JPH11164879A - Bioactive cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biologically activated cement composition which can be directly connected to natural bones and has higher operability. SOLUTION: This biologically activated cement composition is composed of glass or crystallized glass powder containing Ca, polymethacrylate powder, methacrylate monomer, polymerization start agent, and polymerization promoter. It is recommended that the glass or crystallized glass powder containing Ca is composed of 30 to 70% of CaO, 30 to 70% of SiO2 , 0 to 40% of P2 O5 , 0 to 20% of MgO, and 0 to 5% of CaF2 by weight.

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 orthopedic surgery and oral surgery, filling of bone defects, and reconstruction of cranial defects in the field of neurosurgery. 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 comprising a Ca-containing inorganic material powder (apatite, Ca-containing glass, etc.) and a dimethacrylate-based monomer (Bis-GMA, etc.) has been proposed. When this bioactive cement is cured in a living body, Ca ions are eluted from the Ca-containing inorganic material powder exposed on the surface of the cured body, and react with body fluid to form an apatite layer on the surface of the cured body. Can be combined.

[0003]

However, the above-mentioned cement has a drawback that it hardly molds due to rapid hardening and its operability is not very good.

[0004] It is an object of the present invention to provide a bioactive cement composition which can be directly bonded to natural bone and has good operability.

[0005]

The bioactive cement composition of the present invention comprises a glass or crystallized glass powder containing Ca, a polymethacrylate powder, a methacrylate monomer, a polymerization initiator and a polymerization accelerator. Features.

[0006] The Ca-containing glass or crystallized glass powder used in the present invention has a property of eluting Ca ²⁺ ions when it comes into contact with body fluids, whereby a cement-hardened body can be bonded to natural bone. As such glass or crystallized glass, CaO 30 to 70% by weight is used.
_{%, SiO 2 30~70%, P} 2 O 5 0~40%,
MgO 0-20%, CaF ₂ 0-5%, especially CaO
_{40~50%, SiO 2 30~40%,} P 2 O 5
10~20%, MgO 0.5~10%, CaF 2 0
Those having a composition of .about.2% are preferred. Glass and crystallized glass having the above composition exhibit high bioactivity, have high mechanical strength, and can increase the strength of the hardened cement. The content of glass or crystallized glass powder is 5
It is desirably in the range of 80% by weight, and its shape is preferably spherical. In addition, if the surface is subjected to silane coupling treatment, familiarity with the methacrylate monomer is improved and the strength of the cement hardened body is increased, and since the powder surface has a hydrophobic group, blood inhibition is lost, and cement Is easily cured. The silane coupling treatment is preferably performed in a weak acid to neutral range (about pH 5 to 8). This is
If the H is lower than 5, the glass surface is eroded to lower the biological activity, and if the pH is higher than 8, the silane coupling treatment becomes difficult.

[0007] The polymethacrylate-based powder is a component necessary for the polymerization of the methacrylate-based monomer, and its content is preferably 5 to 80% by weight. When the amount of the powder is reduced, the biological activity is reduced. On the other hand, when the amount is too small, the operability is deteriorated, and the methacrylate monomer is hardly polymerized and the mechanical strength is reduced. Examples of the polymethacrylate-based powder include polymethyl methacrylate (PMMA) powder, copolymer powder of methacrylate and styrene, and methacrylate and 2,2-bis [4- (3
Methacryloxy-2-hydroxypropoxy) phenyl] propane (Bis-GMA) copolymer powder or the like can be used.

A methacrylate monomer is a monomer which undergoes two-dimensional polymerization, and although it does not have a high initial strength as compared with a dimethacrylate monomer, its operability is excellent because its 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.

[0009] In addition to methacrylate monomers, dimethacrylate monomers can be added. The dimethacrylate-based monomer is a monomer which is polymerized three-dimensionally to become a high-strength polymer, and is stable in the body for a long time after curing, and is unlikely to have low mechanical strength.
In addition, there is an effect that an unpolymerized layer is formed on the surface of the cured product and the body fluid penetrates into the interior of the cured product. As a result, not only the Ca-containing glass or crystallized glass powder exposed on the surface of the cured body, but also the Ca-containing glass or crystallized glass powder buried therein can exhibit bioactivity. Bis-GM is a dimethacrylate monomer.
A is preferred, but other than this, 2,2-bis (4-methacryloxyethoxyphenyl) propane (Bis-ME
PP), triethylene glycol dimethacrylate (T
EGDMA), diethylene glycol dimethacrylate (DEDMA), ethylene glycol dimethacrylate (EGDMA) and the like can be used. TEGD
Since monomers such as MA, DEGDMA, and EGDMA have low viscosities, they can be used as diluents when the viscosity is too high to handle easily.

The powder-to-liquid ratio of a powder component such as a glass or crystallized glass powder containing Ca and a polymethacrylate-based powder to a liquid component composed of a methacrylate-based monomer or a dimethacrylate-based monomer is expressed as a weight ratio of powder:
It is desirable that the liquid is 50:50 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 by adding to the powder component. The addition amount is 0.1 to 8 with respect to 100 parts by weight of the powder component.
If the amount is less than 0.1 part by weight, there is almost no effect. If the amount is more than 8 parts by weight, the curing time is too fast, and the workability tends to be deteriorated. 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 monomer.
Parts by weight are preferred. If the amount of the polymerization accelerator is less than 0.1 part by weight, the monomer will not be cured unless heated to 100 ° C. or more when polymerizing the monomer, so that it cannot be used in an actual operation site. On the other hand, if the amount is more than 8 parts by weight, the curing time becomes too fast and the workability tends to deteriorate. A tertiary amine such as dimethyl-P-toluidine can be used as the polymerization accelerator.

Further, the bioactive cement composition of the present invention comprises
In addition to the above components, apatite powder, fused silica powder,
Various components such as colloidal silica, drugs, osteogenic factors, polymerization inhibitors, and polymerization inhibitors can be added as needed.

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.

[0016]

The bioactive cement composition of the present invention, which is provided in a powder-liquid system, undergoes a polymerization reaction when the powder and the liquid are mixed, and the curing is completed in about 3 to 15 minutes. Due to its use, the viscosity change during polymerization occurs more slowly than in the case of dimethacrylate monomers. Therefore, the operability is good, and a desired shape can be freely formed within the time until curing.

In addition, cement hardened in vivo elutes Ca ²⁺ ions from glass powder or crystallized glass powder.
The eluted Ca ²⁺ ions react with PO ₄ ⁻ ions in the body fluid to form an apatite layer similar to a living body on the surface of the cured body. Thereby, the hardened cement can chemically bond with the natural bone.

When a dimethacrylate-based monomer is further contained, an unpolymerized layer is formed on the surface of the cured product, and the body fluid penetrates into the interior of the cured product. Therefore, the Ca-containing glass or crystallized glass powder buried in the interior is also mixed with the body fluid. Contact can be made and connection with surrounding bone can be made in a short time.

[0019]

The present invention will be described below in detail based on examples and comparative examples.

Tables 1 to 3 show examples of the present invention (sample No. 1).
7 to 7) and Comparative Examples (Sample Nos. 8 to 11).

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

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

First, a glass powder containing Ca, a crystallized glass powder, a polymethacrylate-based powder, and a hydroxyapatite powder were prepared.

As the Ca-containing glass powder, C is expressed by weight%.
aO 45%, SiO ₂ 34%, P ₂ O ₅ 16%,
A spherical product having a composition of MgO 4.5% and CaF ₂ 0.5% and having an average particle size of 4 μm was used. For the Ca-containing crystallized glass powder, the above glass powder was heat-treated at 1050 ° C. for 5 hours to crystallize. Used. These powders were subjected to a surface treatment using a silane coupling agent adjusted to pH 6.

The hydroxyapatite powder used had an average particle size of 3 μm.

Examples of the polymethacrylate powder include PM
MA powder (average particle size 30 μm, average molecular weight 13,000
0) was prepared.

Next, a glass powder containing Ca, a crystallized glass powder, a polymethacrylate-based powder, and a hydroxyapatite powder were weighed in the proportions shown in the table, and benzoyl peroxide was added as a polymerization initiator and mixed.

As the methacrylate monomer, M
MA is used as a dimethacrylate monomer as Bis-G
MA and TEGDMA were prepared.

Next, MMA, Bis-GMA and TEG
DMA was weighed at the ratio shown in the table, and 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 dimethyl-p-toluidine were set to 2 parts by weight and 1.4 parts by weight, respectively, with respect to 100 parts by weight of the total amount of the monomers so as to cure in about 7 minutes.

[Evaluation] Each sample was evaluated for bending strength, presence or absence of connection with surrounding bone, and operability. The results are shown in each table.

The bending strength was evaluated by a three-point bending test. Each sample was kneaded and cured to obtain a 3 × 4 × 20
A sample having a size of mm was measured. After the sample was implanted into the tibial cavity of the rat, the implanted site was removed 4 weeks after the sample was implanted into the tibial cavity of the rat. evaluated. This was confirmed by observing the surface of the embedded specimen with an electron microscope and conducting EPMA line analysis.

As is clear from the table, the No. 1 of the embodiment of the present invention. The samples of Nos. 1 to 7 had a bending strength of 90 MPa or more, and had sufficient strength for practical use. In addition, the connection with the surrounding bone was recognized, and the operability was good.

On the other hand, the sample No. In No. 8, although the connection with the surrounding bone was recognized, the bending strength was low and the operability was poor. Sample No. Sample No. 9 had high bending strength and bonding with the surrounding bone was recognized, but operability was poor. Sample No. In No. 10, the bending strength was low, and only a part of the connection with the surrounding bone was observed. Sample No. No. 11 was excellent in operability, but no connection with the surrounding bone was observed.

[0038]

As described above, the bioactive cement composition of the present invention directly bonds to natural bone and has practically sufficient mechanical strength. Moreover, it is excellent in operability. Therefore, it is suitable for bonding and fixing an implant material, filling a bone defect, reconstructing a cranial defect, and the like in the fields of the orthopedic field, the neurosurgery field, the oral surgery field, and the like.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ken Longevity 2-7-1 Hararashi, Otsu City, Shiga Prefecture Inside Nippon Electric Glass Co., Ltd. (72) Inventor Hiroshi Komai 2-7-1 Hararashi, Otsu City, Shiga Prefecture Nippon Electric Glass Co., Ltd.

Claims (6)

[Claims] 1. A bioactive cement composition comprising a glass or crystallized glass powder containing Ca, a polymethacrylate powder, a methacrylate monomer, a polymerization initiator and a polymerization accelerator. 2. The glass or crystallized glass powder containing Ca contains 30 to 70% by weight of CaO and SiO _{2
0~70%, P 2 O 5 0~40} %, MgO0~20
%, Claim 1 of bioactive cement composition characterized by having a composition of CaF ₂ 0 to 5%. 3. The polymethacrylate-based powder is a polymethyl methacrylate powder.
Bioactive cement composition. 4. The bioactive cement composition according to claim 1, wherein the methacrylate monomer is methyl methacrylate. 5. The bioactive cement composition according to claim 1, wherein the polymerization initiator is benzoyl peroxide. 6. The bioactive cement composition according to claim 1, wherein the polymerization accelerator is dimethyl-p-toluidine.