DENTAL GLASS POWDER AND DENTAL COMPOSITION

Abstract

A dental glass powder includes 15 to 40% by mass of zinc oxide (ZnO), 20 to 55% by mass of silicon oxide (SiO.sub.2), 6 to 20% by mass of aluminum oxide (Al.sub.2O.sub.3), 1 to 13% by mass of calcium oxide (CaO), and 1 to 19% by mass of fluorine (F).

Claims

1. A dental glass powder comprising: 15 to 40% by mass of zinc oxide (ZnO); 20 to 55% by mass of silicon oxide (SiO.sub.2); 6 to 20% by mass of aluminum oxide (Al.sub.2O.sub.3); 1 to 13% by mass of calcium oxide (CaO), and 1 to 19% by mass of fluorine (F).

2. The dental glass powder according to claim 1, further comprising more than 0% by mass and 15% by mass or less of boron oxide (B.sub.2O.sub.3).

3. The dental glass powder according to claim 1, further comprising more than 0% by mass and 10% by mass or less of phosphorus(V) oxide (P.sub.2O.sub.5).

4. The dental glass powder according to claim 1, further comprising more than 0% by mass and 10% by mass or less of sodium oxide (Na.sub.2O).

5. The dental glass powder according to claim 1, wherein the dental glass powder is used for a dental composition.

6. A dental composition containing a glass powder, the glass powder comprising: 15 to 40% by mass of zinc oxide (ZnO); 20 to 55% by mass of silicon oxide (SiO.sub.2); 6 to 20% by mass of aluminum oxide (Al.sub.2O.sub.3); 1 to 13% by mass of calcium oxide (CaO), and 1 to 19% by mass of fluorine (F).

Description

EXAMPLE

[0074] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the examples.

Examples 1 to 6, Comparative Examples 1 to 7

[0075] Zinc oxide (Zn0), anhydrous silicic acid (SiO.sub.2), aluminum oxide (Al.sub.2O.sub.3), aluminum fluoride (AlF.sub.3), artificial cryolite (Na.sub.3AlF.sub.6), calcium fluoride (CaF.sub.2), calcium carbonate (CaCO.sub.3), phosphorus oxide (P.sub.2O.sub.5), boron oxide (B.sub.2O.sub.3), sodium fluoride (NaF), strontium fluoride (SrF.sub.2), strontium carbonate (SrCO.sub.3), and lanthanum oxide (La.sub.2O.sub.3) were mixed at a predetermined ratio, and then stirred sufficiently with a mortar to obtain a raw material composition. After the raw composition was placed in a platinum crucible, the platinum crucible was placed in the electric furnace. The electric furnace was heated to 1450° C., the raw material composition was melted and homogenized sufficiently, and then flowed into water to obtain a bulk glass. The bulk glass was milled for 4 hours using an alumina ball mill and then passed through a 120-mesh sieve to obtain a glass powder.

[0076] Next, the composition of the glass powder and the number average particle size were evaluated.

<Composition of Glass Powder>

[0077] Using a ZSX Primus II fluorescent X-ray analyzer (manufactured by Rigaku Corporation), the glass powder was analyzed, and the composition of the glass powder was determined.

<Number Average Particle Size of Glass Powder>

[0078] A laser diffraction scattering particle size distributor LA-950 (manufactured by Horiba, Ltd.) was used to measure the number average particle size of glass powder.

[0079] Next, the antibacterial effect, transparency, and inhibition of dental decalcification of the cured product of the glass ionomer cement including glass powder were evaluated.

<Preparation of Kneaded Product of Glass Ionomer Cement>

[0080] A powder component was obtained by mixing 40% by mass of the glass powder with 60% by mass of the fluorosilicate glass powder. Here, the composition of the fluorosilicate glass powder is SiO.sub.2 (26.8% by mass), Al.sub.2O.sub.3 (23.9% by mass), F (14.3% by mass), SrO (33.0% by mass), P.sub.2O.sub.5 (1.4% by mass), and Na.sub.2O (0.6% by mass), and the number average particle size is 7.6 μm.

[0081] A liquid component was obtained by mixing 40% by mass of polyacrylic acid, 50% by mass of water, and 10% by mass of citric acid.

[0082] The powder component and the liquid component were kneaded at a powder-to-liquid ratio of 2.8 to obtain a kneaded product of the glass ionomer cement.

<Antibacterial Effect>

[0083] A mold that is 10 mm in diameter and 2 mm in thickness was filled with the kneaded product of the glass ionomer cement and allowed to stand at 37° C. for 1 hour under the environment of 90% relative humidity (RH) to cure the kneaded product of the glass ionomer cement. The cured product was then removed from the mold and immersed in 10 mL of a brain heart infusion (BHI) medium for 24 hours. After removing the cured product from the BHI medium, Streptococcus mutans (S. mutans) were seeded to an OD540 value of 0.01 and incubated at 37° C. for 24 hours. Next, the OD540 value of the BHI medium cultured with S. mutans was measured to evaluate the antibacterial effect.

[0084] Here, the OD540 value indicates the optical density of light at a wavelength of 540 nm. The value was measured using a plate reader, SpectraMax M2 (manufactured by Molecular Device Japan).

[0085] The criteria for antibacterial effect are as follows. Here, the lower value of the OD540, the higher the antibacterial effect.

[0086] Excellent: The value of OD540 is lower than 0.10.

[0087] Good: The value of OD540 is 0.10 or higher and lower than 0.15.

[0088] Poor: The value of OD540 is 0.15 or higher.

<Transparency>

[0089] A mold that is 15 mm in diameter and 0.5 mm in thickness was filled with the kneaded product of the glass ionomer cement and allowed to stand at 37° C. for 1 hour under the environment of 90% RH to cure the kneaded product of the glass ionomer cement. The cured product was then removed from the mold, and a colorimeter was used to measure the L value on a white background and the L value on a black background. Next, the difference (ΔL) between the L value on the white background and the L value on the black background was calculated.

[0090] The transparency criteria are as follows. Here, the greater the value of ΔL, the higher the transparency.

[0091] Excellent: The value of ΔL is 13 or greater.

[0092] Good: The value of ΔL is 10 or greater and less than 13.

[0093] Poor: The value of ΔL is less than 10.

<Inhibition of Dental Decalcification>

[0094] A sample of bovine dentin was polished with water-resistant polish paper #1200 by injecting water and a polytetrafluoroethylene seal with a 3 mm diameter hole was applied to the flattened polished surface. Next, the kneaded product of the glass ionomer cement was applied to one half of the polished surface corresponding to the hole of the seal, and then left in a constant temperature humidity bath at 37° C. and 100% RH for 24 hours. The kneaded product of the glass ionomer cement was cured to form a cured product. The bovine dentin with cured product formed was immersed in a 37° C. decalcifying fluid (50 mM acetic acid, 1.5 mM calcium chloride, 0.9 mM potassium dihydrogen phosphate, pH 4.5) for 24 hours. At the time, the cured product was not formed on the other half of the polished surface corresponding to the hole of the seal. The other half of the polished surface with cured product not formed was used as a test surface.

[0095] A precision cutting machine was used to cut the bovine dentin with cured product formed so as to have a test piece that is 1 mm thick.

[0096] After the test surface of the test piece was photographed using an X-ray apparatus, the image of the test surface was analyzed using image processing software to determine the extent of mineral loss and evaluate the inhibition of dental decalcification.

[0097] The criteria for the inhibition of dental decalcification are as follows. Here, the smaller the extent of mineral loss, the higher the inhibition of dental decalcification.

[0098] Excellent: The extent of mineral loss is less than 2300% by volume.Math.μm

[0099] Good: The extent of mineral loss is 2300% by

[0100] volume.Math.μm or higher and less than 2600% by volume.Math.μm.

[0101] Poor: The extent of mineral loss is 2600% by volume.Math.μm or higher.

[0102] Next, when the inhibition of dental decalcification was evaluated in the same manner as above, except that the kneaded product of the glass ionomer cement was not applied, the extent of mineral loss was 4557% by volume.Math.μm or higher.

[0103] Table 1 indicates that the evaluation results of the antibacterial effect, transparency, and inhibition of dental decalcification of the cured products of the glass ionomer cements.

TABLE-US-00001 TABLE 1 Examples Comparative Examples 1 2 3 4 5 6 1 2 3 4 5 6 7 ZnO 32.5 19.8 25.0 30.2 15.1 21.5 0 0 40.5 10.6 15.9 24.1 34.5 SiO.sub.2 40.6 41.7 47.1 37.5 50.4 45.6 29.8 25.7 41.6 50.4 26.6 28.6 40.3 Al.sub.2O.sub.3 12.2 15.0 12.8 7.5 17.4 15.9 19.8 19.2 6.4 17.4 19.9 0 6.4 F 5.9 4.7 6.1 5.4 4.8 5.7 11.0 14.1 4.8 9.3 8.1 5.3 0 CaO 8.8 10.5 9.0 10.3 12.3 11.3 0 0.1 4.0 12.3 0 6.7 13.6 SrO 0 0 0 0 0 0 27.0 35.6 0 0 23.9 0 5.2 La.sub.2O.sub.3 0 0 0 0 0 0 6.3 0 0 0 0 35.3 0 P.sub.2O.sub.5 0 0 0 7.0 0 0 3.6 4.1 0 0 3.1 0 0 Na.sub.2O 0 0 0 2.1 0 0 2.5 1.2 2.7 0 2.5 0 0 B.sub.2O.sub.3 0 8.3 0 0 0 0 0 0 0 0 0 0 0 Total 100 100 100 100 100 100 100 100 100 100 100 100 100 Number 7.3 7.8 7.6 8.1 7.6 7.3 8.3 7.8 7.6 8.1 8.3 7.4 7.7 average particle size [μm] Antibacterial Good Good Ex- Ex- Good Ex- Poor Poor Ex- Poor Good Ex- Ex- effect cellent cellent cellent cellent cellent cellent Transparency Ex- Ex- Ex- Good Ex- Ex- Ex- Ex- Poor Ex- Ex- Poor Good cellent cellent cellent cellent cellent cellent cellent cellent cellent Inhibition of Ex- Ex- Ex- Good Ex- Ex- Poor Poor Good Ex- Poor Good Poor dental cellent cellent cellent cellent cellent cellent decalcification

[0104] From Table 1, it can be seen that the glass ionomer cement having the powder components containing the glass powder of Examples 1 to 6 exhibited high antibacterial efficacy, transparency, and inhibition of dental decalcification of the cured products.

[0105] In contrast, the glass ionomer cement having the powder component containing the glass powder of Comparative Example 1 exhibited low antibacterial effect and low inhibition of dental decalcification of the cured product, likely because the glass powder of Comparative Example 1 did not contain zinc and calcium.

[0106] The glass ionomer cement including the powder component containing the glass powder of Comparative Example 2 showed low antibacterial effect of the cured product and low inhibition of dental decalcification, likely because the glass powder of Comparative Example 2 did not contain zinc, and the amount of calcium oxide (CaO) in the glass powder of Comparative Example 2 was 0.1% by mass.

[0107] The glass ionomer cement having the powder component containing the glass powder of Comparative Example 3 showed low transparency of the cured product, likely because the amount of zinc oxide (ZnO) in the glass powder of Comparative Example 3 was 40.5% by mass.

[0108] The glass ionomer cement having the powder component containing the glass powder of Comparative Example 4 showed low antibacterial effect of the cured product, likely because the amount of zinc oxide (ZnO) in the glass powder of Comparative Example 4 was 10.6% by mass.

[0109] The glass ionomer cement having the powder component containing the glass powder of Comparative Example 5 showed low inhibition of dental decalcification of the cured product, likely because the glass powder of Comparative Example 5 did not contain calcium.

[0110] The glass ionomer cement having the powder component containing the glass powder of Comparative Example 6 showed low transparency of the cured product, likely because the glass powder of Comparative Example 6 did not contain aluminum.

[0111] The glass ionomer cement having the powder component containing the glass powder of Comparative Example 7 showed low inhibition of dental decalcification of the cured product, likely because the glass powder of Comparative Example 7 did not contain fluorine.