JPH0233492B2 - FUKUGOTAIKOKABUTSUNOSEIZOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of a precision cast polymer composite molded product having a high packing density of fillers and high strength without containing air bubbles. The obtained molded product can be suitably used as a crown, an inlay, an abutment, an artificial tooth, etc. for aesthetic restoration of a dental crown or an artificial joint.

Conventionally, crowns, inlays, abutments, artificial teeth, etc. have been made of metal, ceramics, or polymeric materials. Metal has the advantage of being able to be precision cast, but has the disadvantages of having a completely different appearance (color tone) from natural teeth, having an uncomfortable thermal conductivity coefficient that is too large, and being expensive. In the case of ceramics,
The aesthetics are good, but the manufacturing process is complicated.
It has drawbacks such as poor impression reproducibility and excessive hardness. Although polymeric materials have advantages such as being inexpensive and easy to manufacture, conventionally only materials with low mechanical strength can be manufactured and have been used only for some restorations of anterior teeth. When manufacturing crowns and the like using polymeric materials, the main method used has been to pile up resin on a positive impression with a brush and then harden it. In this method, a mixture of an organic monomer and an organic polymer powder or a mixture of an organic monomer and a relatively small amount of an inorganic filler has been mainly used as the resin. Adding a large amount of inorganic filler to improve mechanical properties increases the viscosity of the resin, making it difficult to manipulate, so resin crowns that can be used on molars have rarely been put into practical use except for pediatric use. . In addition, this case also has the disadvantage that air bubbles may be mixed in during operation, resulting in deterioration of mechanical properties.

In the present invention, a paste-like composition in which a liquid polymerizable monomer and a filler material powder having a density higher than that of the monomer are mixed is put into a mold in which an impression is taken, and then a centrifugal separator is used to perform high centrifugal gravity. It is based on the discovery that by precipitating and then curing filler powder particles in situ, a molded article can be obtained with a high degree of mechanical properties not attainable using the prior art. When a paste-like composition consisting of a polymerizable monomer and a filling material whose density is 0.4 g/cm ³ or more higher than the monomer is centrifuged at a centrifugal gravity of 500 G or more, the denser filling material settles to the bottom of the mold, and the filling material is The polymerizable monomer fills the densely packed gaps in the material. Then, when the paste composition is cured as it is or taken out from a centrifugal field, a composite molded product with a relatively higher filler content than the conventional technology is obtained, and this molded product has extremely high strength and hardness, and has no air bubbles. It has been found that the esthetics are also great because it does not contain. That is, the present invention comprises a liquid polymerizable monomer and a liquid polymerizable monomer containing 0.4 g/cm ³ of the monomer.
A paste-like composition mixed with filler material powder with a higher density than above is injected into a mold, and the mold is
By placing it under the above centrifugal gravity, a layer with a high content of the filler material is formed at the bottom of the mold, and then the paste composition is polymerized and hardened to harden the layer with a high content of the filler material. This is a method for producing a cured composite material, which is characterized in that it is taken out as a molded product.

The filler powders used in the present invention include crystalline quartz, quartz glass (specific gravity 2.1 to 2.9), various glasses, pulverized fine powders of various ceramics such as aluminum oxide, tantalum oxide, and silicon nitride, and sub-fillers grown in the vapor phase. Aerosil, with micron particle size
Various inorganic material powders such as alumina, boron oxide, silicon nitride, and boron nitride can be used. Further, a powder obtained by covering the above-mentioned inorganic filler powder with an organic polymer such as polymethyl methacrylate (so-called organic filler) can also be used as the filler material powder. Here, as an organic filler, the ratio of inorganic filler and organic polymer is
It is desirable that the ratio is 80/20 to 40/60 (inorganic filler/organic polymer, weight ratio). In addition, inorganic powders such as glass ceramics containing lanthanum, barium glass, and strontium glass provide X-ray opacity to the molded product, which has the advantage of facilitating diagnosis using X-ray photography due to the appropriate contrast with natural teeth. There is. These inorganic fillers are preferably surface-organized by a known method in order to improve their adhesion to the organic matrix portion. Typical surface treating agents include silane treating agents such as γ-methacryloxypropyltrimethoxysilane.

This inorganic filler preferably has a small particle size, preferably 63 μm or less (passes through 250 meshes). In order to improve the strength, it is preferable that the particle size of the inorganic filler is smaller, and preferably 44μ or less (passing through 375 meshes).
Further, it is preferable that the average particle diameter is 10 μm or less, more preferably 5 μm or less. Ultrafine fillers of 1μ or less, especially 0.1μ or less, have the advantage of improving strength and wear resistance, but it may be difficult to increase the packing density, and in this case, they may be mixed with inorganic fillers with larger particle sizes. It is desirable to use it. Further, the submicron ultrafine powder can be used as it is or mixed with an inorganic filler of 1 μm or more and pre-embedded in an organic polymer to form an organic filler. The particle size of the organic filler does not necessarily need to be 63μ or less, as long as the inorganic filler material in the mixed viscosity thick liquid is 63μ or less.

The present invention is essentially different from known centrifugal molding of contact lenses, etc., centrifugal molding of unsaturated polyester resin pipes, etc., in that it uses organic monomers and inorganic fillers with different densities, and is produced under a high centrifugal gravity field. The point is to obtain a molded product with a high filler content while allowing the filler to settle. Therefore, it is necessary that the filling material has a higher density than the uncured matrix, the difference being greater than 0.4 g/cm ³ , and in the case of an organic filler covered with an organic polymer, It is necessary that the density is greater than 0.4 g/cm ³ .

When the above-described method is used, the molded product often has fillers close to close packing, and the filler content is improved. When used for hard tissue repair of the human body, it is preferable that the filler material contains 50% by weight or more, and for tooth repair, it is more preferable that the filler material is 70% by weight or more. When using ultrafine particle inorganic filler, especially when using organic filler, it is difficult to increase the amount of inorganic filler filled, but in order to obtain a molded product with high strength, the inorganic content should be 50% by weight. It is necessary that it is above. When the inorganic content is 50% by weight or more, the ratio of the organic component containing the polymerizable monomer in the charging composition and the organic polymer on the inorganic powder in the case of an organic filler to the inorganic filler material is 70/30. ~20/80 (heavy monomers and organic polymers/inorganic fillers,
If the inorganic content is 60% by weight or more, the composition ratio is 60/40 to 20/80, and by molding with a centrifugal force of 1000 G or more, the inorganic If the content is 70% by weight or more, the preparation composition is 60/40 to 20/80, centrifugal force
Can be obtained by molding at 5000G or more.

Any organic monomer that is radically polymerizable and liquid at room temperature (if a mixture of two or more monomers is used, the mixture is liquid) can be used in the present invention. However, when the cured product is used in the human body, its softening temperature must be 40°C or higher in a wet state. Furthermore, from the viewpoint of aesthetics, durability, and safety, (meth)acrylic acid ester monomers (density 0.8 to 1.4 g/cm ³ ) can be used most effectively.
In particular, polyfunctional monomers are preferred from the viewpoint of strength and performance. Further, polyfunctional monomers having an aromatic ring are particularly preferred. Examples of organic monomers that can be used are:
Styrene, methyl methacrylate, mono, di, tri, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, reaction product of aliphatic diisocyanate and 2-hydroxyethyl methacrylate, pentamethylene diisocyanate or 2, Reaction product of 2,4-trimethylhexamethylene diisocyanate and glycerin di(meth)acrylate, bisphenol A di(meth)acrylate, 2,2-bis[P-(γ-(meth)acryloxy-β-hydroxypropoxy) Phenyl] propane (commonly known as Bis)
-GMA), trimethylolpropane tri(meth)
Acrylate, tetramethylolmethanetetra(meth)acrylate, etc.

In the present invention, a polymerization initiator is added to the paste composition in order to harden the composition. Also,
Polymerization regulators are often added to preserve pre-prepared pasty compositions. The polymerization initiator used in the present invention is not particularly limited, and known radical polymerization catalysts can be used. Examples of usable radical polymerization catalysts include organic peroxides such as benzoyl peroxide, t-butyl perbenzoate, and t-butyl peroxide maleic acid, and azobisisobutyl nitrile. The curing temperature is preferably 50° C. or higher in terms of the strength of the cured product. When the curing temperature is 80°C or higher, a cured product with particularly high strength can be obtained. Benzoyl peroxide is an example of a suitably used catalyst. The polymerization regulator added to the paste composition of the present invention is not particularly limited, and known polymerization regulators may be used. As polymerization regulators that can be used, phenols such as di-t-butyl-p-cresol and hydroquinone monomethyl ether, hydroquinones such as hydroquinone, p-t-butylcatechol, and 2,5-di-t-butylhydroquinone, p- - Examples include quinones such as benzoquinone.

The mold may be made of metal, organic polymer, or inorganic material, but from the viewpoint of operational convenience, known inorganic materials such as gypsum can be conveniently used. In order to repeatedly obtain the same molded product, metal or organic polymer molds can be conveniently used. The shape of the mold is such that the desired molded product can be obtained at the bottom of the mold, as shown in Figure 7.
Preferably, the immediate upper part of the shape is a thin tubular shape, so that the molded product can be easily taken out by cutting the tubular portion after curing.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

Example 1 2,2′-bis[P-(γ-methacryloxy-β
-hydroxypropoxy)phenyl]propane (Bis-GMA) and 25 parts by weight of triethylene glycol dimethacrylate (TEGDMA) (density 1.14 g/cm ³ ), 1.0 part by weight of benzoyl peroxide and 2, 6-di-t-butyl-p
- 25 parts by weight of a composition containing 0.05 parts by weight of cresol (BHT) and a particle size of 0.1 to 63μ (average particle size
75 parts by weight of quartz powder (density 2.66 g/cm ³ ) and ultrafine silicic anhydride (density 2.2 g/cm ³ ) as a thickener.
(Aerosil 380, Nippon Aerosil Co., Ltd.) and 1.8 parts by weight were kneaded to prepare a paste composition (paste A). In a plastic tube with a diameter of 1.6 cm.
10 g was added, centrifuged at 80°C and 10,000 rpm for 1.5 hours using a high-speed centrifuge (Model 18PR-52H, Hitachi Koki), and then heated to 90°C and cured for 30 minutes. In addition,
The gravitational acceleration on the sample at 10000rpm is at the top
7900G, 13500G at the bottom. Cured product (length 5
cm) to determine Brinell hardness and ash content. In addition, a glass tube with an inner diameter of 4 mm and a sealed tip was filled with paste A to a depth of 4.5 cm from the bottom, and it was cured in the same way.
It was cut to a length of 4 mm and the compressive strength of the section was measured. The results are shown in FIGS. 1 to 3.

Comparative Example 1 Paste A of Example 1 was polymerized by heating at 90° C. for 1 hour, and its Brinell hardness, compressive strength, and ash content were measured. The Brinell hardness was 56.7, the compressive strength was 2815 Kg/cm ² and the ash content was 76.8%. As is clear from FIGS. 1 to 3, the sample in Example 1 at a portion approximately 2 cm away from the top surface exhibits higher Brinell hardness, compressive strength, and ash content than the sample in Comparative Example 1.

Example 2 2,2′-bis[P-(γ-methacryloxy-β
A monomer (density 1.12 g/cm ³ ) consisting of 50 parts by weight of -hydroxypropoxy)phenyl]propane (Bis-GMA) and 50 parts by weight of triethylene glycol dimethacrylate (TEGDMA), 0.3 parts by weight of benzoyl peroxide and t- Composition mixed and dissolved with 0.05 parts by weight of butyl-p-cresol (BHT)
30 parts by weight, quartz powder surface-treated with γ-methacryloxypropyltrimethoxysilane (γ-MPS) (particle size is 30μ or less, average particle size 9.0μ.Density
2.66 g/cm ³ ) Ultrafine particle anhydrous silicic acid with a particle size of 0.1 μ or less surface-treated with 50 parts and γ-MPS [Aerosil OX-50 (Nippon Aerosil Co., Ltd.) density 2.2 g/cm ³ ]
A paste composition (paste B) was prepared by kneading 20 parts by weight. Spread the paste into a plastic (polyallomer) tube with an outer diameter of 16 mm and place it 3.5 cm from the bottom.
into a high-speed centrifuge (model 18PR-52H,
(manufactured by Hitachi Koki), temperature 80℃, 10000rpm
After centrifuging for 2 hours, the temperature was raised to 90°C and cured for 30 minutes. Furthermore, at 10,000 rpm, the upper part of the sample is
9600G, the lower part is 13500G. The cured product was cut and the density, Brinell hardness, and ash content of the cured product were measured. The results are shown in FIGS. 4 to 6 together with Comparative Example 2.

Comparative Example 2 The density of the cured product, Brinell hardness, and ash content of a sample obtained by curing Paste B of Example 2 at 90° C. for 1 hour were measured. The results are shown in FIGS. 4 to 6.

The cured product of Example 2 forms a layer with higher cured product density, Brinell hardness, and ash content than Comparative Example 2 at a distance of about 2 cm from the top surface. As is clear from the above examples, the method of the present invention has a higher density and ash content of the cured product than cured products produced by conventional heat polymerization methods, and has improved mechanical properties such as Brinell hardness and compressive strength. Excellent cured products can be obtained.

An example of application of the method of the present invention to dental applications will be described below, but the embodiments are not limited to this method.

Example 3 In order to form an abutment on a tooth in which a root canal was formed, an impression was taken using a silicone impression material, and a working model was prepared by pouring cemented carbide gypsum. A mold release agent was applied on the working model, a base was formed with wax, the wax pattern of the base was removed from the working model, and a wax rod that served as the resin inflow path was attached.
Half of this wax pattern was immersed in cemented carbide plaster to create a half mold, a wax solution dissolved in benzene was applied to the cross-sectional surface, and after drying, the remaining half was buried in cemented carbide plaster. The hardened plaster mold was divided into two parts, and the internal wax was removed to create separate molds. Paste B of Example 2 was placed on top of the mold as shown in Figure 7, and heated at 80°C in a high-speed centrifuge.
After centrifuging at 10,000 rpm for 1 hour, the temperature was raised to 90°C to cure. After cooling, the excess portion of the resin abutment separated from the mold was removed and bonded to the tooth with zinc phosphate cement to form an abutment.

Example 4 A separate mold for an artificial tooth was made of aluminum alloy, and as in Example 3, resin (paste B) was injected and hardened under centrifugal conditions. The surface hardness (Brinell hardness) of the crown of the artificial tooth taken out from the mold was 60.

As described above, according to the present invention, a cured product having a predetermined shape and having superior mechanical properties as compared to the conventional heating polymerization method was obtained.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the sampling position (distance from the upper end) of the cured product and the Brinell hardness of the cured product in the cured products obtained in Example 1 and Comparative Example 1; Similarly, Figure 3 is a graph showing the relationship between the distance from the upper end of the cured product, the ash content, and the compressive strength, respectively, and Figures 4, 5, and 6 are graphs showing the relationship between the distance from the top of the cured product, the ash content, and the compressive strength, respectively, and Figures 4, 5, and 6 are graphs showing the relationship between the distance from the upper end of the cured product, the ash content, and the compressive strength. It is a graph which shows the relationship between the distance from the upper end of the cured product, the density of the cured product, the Brinell hardness, and the ash content. FIG. 7 is a sectional view showing an example of a mold used in the present invention. In FIG. 7, 1 indicates paste B, 2 indicates a plaster mold (1), and 3 indicates a plaster mold (2).

Claims (1)

[Scope of Claims] 1. A liquid polymerizable monomer with a density lower than that of the monomer.
A paste composition mixed with a filler material powder larger than 0.4 g/cm ³ is injected into a mold, and the mold is
A layer with a high content of the filler material is formed at the bottom of the mold by placing it under centrifugal gravity of 500 G or more, and then the paste composition is polymerized and hardened to form a layer with a high content of the filler material. A method for producing a cured composite material, characterized in that it is taken out as a cured molded product. 2. The manufacturing method according to claim 1, wherein the pasty composition is injected into the mold under centrifugal gravity. 3. The manufacturing method according to claim 1 or 2, wherein the paste composition is hardened under centrifugal gravity using a mold. 4. The manufacturing method according to claim 1 or 2, wherein the pasty composition is hardened after the mold is removed from the centrifugal gravity field. 5. The manufacturing method according to claim 3, wherein the centrifugal gravity is 1000 G or more, the paste composition is injected into a mold under centrifugal gravity, and the paste composition is polymerized and hardened under centrifugal gravity. 6. The manufacturing method according to claim 5, wherein the centrifugal gravity is 5000 G or more, the paste composition is injected into a mold under centrifugal gravity, and the paste composition is polymerized and hardened under centrifugal gravity. 7 The polymerizable monomer is one type or a mixture of two or more types of (meth)acrylic acid ester, the filler material powder is an inorganic powder of 63μ or less, and the inorganic powder is covered with an organic polymer. or a mixture thereof, the manufacturing method according to claim 1. 8. The manufacturing method according to claim 7, wherein the inorganic powder is crystalline or vitreous quartz and/or ceramic powder. 9 The ratio of the organic component consisting of the polymerizable monomer and the organic polymer on the inorganic powder to the inorganic powder is
70/30 to 20/80 (polymerizable monomer and organic polymer/inorganic powder, weight ratio), centrifugal gravity 500G
The manufacturing method according to claim 7, wherein a molded product having an inorganic content of 50% by weight or more is produced by molding in the above manner. 10 The ratio of the organic component consisting of the polymerizable monomer and the organic polymer on the inorganic powder and the inorganic powder is 60/40 to 20/80 (polymerizable monomer and organic polymer/inorganic powder, weight ratio) and centrifugal gravity
Claim 7, which produces a molded product with an inorganic content of 60% by weight or more by molding at 1000G or more
Manufacturing method described in section. 11 The ratio of the organic component consisting of the polymerizable monomer and the organic polymer on the inorganic powder and the inorganic powder is 60/40 to 20/80 (polymerizable monomer and organic polymer/inorganic powder, weight ratio) and centrifugal gravity
The manufacturing method according to claim 7, wherein a molded product having an inorganic content of 70% by weight or more is manufactured by molding at 5000G or more. 12 The shape of the inner surface of the lower part of the mold is such that a desired molded product can be obtained, and the upper part of the mold has a thin tubular shape, and after curing, the mold can be molded by cutting the tubular part. The manufacturing method according to claim 1, wherein the molded product can be easily taken out. 13. The manufacturing method according to claim 1, wherein the shape of the mold is selected so that the molded product to be taken out can be used as an inlay, a crown, an abutment, or an artificial tooth in the dental field. 14. The manufacturing method according to claim 1, wherein the molded product is used as a dental restorative material.