Dental fluoroaluminosilicate glass powder

Abstract

One aspect of the present invention involves fluoroaluminosilicate glass powder. Dental fluoroaluminosilicate glass powder, with a diameter by volume. In the 50th percentile, it is 5.0 micrometers or more and 9.0 micrometers or more. Less than and whose diameter by volume in the 10th percentile is... 2.4 micrometers or more

Description

Dental Fluoroaluminosilicate Glass Powder

[0001] The present invention relates to a dental fluoroaluminosilicate glass powder and a glass ionomer cement.

[0002] Glass ionomer cement has excellent properties, such as extremely good affinity with the body, excellent aesthetics due to its translucent hardened form, excellent adhesion to tooth tissues such as enamel and dentin, and cariostatic properties due to fluoride. For these reasons, glass ionomer cement is widely used for filling carious cavities, bonding orthodontic bands for crowns, inlays, and bridges, filling cavity linings, root canals, building abutments, and preventive sealing.

[0003] Glass ionomer cement generally contains an aqueous solution of a polycarboxylic acid polymer and a fluoroaluminosilicate glass powder (see, for example, Patent Document 1).

[0004] Here, when the aqueous solution of the polycarboxylic acid polymer and the fluoroaluminosilicate glass powder are kneaded, the aluminum ions (Al ３＋ ) and the conjugate base of the polycarboxylic acid polymer undergo ionic crosslinking, resulting in hardening.

[0005] International Publication No. 2016 / 002600

[0006] It is generally desired to improve the compressive strength of the hardened glass ionomer cement, and one possible way to achieve this is to use a fluoroaluminosilicate glass powder with a small particle size.

[0007] However, when a fluoroaluminosilicate glass powder having a small particle size is used, there is a problem in that the time from the start of mixing the aqueous solution of the polycarboxylic acid polymer and the fluoroaluminosilicate glass powder until hardening, i.e., the working time of the glass ionomer cement, becomes shorter.

[0008] An object of one aspect of the present invention is to provide a dental fluoroaluminosilicate glass powder that can extend the working time of glass ionomer cement and increase the compressive strength of the hardened glass ionomer cement.

[0009] In one aspect of the present invention, a dental fluoroaluminosilicate glass powder has a 50% volumetric diameter of 5.0 μm or more and 9.0 μm or less, and a 10% volumetric diameter of 2.4 μm or more.

[0010] According to one aspect of the present invention, it is possible to provide a dental fluoroaluminosilicate glass powder that can extend the working time of glass ionomer cement and increase the compressive strength of the hardened glass ionomer cement.

[0011] Next, an embodiment of the present invention will be described.

[0012] <Dental Fluoroaluminosilicate Glass Powder> The 50% volumetric diameter (d50) of the dental fluoroaluminosilicate glass powder of this embodiment is 5.0 μm or more and 9.0 μm or less, and preferably 5.1 μm or more and 8.0 μm or less. If the d50 of the dental fluoroaluminosilicate glass powder is less than 5.0 μm, the working time of the glass ionomer cement will be shortened. On the other hand, if the d50 of the dental fluoroaluminosilicate glass powder is more than 9.0 μm, the compressive strength of the cured glass ionomer cement will be reduced.

[0013] The 10% volumetric diameter (d10) of the dental fluoroaluminosilicate glass powder of this embodiment is 2.4 μm or more, and preferably 2.7 μm or more. If the d10 of the dental fluoroaluminosilicate glass powder is less than 2.4 μm, it will be impossible to knead the dental fluoroaluminosilicate glass powder with the aqueous solution of the polycarboxylic acid polymer.

[0014] The d10 of the dental fluoroaluminosilicate glass powder of this embodiment is usually 4.8 μm or less.

[0015] The 90% volumetric diameter (d90) of the dental fluoroaluminosilicate glass powder of this embodiment is preferably 13.0 μm or more and 20.0 μm or less, and more preferably 14.0 μm or more and 19.0 μm or less. When the dental fluoroaluminosilicate glass powder of this embodiment has a d90 of 13.0 μm or more, the working time of the glass ionomer cement is further extended, and when it is 20.0 μm or less, the compressive strength of the hardened glass ionomer cement is further increased.

[0016] The fluorine (F) content in the dental fluoroaluminosilicate glass powder of this embodiment is preferably 1 to 30 mass %, more preferably 3 to 20 mass %.

[0017] The content of aluminum in the dental fluoroaluminosilicate glass powder of this embodiment is aluminum oxide (Al ２ O ３ The amount converted into the total mass of the polymer is preferably 15 to 35 mass %, and more preferably 20 to 30 mass %.

[0018] The content of silicon in the dental fluoroaluminosilicate glass powder of this embodiment is silicon oxide (SiO ２ The amount converted into the total mass of the polymer is preferably 15 to 50 mass %, and more preferably 20 to 40 mass %.

[0019] The content of phosphorus in the dental fluoroaluminosilicate glass powder of this embodiment is phosphorus (V) oxide (P ２ O ５ The amount converted into the total mass of the polymer is preferably 0 to 10 mass %, and more preferably 1 to 5 mass %.

[0020] The sodium content in the dental fluoroaluminosilicate glass powder of this embodiment is sodium oxide (Na ２ O), the amount is preferably 0 to 15% by mass, more preferably 1 to 10% by mass.

[0021] The content of potassium in the dental fluoroaluminosilicate glass powder of this embodiment is potassium oxide (K ２O), the amount is preferably 0 to 10% by mass, more preferably 1 to 5% by mass.

[0022] The strontium content in the dental fluoroaluminosilicate glass powder of this embodiment is preferably 0 to 40 mass %, and more preferably 10 to 30 mass %, converted into strontium oxide (SrO).

[0023] The lanthanum content in the dental fluoroaluminosilicate glass powder of this embodiment is lanthanum oxide (La ２ O ３ The amount converted into the total mass of the polymer is preferably 0 to 50 mass %, and more preferably 1 to 40 mass %.

[0024] The dental fluoroaluminosilicate glass powder of this embodiment can be applied to, for example, glass ionomer cement.

[0025] <Glass Ionomer Cement> The glass ionomer cement of this embodiment contains the dental fluoroaluminosilicate glass powder of this embodiment and an aqueous solution of a polycarboxylic acid polymer.

[0026] The polycarboxylic acid polymer is not particularly limited, but for example, a homopolymer or copolymer of an α,β-unsaturated carboxylic acid can be used.

[0027] Examples of the α,β-unsaturated carboxylic acid include acrylic acid, methacrylic acid, 2-chloroacrylic acid, 3-chloroacrylic acid, aconitic acid, mesaconic acid, maleic acid, itaconic acid, fumaric acid, glutaconic acid, and citraconic acid.

[0028] The polycarboxylic acid polymer may also be a copolymer of an α,β-unsaturated carboxylic acid and a monomer copolymerizable with the α,β-unsaturated carboxylic acid.

[0029] Examples of components that can be copolymerized with the α,β-unsaturated carboxylic acid include acrylamide, acrylonitrile, methacrylic acid esters, acrylates, vinyl chloride, allyl chloride, and vinyl acetate.

[0030] In this case, the ratio of the α,β-unsaturated carboxylic acid to the monomers constituting the polycarboxylic acid polymer is preferably 50% by mass or more.

[0031] The polycarboxylic acid polymer is preferably a homopolymer or copolymer of acrylic acid or itaconic acid.

[0032] At least a part of the polycarboxylic acid polymer may be in the form of powder.

[0033] In the glass ionomer cement of this embodiment, when the dental fluoroaluminosilicate glass powder and the aqueous solution of the polycarboxylic acid polymer are kneaded, the mass ratio of the dental fluoroaluminosilicate glass powder to the aqueous solution of the polycarboxylic acid polymer (hereinafter referred to as powder-liquid ratio) is preferably 1 to 5, and more preferably 2.8 to 4.0. When the powder-liquid ratio is 1 or more, the compressive strength of the set body of the glass ionomer cement becomes higher, and when it is 5 or less, it becomes easier to knead the dental fluoroaluminosilicate glass powder and the aqueous solution of the polycarboxylic acid polymer.

[0034] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0035] <Preparation of fluoroaluminosilicate glass powder> Silica (SiO ２ ) 28 g, alumina (Al ２ O ３ ) 10 g, aluminum fluoride (AlF ３ ) 18g, strontium fluoride (SrF ２ ) 17 g, aluminum phosphate (AlPO ４ ) 11g, Creolite (Na ３ AlF ６ ) 6g, potassium fluoride (KF) 6g, lanthanum oxide (La ２ O ３) were thoroughly mixed in a mortar. The resulting mixture was placed in a porcelain crucible and placed in an electric furnace. The electric furnace was heated to 1,300°C, and the mixture was melted and thoroughly homogenized, and then poured into water to obtain a fluoroaluminosilicate glass mass. The resulting fluoroaluminosilicate glass mass was pulverized in a ball mill for 20 hours and then passed through a 120-mesh sieve to obtain a fluoroaluminosilicate glass powder.

[0036] The resulting fluoroaluminosilicate glass powder was analyzed by fluorescent X-ray analysis and was found to have the following composition.

[0037] F: 18% by mass Na ２ O: 3% by mass Al ２ O ３ :22 mass% SiO ２ :22 mass% P ２ O ５ :5 mass% K ２ O: 5% by mass SrO: 21% by mass La ２ O ３ The resulting fluoroaluminosilicate glass powder was further pulverized using a ball mill to adjust the particle size distribution, thereby obtaining fluoroaluminosilicate glass powders of Examples 1 to 6 and Comparative Examples 1 to 3.

[0038] <Particle size distribution of fluoroaluminosilicate glass powder> The particle size distribution of the fluoroaluminosilicate glass powder was measured using a laser diffraction / scattering particle size distribution analyzer LA-950 (manufactured by Horiba, Ltd.). Specifically, the fluoroaluminosilicate glass powder was first dispersed in a 0.1 mass% aqueous hexametaphosphoric acid solution to obtain a suspension. Next, a small amount (0.5 ml) of the suspension was added to the circulated 0.1 mass% aqueous hexametaphosphoric acid solution, and the particle size distribution of the fluoroaluminosilicate glass powder was measured.

[0039] <Working Time of Glass Ionomer Cement> Fluoroaluminosilicate glass powder and a 50% by mass aqueous solution of polyacrylic acid were mixed at a predetermined powder-liquid ratio (see Table 1). Next, a spatula was brought into contact with the glass ionomer cement mixture, and the mixture was lifted up onto the spatula to check whether the glass ionomer cement mixture adhered to the spatula. This procedure was repeated. The time from the start of mixing the fluoroaluminosilicate glass powder and the 50% by mass aqueous solution of polyacrylic acid until the glass ionomer cement mixture no longer adhered was measured and used as the working time of the glass ionomer cement.

[0040] The criteria for determining the operating allowance time for glass ionomer cement are as follows:

[0041] Excellent: The glass ionomer cement had a working time of 1 minute 30 seconds or more. Good: The glass ionomer cement had a working time of 1 minute 15 seconds or more but less than 1 minute 30 seconds. Poor: The glass ionomer cement had a working time of less than 1 minute 15 seconds. <Compressive Strength of Hardened Glass Ionomer Cement> Fluoroaluminosilicate glass powder and a 50% by weight aqueous polyacrylic acid solution were mixed at a predetermined powder-liquid ratio (see Table 1) to obtain a glass ionomer cement mixture. Next, 4.2 g of the glass ionomer cement mixture was filled into a 6 mm high, 4 mm diameter mold, pressed, and then allowed to stand in a thermostatic chamber at 37°C and 100% RH for 1 hour. After removing the mold from the thermostatic chamber, the hardened glass ionomer cement was removed from the mold and immersed in 37°C water for 24 hours. Next, after wiping off the moisture from the hardened glass ionomer cement, a load was applied in the longitudinal direction of the hardened glass ionomer cement using a precision universal testing machine Autograph (manufactured by Shimadzu Corporation), and the load at which the hardened glass ionomer cement broke (hereinafter referred to as the maximum load) was measured.

[0042] Next, the compressive strength C [MPa] of the hardened glass ionomer cement was calculated using the formula: C = 4p / (πd ２) where p is the maximum load [N], and d is the diameter [mm] of the hardened glass ionomer cement.

[0043] The criteria for judging the compressive strength of hardened glass ionomer cement are as follows:

[0044] Good: When the compressive strength of the hardened glass ionomer cement is 200 MPa or more. Poor: When the compressive strength of the hardened glass ionomer cement is less than 200 MPa. Table 1 shows the evaluation results of the operating time of the glass ionomer cement and the compressive strength of the hardened glass ionomer cement.

[0045] From Table 1, it can be seen that when the fluoroaluminosilicate glass powders of Examples 1 to 6 are used, the working time of the glass ionomer cement is extended and the compressive strength of the hardened glass ionomer cement is increased.

[0046] In contrast, the fluoroaluminosilicate glass powder of Comparative Example 1 has a d50 of 10.1 μm, and therefore the compressive strength of the hardened glass ionomer cement is low.

[0047] Furthermore, the fluoroaluminosilicate glass powders of Comparative Examples 2 and 3 had d10 values ​​of 2.0 μm and 1.3 μm, respectively, and therefore could not be kneaded with a 50% by mass aqueous solution of polyacrylic acid.

[0048] This application claims priority from basic application No. 2018-103396, filed with the Japan Patent Office on May 30, 2018, the entire contents of which are incorporated herein by reference.

Claims

1. Dental fluoroaluminosilicate glass powder whose volume diameter in its 50th percentile is 5.0 µm or greater and 9.0 µm or less, and whose volume diameter in its 10th percentile is 2.4 µm or greater.

2. Dental fluoroaluminosilicate glass powder according to Proposition 1, whose volume diameter in its 90th percentile is 13.0 µm or greater and 20.0 µm or less.

3. Dental fluoroaluminosilicate glass powder according to Proposition 1, where the powder is useful for glass ionomer cement.

4. Glass ionomer cement composed of: Dental fluoroaluminosilicate glass powder of Proposition 1; and an aqueous solution of a polymer based on polycarboxylic acid.