DENTAL GLASS POWDER AND DENTAL CEMENT

Abstract

An embodiment of the present invention, in a dental glass powder, contains zinc, silicon, fluorine and silver, and does not substantially contain aluminum.

Claims

1. A dental glass powder, comprising: zinc, silicon, fluorine and silver, wherein the dental glass powder does not substantially contain aluminum.

2. A dental cement, comprising: a first component containing the dental glass powder as claimed in claim 1; and a second component containing a polycarboxylic acid polymer and water.

Description

EXAMPLE

[0058] Hereinafter, working examples of the present invention will be described, but the present invention is not limited to the working examples.

Working Examples 1 to 7

[0059] Zinc oxide (ZnO), anhydrous silicic acid (SiO.sub.2), calcium fluoride (CaF.sub.2), silver oxide (Ag.sub.2O), calcium phosphate (Ca.sub.3(PO.sub.4).sub.2), strontium fluoride (SrF.sub.2), phosphorus oxide (P.sub.2O.sub.5), lanthanum oxide (La.sub.2O.sub.3) and sodium fluoride (NaF) were mixed at a predetermined ratio, and then mixed and stirred sufficiently with a mortar, thereby producing a raw material composition. The raw material composition was placed in a platinum crucible and placed in an electric furnace. The electric furnace was heated to 1300 C., melted and homogenized sufficiently, and then circulated into water to form a bulk glass. The obtained bulk glass was pulverized with an alumina ball mill for 20 hours and then was caused to pass through a 120 mesh sieve to produce a glass powder.

Comparative Examples 1 to 4

[0060] In preparing the raw material composition, a glass powder was produced in the same manner as the working examples 1 to 7, except that aluminum oxide (Al.sub.2O.sub.3) was added and was mixed in a predetermined proportion.

Comparative Examples 5 and 6

[0061] In producing the raw material composition, a glass powder was produced in the same manner as the working examples 1 to 7, except that silver oxide (Ag.sub.2O) was not added and was mixed in a predetermined proportion.

[0062] Next, the number average particle diameter and the composition of the glass powder were evaluated.

[0063] <Number Average Particle Diameter of Glass Powder>

[0064] The particle size distribution of the glass powder was measured using Laser Diffraction/Scattering Particle Size Distribution Analyzer LA-950 (manufactured by Horiba, Ltd.). The number average particle diameter of the glass powder in both the working examples and the comparative examples was 6 to 9 m.

[0065] <Composition of Glass Powder>

[0066] The glass powder was analyzed and its composition was determined using ZSX Primus II (manufactured by Rigaku Corporation) of an X-ray fluorescence spectrometer.

[0067] Table 1 shows the evaluation results of the composition of the glass powder [mass %].

[0068] In the meantime, although the aluminum compound was not added to the glass powders of the working examples 1 to 7 and the comparative examples 5 and 6 when producing the raw material composition, 0.3 to 0.7 mass % of aluminum oxide (Al.sub.2O.sub.3) was detected. This is considered to be derived from the contamination of alumina from alumina balls or alumina pots used to pulverize the bulk glass, or the detection error of the X-ray fluorescence spectrometer.

[0069] Next, the dental decalcification inhibition effect and antimicrobial properties of the cement were evaluated.

[0070] <Production of Cement Admixture>

[0071] The glass powder as the first component and the 50 mass % aqueous solution of polyacrylic acid as the second component were mixed so that the mass ratio of the first component to the second component was 2.3 and then was kneaded to form kneaded cement.

[0072] <Inhibition Effect of Tooth Demineralization>

[0073] After bovine dentin was polished and planarized with water-resistant polished paper #1200 while supplying water, a polytetrafluoroethylene seal with a 3-mm diameter hole was attached to the polished surface of the bovine dentin. Next, after the kneaded cement was applied to a half of the surface of the hole in the polished surface of the bovine dentin on which the polytetrafluoroethylene seal was attached, the kneaded cement was hardened by leaving the bovine dentin in a thermostatic bath maintained at 37 C. and 100% relative humidity. The hardened bovine dentin was then immersed in a 37 C. demineralizing solution for 24 hours. At this time, the half of the surface of the hole in the polished surface of the bovine dentin on which the seal was attached was not hardened, and the surface that the demineralizing solution touches was made a test surface.

[0074] Here, the decalcifying liquid is a mixture of 50 mM aqueous acetic acid solution, 1.5 mM aqueous calcium chloride solution and 0.9 mM aqueous potassium dihydrogen phosphate solution, with a pH of 4.5.

[0075] The hardened bovine dentin was then cut and tested using a precise cutting machine to provide a thickness of 1 mm.

[0076] Next, the test specimen was photographed by a transmission method using an X-ray inspection apparatus, and the taken image was analyzed using image processing software to determine the amount of mineral loss, and the tooth demineralization inhibition effect was evaluated.

[0077] The criteria for the inhibition of tooth demineralization are as follows. The lower the mineral loss becomes, the higher the tooth demineralization inhibition effect becomes.

[0078] Good: Amount of mineral loss is less than 2300 volume %.Math.m

[0079] Poor: Amount of mineral loss is 2300 volume %.Math.m or more and 2800 volume %.Math.m or less

[0080] Very Poor: Mineral loss is 2800 volume %.Math.m or more

[0081] In the meantime, when the tooth demineralization inhibition effect of the produced test object was evaluated in the same manner as the above except that the kneaded cement was not applied, the mineral loss amount was not less than 4231 volume %.Math.m.

[0082] <Antimicrobial Properties>

[0083] After a mold having a diameter of 10 mm and a thickness of 2 mm was filled with the kneaded cement, the kneaded cement was hardened by leaving the kneaded cement in an environment of a temperature at 37 C. and 100% relative humidity for an hour. The hardened material was then removed from the mold and was immersed in 10 mL of BrainHart's Infusion (BHI) culture medium for 24 hours. Next, after removing the hardened material from the BHI culture medium, Streptococcus mutans (S. mutans) were seeded so that an OD600 value became 0.01, and were incubated at 37 C. for 24 hours. Next, the OD600 value of the BHI culture medium that cultured S. mutans was measured to assess its antimicrobial properties.

[0084] Here, the OD600 value means an optical density of 600 nm wavelength, and was measured using the plate reader SpectraMax M2 (manufactured by Molecular Devices Japan).

[0085] The determination criteria for antimicrobial properties are as follows. The lower the OD600 value, the higher the antimicrobial properties.

[0086] Good: If OD600 is less than 0.10

[0087] Poor: OD600 is not less than 0.10 and less than 0.20

[0088] Very Poor: OD600 is not less than 0.20

[0089] Table 1 shows the evaluation results of the dental decalcification inhibition effect and antimicrobial properties of the cement.

TABLE-US-00001 TABLE 1 WORKING EXAMPLE COMPARATIVE EXAMPLE 1 2 3 4 5 6 7 1 2 3 4 5 6 SiO.sub.2 29.7 30.5 28.6 26.7 34.8 32.1 37.2 27.2 23.6 25.4 25.5 31.4 33.0 Al.sub.2O.sub.3 0.3 0.3 0.4 0.3 0.6 0.3 0.7 25.4 21.3 23.0 24.3 0.4 0.3 F 4.3 4.5 4.2 3.9 3.2 3.0 4.7 13.5 11.2 11.6 9.4 4.6 3.0 CaO 6.4 6.6 6.2 5.8 12.1 1.8 6.8 SrO 12.4 13.3 15.8 28.0 22.3 30.2 13.2 La.sub.2O.sub.3 29.9 30.8 28.9 27.0 6.0 31.7 P.sub.2O.sub.5 4.2 12.1 3.5 10.6 4.4 Na.sub.2O 3.5 6 5 ZnO 23.6 24.3 22.8 21.9 47.3 44.9 30.7 4.6 25.1 50.5 Ag.sub.2O 5.8 3.0 8.9 14.4 1.7 2.2 11.1 7.1 1.2 DENTAL GOOD GOOD GOOD GOOD GOOD GOOD GOOD POOR VERY VERY VERY GOOD GOOD DECALCIFICATION POOR POOR POOR INHIBITION EFFECT MINERAL 2046 2292 1912 2232 1736 1860 1653 2514 3015 3125 2924 2142 1553 LOSS AMOUNT [volume % .Math. m] ANTIMICROBIAL GOOD GOOD GOOD GOOD GOOD GOOD GOOD VERY VERY GOOD GOOD POOR POOR PROPERTIES POOR POOR OD600 VALUE 0.06 0.05 0.02 0.01 0.02 0.02 0.03 0.29 0.28 0.03 0.02 0.19 0.15

[0090] TABLE 1 indicates that the cement containing the glass powder of the working examples 1 to 7 has a high tooth demineralization effect and high antimicrobial properties.

[0091] In contrast, because the cement containing the glass powder of the comparative examples 1 to 4 has a content of aluminum oxide (Al.sub.2O.sub.3) in a range of 21.3 to 25.4 mass %, the tooth demineralization inhibition effect is low.

[0092] In addition, the cement containing the glass powder of the comparative examples 1, 2, 5 and 6 has low antimicrobial properties because the glass powder does not contain silver.

[0093] This international application claims priority to Japanese Patent Application No. 2017-192518, filed Oct. 2, 2017, and the entire contents of Japanese Patent Application No. 2017-192518 are incorporated herein by reference.