JPH0314282B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a composite restorative material characterized in that mixed particles having at least two specified average particle diameters, large and small, are used as a filler. Composite restorative materials are used, for example, throughout the dental field, and are either filled or applied to the tooth to be treated intraorally and then polymerized, or are given an appropriate form outside the oral cavity, polymerized, and then placed on the tooth. There are things that are glued or joined together. [Prior art and problems to be solved by the invention] Composite restorative materials used in dentistry are different from ordinary composite materials due to their special characteristics in use; their main components are liquid polymerizable monomers and inorganic materials. It is delivered to the user in the form of a paste-like mixture with fillers, and after polymerization and hardening during various intra-oral or extra-oral operations by a doctor, it becomes a conventional hard composite material. Therefore, the performance required for such a composite restorative material is divided into the performance required for a paste-like mixture and the performance required for a hard material after polymerization and hardening. In other words, the former relates to the operational performance of kneading, filling, and forming paste into tooth shapes, while the latter relates to mechanical and physical properties such as compressive strength and tensile strength required of ordinary materials. It is. In order to enhance the various performances required of such composite restorative materials, many innovations and improvements have been made in terms of the chemical structure of polymerizable monomers, the material, particle size, shape, etc. of fillers. It's here. For example, the polymerizable monomer may be an acrylate compound or a methacrylate compound, the material of the filler may be an inorganic oxide, a resin or a composite resin, and the particle size may be a combination of fillers of various sizes. In addition, fibrous, spherical, rod-like, amorphous, etc. shapes are being considered, and materials with better performance than conventional materials made of polymerizable monomers alone are now being obtained. However, on the other hand, composite restorative materials used in dentistry have gone from being used simply for filling and restoring carious cavities, to recently being used for filling cavities in the roots of teeth after pulp extraction, for example. At the same time, attempts are being made to apply it to the restoration of areas where metal materials have been used in the past, such as in restoring the shape of lost tooth crowns. When applied to such special uses,
In addition to the performance required of conventional composite restorative materials, new performance is required. For example, when used for constructing an abutment after pulp extraction as described above, a composite restorative material with particularly excellent performance is desired in the following respects. First of all, at the stage of paste-like composite restorative material before hardening, first of all, when filling the dental pulp cavity with the restorative material after pulp extraction, it goes without saying that it can be easily inserted into the cavity, but also that it can be easily inserted into the pulp cavity wall. It is important to have fluidity that quickly spreads to the inside of the minute dentinal tubules that exist. Second, in order to perform the function of restoring the lost shape of the tooth crown, in addition to fluidity, appropriate hardness of the paste is required to facilitate shaping. Next, the paste that has been filled and formed in this way undergoes a polymerization and hardening reaction to become a hard composite restorative material that can withstand various forces in the oral cavity. This is accompanied by volumetric contraction. That is, the smaller the degree of shrinkage during curing (hereinafter referred to as polymerization shrinkage rate), the smaller the strain and gap at the interface between the tooth and the composite restorative material, and the better the adhesive and sealing properties of the restorative material. Furthermore, the polymerized and hardened composite restorative material is surrounded by ivory tissue and metal materials and is exposed to harsh conditions in the oral cavity. It is a characteristic of In other words, the closer the coefficient of thermal expansion of the restorative material is to that of the surrounding ivory tissue or metal material, the lower the local stress at the interface, and the better the restorative material. The volumetric shrinkage rate and coefficient of thermal expansion after curing of the composite restorative material as described above are also related to the type of polymerizable monomer, which is one of the components of the composite restorative material, but the degree of is small and largely depends on the content of another component, the inorganic filler. That is, the higher the content of the inorganic filler, the lower the polymerization shrinkage rate and the lower the coefficient of thermal expansion. As mentioned above, the content of the inorganic filler is as high as possible, and at the same time, it has the appropriate hardness to facilitate the fluidity and shape that can reach not only the inside of the dental pulp cavity but also the inside of the dentinal tubules on the inner wall of the cavity. In order to obtain a paste-like composite restorative material, various studies have been made, particularly regarding the size, particle size distribution, shape, etc. of the filler, but no solution has yet been reached. For example, in Special Publication No. 44-19388,
It has been proposed to use inorganic spherules with a size of 1 to 100 μm as a filler, but such a method that uses only fillers with a relatively large particle size of 1 μm or more requires increasing the filler content. However, at the same time, the flowability is reduced and prompt filling of details becomes insufficient. Also, German Patent Publication No.
No. 2403211 proposes using a filler with a diameter of 0.7 μm or less, but in this case, although fluidity is improved, it is difficult to give a shape. moreover,
In JP-A-57-120506, 10 to 55% of the filler is smaller than 0.5 μm, preferably 0.1 μm or less.
It has been proposed to use a mixture with a filler having a thickness of 0.5 to 80 μm. However, when using ultrafine particles of about 0.02 μm, which are specifically used in this publication, a high filler content is achieved in the entire pulp cavity, but in small localized areas such as dentinal tubules. In the cavity, the filling material with a large particle size in the mixed filling material remains in the pulp cavity, and only the composite restorative material with a low content of inorganic filler consisting of ultrafine particle portions and polymerizable monomers enters. The filler content in the composite restorative material in local voids such as dentinal tubules (hereinafter referred to as detailed filler content) is related to the sealing and adhesion of the interface between the dentine tissue and the hardened composite restorative material. This is an important factor. In other words, when the content of the detailed filling material decreases, the volume shrinkage due to polymerization and hardening of the composite restorative material within the local voids increases, resulting in distortion and voids between the tooth structure and the sealing and adhesion of the interface. decreases. For these reasons, the method proposed in the above-mentioned publication cannot be said to provide sufficient sealing and adhesion at the interface, and a method is desired that further increases the content of the fine filler. [Means for Solving the Problems] In order to solve the problems desired in dental composite restorative materials as described above, the present inventors have specifically developed a filling material, which is one of the components of the composite restorative materials. As a result of intensive research on the shape and particle size distribution, we found that by using mixed particles with at least two types of average particle sizes, large and small, we were able to achieve a high content of filler while also reducing the small tubes in the wall of the pulp cavity. It has sufficient fluidity to reach the inside, has a high content of small filler in the part that has entered the inside of the tubule, has excellent adhesion and sealing properties to the tooth structure, and is hard enough to form the shape of the tooth crown. We have completed a paste-like composite repair material that also has the following properties and have proposed it here. That is, the present invention provides a dental composite restorative material containing a polymerizable monomer, a filler, and a polymerization initiator, in which (a) particles (A) having an average particle size of 1.0 to 100 μm are 5 to 95 μm;
(b) particles having an average particle diameter of 0.1 to 1.0 μm and a standard deviation value of 1.30 or less (B) 95 to 5% by weight; It is a material. The polymerizable monomer used in the present invention is not particularly limited, and for example, known monomers used as dental composite restorative materials can be used. Examples of generally preferred polymerizable monomers include various acrylic acid compounds, methacrylic acid compounds, acrylic ester compounds, methacrylic ester compounds, urethane compounds, styrene compounds, etc. that can be used for dental purposes. Polymerizable compounds can be used without limitation. More specifically, examples of the above compounds include 2,2-bis[4(2-hydroxy-3-methacryloxypropoxy)phenyl]propane, methyl methacrylate, bismethacryloethoxyphenylpropane, triethylene glycol dimethacrylate, Diethylene glycol dimethacrylate, tetramethylolmethyl triarylate, tetramethylolmethyltetraacrylate, tetramethylolmethane trimethacrylate, trimethylolethane trimethacrylate,
There are also urethane compounds represented by the following structural formula. However, in the above formula, R ₁ , R ₂ , R ₃ and R ₄ are the same or different H or CH ₃ and (-A)- is (-CH ₂ )- ₆
，

[expression] or

〔Effect of the invention〕

When the composite restorative material obtained by the present invention is used in the dental field, the filler content can be increased from 80% by weight to 95% by weight, as shown in the examples below. It has a small volumetric shrinkage rate, a significantly small coefficient of thermal expansion after curing, and excellent mechanical strength. In particular, despite the high filler content reaching 80% to 95% by weight, the restorative material according to the present invention does not lose its fluidity, which extends to the fine details in the pulp cavity, and The content of the filling material in the restorative material is high, it has excellent adhesion to the tooth structure, and it also maintains operability when shaping the crown of the tooth. It has excellent performance not found in other materials, and its effects are remarkable. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, the definitions of various quantities related to the properties of materials shown in the text and examples and the methods for measuring them are as follows. (1) Standard deviation values of particle size and particle size distribution Take a scanning or transmission electron micrograph of a powder, and calculate the number of particles (n) observed within a unit field of view of the photo, and the particle size (diameter Xi ) is calculated using the following formula. Standard deviation value = X + σn-1/X However,

【formula】

(2) Average symmetry value of particles Take a scanning electron micrograph of the powder, and calculate the number of particles (n), the maximum width of the particles as the diameter (L), and the major axis of the particles observed within the unit field of view of the photo. With the maximum width in the direction orthogonal to the minor axis (B), n, L, and B are calculated using the following formula. (3) Specific surface area A rapid surface area measurement device SA-1000 manufactured by Shida Kagaku Kikai Kogyo Co., Ltd. was used. The measurement principle is the BET method. (4) Compressive strength Depending on the type of polymerization initiator, the paste-like composite restorative material can be polymerized at 37℃ for 30 minutes, or it can be cured using a commercially available visible light irradiator “Opteirax” (manufactured by Demetron). After polymerization by light irradiation for 37 min,
A test piece was immersed in water at ℃ for 24 hours. Its size and shape are cylindrical with a diameter of 4 mm and a height of 10 mm. This test piece was attached to a testing machine (Toyo Baudouin, UTM-5T), and the compressive strength was measured at a crosshead speed of 10 mm/min. (5) Tensile strength Depending on the type of polymerization initiator, the paste-like composite restorative material may be polymerized at 37℃ for 30 minutes, or a commercially available visible light irradiator "Opteirax" (manufactured by Demetron) may be used to After polymerization by light irradiation for 37 min,
A test piece was immersed in water at ℃ for 24 hours. Its size and shape are cylindrical with a diameter of 6 mm and a height of 6 mm. This test piece was mounted on a testing machine (Toyo Baudouin, UTM-5T), and the tensile strength was measured at a crosshead speed of 10 mm/min. (6) Bending strength Depending on the type of polymerization initiator, the paste-like composite restorative material may be polymerized at 37°C for 30 minutes, or it may be After polymerization by light irradiation for 37 min,
The test piece was immersed in water at ℃ for 24 hours.
Its size and shape are 2 x 2 x 25 mm prismatic. The bending test was conducted using a bending test device with a distance between fulcrums of 20 mm attached to a UTM-5T manufactured by Toyo Baudouin, and a crosshead speed of 0.5 mm/min. (7) Surface hardness Depending on the type of polymerization initiator, the paste composite restorative material may be polymerized at 37°C for 30 minutes, or a commercially available visible light irradiator "Opteirax" (manufactured by Demetron) may be used to cure the paste. After polymerization by light irradiation for 37 min,
A test piece was immersed in water at ℃ for 24 hours. Its size and shape are plate-like, 2.5 x 10 x 10 mm. The measurement used a micro Brinell hardness test. (8) Coefficient of thermal expansion Depending on the type of polymerization initiator, paste composite restorative materials are polymerized at 37°C for 24 hours, or polymerized by irradiation for 1 minute using the visible light irradiator mentioned above. was used as the test piece. Its size and shape are the same as those used in the compression test. The measurement was performed using Thermoflex manufactured by Rigaku Denki Co., Ltd., and was determined based on the coefficient of linear expansion between 20°C and 50°C. (9) Water absorption rate Depending on the type of polymerization initiator, the paste-like composite restorative material may be polymerized at 37°C for 30 minutes, or it may be irradiated with the visible light irradiator mentioned above for 1 minute to polymerize, and then polished. After polishing the surface with paper (Nihon Kenshi, No. 1000), it was stored in an anhydrous magnesium sulfate desiccator at 37°C until it reached a constant volume. Thereafter, it was immersed in water at 37°C, and its weight was measured 24 hours later. The water absorption rate is calculated by dividing the increased weight (mg) by the surface area (cm ² ) of the test piece before immersion. The size and shape of this test piece was a plate of 1.0 x 10 x 10 mm. (10) Paste flow rate Fill a plastic syringe with an inner diameter of 5 mm, a length of 20 mm, and an outlet diameter of 1 mm with approximately 0.2 ml of paste composite restorative material, push the piston into the cylinder approximately 3 mm, and secure the piston with a stopper. After that, I applied a load of 700g to the piston and attached a dial gauge. The piston used here has an outer diameter of 5
It was made of plastic with a length of 70 mm, but the part that came into contact with the composite material was made of rubber. The distance traveled by the piston 10 seconds after the stopper was removed was measured using a dial gauge, and the distance was expressed as the amount of paste flow. The larger the moving distance, the easier the flow and the lower the viscosity of the composite restorative material. (11) Pressure filling rate A plastic cylinder with an inner diameter of 4 mm, a length of 12 mm, and an outlet diameter of 1 mm and a plastic piston with an outer diameter of 4 mm and a length of 70 mm were used. However, four elliptical grooves with a radius of 1 mm and a center angle of 40 degrees were formed vertically on the piston, so that the cross section of the piston was cross-shaped. In a room at 23°C, the cylinder was filled to the brim with paste-like composite restorative material, taking care not to introduce any air bubbles. Then, push the piston at a speed of 1 mm per second,
The length of the paste-like composite restorative material flowing out from the outlet of the cylinder was measured. This operation was repeated five times, the average value of the outflow length was taken as Lmm, and the pressure filling rate was calculated using the following formula. Pressure filling rate = L/12 x 100 (%) Composite restorative material that is difficult to give shape to and is difficult to pressurize easily flows out from the groove of the piston, and the amount of composite restorative material that flows out to the outlet of the cylinder decreases. , the pressure welding filling rate becomes low. (12) Detailed filling material content A fresh bovine tooth was cut approximately 5 mm from the root side and the pulp was extracted. The pulp cavity was etched with a 35% orthophosphoric acid aqueous solution for 30 seconds, washed with water, and washed with water in an ultrasonic cleaner for 10 minutes. Furthermore, after washing with methanol, it was dried with air blow. Five bovine teeth treated in this way were filled with a paste-like composite restorative material from the tooth root side using a dental restorative material filling syringe.
After further raising the layer to a thickness of 3 mm, it was covered with a polypropylene film (thickness: 50 μm). A load of 5 kg was applied from above the cover for 1 minute, and then depending on the type of polymerization initiator, polymerization was carried out by irradiating it with light for 1 minute using a visible light irradiator, or polymerization was carried out at 37° C. for 12 hours. This was left in a 12N hydrochloric acid aqueous solution at 25°C for 7 days to completely dissolve and remove the dentin, thereby recovering only the hardened composite restorative material.After washing with water, the thin fibrous parts corresponding to dentinal tubules were recovered. and the part corresponding to the dental pulp cavity. Among these, the thin fibrous parts were further washed with methanol, and after air drying,
Dry under reduced pressure for 12 hours. The fibrous hardened body obtained in this way was placed on a thermobalance (manufactured by Shimadzu Corporation, DT-
30), the content of the inorganic filler contained in the cured body was calculated as a percentage from the weight loss rate at 700°C, and this was defined as the detailed filler content. (13) Polymerization shrinkage rate The inner diameter of one end is 2 mm, the inner diameter of the other end is 1.5 mm,
Silicone oil was applied as a mold release agent to a Pyrex glass tube with a length of 24,000 mm, and it was thoroughly wiped off. The glass tube was filled to the brim with the composite restorative material kneaded in a room at 23°C and stored in a heated greenhouse at 37°C for 3 hours or irradiated with light for 1 minute. 37℃
When stored in a constant temperature room, the composite restoration material was taken out after 3 hours and cooled to room temperature in a room at 23°C, and its length was measured with a micrometer. The difference between this length and the length of the glass tube divided by the length of the glass tube was multiplied by 100, which was taken as the polymerization shrinkage rate. Example 1 Glass beads manufactured by Toshiba Balloteini, with an average particle size of 18 μm and an average uniformity of 0.95, were surface-treated with 1% by weight of γ-methacryloxypropyltrimethoxysilane. This is referred to as a surface treated filler (A-1). 100 to 150 mesh α-quartz is ground with a vibrating ball mill, particle size range is 1 to 40 μm, average particle size is
A non-spherical (pulverized) powder of 9 μm was obtained. This was subjected to surface treatment in the same manner as (A-1), and this was designated as surface-treated filler (A-2). Ethyl silicate (manufactured by Nippon Colcoat) 350
A solution of g dissolved in methanol 2.0 is called solution A. 28% ammonia water 0.9 and methanol 3.6
Let the mixed solution be liquid B. Liquids A and B were kept at 20°C, and liquid A was added dropwise to liquid B at a rate of 7 ml per minute while stirring liquid B with a stirrer equipped with a bladed stirring rod. As the amount dropped increased, the color of liquid B became white. The white solution was rotary evaporated to remove the solvent and yield a white powder. This powder is calcined at 1000℃ for 1 hour, and the particle size range is
0.21-0.35μm, average particle diameter 0.25μm, standard deviation value
It was a spherical powder with an average uniformity value of 1.08 and 0.99. This powder was surface-treated with 5% by weight of γ-methacryloxypropylmethoxysilane, and this was designated as a surface-treated filler (B-1). 40 parts by weight of triethylene glycol dimethacrylate (hereinafter referred to as TEGDMA) and 2,2-bis[P-(γ-methacryloxy-P-hydroxypropoxy)phenyl]propane (hereinafter referred to as Bis-
60 parts by weight (referred to as GMA) were mixed and divided into two parts. Then, on one side, N,N-diethanol-
1.5 parts by weight of P-toluidine and 1.8 parts by weight of benzoyl peroxide were mixed in the other part. These are used as polymerizable monomers for paste A and paste B, respectively. A polymerizable monomer for paste A or paste B is added to the filler containing 40 parts by weight of the filler (A-1), 40 parts by weight of the filler (A-2), and 20 parts by weight of the filler (B-1). A paste A or a paste B composite restorative material was obtained by blending a polymerizable monomer for use and thoroughly kneading it in an alumina mortar. At this time, the content of the silanized filler in the composite restorative material was 86.2% by weight, and the viscosity of the paste was appropriate for operation. The paste flow rate of this composite restorative material was 1.7 mm, the pressure filling rate was 93.3%, the detail filler content was 72%, and the polymerization shrinkage rate was 0.17%. The physical properties of the above paste A and paste B were mixed in equal amounts at room temperature for 30 seconds and cured. As a result, the thermal expansion coefficient was 18.2 ppm/℃, and the water absorption rate was 0.19.
mg/cm ² , surface hardness 70.0, compressive strength 3770Kg/cm ² ,
The tensile strength was 634 Kg/cm ² and the bending strength was 1250 Kg/cm ² . Examples 2 to 7 Toyota's method (Journal of the Japanese Society of Dental Materials and Instruments Machinery 36 (1),
78 (1979)), an aqueous water glass solution was added to a mixed solvent of nonionic surfactants (polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan monostearate) and benzene to prepare an emulsion. It was added to an aqueous barium chloride solution with stirring to obtain a white powder of microspherical barium silicate. This white powder was washed with water to completely remove barium, and then calcined at 1000°C for 1 hour. The powder was amorphous silica with a particle size range of 1.0 to 10 μm, an average particle size of 5 μm, and an average symmetry value of 0.96. . This particle was surface-treated in the same manner as (A-1) of Example 1, and is designated as (A-3). 250 mesh α-quartz is ground with a vibrating ball mill, particle size range is 0.7-0.9μm, average particle size is 0.77μm.
A non-spherical powder with a standard deviation value of 1.23 was obtained. This was surface-treated in the same manner as (B-1) of Example 1 and is designated as (B-2). Ultrafine silica (manufactured by Aerosil, Aerosil)
130), BET specific surface of 130m ² /g and average particle size of approximately 16μ
(B-3) is obtained by surface treating m with 10% by weight of γ-methacryloxypropyltrimethoxysilane. Surface treated filler (A-1), (A-
2) and/or (B-1) and a polymerizable monomer and/or (A-3), (B-2) and/or (B-3), paste in the same manner as in Example 1. was prepared, and the paste flow rate, pressure filling rate, and detail filler content were measured. Furthermore, the physical properties of the cured composite restorative material were measured, and the results are summarized in Table 1. Comparative Examples 1 to 5 In the manufacturing method of (B-1) described in Example 1,
All except that the dropping rate of liquid A was 50 ml per minute (B
-1) Particle size range 0.25
~0.91μm, average particle size 0.39μm, standard deviation value 1.76,
A spherical powder with an average uniformity value of 0.85 was obtained. Thereafter, the surface was treated with 5% by weight of γ-methacryloxypropylmethoxysilane. This is referred to as a surface treated filler (B-4). Surface treated filler (A-1), (A-2), (A-
3), (B-1), (B-3) and/or (B-
4), a paste was prepared in the same manner as in Example 1, and the paste flow rate, pressure filling rate, and detail filler content were measured. Furthermore, the results of measuring the physical properties of the cured composite restorative material are summarized in Table 2.

【table】

【table】

【table】

[Table] Example 8 Silica-titania spherical particles having an average particle diameter of 18 μm and an average uniformity of 0.95 were surface-treated with 1% by weight of γ-methacrylopropyltrimethoxysilane. This is referred to as a surface treated filler (A-4). 100 to 150 meshes of α-quartz were ground in a vibrating ball mill to obtain a non-spherical (pulverized) powder with a particle size range of 1 to 40 μm and an average particle size of 9 μm. This was surface-treated in the same manner as (A-4), and a surface-treated filler (A-4) was prepared.
5). Particle size range 0.21-0.35μm, average particle size 0.25μm,
Silica titania spherical particles having a standard deviation value of 1.08 and an average uniformity value of 0.99 were surface-treated with 5% by weight of γ-methacryloxypropylmethoxysilane, and this was used as a surface-treated filler (B-5). Meanwhile, camphorquinone 0.5 as a photosensitizer
parts by weight and 0.5 parts by weight of N,N-dimethylaminoethyl methacrylate as a curing accelerator were mixed and dissolved. 40 parts by weight (A-4), 40 parts by weight (A-5),
and 20 parts by weight of the filler (B-5) was blended with a polymerizable monomer for paste in a dark room, and thoroughly kneaded in an alumina mortar to obtain a composite restorative material.
At this time, the content of the silanized filler in the composite restorative material was 86.2% by weight, and the viscosity of the paste was appropriate for operation. The paste flow rate of this composite restorative material was 1.7 mm, the pressure filling rate was 91.6%, the detail filler content was 72%, and the polymerization shrinkage rate was 0.15%. The above paste was cured by irradiation with a commercially available visible light irradiator "Opteirax" (manufactured by Demetron), and its physical properties were measured. As a result, the thermal expansion coefficient was 14.3 ppm/℃, and the water absorption rate was 0.15 mg/℃. ^cm2 , surface hardness 70.0, compressive strength 3730Kg/ ^cm2 , tensile strength 628
Kg/cm ² , and the bending strength was 1200 Kg/cm ² . Examples 9-12 Polymerizable monomers used in Example 1, Examples 1-7
Using the filler described in Table 3 and the photosensitizer and curing accelerator shown in Table 3, a paste was prepared in the same manner as in Example 1, and the paste flow rate, pressure filling rate, and detail filler content were determined. It was measured. Furthermore, the physical properties of the cured composite restorative material were measured and the results are presented.
4.

【table】

【table】

【table】

Claims (1)

[Scope of Claims] 1. In a composite restorative material containing a polymerizable monomer, a filler, and a polymerization initiator, as a filler, (a) particles (A) having an average particle size of 1.0 to 100 μm;
(b) particles having an average particle size of 0.1 to 1.0 μm and a standard deviation value of 1.30 or less (B) 95 to 5% by weight; Material. 2. The composite restorative material according to claim 1, wherein both the particles (A) and the particles (B) are approximately spherical. 3. The composite restorative material according to claim 1, wherein the standard deviation value of the particles (B) is 1.20 or less.