as a cement material for adhesive fixation of implant materials and filling of bone defects and reconstruction of cranial defects in the field of neurosurgery, which are used in the fields of orthopedics and oral surgery. Bioactive cements have been proposed that combine directly with the cement. For example, a cement in which a bioactive filler powder (apatite, Ca-containing glass, etc.) is added to PMMA cement has been proposed.

[0003]

When the above bioactive cement is cured in a living body, Ca ions are eluted from the filler powder exposed on the surface of the cured product, and react with the body fluid to form an apatite layer on the surface of the cured product. As a result, it can be chemically bonded to natural bone.

[0004] Incidentally, it is known that PMMA cement generally has not so high mechanical strength. Although the mechanical strength of the bioactive cement is slightly improved by the addition of the bioactive filler powder, it is still insufficient, and further improvement is required.

It is an object of the present invention to provide a bioactive cement composition having high mechanical strength.

[0006]

The present inventors have conducted various studies. As a result, the bioactive cement using PMMA cement has been found to be more suitable as the shape of the bioactive filler powder is closer to a true sphere and the methacrylate-based polymer powder is obtained. It has been found that the larger the molecular weight of the polymer, the higher the mechanical strength, and this is proposed as the present invention.

That is, the bioactive cement composition of the present invention comprises a bioactive filler comprising a bioactive filler powder, a methacrylate polymer powder, a methacrylate monomer, a polymerization initiator, and a polymerization accelerator. The powder is spherical, and the weight average molecular weight of the methacrylate polymer powder is 150,000 or more.

[0008]

The bioactive cement composition of the present invention can achieve extremely high mechanical strength by using a spherical bioactive filler powder and a methacrylate polymer powder having a weight average molecular weight of 150,000 or more.

The bioactive filler used in the present invention
Powder chemically bonds with natural bone when implanted in vivo
It has the characteristic that cement
The cured body can be combined with natural bone. With bioactive filler powder
And hydroxyapatite, tertiary calcium phosphate
Calcium phosphate compounds such as_Two−
P_Two O_Five-MgO-CaF_TwoSystem containing Ca or glass
Crystallized glass can be used. In particular, CaO 30% by weight
70%, SiO_Two 30-70%, P_Two O_Five 0-40%,
MgO 0-20%, CaF_Two 0-5%, preferably C
aO 40-50%, SiO_Two 30-40%, P_Two O_Five 
10-20%, MgO 0.5-10%, CaF_Two 0 to
CaO-SiO having a composition of 2%_Two−P_Two O_Five-MgO
-CaF _TwoSystem glass or crystallized glass can be used
desirable. Glass is more bioactive than crystallized glass.
If you want to obtain higher biological activity,
You just have to select the lath.

[0010] As the bioactive filler powder, a powder having a spherical shape having a large effect of increasing the mechanical strength of the hardened cement is used. The form of the filler powder is preferably higher as the shape closer to a true sphere is more effective in improving the mechanical strength,
The shape may be a rounded shape having almost no sharp corners such as an elliptical sphere, a spindle shape, a gourd shape, or the surface may have some irregularities. To obtain a spherical filler powder, for example, a glass (or crystallized glass) powder may be supplied to a high-temperature flame, re-melted, and then rapidly cooled. In such filler powder, cracks in particles generated by pulverization and the like disappear when remelted, and have a smooth fired surface, so that the mechanical strength of the particles themselves is high, and the mechanical strength of the cement hardened body is increased. Can be improved. Moreover, it shows good fluidity, and has good compatibility with monomers.

The content of the bioactive filler powder is 10
Preferably it is ~ 80% by weight. When the content of the bioactive filler powder is less than 10% by weight, the bioactivity becomes insufficient. When the content exceeds 80% by weight, the operability of the cement is deteriorated, and the monomer is hardly polymerized, and the mechanical strength is reduced. In addition, if silane coupling treatment is performed, familiarity with the methacrylate monomer is improved, and the strength of the cured cement body is increased.In addition, since the powder surface has a hydrophobic group, blood inhibition is lost, and the cement hardens. It will be easier. The silane coupling treatment is preferably performed in a weak acid to neutral range (about pH 5 to 8).

The methacrylate polymer powder used in the present invention is a component necessary for the polymerization of the methacrylate monomer, and swells and dissolves with the monomer.
It works effectively to form a cured body. Examples of the polymer powder include polymethyl methacrylate (PMMA) powder, methacrylate and styrene copolymer powder, and methacrylate and 2,2-bis [4- (3 methacryloxy-2-hydroxypropoxy) phenyl] propane (Bis-G).
MA) or the like.

[0013] The higher the molecular weight of the polymer powder, the higher the strength of the resin itself. Moreover, it is considered that the dissolution in the monomer during the polymerization of the cement is stopped only on the surface, and most of the core remains in the cured product and acts as a filler, contributing to the improvement of mechanical strength. Therefore, a methacrylate-based polymer powder having a weight average molecular weight of 150,000 or more is used. When a polymer having a weight-average molecular weight of less than 150,000 is used, the strength of the resin itself is reduced, and the resin is almost dissolved during polymerization, so that a sufficiently high mechanical strength cannot be obtained. The larger the weight average molecular weight of the polymer powder is, the more preferable it is. However, if the polymer exceeds 1.5 million, it is difficult to swell and dissolve, and the operability is deteriorated. The preferred range of the weight average molecular weight of the methacrylate polymer powder is from 200,000 to 1.3 million.

The shape of the methacrylate-based polymer powder is not limited, but it is desirable to use a hardened cement having a spherical shape which has the effect of increasing the mechanical strength. The average particle size is 1 to 500 μm, especially 1 to 1 μm.
It is preferably in the range of 00 μm. Average particle size is 1
If it is smaller than μm, the viscosity of the cement becomes too high, making it difficult to operate, and if it exceeds 500 μm, the dissolution rate in the monomer becomes too slow, and the feel becomes rough and operation becomes difficult. Further, the content of the methacrylate-based polymer powder is preferably from 5 to 80% by weight. When the content is more than this, the bioactive filler powder becomes relatively small, so that the bioactivity is reduced. At the same time, the methacrylate monomer is hardly polymerized and the mechanical strength is reduced.

The methacrylate monomer used in the present invention is a monomer which undergoes two-dimensional polymerization. Although it does not have a high initial strength as compared with the dimethacrylate monomer, its operability is excellent because the viscosity does not increase rapidly during curing. After curing, it is stable in the body for a long period of time, and the mechanical strength is not easily reduced. As the methacrylate-based monomer, methyl methacrylate (MMA), which is currently used in the field of orthopedic surgery, is most preferable, but ethyl methacrylate and the like can also be used. The content of the methacrylate monomer is preferably from 10 to 60% by weight. If the amount of the methacrylate-based monomer is less than 10% by weight, it is difficult to polymerize and the mechanical strength is reduced. If the amount is more than 60% by weight, the biological activity is reduced.

In addition to methacrylate monomers, dimethacrylate monomers can be added. A dimethacrylate monomer is a monomer that is polymerized three-dimensionally to become a high-strength polymer, and after curing, is stable in the body for a long period of time, and is unlikely to have low mechanical strength.
Bis-GMA as a dimethacrylate monomer,
2,2-bis (4-methacryloxyethoxyphenyl)
Propane (Bis-MEPP), triethylene glycol dimethacrylate (TEGDMA), diethylene glycol dimethacrylate (DEDMA), ethylene glycol dimethacrylate (EGDMA), and the like can be used.

The powder-liquid ratio of a powder component composed of a bioactive filler powder, a methacrylate-based polymer powder, etc. to a liquid component composed of a methacrylate-based monomer or a dimethacrylate-based monomer is 50:50 by weight.
Desirably, the ratio is up to 90:10.

Further, the bioactive cement composition of the present invention contains a polymerization initiator and a polymerization accelerator.

The polymerization initiator is used after being added to the powder component. The addition amount is 0.1 to 1 with respect to 100 parts by weight of the liquid component.
0 parts by weight is preferable, and if less than 0.1 parts by weight, there is almost no effect, and if more than 10 parts by weight, the curing time becomes too fast, and the operability tends to deteriorate. In addition, as a polymerization initiator, benzoyl peroxide, tri-n-butylborane, or the like can be used.

The polymerization accelerator is used by adding it to the liquid component. The addition amount is 0.1 to 8 with respect to 100 parts by weight of the liquid component.
Parts by weight are preferred. If the amount of the polymerization accelerator is less than 0.1 part by weight, it will not be cured unless heated to 100 ° C. or more when polymerizing the monomer, so that it cannot be used in actual surgery.
On the other hand, if the amount is more than 8 parts by weight, the curing time becomes too fast, and the operability is likely to deteriorate. As the polymerization accelerator, N, N
Tertiary amines such as -dimethyl-P-toluidine can be used.

Further, the bioactive cement composition of the present invention comprises
In addition to the above components, various components such as alumina, silica, a drug, a bone forming factor, a polymerization inhibitor, a polymerization inhibitor, and an antioxidant can be added as necessary.

The form of providing the bioactive cement composition of the present invention is a powder-liquid system, and the user may use a mixture of powder and liquid.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments.

Tables 1 and 2 show examples of the present invention (sample No. 1).
To 8) and Table 3 show comparative examples (Sample Nos. 9 to 11).

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[Preparation of Samples] Each sample was prepared as follows.

First, a bioactive filler powder and a methacrylate polymer powder were prepared.

The bioactive filler powder was prepared as follows. First, CaO 45% by weight and SiO ₂ 34
%, P ₂ O ₅ 16%, MgO 4.5%, CaF ₂ 0.
A glass powder obtained by pulverizing and classifying a Ca-containing glass having a composition of 5% and a crystallized glass powder obtained by heat-treating this at 1050 ° C. for 5 hours for crystallization and then pulverizing and classifying again were prepared. Next, add glass powder or crystallized glass powder to 1
After being supplied into a flame of 500 ° C. or more and blown off while being re-melted, the specific surface area is 1.0 m by rapid cooling.
^{A 2} / g spherical bioactive filler powder was prepared. The crushed filler used was glass powder adjusted to have a specific surface area of 1.0 m ² / g. Next, the pH of each powder
The surface treatment was performed with the silane coupling agent prepared in No. 6.

As the methacrylate polymer powder,
Average particle size 30 to 100 μm, weight average molecular weight 5 to 130
Ten thousand PMMA powders were prepared.

Next, the bioactive filler powder and the methacrylate-based polymer powder were weighed at the ratios shown in the table, and benzoyl peroxide was added as a polymerization initiator and mixed.

As the methacrylate monomer, M
MA was prepared, and N, N-dimethyl-p-toluidine was added as a polymerization accelerator and kneaded.

Thus, a powder-liquid type sample was obtained.

The amounts of benzoyl peroxide and N, N-dimethyl-p-toluidine were 5 parts by weight and 2 parts by weight, respectively, with respect to 100 parts by weight of the total amount of the monomers so that the curing was effected in about 7 minutes. did.

[Evaluation] Each sample was evaluated for apatite-forming ability, bending strength of the cured product, and operability.
The results are shown in the table.

As is clear from the table, the sample No. Nos. 1 to 9 all had the ability to form apatite in the simulated body fluid. Furthermore, the flexural strength of the cured body is 120 MPa or more at the initial stage, and the strength after immersion in physiological saline is 1
It was at least 05 MPa and very high strength. The operability was good.

On the other hand, the comparative example No. Samples 8 and 9 showed formation of apatite and had good operability, but had low mechanical strength due to the use of PMMA powder having a small weight average molecular weight. No. In the sample No. 10, the formation of apatite was recognized and the operability was good, but the mechanical strength was low because the crushed material was used as the bioactive filler powder.

The apatite-forming ability was determined by immersing the cement in a simulated body fluid at 37 ° C. immediately after setting the cement, taking out the specimen three days later, observing the surface with an electron microscope, and confirming the presence or absence of apatite crystals. The flexural strength was determined by kneading and hardening each sample to prepare a test piece having a size of 3 × 4 × 20 mm. Then, the initial strength and the strength after being immersed in physiological saline for one month were evaluated by a three-point bending test ( (Span 16 mm). As for operability, the easiness of work when the cement was kneaded by hand was evaluated.

[0040]

According to the bioactive cement composition of the present invention provided in a powder-liquid system, a polymerization reaction occurs when the powder and the liquid are mixed, and the curing is completed in about 3 to 15 minutes. It has good operability due to its viscosity, and can be formed into a desired shape within the time until curing, and can be easily filled into the application site.

The cement hardened in the living body forms an apatite layer similar to the living body on the surface of the hardened material by the bioactive filler powder. Thereby, the hardened cement can chemically bond with the natural bone.

Moreover, the cured product has practically sufficient mechanical strength.

As described above, the bioactive cement composition of the present invention directly bonds to natural bone, has high mechanical strength, and is excellent in operability, and is used in the fields of orthopedic surgery, neurosurgery, oral surgery and the like. It is suitable for bonding and fixing an implant material, filling a bone defect, reconstructing a skull defect, etc.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshiro Kitamura 2-7-1 Hararashi, Otsu-shi, Shiga F-term in Nippon Electric Glass Co., Ltd. 4C081 AB04 AB06 AC04 BA13 BB04 BB08 BB09 CA082 CC05 CC08 CE08 CE11 CF011 CF021 CF031 CF041 CF051 CF061 CF132 CF152 DB02 DC03 DC13 EA05 4C089 AA06 BA03 BA11 BA13 BA16 BC06 BC13 BD01 BD02 BE02 CA03 CA07 CA09

Claims (4)

[Claims] 1. A bioactive cement comprising a bioactive filler powder, a methacrylate polymer powder, a methacrylate monomer, a polymerization initiator, and a polymerization accelerator, wherein the bioactive filler powder is spherical, and the methacrylate polymer powder A bioactive cement composition characterized by having a weight average molecular weight of 150,000 or more. 2. The bioactive cement composition according to claim 1, wherein the methacrylate polymer powder is spherical. 3. The bioactive cement composition according to claim 1, wherein the methacrylate-based polymer powder has an average particle size in the range of 1 to 500 μm. 4. The bioactive cement composition according to claim 1, wherein the bioactive filler powder is made of glass containing Ca or crystallized glass.