Oral composition

Abstract

To provide an oral composition that suppresses a deterioration of a tooth stain removal effect of an anionic surfactant while containing potassium nitrate.SOLUTION: An oral composition contains hydroxyapatite particles, an anionic surfactant, and potassium nitrate. For the hydroxyapatite particles, in a powder X-ray diffraction pattern measured by CuKα characteristic X-ray, the ratio of a diffraction peak intensity around 2θ=32° to a diffraction peak intensity around 2θ=26° is 0.8-1.5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to oral compositions, and more specifically to an oral composition containing an anionic surfactant, potassium nitrate, and hydroxyapatite particles, which has an anti-hypersensitive effect due to nerve dullness and an effect of removing stains from teeth. [Background technology]

[0002] Dentin hypersensitivity is a condition in which dentin is exposed due to wear or loss of tooth enamel or gingival recession, and transient pain is felt when this dentin is subjected to external stimuli such as temperature stimuli from cold foods and drinks, chemical stimuli such as sweet or sour tastes, or mechanical stimuli such as brushing. Because these stimuli stimulate the pulp nerves through the dentinal tubules present on the dentin surface, treatments in dental clinics and the like involve covering the exposed dentin surface and sealing the dentinal tubules. Oral hygiene products used at home and elsewhere involve methods of sealing the dentinal tubules and desensitizing the nerves, and it is known that potassium salts such as potassium nitrate are incorporated into oral compositions as desensitizing ingredients (Patent Document 1).

[0003] Tooth stains, commonly known as stains, are formed when polyphenols in food and drink bind to and deposit on the pellicle formed on the tooth surface by salivary proteins. Known methods for removing these stains include chemical removal using oral compositions containing anionic surfactants and mechanical removal using oral compositions containing abrasives.

[0004] However, when potassium nitrate and an anionic surfactant are used in combination, the anionic surfactant forms an insoluble precipitate with potassium ions, resulting in reduced foaming properties. Several solutions to this problem have been proposed. Examples include the use of a water-soluble polymer in combination with propylene glycol alginate (Patent Document 2) and a specific polyoxyethylene-polyoxypropylene-added nonionic surfactant (Patent Document 3). On the other hand, the use of the above ingredients in combination also poses the problem of reduced ability of the anionic surfactant to remove dental stains, but no solutions have been proposed to address this issue. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-281551 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-119520 [Patent Document 3] Japanese Patent Application Laid-Open No. 2018-104295 Summary of the Invention [Problem to be solved by the invention]

[0006] To provide an excellent oral composition which suppresses the reduction in tooth stain removal effect caused by an anionic surfactant when potassium nitrate is compounded, and has both an anti-hypersensitivity effect due to nerve dullness and a tooth stain removal effect. [Means for solving the problem]

[0007] The present inventors have conducted extensive research in light of the above-mentioned problems and have surprisingly found that the above-mentioned problems can be solved by using specific hydroxyapatite particles (hydroxyapatite particles having an X-ray diffraction pattern in which the ratio of the diffraction peak intensity around 2θ=32° to the diffraction peak intensity around 2θ=26° is 0.8 to 1.5), potassium nitrate, and an anionic surfactant in combination.

[0008] The present invention includes, for example, the inventions described below. Section 1. Contains hydroxyapatite particles, an anionic surfactant, and potassium nitrate, The hydroxyapatite particles are characterized in that the ratio of the diffraction peak intensity around 2θ=32° to the diffraction peak intensity around 2θ=26° in a powder X-ray diffraction pattern measured with CuKα characteristic X-rays is 0.8 to 1.5. Oral composition. Section 2. Item 2. The oral composition according to Item 1, wherein the anionic surfactant is at least one selected from the group consisting of sodium lauryl sulfate, disodium polyoxyethylene alkyl sulfosuccinate, and olefin sulfonate. Section 3. Item 3. The oral composition according to item 1 or 2, containing 5% by mass of potassium nitrate. Section 4. Item 4. The oral composition according to any one of Items 1 to 3, comprising 0.1 to 5% by mass of the anionic surfactant. Section 5. Item 5. The oral composition according to any one of Items 1 to 4, wherein the hydroxyapatite particles have a Ca / P molar ratio of less than 1.67. Section 6. Item 6. The oral composition according to any one of Items 1 to 5, wherein the hydroxyapatite particles have a median diameter of 5 μm or less. Section 7. Item 7. The oral composition according to any one of Items 1 to 6, wherein the hydroxyapatite particles have a specific surface area of ​​55 to 200 m2 / g. Section 8. Item 8. The oral composition according to any one of Items 1 to 7, wherein the hydroxyapatite particles have a powder X-ray diffraction pattern measured using CuKα characteristic X-rays in which the ratio of the diffraction peak intensity around 2θ=34° to the diffraction peak intensity around 2θ=32° is 1 or less. Section 9. The hydroxyapatite particles are aggregates of hydroxyapatite platelet crystals. Item 9. The oral composition according to any one of items 1 to 8. Section 10. Item 10. The oral composition according to any one of Items 1 to 9, which is used to remove stains from teeth. Section 11. An agent for suppressing a decrease in the stain removal ability of an anionic surfactant, comprising hydroxyapatite particles, The hydroxyapatite particles have a powder X-ray diffraction pattern measured with CuKα characteristic X-rays in which the ratio of the diffraction peak intensity around 2θ=32° to the diffraction peak intensity around 2θ=26° is 0.8 to 1.5. An agent that prevents the stain removal power of anionic surfactants from decreasing. Section 12. A method for suppressing a decrease in the stain removal ability of an anionic surfactant by adding hydroxyapatite particles to an oral composition containing potassium nitrate and an anionic surfactant, The hydroxyapatite particles have a powder X-ray diffraction pattern measured with CuKα characteristic X-rays in which the ratio of the diffraction peak intensity around 2θ=32° to the diffraction peak intensity around 2θ=26° is 0.8 to 1.5. A method for suppressing a decrease in the stain removal ability of an anionic surfactant. [Effects of the Invention]

[0009] An excellent oral composition is provided which has both an anti-hypersensitivity effect due to nerve dullness and an effect of removing stains from teeth. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows the X-ray diffraction peaks of the hydroxyapatite particles of Production Example 1. [Figure 2] 1 shows the X-ray diffraction peaks of commercially available reagent hydroxyapatite particles. [Figure 3] 1 shows the X-ray diffraction peaks of the hydroxyapatite particles of Production Example 2. [Figure 4] 1 shows the X-ray diffraction peaks of the hydroxyapatite particles of Production Example 3. [Figure 5]1 shows the X-ray diffraction peaks of the hydroxyapatite particles of Production Example 4. [Figure 6] 1 shows the X-ray diffraction peaks of the hydroxyapatite particles of Production Example 5. [Figure 7] The stain removal power test results are shown below. DETAILED DESCRIPTION OF THE INVENTION

[0011] Each embodiment of the present invention will be described in more detail below. The present invention preferably includes oral compositions, particularly oral compositions containing an anionic surfactant, potassium nitrate, and specific hydroxyapatite particles, but is not limited thereto, and the present invention includes all of the compositions disclosed herein and recognizable by those skilled in the art.

[0012] The anionic surfactant used in the present invention can be exemplified as alkyl sulfate, polyoxyethylene alkyl ether sulfate, alkyl sulfosuccinate, polyoxyethylene alkyl ether sulfosuccinate, acylamino acid salt, acyltaurine salt, alkyl ether carboxylate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, fatty acid monoglyceride sulfate, alkyl sulfoacetate, olefin sulfonate etc.Among them, alkyl sulfate, polyoxyethylene alkyl ether sulfate, alkyl sulfosuccinate, polyoxyethylene alkyl ether sulfosuccinate, olefin sulfonate are preferred, and alkyl sulfate, polyoxyethylene alkyl ether sulfosuccinate, olefin sulfonate are more preferred.In addition, as salt, alkali metal salt or alkaline earth metal salt is preferred, for example, sodium salt, potassium salt, magnesium salt etc. can be enumerated, among which sodium salt is preferred.

[0013] The alkyl chain length of the alkyl sulfate salts and polyoxyethylene alkyl ether sulfosuccinate salts used in the present invention includes saturated / unsaturated alkyl groups having 8 to 18 carbon atoms. Of these, the carbon number distribution of the alkyl group is preferably 10 to 18, more preferably 10 to 16, and even more preferably 10 to 12. Furthermore, olefin sulfonates are preferably those having 14 to 16 carbon atoms. These anionic surfactants are preferably blended in an amount of 0.01 to 5% by mass, more preferably 0.05 to 4.5% by mass, and particularly preferably 0.1 to 4% by mass, of the total oral composition.

[0014] The amount of potassium nitrate used in the present invention is not particularly limited, but in order to exert the anti-dentin hypersensitivity effect, it is preferably blended in an amount of 1 to 10% by mass, more preferably 3 to 8% by mass, and particularly preferably 5% by mass, based on the entire oral composition. The greater the amount of potassium nitrate blended, the greater the anti-dentin hypersensitivity effect, but blending in a large amount is not preferred because it imparts a salty and bitter taste.

[0015] The specific hydroxyapatite particles used in the present invention are hydroxyapatite particles having an X-ray diffraction pattern in which the ratio of the diffraction peak intensity around 2θ=32° to the diffraction peak intensity around 2θ=26° is 0.8 to 1.5.

[0016] The diffraction peak near 2θ=26° is a peak of hydroxyapatite, specifically a diffraction peak at 2θ=25.5 to 26.5°, preferably a diffraction peak at 2θ=25.8 to 26.2°. When there are multiple diffraction peaks near 2θ=26°, this means the diffraction peak with the highest intensity.

[0017] The diffraction peak near 2θ=32° is a peak of hydroxyapatite, specifically a diffraction peak at 2θ=31.5 to 32.5°, preferably a diffraction peak at 2θ=31.8 to 32.2°. When there are multiple diffraction peaks near 2θ=32°, the diffraction peak with the highest intensity is the one with the highest intensity.

[0018] In this specification, the X-ray diffraction pattern refers to a powder X-ray diffraction pattern measured using CuKα characteristic X-rays. The measurement conditions are, for example, as follows: target: Cu, tube voltage: 40 kV, tube current: 30 mA, sampling width: 0.02°, scan speed: 2.00° / min, divergence slit: 1.0°, scattering slit: 1.0°, receiving slit: 0.3 mm.

[0019] The specific hydroxyapatite particles have a ratio (32° / 26°) of the diffraction peak intensity around 2θ=32° to the diffraction peak intensity around 2θ=26° of 0.8 to 1.5, preferably 0.9 to 1.3, more preferably 1.0 to 1.25, even more preferably 1.05 to 1.2, and still more preferably 1.05 to 1.15.

[0020] It is preferred that each of the specific hydroxyapatite particles is an aggregate of hydroxyapatite plate crystals. The shape of the plate crystals constituting the specific hydroxyapatite particles is not particularly limited, and examples thereof include circular, polygonal (particularly hexagonal), rod-like, and combinations thereof. The plate crystals may be in either a state in which the faces are folded or in a state in which the faces are not folded and maintain a planar structure. Typically, plate hydroxyapatite crystals have a structure called a hexagonal crystal, with the top face of the plate being the c-plane and the side face being the a-plane. When a particle is formed from multiple crystals, the crystals are called crystallites.

[0021] The specific hydroxyapatite particles are particles containing hydroxyapatite as a main component, and preferably particles essentially consisting of hydroxyapatite. In the X-ray diffraction pattern of the specific hydroxyapatite particles, even if other substances (e.g., monetite, etc.) are contained, the peaks are not observed separately or the peak intensities are relatively low. Therefore, the specific hydroxyapatite particles are distinguishable from particles in which the peak intensities of these peaks are high.

[0022] The specific hydroxyapatite particles preferably have an X-ray diffraction pattern in which the ratio of the diffraction peak intensity around 2θ=34° to the diffraction peak intensity around 2θ=32° (34° / 32°) is 1 or less. The diffraction peak around 2θ=34° is specifically a diffraction peak at 2θ=33.5 to 34.5°, preferably a diffraction peak at 2θ=33.8 to 34.2°. When there are multiple diffraction peaks around 2θ=34°, the diffraction peak with the highest intensity is the one with the highest intensity. The peak intensity ratio is preferably 0.1 to 1, more preferably 0.2 to 0.9, even more preferably 0.3 to 0.8, still more preferably 0.4 to 0.7, and particularly preferably 0.4 to 0.6.

[0023] The specific hydroxyapatite particles preferably have a sum of the areas of all diffraction peaks within the range of 25.5°≦2θ≦26.5° and 31.5°≦2θ≦32.5° of 30 to 45% of the sum of the areas of all diffraction peaks within the range of 25°≦2θ≦35°, where 100% is the sum. This value is preferably 33 to 42%, more preferably 35 to 40%. Furthermore, the specific hydroxyapatite particles preferably have a crystallite size of 4 to 12 nm, more preferably 5 to 10 nm, calculated from the diffraction peak due to the (130) plane near 2θ=40°.

[0024] The Ca / P molar ratio of the specific hydroxyapatite particles is not particularly limited as long as it is a value that hydroxyapatite can assume. While not intending to restrictively interpret it, it is believed that in the specific hydroxyapatite particles, a portion of the calcium is substituted with other elements (such as sodium), and therefore the Ca / P molar ratio may be relatively low. From this perspective, the Ca / P molar ratio of the specific hydroxyapatite particles is preferably less than 1.67, more preferably 1.65 or 1.60 or less, even more preferably 1.55 or 1.50 or less, and even more preferably 1.45 or 1.40 or less. The lower limit of the Ca / P molar ratio of the specific hydroxyapatite particles is not particularly limited and may be, for example, 1.0, 1.1, or 1.2. The Ca / P molar ratio is a value calculated from the Ca and P contents of the specific hydroxyapatite particles measured by inductively coupled plasma atomic emission spectroscopy.

[0025] The median diameter (d50) of the specific hydroxyapatite particles is not particularly limited, but is preferably 5 μm or less, more preferably 4.5 μm or less. The lower limit of the median diameter is not particularly limited, but examples include 1 μm or more, 2 μm or more, or 3 μm or more. More specifically, it is 1 to 5 μm. The median diameter is a value measured by a laser diffraction / scattering method. More specifically, it is a value measured by dry particle size distribution measurement using a laser diffraction particle size distribution analyzer.

[0026] The specific surface area of ​​the specific hydroxyapatite particles is not particularly limited, but is, for example, 30 m / g or more, preferably 40 m / g or more, more preferably 50 m / g or more, and even more preferably 55 m / g or more. The upper limit of the specific surface area is not particularly limited, but is, for example, 150 m / g, 120 m / g, 100 m / g, or 90 m / g. The specific surface area is a value measured by nitrogen gas adsorption.

[0027] The specific hydroxyapatite particles can be prepared, for example, by a method for producing hydroxyapatite particles, which includes a step of mixing an aqueous solution of an alkali phosphate having a pH of 4 or more and less than 7 with a calcium hydroxide slurry and reacting the mixture at 35 to 85°C.

[0028] The alkali phosphate salt is not particularly limited and includes hydrates and anhydrates. Examples of the alkali phosphate salt include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, tetrasodium pyrophosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, etc., preferably sodium phosphate salts such as sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, etc., more preferably sodium dihydrogen phosphate.

[0029] The concentration of the alkali phosphate in the aqueous alkali phosphate solution is not particularly limited and is, for example, 3 to 50% by mass, preferably 3 to 30% by mass, more preferably 5 to 20% by mass, and even more preferably 7 to 15% by mass.

[0030] The pH of the aqueous solution of alkali phosphate is preferably 4 or more and less than 7. The pH is more preferably 5 to 6.5. As described below, when the pH of the aqueous solution of alkali phosphate is relatively low (for example, when the pH is 4 or more and less than 5), it is desirable to use an anhydride as the alkali phosphate and set the reaction temperature to a relatively high temperature, for example, 65 to 85°C, preferably 70 to 85°C, more preferably 75 to 85°C.

[0031] The calcium hydroxide slurry has oxalic acid reactivity, and the calcium hydroxide slurry is preferably a slurry of calcium hydroxide having a specific reactivity with oxalic acid.

[0032] The reactivity towards oxalic acid can be expressed, for example, by the following definition: Oxalic acid reactivity: 40 g of 0.5 mol / L oxalic acid aqueous solution kept at 25±1°C was added all at once to 50 g of calcium hydroxide slurry prepared to a concentration of 5% by mass and kept at 25±1°C, and the time (minutes) until the pH reached 7.0 after addition.

[0033] The specific reactivity to oxalic acid, as defined above, is preferably 1 to 40 minutes, more preferably 5 to 30 minutes, and even more preferably 10 to 20 minutes.

[0034] The BET specific surface area of ​​the calcium hydroxide slurry is preferably 5 m / g or more, more preferably 6 m / g or more. The upper limit of the BET specific surface area is not particularly limited, but is, for example, 20 m / g, 15 m / g, or 10 m / g.

[0035] A calcium hydroxide slurry having high oxalic acid reactivity (e.g., reactivity with the specific oxalic acid described above) can typically be obtained by grinding a calcium hydroxide slurry. The grinding treatment can further increase the oxalic acid reactivity (shorten the time defined above). The grinding treatment is carried out, for example, using a bead mill. The conditions for the grinding treatment are not particularly limited, and can be, for example, the conditions according to the method described in JP 2017-036176 A.

[0036] Calcium hydroxide slurry can be prepared, for example, by reacting water with quicklime (calcium oxide) obtained by calcining limestone. For example, limestone is calcined in a kiln at about 1000°C to produce quicklime, and about 10 times the amount of hot water is added to the quicklime and stirred for 30 minutes to prepare calcium hydroxide slurry.

[0037] The solid content concentration of the calcium hydroxide slurry is not particularly limited, but is, for example, 1 to 30 mass %, preferably 3 to 20 mass %, more preferably 5 to 15 mass %, and even more preferably 6 to 12 mass %.

[0038] The ratio of the amount of the aqueous alkali phosphate solution to the amount of the calcium hydroxide slurry is not particularly limited as long as it is a ratio that allows the production of hydroxyapatite particles. The ratio is preferably adjusted so that the Ca / P molar ratio is 0.3 to 0.7, more preferably 0.4 to 0.6, and even more preferably 0.45 to 0.55.

[0039] The manner in which the aqueous alkali phosphate solution and the calcium hydroxide slurry are mixed is not particularly limited. Examples include an embodiment in which the calcium hydroxide slurry is added to a reaction vessel containing the aqueous alkali phosphate solution (Embodiment 1), an embodiment in which the aqueous alkali phosphate solution is added to a reaction vessel containing the calcium hydroxide slurry (Embodiment 2), and an embodiment in which the aqueous alkali phosphate solution and the calcium hydroxide slurry are added to the reaction vessel simultaneously (Embodiment 3). Among these, Embodiment 1 is preferred. During the addition to the reaction vessel, the liquid in the reaction vessel is usually stirred.

[0040] The addition to the reaction vessel is desirably carried out over a certain period of time, for example, 10 to 90 minutes, preferably 20 to 60 minutes, and more preferably 20 to 40 minutes.

[0041] The reaction is usually carried out under stirring. The reaction temperature is 35 to 85°C. The reaction temperature is preferably 40 to 75°C, more preferably 45 to 70°C, even more preferably 50 to 70°C, and even more preferably 55 to 65°C. When the pH of the aqueous solution of alkali phosphate is relatively low (for example, when the pH is 4 or higher but less than 5), the reaction temperature is relatively high, for example, 65 to 85°C, preferably 70 to 85°C, and more preferably 75 to 85°C. The reaction time (of the alkali phosphate) The time period starting from when the aqueous acid alkali salt solution and the calcium hydroxide slurry are completely mixed (in the above-mentioned embodiments 1 to 3, the time period starting from when the addition of the aqueous acid alkali salt solution and the calcium hydroxide slurry is completed) is, for example, 10 to 180 minutes, preferably 20 to 120 minutes, more preferably 40 to 90 minutes, and even more preferably 50 to 70 minutes.

[0042] The specific hydroxyapatite particles produced by the above process may be subjected to a purification treatment, such as filtration or washing, if necessary. Furthermore, the particles may be subjected to a drying treatment if necessary.

[0043] The specific hydroxyapatite particles can be contained in the oral composition in an amount of, for example, about 1 to 10% by mass. The upper or lower limit of the content range may be, for example, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, or 9.5% by mass. For example, the range is more preferably 2 to 8% by mass or 3 to 7% by mass.

[0044] The oral composition of the present invention can be produced by a conventional method. Examples of the oral composition of the present invention include toothpaste, liquid toothpaste, gel, paste, ointment, liniment, mouthwash, and spray. Among these, toothpaste, liquid toothpaste, gel, paste, ointment, and liniment are preferred, with toothpaste, gel, and paste being particularly preferred. Furthermore, the oral composition of the present invention can be used as a pharmaceutical, quasi-drug, or cosmetic.

[0045] The oral composition of the present invention may further contain any known optional components that can generally be incorporated into oral compositions, either alone or in combination of two or more, within the scope that does not impair the effects of the present invention.

[0046] Such known optional ingredients include, for example, surfactants, abrasives, wetting agents, thickeners, sweeteners, preservatives, colorants, pH adjusters, stabilizers, flavoring agents, astringents, other medicinal ingredients, and the like.

[0047] The surfactant may further include, for example, a nonionic surfactant or an amphoteric surfactant. Specific examples of nonionic surfactants include fatty acid esters, fatty acid alkanolamides, sorbitan fatty acid esters, fatty acid monoglycerides, polyglycerin fatty acid esters, polyoxyethylene alkylphenyl ethers, alkylglycosides, diethyl sebacate, polyoxyethylene hydrogenated castor oil, and fatty acid polyoxyethylene sorbitan. Examples of amphoteric surfactants include alkyldimethylaminoacetic acid betaine, alkylamidopropyldimethylaminoacetic acid betaine, N-acyl-N-carboxymethyl-N-hydroxyethylethylenediamine, and N-alkylaminoethylglycine. These surfactants may be used alone or in combination of two or more. The amount of surfactant used is typically 0.1 to 5% by mass based on the total amount of the composition.

[0048] Examples of abrasives include dibasic calcium phosphate dihydrate and anhydrous calcium phosphate, calcium phosphate, tribasic calcium phosphate, calcium carbonate, calcium pyrophosphate, aluminum hydroxide, alumina, anhydrous silicic acid, silica gel, aluminum silicate, insoluble sodium metaphosphate, tribasic magnesium phosphate, magnesium carbonate, calcium sulfate, polymethyl methacrylate, bentonite, zirconium silicate, hydroxyapatite, synthetic resins, etc. These abrasives can be used alone or in combination of two or more.

[0049] Examples of humectants include sorbitol, ethylene glycol, propylene glycol, glycerin, 1,3-butylene glycol, polypropylene glycol, xylitol, maltitol, lactitol, palatinit, polyethylene glycol, etc. These humectants can be blended alone or in combination of two or more.

[0050] Examples of thickeners include cellulose derivatives such as hydroxypropyl cellulose, hydroxypropylmethyl cellulose, hydroxymethylethyl cellulose, and the like, gums such as xanthan gum, locust bean gum, carrageenan, tragacanth gum, karaya gum, gum arabic, and gellan gum, synthetic binders such as polyvinyl alcohol, sodium polyacrylate, carboxyvinyl polymer, and polyvinylpyrrolidone, inorganic binders such as thickening silica, aluminum silica gel, and Veegum, sodium alginate, pectin, agar, gelatin, soybean polysaccharides, sodium chondroitin sulfate, and sodium hyaluronate. These thickeners can be blended alone or in combination of two or more.

[0051] Examples of sweeteners include saccharin sodium, acesulfame potassium, stevioside, neohesperidyl dihydrochalcone, glycyrrhizin, perillartine, thaumatin, aspartyl phenylalanyl methyl ester, and p-methoxycinnamic aldehyde. These sweeteners can be used alone or in combination of two or more. The amount of the sweetener used is usually 0.01 to 1% by mass of the total amount of the composition.

[0052] Examples of preservatives include parabens such as methylparaben, ethylparaben, propylparaben, and butylparaben, sodium benzoate, phenoxyethanol, alkyldiaminoethylglycine hydrochloride, etc. These preservatives can be used alone or in combination of two or more.

[0053] Examples of pH adjusters include citric acid, phosphoric acid, malic acid, pyrophosphoric acid, lactic acid, tartaric acid, glycerophosphoric acid, acetic acid, nitric acid, or chemically acceptable salts thereof, sodium hydroxide, etc. These pH adjusters can be blended alone or in combination of two or more.

[0054] Examples of stabilizers include sodium edetate, sodium thiosulfate, sodium sulfite, sodium chloride, calcium lactate, lanolin, triacetin, castor oil, magnesium sulfate, etc. These stabilizers can be blended alone or in combination of two or more.

[0055] Examples of flavoring agents include tea extract, dry distillate of tea, propolis extract, and sodium glutamate.

[0056] Examples of astringents include sodium bicarbonate and aluminum lactate.

[0057] Other medicinal agents include fluorine compounds such as sodium fluoride, sodium monofluorophosphate, and stannous fluoride; enzymes such as dextranase, mutanase, amylase, protease, and lytic enzyme (Retec Enzyme); tranexamic acid, ε-aminocaproic acid, aluminum chlorohydroxyallantoin, allantoin, dihydrocholesterol, glycyrrhizic acids, glycyrrhetinic acid, bisabolol, isopropylmethylphenol, glycerophosphate, chlorophyll, copper gluconate, sodium chloride, water-soluble inorganic phosphate compounds, chlorhexidine salts, triclosan, and cetylpyridinium chloride. vitamins such as dl-α-tocopherol acetate, pyridoxine acetate, and ascorbic acid or a salt thereof; plant extracts such as aloe, ginkgo leaf, agaricus, oolong tea, chamomile, quince, gymnema, kumazasa, sweet tea, eucommia tea, houttuynia cordata, Job's tears, megusurinoki, mugwort, green tea, rooibos, lemon balm, rosemary, crab mint, Luo Han Guo, perilla, cranberry, yarrow, elder, licorice, peppermint, eucalyptus, guarana, licorice, linden, hops, cacao, mulberry leaf, thyme, and Scutellaria Root; lactic acid bacteria; and hydrogen peroxide. [Example]

[0058] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0059] [Production of hydroxyapatite] <Production Example 1> A 10.7% by mass aqueous solution of sodium dihydrogen phosphate dihydrate and an 8.6% by mass solids ground calcium hydroxide slurry (BET specific surface area: 6.7 m / g, oxalic acid reactivity: 15 minutes 30 seconds, JP 2017-036176 A) were prepared to a Ca / P molar ratio of 0.5. The sodium dihydrogen phosphate dihydrate aqueous solution was placed in a stainless steel beaker and heated to 60°C with stirring until the stirring stopped. A 10% aqueous solution of NaOH was added to adjust the pH to 5.5. The calcium hydroxide slurry was added over 30 minutes. After the addition, the mixture was stirred for an additional hour, filtered, washed with water, and dried at 80°C to obtain hydroxyapatite particles (powder).

[0060] The obtained hydroxyapatite particles were subjected to X-ray crystal diffraction, specific surface area measurement, particle size distribution measurement, and Ca / P molar ratio measurement.

[0061] Measurements were performed using a MultiFlex X-ray diffractometer (Rigaku Corporation) over the 2θ range of 25–45°. The measurement conditions were as follows: target: Cu, tube voltage: 40 kV, tube current: 30 mA, sampling width: 0.02°, scan speed: 2.00° / min, divergence slit: 1.0°, scattering slit: 1.0°, receiving slit: 0.3 mm. The results are shown in Figure 1. Figure 2 also shows the X-ray diffraction pattern of commercially available reagent hydroxyapatite (reagent hydroxyapatite). The ratio of the diffraction peak intensity due to the (211) plane near 2θ = 32° to the diffraction peak intensity due to the (002) plane near 2θ = 26° was 1.1, significantly lower than the peak intensity ratio of 2.7 for reagent hydroxyapatite. This indicates that the obtained hydroxyapatite particles are aggregates of platelet crystals with a relatively large amount of exposed c-plane. Furthermore, the sum of the areas of all diffraction peaks within the range of 25° ≤ 2θ ≤ 35° is 100%, whereas the sum of the areas of all diffraction peaks within the range of 25.5° ≤ 2θ ≤ 26.5° and 31.5° ≤ 2θ ≤ 32.5° is 37.2%. This is significantly lower than the 52.1% observed for reagent hydroxyapatite, and the relatively broad X-ray diffraction pattern also indicates low crystallinity. Furthermore, the crystallite size calculated from the diffraction peak due to the (130) plane near 2θ = 40° is 7 nm, which is significantly smaller than the 52 nm observed for reagent hydroxyapatite, also indicating low crystallinity.

[0062] The specific surface area of ​​the hydroxyapatite particles was measured by nitrogen gas adsorption using a fully automatic specific surface area measuring device, Macsorb HM model-1208 (manufactured by Mountec Co., Ltd.) and was found to be 61.9 m2 / g.

[0063] The particle size distribution of the hydroxyapatite particles was measured by dry particle size distribution measurement using a laser diffraction particle size distribution analyzer MASTER SIZER 3000 (manufactured by Malvern Panalytical Co., Ltd.) and the median diameter (d50) was found to be 3.76 μm.

[0064] The Ca / P molar ratio of the hydroxyapatite particles was calculated from the Ca and P contents measured by inductively coupled plasma atomic emission spectrometry using an iCAP 6000 ICP-OES (manufactured by ThermoFisher). The Ca / P molar ratio was found to be 1.33.

[0065] <Production Example 2> A 10.7% by mass aqueous solution of sodium dihydrogen phosphate dihydrate and an 8.6% by mass solids ground calcium hydroxide slurry (BET specific surface area: 7.9 m / g, oxalic acid reactivity: 12 minutes 30 seconds, JP 2017-036176 A) were prepared to a Ca / P molar ratio of 0.5. The sodium dihydrogen phosphate dihydrate aqueous solution was placed in a stainless steel beaker and heated to 60°C with stirring until the stirring stopped. A 10% aqueous solution of NaOH was added to adjust the pH to 6.0. The calcium hydroxide slurry was then added over 30 minutes. After the addition, the mixture was stirred for an additional hour, filtered, washed with water, and dried at 80°C to obtain hydroxyapatite particles (powder).

[0066] The obtained hydroxyapatite particles were subjected to X-ray crystal diffraction and specific surface area measurement in the same manner as in Production Example 1.

[0067] The results of X-ray crystal diffraction are shown in Figure 3. The ratio of the diffraction peak intensity due to the (211) plane near 2θ = 32 ° to the diffraction peak intensity due to the (002) plane near 2θ = 26 ° was 1.1, which was the same value as in Production Example 1. Furthermore, the sum of the areas of all diffraction peaks within the range of 25 ° ≦ 2θ ≦ 35 ° was 100%, and the sum of the areas of all diffraction peaks within the range of 25.5 ° ≦ 2θ ≦ 26.5 ° and the range of 31.5 ° ≦ 2θ ≦ 32.5 ° was 38.6%. Furthermore, the crystallite size calculated from the diffraction peak due to the (130) plane near 2θ = 40 ° was 7 nm.

[0068] The specific surface area was 75.4 m2 / g.

[0069] <Production Example 3> A 10.7% by mass aqueous solution of sodium dihydrogen phosphate dihydrate and an 8.6% by mass solids ground calcium hydroxide slurry (BET specific surface area: 7.9 m / g, oxalic acid reactivity: 12 minutes 30 seconds, JP 2017-036176 A) were prepared to a Ca / P molar ratio of 0.5. The sodium dihydrogen phosphate dihydrate aqueous solution was placed in a stainless steel beaker and heated to 40°C with stirring until the stirring stopped. A 10% aqueous solution of NaOH was added to adjust the pH to 5.5. The calcium hydroxide slurry was added over 50 minutes. After the addition, the mixture was stirred for another hour, filtered, washed with water, and dried at 80°C to obtain hydroxyapatite particles (powder).

[0070] The obtained hydroxyapatite particles were subjected to X-ray crystal diffraction and specific surface area measurement in the same manner as in Production Example 1.

[0071] The results of X-ray crystal diffraction are shown in Figure 4. The ratio of the diffraction peak intensity due to the (211) plane near 2θ = 32 ° to the diffraction peak intensity due to the (002) plane near 2θ = 26 ° was 1.2, which was the same value as in Production Example 1. Furthermore, the sum of the areas of all diffraction peaks within the range of 25 ° ≦ 2θ ≦ 35 ° was 100%, and the sum of the areas of all diffraction peaks within the range of 25.5 ° ≦ 2θ ≦ 26.5 ° and the range of 31.5 ° ≦ 2θ ≦ 32.5 ° was 36.0%. Furthermore, the crystallite size calculated from the diffraction peak due to the (130) plane near 2θ = 40 ° was 6 nm.

[0072] The specific surface area was 81.5 m2 / g.

[0073] <Production Example 4> A 10.7% by mass anhydrous aqueous solution of sodium dihydrogen phosphate and a 8.6% by mass ground calcium hydroxide slurry (BET specific surface area: 7.9 m / g, oxalic acid reactivity: 12 minutes 30 seconds, JP 2017-036176 A) were prepared so that the Ca / P molar ratio was 0.5. The anhydrous aqueous solution of sodium dihydrogen phosphate was placed in a stainless steel beaker and heated to 80°C with stirring. The pH was left at 4.2 without adjustment. The calcium hydroxide slurry was added thereto over 30 minutes. After the addition was completed, the mixture was stirred for another hour, then filtered, washed with water, and dried at 80°C to obtain hydroxyapatite particles (powder).

[0074] The obtained hydroxyapatite particles were subjected to X-ray crystal diffraction and specific surface area measurement in the same manner as in Production Example 1.

[0075] The results of X-ray crystal diffraction are shown in Figure 5. The ratio of the diffraction peak intensity due to the (211) plane near 2θ = 32 ° to the diffraction peak intensity due to the (002) plane near 2θ = 26 ° was 1.4, which was the same value as in Production Example 1. Furthermore, the sum of the areas of all diffraction peaks within the range of 25 ° ≦ 2θ ≦ 35 ° was 100%, and the sum of the areas of all diffraction peaks within the range of 25.5 ° ≦ 2θ ≦ 26.5 ° and the range of 31.5 ° ≦ 2θ ≦ 32.5 ° was 37.8%. Furthermore, the crystallite size calculated from the diffraction peak due to the (130) plane near 2θ = 40 ° was 9 nm.

[0076] The specific surface area was 163.4 m2 / g.

[0077] <Production Example 5> A 10.7% by mass anhydrous aqueous solution of sodium dihydrogen phosphate and a 8.6% by mass ground calcium hydroxide slurry (BET specific surface area: 7.9 m / g, oxalic acid reactivity: 12 minutes 30 seconds, JP 2017-036176 A) were prepared so that the Ca / P molar ratio was 0.5. The anhydrous aqueous solution of sodium dihydrogen phosphate was placed in a stainless steel beaker and heated to 60°C with stirring. The pH was left at 4.2 without adjustment. The calcium hydroxide slurry was added thereto over 30 minutes. After the addition was completed, the mixture was stirred for another hour, then filtered, washed with water, and dried at 80°C to obtain hydroxyapatite particles (powder).

[0078] The obtained hydroxyapatite particles were subjected to X-ray crystal diffraction and specific surface area measurement in the same manner as in Production Example 1.

[0079] The results of X-ray crystal diffraction are shown in Figure 6. The ratio of the diffraction peak intensity due to the (211) plane near 2θ = 32 ° to the diffraction peak intensity due to the (002) plane near 2θ = 26 ° was 1.1, which was the same value as in Production Example 1. Furthermore, the sum of the areas of all diffraction peaks within the range of 25 ° ≦ 2θ ≦ 35 ° was 100%, and the sum of the areas of all diffraction peaks within the range of 25.5 ° ≦ 2θ ≦ 26.5 ° and the range of 31.5 ° ≦ 2θ ≦ 32.5 ° was 31.6%. Furthermore, the crystallite size calculated from the diffraction peak due to the (130) plane near 2θ = 40 ° was 7 nm.

[0080] The specific surface area was 94.7 m2 / g.

[0081] [Stain removal power study] Measurements were carried out using a modified method of Stooky et al. (J. Dent. Res., Vol. 61, No. 11, 1236-1239, 1982), and the stain removal rate (%) was calculated.

[0082] <Preparation of test solution> A test solution for stain removal testing was prepared according to the formulation in Table 1. The following components were used: sodium lauryl sulfate (Kao Corporation, trade name "Emeral 10PT"), potassium nitrate (Otsuka Chemical Co., Ltd., trade name "Potassium Nitrate"), and hydroxyapatite A (Tomita Pharmaceutical Co., Ltd., trade name "Hydroxyapatite").

[0083] [Table 1]

[0084] <Creating a colored tooth model hydroxyapatite disk> A hydroxyapatite disk (manufactured by HOYA Technosurgical, trade name "APP-610") was immersed in the solution for the specified time in the order shown in Table 2. This procedure was repeated 12 times, and then the disk was allowed to air dry to prepare a colored tooth model. The black tea extract was obtained by boiling three tea bags (manufactured by Lipton, trade name "Lipton Yellow Label") in 600 ml of distilled water for three minutes.

[0085] [Table 2]

[0086] <Stain removal test and calculation of stain removal rate> The tooth-stained model hydroxyapatite disk was completely immersed in 3 ml of a solution prepared according to the formulation in Table 1 and left to stand for 1 minute, then immersed in distilled water for 1 minute to wash, and then air-dried. The color changes of the hydroxyapatite disk before staining, after staining, and after stain removal were measured using a color difference meter (Konica Minolta, product name "Fluorescence Spectrodensitometer FD-5") in the L*a*b* color system. The values ​​before staining were defined as L*0, a*0, b*0, the values ​​after staining were defined as L*1, a*1, b*1, and the values ​​after stain removal were defined as L*2, a*2, b*2, and the stain removal rate was calculated using the formula shown in Equation 1.

[0087]

number

[0088] The results of the stain removal test are shown in Figure 7. As shown in Figure 7, the combined use of sodium lauryl sulfate and potassium nitrate (Comparative Example 3) significantly reduces the stain removal rate compared to the use of sodium lauryl sulfate alone (Comparative Example 1). Furthermore, although the combined use of sodium lauryl sulfate and the hydroxyapatite of Production Example 1 (Comparative Example 2) reduces the stain removal rate, the combined use of sodium lauryl sulfate and the hydroxyapatite of Production Example 1 in the presence of potassium nitrate (Example 1) significantly suppresses the decrease in the stain removal rate and exhibits a stain removal power equal to or greater than that of the use of sodium lauryl sulfate alone. This effect of the hydroxyapatite of Production Example 1 does not occur with hydroxyapatite A (Comparative Example 4).

[0089] Formulation examples of the oral cavity composition of the present invention are shown in Tables 3 to 5. The blending amount (%) of each formulation is by mass % unless otherwise specified. The hydroxyapatites described in Production Examples 1 to 5 may be used alone or in combination of two or more types.

[0090] [Table 3]

[0091] [Table 4]

[0092] [Table 5]

Claims

1. Contains hydroxyapatite particles, an anionic surfactant, and potassium nitrate, the ratio of the diffraction peak intensity around 2θ=32° to the diffraction peak intensity around 2θ=26° in a powder X-ray diffraction pattern of the hydroxyapatite particles measured with CuKα characteristic X-rays is 0.8 to 1.5; The hydroxyapatite particles have a Ca / P molar ratio of less than 1.67 and a specific surface area of ​​55 to 200 m ２ / g, The anionic surfactant is at least one selected from the group consisting of sodium lauryl sulfate, disodium polyoxyethylene alkyl sulfosuccinate, and olefin sulfonate. characterized in that Oral composition.

2. The oral composition of claim 1 , wherein the anionic surfactant is sodium lauryl sulfate.

3. An agent for suppressing a decrease in the stain removal power of an anionic surfactant, for an oral composition containing potassium nitrate and an anionic surfactant, comprising: the ratio of the diffraction peak intensity around 2θ=32° to the diffraction peak intensity around 2θ=26° in a powder X-ray diffraction pattern of the hydroxyapatite particles measured with CuKα characteristic X-rays is 0.8 to 1.5; The hydroxyapatite particles have a Ca / P molar ratio of less than 1.67 and a specific surface area of ​​55 to 200 m ２ / g, The anionic surfactant is at least one selected from the group consisting of sodium lauryl sulfate, disodium polyoxyethylene alkyl sulfosuccinate, and olefin sulfonate. An agent that prevents the stain removal power of anionic surfactants from decreasing.

4. A method for suppressing a decrease in the stain removal ability of an anionic surfactant, comprising adding hydroxyapatite particles to an oral composition containing potassium nitrate and an anionic surfactant, the ratio of the diffraction peak intensity around 2θ=32° to the diffraction peak intensity around 2θ=26° in a powder X-ray diffraction pattern of the hydroxyapatite particles measured with CuKα characteristic X-rays is 0.8 to 1.5; The hydroxyapatite particles have a Ca / P molar ratio of less than 1.67 and a specific surface area of ​​55 to 200 m ２ / g, A method for suppressing a decrease in the stain removing ability of an anionic surfactant, wherein the anionic surfactant is at least one selected from the group consisting of sodium lauryl sulfate, disodium polyoxyethylene alkyl sulfosuccinate, and olefin sulfonate.

Images