JP2638349C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dental filling composition, and more particularly, to a paste having good operability, transparency and mechanical strength of a cured product. The present invention relates to a dental filling composition which has a good surface roughness and excellent gloss smoothness on the surface of a cured product and a small water absorption. 2. Description of the Related Art Conventionally, a dental filling composition comprising a polymerizable monomer and an inorganic filler as components has been used for repairing and prosthetic teeth, repairing teeth, artificial crowns and other uses. ing. Natural or synthetic silica is often used alone or in combination as the inorganic filler. The higher the content of the filler, the greater the strength of the composition after polymerization and curing, and the higher the coefficient of thermal expansion is close to the dentin, which is preferable. When the mixture was dispersed and mixed, the viscosity of the obtained paste was extremely increased, so that only about 50 to 60% by weight could be compounded without increasing the compounding amount of silica. In addition, there is also a problem that the filler obtained by the crushing method is inferior in the smoothness of the polished surface even after finishing polishing after curing. [0003] Therefore, recently, spherical silica has been used as a filler instead of the filler by the crushing method (Japanese Patent Publication No. 1-57082, Japanese Patent Application Laid-Open No. 58-152804, etc.).
. However, also in these cases, the filling amount cannot exceed 80% by weight,
The flexural strength after curing was also high, being 900 kg / cm ² . In order to improve this point, a hybrid of ultra-fine silica and crushed glass has been proposed (Japanese Patent Laid-Open No. Sho 63/63).
-88110). However, in this case as well, although the strength was slightly improved, the cured product had poor surface smoothness. In addition, when the proportion of the fine particles in the filler is increased, the surface smoothness is improved, but there is a problem that the water absorption is also increased, and a well-balanced dental filling composition has not yet been obtained. Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve such problems, and as a result, a spherical inorganic oxide mixture having a specific average particle diameter combined is used as a filler. It was found that such a problem was solved by using this in a specific blending ratio, and the present invention was reached. That is, an object of the present invention is to provide a dental filling composition in which the operability of the paste is good, the transparency and mechanical strength of the cured product are good, and the gloss and smoothness of the surface of the cured product is excellent. is there. An object of the present invention is to provide a dental filling composition comprising a polymerizable monomer and an inorganic filler, wherein the inorganic filler has a spherical inorganic oxide having a particle diameter in a range of 0.01 to 30 μm. And at least two groups having different average particle diameters, the group including spherical inorganic oxides having an average particle diameter in the range of 1 to 30 μm, and having an average particle diameter close to each other in two groups. A spherical inorganic oxide having a particle diameter ratio of 2 or more, and a group having a large average particle diameter occupying 50% or more of the total weight of the two groups; It is easily achieved by a dental filling composition containing a spherical inorganic oxide mixture, wherein the oxide particles are dry-mixed in advance. Hereinafter, the present invention will be described in detail. The polymerizable monomer of the present invention is not particularly limited as long as it is used for a dental filling composition, and various types may be used. Good to use. The most typical examples of the vinyl monomer include a polymerizable vinyl monomer having an acryl group and / or a methacryl group. Specifically, for example, esters with monohydric or dihydric alcohols such as α-cyanoacrylic acid, (meth) acrylic acid, urethane (meth) acrylic acid, crotonic cinnamic acid, sorbic acid, maleic acid, and itaconic acid. (Meth) acrylamides such as N-isobutylacrylamide, vinyl esters of carboxylic acids such as vinyl acetate, vinyl ethers such as butyl vinyl ether,
Mono-N-vinyl compounds such as N-vinylpyrrolidone, styrene derivatives and the like are mentioned, and particularly the following monofunctional and polyfunctional (meth) acrylates and urethane (meth) acrylates Is preferred. (I) monofunctional methyl (meth) acrylate, n- or i-propyl (meth) acrylate,
(Meth) acrylic acid n-, i- or t-butyl, 2-hydroxyethyl (meth) acrylate and the like. (Ii) Bifunctional general formula Wherein n is an integer of 3 to 20, and R represents hydrogen or a methyl group. For example, di (meth) acrylates such as propane diol, butane diol, hexane diol, octane diol, nonane diol, decane diol, and eicosane diol; [Where n represents an integer of 1 to 14, and R represents hydrogen or a methyl group. ] The compound shown by these. For example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dodecaethylene glycol,
In addition to di (meth) acrylates such as tetradecaethylene glycol, propylene glycol, dipropylene glycol, and tetradecapropylene glycol, glycerin di (meth) acrylate, 2,2′-bis [p- (γ-methacryloxy-β- (Hydroxypropoxy) phenylpropane (Bis-GMA), bisphenol A dimethacrylate, neopentyl glycol di (meth) acrylate,
2,2'-di (4-methacryloxypolyethoxyphenyl) propane (ethoxy groups 2 to 10 in one molecule), 1,2-bis (3-methacryloxy-2-hydroxypropoxy) butane and the like. (Iii) Trifunctional or higher trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate and the like. (Iv) Urethane (meth) acrylate-based reaction product of 2 mol of hydroxyl group-containing (meth) acrylate monomer and 1 mol of diisocyanate, urethane prepolymer having NCO at both terminals and (meth) acrylate monomer having hydroxyl group The structure of such a reaction product is represented by the following formula. Embedded image [Wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group, and R ₃ is an organic residue. These vinyl monomers may be used alone or as a mixture as necessary. In the present invention, a polymerization initiator may be used as necessary. The polymerization initiator to be used is not particularly limited, and a known one is used. As the polymerization means, a method using light energy, a method using a peroxide and a promoter, and the like can be used. Another component of the dental filling composition of the present invention is an inorganic filler. The inorganic filler used in the present invention has a particle diameter of 0.01 to 30 μm, preferably 0.01 to 10 μm,
More preferably, it is a spherical inorganic oxide in the range of 0.01 to 5 μm. The inorganic filler is not particularly limited as long as it is an inorganic oxide having a particle diameter in the above range. By using such particles, a dental filler excellent in gloss smoothness can be obtained. Inorganic oxides in the above range generally preferably used include amorphous silica and Periodic Table I.
At least one member selected from the group consisting of group III, group II, group III and group IV
An inorganic oxide mainly composed of a metal component and a silicon component, or alumina, titania, zirconia, or the like. In order to provide transparency and lubricity which are preferable as a dental filler, it is desirable that the difference in the refractive index between the components of the composition is not so large. Judging comprehensively from the availability of raw materials and the ease of manufacturing spherical particles,
Amorphous silica, particularly spherical silica synthesized by hydrolysis polymerization of alkoxysilane, is preferred. Further, when these spherical silicas are used, it is preferable to use those which are dried and calcined at 500 ° C. or higher. Further, in some cases, the difference in refractive index between the compositions is further reduced to increase the transparency, or a component having a higher specific gravity is added to facilitate imaging on X-rays. A mixed oxide can also be appropriately selected. The inorganic filler used in the present invention needs to be a mixture composed of at least two groups having different average particle diameters. The mixture may be the same or different, and the groups having different average particle diameters may not necessarily be two groups, but may be three or more groups. However, in the present invention, the average particle diameter in such a group is 1 to 30 μm, preferably 1 to 10 μm, more preferably 1 to 5 μm.
It is essential that at least one group consisting of spherical inorganic oxides in the range of μm is included. The other group may have an average particle diameter in the range of 1 to 30 μm or another range as long as the other conditions, particularly the conditions relating to the particle size difference, are satisfied. It is preferred that the group be in the range of less than. Further, the distribution of the average particle diameter of the inorganic filler is as follows.
It is necessary that the ratio of the average particle diameter in two groups is 2 or more, preferably 3 to 100. Here, the two groups whose average particle diameters are close to each other are, for example, in the case of an inorganic filler composed of three particle groups having an average particle diameter of 0.3 μm, 0.7 μm and 1.5 μm, the average particle diameter is The two groups of 0.3 μm and 0.7 μm and the two groups with average particle diameters of 0.7 μm and 1.5 μm are called two groups whose average particle diameters are close to each other. Of course, when the inorganic filler is composed of two groups having different average particle diameters, those two groups are referred to as two groups whose average particle diameters are close to each other. In the present invention, it is necessary that, of the two groups having an average particle diameter close to each other, the group having the larger average particle diameter occupies 50% or more of the total weight of the two groups.
Preferably, it occupies 60 to 80%. By blending in such a range, smaller particles can enter the gap between the large particles, and the packing ratio can be improved. In general, the particle size distribution of each particle group is preferably relatively narrow, and is generally 2 or less, more preferably 1.5 or less, and most preferably 1.2 or less in terms of standard deviation. Is selected. When the particle size ratio between the groups is considerably large, that is, when there is a considerable difference in the particle size of the main part of the two particle groups, the particle size distribution of each particle group is relatively wide even if the gap between the large particles is large. May be sufficiently filled with small particles, and may not cause a problematic void. Therefore, the particle size distribution of each particle group may be appropriately selected in consideration of the particle diameter ratio in each case. Various methods for producing particles of a required size are known. Large particles can be grown by using a growth method of growing seed crystals in a stepwise manner. By selecting, particles of a desired size can be obtained. The inorganic filler used in the present invention is desirably subjected to a surface treatment from the viewpoint of improving dispersibility with the monomer component. When silica is used as the inorganic filler, examples of the surface treatment agent include γ-methacryloxypropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinylacetoxysilane, and vinyltri (methoxyethoxy) silane. An organosilicon compound is used, and silanization is performed by a usual method. When preparing the dental filling composition of the present invention, the inorganic filler is usually 50 to 90% by volume, preferably 70 to 90% by volume, more preferably 80 to 90% by volume based on the whole filling composition. It is blended in the range of volume%. Then, the inorganic filler and the polymerizable monomer are dispersed and mixed. If the filling amount of the inorganic filler is too small, the viscosity of the filling composition itself is low, which is inconvenient when processing for dental use, while if too large, the filling composition cannot maintain a clay state. . In the present invention, it is important that the two groups of inorganic oxide particles described above are mixed in a dry gas stream in advance before being mixed with the polymerizable monomer. In the case of dry mixing, industrial operability is good, and more preferable uniform mixing of particles can be performed. Examples of the dry mixing method include an air-flow mixer and a fluidizing mixer, but also a V-type mixer, a ribbon-type mixer, a screw-type mixer, a disk-type rotary mixer, and the like. Good. Of these, a method of mixing both particles in an air stream is particularly desirable. As a mixing method in an air stream, for example, a jet mill type, an air blender type or a jet-o-miser type is suitable. EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. In the following Examples and Comparative Examples, silica particles were used as the inorganic filler, surface treatment of the silica particles was performed by the following method [1], and a polymerizable monomer was prepared. A test piece was prepared and each physical property was measured. [1] Surface Treatment of Silica Particles The treatment is performed on silica particles by applying γ-methacryloxypropyl t
4% by weight of rimoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added, mixed and stirred in a water-ethanol solvent, and then dried at 80 ° C. for 2 hours and further at 105 ° C. for 5 hours in a hot air drier to prepare a silane-treated filler. Preparation of Polymerizable Monomer Dimethacryloxyethyl trimethylhexame
Tylene di-urethane (VDMA: manufactured by Shin-Nakamura Chemical Co., Ltd.) and Tr
i-ethylene glycol dimethacrylate (TEG
DMA: Shin-Nakamura Chemical Co., Ltd.) in a ratio of 70:30 (wt%) to a monomer such as Camp horoquinone (Aldrich) 0.5 as a photosensitizer.
wt%, N, N-dimethylaminoethymetha as a reducing agent
0.5 wt% of crylate (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to prepare a resin monomer. [2] Methods for Testing and Measuring Physical Properties Preparation of Test Specimens 1) Compressive strength The filling composition was filled into a stainless steel hole having a hole with an inner diameter of 3 mm and a height of 6 mm, and both upper and lower surfaces were pressed with glass plates, and a visible light irradiator Econolite (manufactured by Yoshida Co., Ltd.) )
Light irradiation was performed for 40 seconds from both lower surfaces. The test piece was released from the mold. 2) Flexural Strength The filling composition is filled into a hole of a stainless steel mold having a thickness of 2 mm, a width of 2 mm, and a length of 25 mm, and pressed with a glass plate. )
Light irradiation was performed for 120 seconds from both upper and lower sides in the thickness direction. The test pieces were released from all molds. 3) Hardness The filling composition is filled into a hole of a stainless steel mold having a hole having an inner diameter of 20 mm and a height of 2 mm, and both upper and lower surfaces are pressed by a glass plate, and then subjected to a test by the same polymerization method as in 2). A piece was prepared, and the glass pressure contact surface was polished with a No. 1500 Sic abrasive paper to obtain a measurement surface. 4) Water Absorption The filling composition is filled in a hole of a stainless steel mold having a thickness of 3 mm, a width of 15 mm, and a length of 20 mm, and both upper and lower surfaces are pressed by a glass plate. Was prepared, and each surface was polished with No. 240 Sic abrasive paper. Compressive strength, flexural strength, hardness and test pieces were tested immediately after immersion in water at 37 ° C. for 24 hours. Moreover, the water-absorbing test piece was stored in the air at 37 ° C. after the preparation until the weight reached a constant weight value. 5) Surface Lubricity After curing 0.2 g of the filling composition material for 20 seconds with light irradiation, the light irradiation surface was polished at a white point (manufactured by Matsukaze Co., Ltd.) and judged by visual observation. [0029] 2. Test method 1) Compression strength The test was performed at a crosshead speed of 2 mm / min using an Instron universal testing machine (MODEL 4206). 2) Bending strength The test was performed at a crosshead speed of 0.5 mm / min using an Instron universal testing machine (MODEL 4206). 3) Hardness Using a Knoop hardness tester (MVK-E manufactured by Akashi Seisakusho), the test was performed under the conditions of a load of 50 kg and a load holding time of 20 seconds. 4) Water absorbency Stored in the air at 37 ° C., immersed in water at 37 ° C. when the weight reaches a constant weight (m ₁ ), measured the weight (m ₂ ) after 24 hours, The water absorption was calculated. (M ₂ −m ₁ ) / specimen surface area (Example 1) 93.0 g of Si (OC ₂ H ₅ ) ₄ (special grade reagent) was added to ethyl alcohol (special grade reagent).
Solution A dissolved in 670.7 g, 223.6 g of a 28% by weight aqueous NH ₄ OH solution, and solution B in which 173.9 g of distilled water were dissolved in 19999.5 g of ethyl alcohol were mixed and stirred, and reacted at 20 ° C. for 1 hour. . After the solid content was separated from the solution using a centrifugal separator, it was dried and crushed, calcined at 1050 ° C. for 1 hour, and crushed again to obtain silica particles. As a result of image analysis of a scanning electron microscope photograph of the silica particles, the silica particles were spherical particles having an average particle diameter of 0.3 μm and a standard deviation of 1.05. Next, 225.0 g of CH ₃ Si (OC ₂ H ₅ ) ₃ was added to a mixed solution of 18.8 g of a 28% by weight aqueous NH ₄ OH solution and 1500.0 g of distilled water, followed by stirring at 20 ° C. for 1 hour. Thereafter, the mixture was heated to 50 ° C. and further stirred for 1 hour. After the solid content was separated from the solution using a centrifugal separator, it was dried and crushed, calcined at 1100 ° C. for 1 hour, and crushed again to obtain silica particles. Image analysis of a scanning electron micrograph of the silica particles revealed that the particles were true spherical particles having an average particle size of 1.5 μm and a standard deviation of 1.08. Next, 6.8 kg of the 0.3 μm silica particles and 2.6 kg of the 1.5 μm silica particles obtained as described above were mixed with a jet mill type mixer (a single-track jet manufactured by Seishin Enterprise Co., Ltd.). 2.6 μm particles using a mill STJ-200).
kg / Hr, air pressure 7.5 k at feed rate of 0.3 kg particles 1.0 kg / Hr
The mixing treatment was performed under the conditions of g / cm ² and an air supply rate of 3.4 m ³ / min. After treating the mixed silica particles by the surface treatment of the above [1], the silica particles are mixed with the monomer prepared in the above [1] so as to have a packing ratio shown in Table 1 by Ishikawa stirring agitation. Machine (Co., Ltd.)
After the mixing treatment using Ishikawa Plant), a test piece was prepared and measured. Example 2 A mixed particle of 0.3 μm silica particles and 1.5 μm silica particles mixed and collected in Example 1 was fed at a feed rate of 3.6 kg / Hr in the same manner as in Example 1. Under the conditions, the mixing treatment was performed again, and the measurement was performed in the same manner as in Example 1. Example 3 The same operation as in Example 2 was performed, except that the mixing process performed in Example 2 was repeated once more. (Comparative Example 1) In Example 1, the surface treatment was performed separately without previously mixing the silica particles, and this was directly mixed with the monomer. The pieces could not be created. (Comparative Example 2) In Comparative Example 1, the filling rate of the silica particles was set to the maximum amount (77%) at which a test piece of the filling composition could be prepared, and the results obtained when the same operation was performed for the others were shown. It is shown in FIG. [Table 1] According to the present invention, in the dental filling composition in which the inorganic filler specified in the present invention is mixed with a polymerizable monomer, small particles are efficiently filled in the gaps between the large particles. Therefore, the amount of the inorganic filler can be increased while maintaining a high degree of fluidity in a paste state, and the adhesiveness is low and the workability such as filling in a defective portion is excellent. A dental filling composition having excellent gloss smoothness, low water absorption, high mechanical strength, and well-balanced physical properties as compared with conventional products can be obtained.

Claims (1)

Claims: 1. A dental filling composition comprising a polymerizable monomer and an inorganic filler, wherein the inorganic filler has a spherical shape having a particle size of 0.01 to 30 μm. Comprising at least two groups having different average particle diameters. One of the groups includes spherical inorganic oxides having an average particle diameter in the range of 1 to 30 μm, and the average particle diameters are close to each other. A spherical inorganic oxide mixture in which the ratio of the average particle diameter is 2 or more in the two groups and the group having the large average particle diameter accounts for 50% or more of the total weight of the two groups; and A dental filling composition characterized in that the two groups of inorganic oxide particles are previously mixed in a dry air stream . 2. The dental filling composition according to claim 1, wherein the inorganic filler is spherical silica synthesized by hydrolysis polymerization of alkoxysilane.