Dental glass and method for producing the same

Abstract

To provide a dental glass having sufficient antibacterial properties by zinc.SOLUTION: The dental glass contains 41 mass% or more and 52 mass% or less of ZnO, 47 mass% or more and 51 mass% or less of P2O5, 7 mass% or less of MgO, and 9 mass% or less of CaO. The content of fluorine in the dental glass is preferably 3% by mass or less. In addition, the dental glass can be easily produced through a mixing step of mixing a raw material solution containing a zinc salt solution, a phosphate solution, a magnesium salt solution as an optional component, and a calcium salt solution as an optional component to generate an aggregate in the raw material solution, and a drying step of drying the aggregate to obtain a powder.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present application relates to dental glasses with antibacterial properties due to an appropriate amount of zinc, and to a method for producing the same. [Background technology]

[0002] Dental glass is used as a tooth filler. Patent Document 1 discloses a water-soluble dental glass containing K2O, PO5, CaO, ZnO, and F. Patent Document 1 suggests that adding zinc to the water-soluble dental glass may provide antibacterial properties. However, the zinc content of the water-soluble dental glass in Patent Document 1 provides almost no antibacterial properties against Escherichia coli and Staphylococcus aureus. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-57915 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to provide a dental glass that has antibacterial properties due to an appropriate amount of zinc. [Means for solving the problem]

[0005] The present application discloses a dental glass, a method for manufacturing a dental glass, and a dental material according to the following aspects. (1) Dental glass containing 41% by mass or more and 52% by mass or less of ZnO, 47% by mass or more and 51% by mass or less of P2O5, 7% by mass or less of MgO, and 9% by mass or less of CaO. (2) In (1), the dental glass contains 48% by mass or more and 52% by mass or less of ZnO and 0.8% by mass or more and 2.6% by mass or less of MgO. (3) Dental glass according to (1) or (2), in which the fluorine content is 3% by mass or less.

[0006] (4) A method for manufacturing dental glass according to any one of (1) to (3), comprising a mixing step of mixing a raw material liquid containing a zinc salt solution, a phosphate solution, an optional magnesium salt solution, and an optional calcium salt solution to produce an aggregate in the raw material liquid, and a drying step of drying the aggregate to obtain a powder. (5) A method for producing dental glass according to (4), further comprising a washing step of washing the aggregates with a liquid before the drying step. (6) A method for producing dental glass according to (4) or (5), further comprising a grinding step of grinding the powder material to obtain the powder material.

[0007] (7) A dental material comprising the dental glass according to any one of (1) to (3) and dental cement. [Effects of the Invention]

[0008] The dental glass of the present application contains ZnO at a specified content. As a result, the dental glass of the present application has antibacterial properties due to zinc. The dental glass of the present application is manufactured using a liquid phase method. As a result, dental glass with antibacterial properties can be easily manufactured. The dental material of the present application contains the dental glass of the present application. As a result, the dental material of the present application has high antibacterial properties against bacteria that cause tooth decay. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a powder X-ray diffraction chart of the dental glasses of Examples 1 to 3. [Figure 2] SEM image of the dental glass of Example 2. [Figure 3] 1 is a particle size distribution histogram of the dental glasses of Examples 1 to 3 after grinding. [Figure 4] 1 is a powder X-ray diffraction chart of the dental glasses of Examples 4 to 6. [Figure 5]1 is a powder X-ray diffraction chart of the dental glasses of Examples 7 to 10. [Figure 6] 1 shows powder X-ray diffraction charts of dental glasses of Examples 11 to 15. [Figure 7] 1 shows powder X-ray diffraction charts of dental glasses of Examples 16 to 18. [Figure 8] SEM image of the dental glass of Example 8. [Figure 9] 1 is a particle size distribution histogram of primary particles of dental glasses of Examples 4 to 18. [Figure 10] 1 is a graph showing the antibacterial properties of the dental glass of the example and a commercially available dental cement against Escherichia coli. [Figure 11] 1 is a graph showing the antibacterial properties of the dental glass of the example and a commercially available dental cement against Staphylococcus aureus. [Figure 12] 1 is a graph showing the antibacterial properties of dental glasses of Comparative Examples 4 to 9 and Examples 4 to 18 against Escherichia coli. [Figure 13] 1 is a graph showing the antibacterial properties of dental glasses of Comparative Examples 4 to 9 and Examples 4 to 18 against Staphylococcus aureus. [Figure 14] 1 is a graph showing the antibacterial properties against Escherichia coli of the dental glasses of Comparative Examples 1 to 3 and Examples 1 to 3 and a commercially available dental cement. [Figure 15] 1 is a graph showing the antibacterial properties of the dental glasses of Comparative Examples 1 to 3 and Examples 1 to 3 and a commercially available dental cement against Staphylococcus aureus. [Figure 16] Graph showing the antibacterial properties of dental materials of Examples against Streptococcus mutans. DETAILED DESCRIPTION OF THE INVENTION

[0010] The dental glass, manufacturing method for dental glass, and dental material of the present application will be described below based on embodiments and examples. Repetitive explanations will be omitted where appropriate. The dental glass of the present application contains ZnO and P2O5. The ZnO content in the dental glass of the embodiment is 41% by mass or more and 52% by mass or less. Since the ZnO content is 41% by mass or more, the dental glass of the embodiment has antibacterial properties against Escherichia coli and Staphylococcus aureus. Note that if the ZnO content exceeds 52% by mass, it becomes difficult to form an amorphous structure.

[0011] The P2O5 content in the dental glass of the embodiment is 47% by mass or more and 51% by mass or less. This P2O5 content forms an amorphous structure. The dental glass of the embodiment may contain one or more of MgO and CaO. The MgO content in the dental glass of the embodiment is 7% by mass or less, and the CaO content is 9% by mass or less. Fluoride has the effect of weakening the activity of bacteria that cause tooth decay. However, if excessive fluoride is released into the mouth, it may cause symptoms of poisoning.

[0012] For this reason, the fluorine content in the dental glass of the embodiment is preferably 3% by mass or less, more preferably 1% by mass or less, and even more preferably only unavoidable impurities. Furthermore, although silver has antibacterial properties, it reacts with sulfur present in the oral cavity to form silver sulfide, which turns black. For this reason, the dental glass of the embodiment preferably does not contain silver other than unavoidable impurities. Potassium relieves toothache caused by external stimuli such as hypersensitivity. For this reason, the dental glass of the embodiment may contain a potassium component, such as KO.

[0013] The fact that the dental glass of the embodiment is glass, i.e., amorphous, can be confirmed by powder X-ray diffraction measurement. The dental glass of the embodiment may be a composite of an amorphous phase and a crystalline phase. The dental glass of the present application can be used as a dental material such as a dental filler by blending it with dental cement. That is, the dental material of the embodiment of the present application comprises the dental glass of the embodiment and dental cement. The dental material of the embodiment containing the dental glass of the embodiment has higher antibacterial properties against bacteria that cause tooth decay than dental cement itself.

[0014] The dental glass of the embodiment can be produced by a melting method or a liquid phase method. In the melting method, raw materials including a zinc compound, a phosphorus compound, and optionally one or more magnesium compounds and calcium compounds are mixed, heated to or above the melting point of each raw material to melt, and then cooled and solidified to obtain dental glass as a mass. The mass is then crushed to obtain dental glass as a crushed product. The mass is crushed using, for example, an automatic mortar crusher.

[0015] The average particle size of dental glass, which is a pulverized product obtained by the fusion method, is larger than the average particle size of the primary particles of dental glass, which is a powder product obtained by the liquid-phase method described below. The pulverized product obtained by the fusion method has a large average particle size because plate-shaped lumps approximately 10 to 50 mm in size and 1 mm thick are crushed in an automatic mortar and pestle grinder. In contrast, the powder product obtained by the liquid-phase method has a small average particle size of primary particles, and can be easily refined simply by breaking down the agglomerates between primary particles.

[0016] The average particle size of dental glass, which is a pulverized product obtained by the melting method, is, for example, several μm, while the average particle size of dental glass, which is a powder obtained by the liquid phase method, is, for example, several hundred nm. The average particle size of dental glass is the numerical average value of particle sizes in the particle size distribution of the primary particles of the dental glass. Dental glass with a small average particle size, for example, an average particle size of 30 nm to 300 nm, tends to have improved antibacterial properties against Escherichia coli and Staphylococcus aureus as the MgO content increases.

[0017] The dental glass of the embodiment can be manufactured by a liquid phase method, which is simpler than a melting method. The manufacturing method of the dental glass of the embodiment of the present application includes a mixing step and a drying step. In the mixing step, a raw material liquid containing a zinc salt solution, a phosphate solution, an optional magnesium salt solution, and an optional calcium salt solution is mixed to form aggregates in the raw material liquid. For example, a mixed liquid containing a zinc salt solution, an optional magnesium salt solution, and an optional calcium salt solution may be prepared in advance, and the mixed liquid may be added to a phosphate solution to prepare the raw material liquid and form aggregates in the raw material liquid.

[0018] The term "optional component" means that it may or may not be present. In other words, one or more of the magnesium salt solution and the calcium salt solution may or may not be used as a raw material. The raw material solution may also contain ions other than zinc, phosphate, magnesium, and calcium ions. For example, the raw material solution may contain potassium ions, sodium ions, strontium ions, barium ions, titanium ions, niobium ions, tantalum ions, aluminum ions, gallium ions, borate ions, or silicate ions.

[0019] Zinc salts include zinc chloride, zinc nitrate, zinc acetate, and zinc lactate. Phosphate salts include potassium pyrophosphate and sodium pyrophosphate. Magnesium salts include magnesium chloride, magnesium nitrate, magnesium acetate, and magnesium lactate. Calcium salts include calcium chloride, calcium nitrate, calcium acetate, and calcium lactate. In addition, solutions of various salts are preferably aqueous solutions because they are easy to handle.

[0020] In the drying step, the aggregate is dried to obtain dental glass as a powder. The method for producing dental glass of the embodiment may further include a washing step before the drying step. In the washing step, the aggregate is washed with a liquid. When the raw material is an aqueous solution, it is preferable to wash the aggregate with water. The method for producing dental glass of the embodiment may further include a crushing step after the drying step. In the crushing step, the powder is crushed to obtain dental glass as a powder. The powder is crushed using, for example, an agate mortar. [Example]

[0021] (Manufacturing dental glass by the fusion method) Zinc oxide (ZnO) (Kishida Chemical Co., Ltd., special grade), phosphoric acid (H3PO4) (Kishida Chemical Co., Ltd., special grade), magnesium oxide (MgO) (Kishida Chemical Co., Ltd., special grade), and calcium carbonate (CaCO3) (Kishida Chemical Co., Ltd., special grade) were mixed in water in the amounts shown in Table 1 below, and then dried overnight at 140°C to obtain a raw material powder. This raw material powder was placed in a platinum crucible and melted at 1500°C, poured out of the platinum crucible, sandwiched between stainless steel plates, and rapidly cooled to obtain a plate-like mass.

[0022] The platelets were pulverized using an automatic mortar pulverizer (Nittokagaku Co., Ltd., ALG-200WD) to obtain dental glasses of Examples 1 to 3 and Comparative Examples 1 to 3, which were pulverized materials containing ZnO, PO, MgO, and CaO. The results are shown in Table 1 below. The mass percentages of ZnO, PO, MgO, and CaO in the pulverized materials were calculated by X-ray fluorescence analysis (the same applies below). Figure 1 shows powder X-ray diffraction charts of these dental glasses. The powder X-ray diffraction charts of all dental glasses showed broad halo peaks between 20° and 40°, confirming their amorphous nature.

[0023] Figure 2 is an SEM image of the dental glass of Example 2. As shown in Figure 2, the particle size of the dental glass of Example 2 after crushing ranged from a minimum of 0.04 μm to a maximum of 38.5 μm. Furthermore, the particle size distribution of the dental glasses of Examples 1 to 3 after crushing was measured collectively using SEM images. The results are shown in Figure 3. From the particle size distribution measurement results, the minimum particle size of the dental glasses of Examples 1 to 3 after crushing was 40 nm, the maximum particle size was 49 μm, the median particle size was 680 nm, and the average particle size was 4.0 μm.

[0024] [Table 1]

[0025] (Liquid-phase method for manufacturing dental glass) Zn 2+ , Mg 2+ , and Ca 2+ A mixed aqueous solution was prepared by mixing an aqueous solution of zinc chloride (ZnCl2) (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), an aqueous solution of magnesium chloride hexahydrate (MgCl2·6H2O) (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade), and an aqueous solution of calcium chloride (CaCl2) (Fujifilm Wako Pure Chemical Industries, Ltd., special reagent grade) so that the total concentration was 1 M. This mixed aqueous solution was added dropwise to a 0.2 M aqueous solution of potassium pyrophosphate (K4P2O7) (Sigma-Aldrich, 322431) to prepare a raw material solution, and aggregates were obtained in this raw material solution.

[0026] The aggregates were washed with pure water and then dried at 200°C for 1 day to obtain a powder. The powder was lightly crushed using a mortar and pestle to obtain the dental glasses of Examples 4 to 18 and Comparative Examples 4 to 9, which were powders containing ZnO, PO, MgO, CaO, and KO. The results are shown in Table 2 below. Figures 4 to 7 are powder X-ray diffraction charts for the dental glasses of Examples 4 to 18. The powder X-ray diffraction charts for all dental glasses showed broad halo peaks between 20° and 40°, confirming their amorphous nature. Furthermore, in the powder X-ray diffraction charts for the dental glasses of Examples 4 to 18, peaks derived from zinc phosphate crystals were observed above the broad halo peaks. These dental glasses are composites of an amorphous phase and a crystalline phase.

[0027] Figure 8 is an SEM image of the dental glass of Example 8. The particle size of the primary particles of the dental glass of Example 8 measured based on Figure 8 was approximately 211 nm. The particle size of the dental glass obtained by the liquid phase method was smaller than that of the dental glass obtained by the fusion method. Furthermore, the particle size distribution of the primary particles of the dental glasses of Examples 4 to 18 was measured collectively using the same measurement method as for the dental glass obtained by the fusion method. The results are shown in Figure 9. From the particle size distribution measurement results, the minimum particle size of the primary particles of the dental glasses of Examples 4 to 18 was 30 nm, the maximum particle size was 920 nm, the median particle size was 190 nm, and the average particle size was 200 nm.

[0028] [Table 2]

[0029] (Antibacterial evaluation of dental glass) Approximately 200 μg of the pulverized material obtained by the melting method or the powder obtained by the liquid-phase method was uniaxially pressed at 20 MPa for 5 minutes to prepare cylindrical specimens with a diameter of 10 mm and a thickness of 0.8 mm. For comparison, a commercial dental cement A containing SiO2, Al2O3, SrO, ZnO, Na2O, CaO, La2O3, PO5, and fluorine was filled into a mold with an inner diameter of 10 mm and a depth of 1.0 mm, cured, and then polished with #1000 waterproof abrasive paper to prepare a cylindrical specimen. Cylindrical specimens of commercial dental cement B containing SiO2, Al2O3, SrO, Na2O, PO5, and fluorine were prepared in the same manner as for dental cement A.

[0030] The antibacterial properties of the dental glasses of the Examples and Comparative Examples and the commercially available dental cement were evaluated by the following method. 6 After inoculating 100 μL of E. coli bacterial solution containing CFU / mL, specimens of dental glass, dental cement A, and dental cement B from Examples 1 to 18 were placed at the center of the agar medium. After culturing at 37°C for 24 hours, the width W of the formed inhibition zone, i.e., the difference between the radius of the inhibition zone and the radius of the specimen, was measured to evaluate the antibacterial activity against E. coli. 5 × 10 6 The antibacterial activity against Staphylococcus aureus was also evaluated using 100 μL of a bacterial solution of Staphylococcus aureus at CFU / mL. The results are shown in Figures 10 and 11.

[0031] As shown in Figures 10 and 11, the inhibition zone widths of the dental glasses of Examples 1 to 18 were 0.75 mm to 6 mm. This indicates that the dental glasses of Examples 1 to 18 have antibacterial properties against Escherichia coli and Staphylococcus aureus. On the other hand, commercially available dental cements A and B did not show an inhibition zone. This indicates that commercially available dental cements A and B did not have antibacterial properties against Escherichia coli and Staphylococcus aureus.

[0032] The antibacterial properties of the dental glasses of Comparative Examples 4 to 9 against Escherichia coli and Staphylococcus aureus were evaluated using the same method as in the antibacterial property evaluation described above. The results are shown in Figures 12 and 13. Figures 12 and 13 also show the evaluation results (same as Figures 10 and 11) of the antibacterial properties of the dental glasses of Examples 4 to 18, which were produced using the same liquid-phase method. As shown in Figures 12 and 13, the dental glasses of Comparative Examples 4 to 9, which contained 38% or less of ZnO by mass, did not have antibacterial properties against Escherichia coli and Staphylococcus aureus. Furthermore, as can be seen from Figures 11, 13, and Table 2, the dental glasses of Examples 11, 12, 13, 14, and 16, which contained 48% to 52% by mass of ZnO and 0.8% to 2.6% by mass of MgO, had particularly high antibacterial properties against Staphylococcus aureus.

[0033] The antibacterial properties of the dental glasses of Comparative Examples 1 to 3 against Escherichia coli and Staphylococcus aureus were evaluated using the same method as in the antibacterial property evaluation described above. The results are shown in Figures 14 and 15. Figures 14 and 15 also show the antibacterial property evaluation results (the same as the results shown in Figures 10 and 11) for the dental glasses of Examples 1 to 3, which were produced using the same melting method, and for dental cements A and B for reference. As shown in Figures 14 and 15, the dental glasses of Comparative Examples 1 to 3, which had a ZnO content of 31% by mass or less, had almost no antibacterial property against Escherichia coli. Furthermore, the dental glasses of Comparative Examples 1 to 3 had no antibacterial property against Staphylococcus aureus.

[0034] (Antibacterial evaluation of dental materials) 30 mg of the dental glass of Example 7, Example 8, Example 9, Example 11, Example 12, or Example 13 was mixed with 270 mg of dental cement A to prepare 300 mg of dental material. 300 mg of each dental material was filled into a silicone mold with an inner diameter of 10.0 mm and a depth of 2.0 mm and cured using a dental polymerization light irradiator (G-Light Prima II, GC). The surfaces of these cured materials were polished with #1000 waterproof abrasive paper to prepare evaluation specimens for Examples 7, 8, 9, 11, 12, and 13. Comparative evaluation specimens consisting of only 300 mg of dental cement A were also prepared using the same procedure.

[0035] The test bacteria, Streptococcus mutans, the causative bacterium of dental caries, was cultured on a Brain Heart Infusion agar plate at 35°C for 24 hours, and the grown colonies were suspended in Brain Heart Infusion medium (manufactured by Eiken Chemical Co., Ltd.) to obtain a concentration of approximately 1 x 10 7 A mutans streptococcus liquid containing CFU / mL of mutans streptococcus was obtained. The following eight types of samples were prepared using the evaluation samples of each example, the comparative evaluation samples, and the mutans streptococcus liquid.

[0036] Sample 1: 1 mL of Streptococcus mutans solution Sample 2: 2 mL of Streptococcus mutans solution added to the comparative evaluation sample Sample 3: 2 mL of Streptococcus mutans solution added to the evaluation sample from Example 7 Sample 4: 2 mL of Streptococcus mutans solution added to the evaluation sample of Example 8 Sample 5: 2 mL of Streptococcus mutans solution added to the evaluation sample of Example 9 Sample 6: 2 mL of Streptococcus mutans solution added to the evaluation sample from Example 11 Sample 7: 2 mL of Streptococcus mutans solution added to the evaluation sample from Example 12 Sample 8: 2 mL of Streptococcus mutans solution added to the evaluation sample from Example 13

[0037] These eight samples were incubated at 37°C for 12 hours. Then, the optical density (OD) of each sample was measured when irradiated with visible light at a wavelength of 600 nm using an ultraviolet spectrophotometer (Corona Electric Co., Ltd., SH-1000). The results are shown in Figure 16. As shown in Figure 16, compared to the Streptococcus mutans solution containing dental cement alone (Sample 2), the Streptococcus mutans solutions containing dental cement and the dental glass of the example (Samples 3 to 8) had lower optical densities, i.e., lower Streptococcus mutans concentrations. This result indicates that the dental materials containing dental cement and the dental glass of the example have stronger antibacterial properties against caries-causing bacteria than dental cement itself.

Claims

1. ZnO is 41 mass % or more and 52 mass % or less, P ２ O ５ 47% by mass or more and 51% by mass or less of ZnO, 7% by mass or less of MgO, and 9% by mass or less of CaO.

2. In claim 1, A dental glass containing ZnO in an amount of 48% by mass or more and 52% by mass or less, and MgO in an amount of 0.8% by mass or more and 2.6% by mass or less.

3. In claim 1 or 2, A dental glass having a fluorine content of 3% by mass or less.

4. 3. A method for producing dental glass according to claim 1 or 2, comprising the steps of: a mixing step of mixing a raw material liquid containing a zinc salt solution, a phosphate solution, an optional magnesium salt solution, and an optional calcium salt solution to generate aggregates in the raw material liquid; a drying step of drying the agglomerate to obtain a powder product; A method for producing dental glass comprising the steps of:

5. In claim 4, A method for producing dental glass, further comprising a washing step of washing the aggregates with a liquid before the drying step.

6. In claim 4, The method for producing dental glass further comprises a grinding step of grinding the powder material to obtain a powder material.

7. A dental material comprising the dental glass according to claim 1 or 2 and dental cement.

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