Oral care composition

Abstract

An oral care composition is disclosed comprising tetracalcium phosphate and a water-soluble calcium source; wherein the water-soluble calcium source comprises calcium chloride, calcium nitrate, calcium acetate, calcium lactate, calcium formate, calcium malate, calcium propionate, calcium butyrate, calcium bicarbonate, calcium glycerophosphate, calcium gluconate, calcium ascorbate, calcium glycinate or mixtures thereof; and wherein the composition is an aqueous composition and the water content is at least 5% by weight of the composition.

Description

[0001] ORAL CARE COMPOSITION

[0002] Field of the Invention

[0003] The present invention relates to an oral care composition comprising tetracalcium phosphate and a water-soluble calcium source. The invention also relates to a method for remineralizing and / or reducing sensitivity and / or combating dental erosion or dental caries of teeth of an individual by applying such compositions to the oral cavity of the individual.

[0004] Background of the Invention

[0005] Dental erosion, dental caries, and tooth sensitivity are common issues that can significantly impact oral health and quality of life. These dental problems are of great concern to consumers worldwide. Teeth have dentin covered by a layer of enamel on the outside. Teeth face constant threats from chemical and physical forces, such as bacteria-derived acids and mechanical wear, resulting in demineralization and weakening of enamel and the underlying dentin. The enamel is composed of hydroxyapatite crystals that form a porous surface. Dental erosion starts in the enamel and can move to the underlying dentin. It is important to prevent or slow down the erosion of enamel to keep good oral health. Fluoride is commonly used in oral care products to combat dental erosion or dental caries. The resulting fluorapatite composition is harder than the original hydroxyapatite composition and more resistant to acid attack.

[0006] Tooth hypersensitivity is a prevalent dental condition characterized by sharp pain or discomfort in response to various stimuli, such as hot or cold temperatures, sweet or acidic foods, or mechanical pressure. It occurs when underlying dentin becomes exposed due to enamel erosion, gum recession, or dental caries. The dentin of the tooth generally contains channels, called tubules, which provide for an osmotic flow between the inner pulp region of the tooth and the outer root surfaces. When root surfaces are exposed, dentinal tubules are also exposed.

[0007] The currently accepted theory for tooth hypersensitivity is the hydrodynamic theory, based on the belief that open exposed dentinal tubules allow fluid flow through the tubules. This flow excites the nerve endings in the dental pulp. Clinical replica of sensitive teeth viewed in a SEM (scanning electron microscopy) reveal varying numbers of open or partially occluded dentinal tubules. Efforts have been made over the years to treat tooth hypersensitivity. One approach is to reduce the excitability of the nerve in a sensitive tooth by using “nerve-depolarising agents” comprising strontium ions, potassium salts such as potassium nitrate, potassium bicarbonate, potassium chloride and the like. These nerve-depolarising agents function by interfering with neural transduction of the pain stimulus to make the nerve less sensitive.

[0008] Another approach is to use “tubule blocking agents” that fully or partially occlude tubules such as polystyrene beads, apatite, polyacrylic acid, mineral hectorite clay and the like. These tubule blocking agents function by physically blocking the exposed ends of the dentinal tubules, thereby reducing dentinal fluid movement and reducing the irritation associated with the shear stress described by the hydrodynamic theory.

[0009] There is still a need for an improved oral care composition that can effectively remineralize the enamel and dentin, reduce tooth sensitivity, combat dental erosion or dental caries of teeth of an individual in need thereof.

[0010] Summary of the Invention

[0011] In a first aspect, the present invention is directed to an oral care composition comprising: a) tetracalcium phosphate; b) a water-soluble calcium source; wherein the water-soluble calcium source comprises calcium chloride, calcium nitrate, calcium acetate, calcium lactate, calcium formate, calcium malate, calcium propionate, calcium butyrate, calcium bicarbonate, calcium glycerophosphate, calcium gluconate, calcium ascorbate, calcium glycinate or mixtures thereof; and wherein the composition is an aqueous composition and the water content is at least 5% by weight of the composition.

[0012] In a second aspect, the present invention is directed to a packaged oral care product comprising the oral care composition of the first aspect of this invention.

[0013] In a third aspect, the present invention is directed to a method for remineralizing and / or reducing sensitivity and / or combating dental erosion or dental caries of teeth of an individual comprising the step of applying the composition of any embodiment of the first aspect to the oral cavity of the individual. The method is preferably for non-therapeutic benefits. The term “combating dental erosion or dental caries” in the context of the present invention means preventing, inhibiting, reducing and / or treating dental erosion or dental caries. All other aspects of the present invention will more readily become apparent upon considering the detailed description and examples which follow.

[0014] Detailed Description of the Invention

[0015] Except in the examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and / or use may optionally be understood as modified by the word “about”.

[0016] All amounts are by weight of the final composition, unless otherwise specified. It should be noted that in specifying any ranges of values, any particular upper value can be associated with any particular lower value.

[0017] For the avoidance of doubt, the word “comprising” is intended to mean “including” but not necessarily “consisting of’ or “composed of”. In other words, the listed steps or options need not be exhaustive.

[0018] The disclosure of the invention as found herein is to be considered to cover all embodiments as found in the claims as being multiply dependent upon each other irrespective of the fact that claims may be found without multiple dependency or redundancy.

[0019] Where a feature is disclosed with respect to a particular aspect of the invention (for example a composition of the invention), such disclosure is also to be considered to apply to any other aspect of the invention (for example a method of the invention) mutatis mutandis.

[0020] The term “remineralization” in the context of the present invention means in situ (i.e. in the oral cavity) generation of calcium phosphate on teeth to reduce the likelihood of tooth sensitivity, tooth decay, regenerate enamel and / or improve the appearance of teeth by whitening through the generation of such new calcium phosphate. Preferably, the new calcium phosphate layers on teeth are from 10 nm to 20 microns, more preferably from 75 nm to 10 microns, and most preferably from 150 nm to 5 microns thick including all ranges subsumed therein).

[0021] The term “oral care composition" in the context of the present invention refers to a composition that is delivered to the oral surfaces. The composition may be a product which, during the normal course of usage, is not for the purpose of systemic administration or intentionally swallowed but is rather retained in the oral cavity for a time sufficient to contact substantially all of the dental surfaces and / or oral tissues for the purposes of oral activity. Examples of the oral composition include a toothpaste or a dentifrice, a mouthwash or a mouth rinse, powder (e.g., tooth powder), lozenge, mint, cream, strip or gum (e.g., chewing gum), a film, a topical oral gel, a serum and a denture cleanser and the like. Typically the composition will be packaged. In tooth paste or gel form, the composition may be packaged in a conventional plastic laminate, metal tube or a single compartment dispenser. The same may be applied to dental surfaces by any physical means, such as a toothbrush, fingertip or by an applicator directly to the sensitive area. In liquid mouthwash form the composition may be packaged in a bottle, sachet or other convenient container.

[0022] The composition of the invention preferably is used to clean the surfaces of the oral cavity. Accordingly, preferred product forms for compositions of the invention are those which are suitable for brushing and / or rinsing the surfaces of the oral cavity.

[0023] The composition of the invention is most preferably in the form of a dentifrice or a toothpaste. The term "dentifrice" in the context of the present invention refers to an oral composition which is used to clean the surfaces of the oral cavity. Such a composition is not intentionally swallowed for purposes of systemic administration of therapeutic agents, but is applied to the oral cavity, used to treat the oral cavity and then expectorated. Typically such a composition is used in conjunction with a cleaning implement such as a toothbrush, usually by applying it to the bristles of the toothbrush and then brushing the accessible surfaces of the oral cavity. The term “toothpaste” in the context of the present invention means a paste or gel dentifrice for use with a cleaning implement such as a toothbrush. Preferably the dentifrice / toothpaste is in the form of an extrudable semi-solid such as a cream, paste or gel (or mixture thereof).

[0024] Tetracalcium phosphate is an inorganic compound with the formula Ca^PO^O, which is also known by the mineral name hilgenstockite. Tetracalcium phosphate can be prepared by heating calcium hydroxide and dicalcium phosphate dihydrate at high temperatures, or by reacting calcium oxide with phosphoric acid.

[0025] The oral care composition of the present invention preferably comprises from 0.1 to 80% by weight of tetracalcium phosphate, more preferably from 0.5 to 50%, even more preferably from 1 to 30% and most preferably from 1.5 to 20%, based on total weight of the oral care composition and including all ranges subsumed therein.

[0026] The water-soluble calcium source suitable for use in this invention is limited only to the extent that the same may be used in the mouth. The term “water-soluble” in the context of the present invention means a source that dissolves in water to give a concentration of at least 0.1 moles per litre.

[0027] Examples of suitable water-soluble calcium source includes, but not limited to, calcium chloride, calcium nitrate, calcium acetate, calcium lactate, calcium formate, calcium malate, calcium propionate, calcium butyrate, calcium bicarbonate, calcium glycerophosphate, calcium gluconate, calcium ascorbate, calcium glycinate or mixtures thereof. Preferably, the water- soluble calcium source is calcium chloride, calcium nitrate, calcium glycinate, calcium glycerophosphate, calcium gluconate or mixtures thereof. More preferably the water-soluble calcium source is calcium glycinate, calcium glycerophosphate, calcium gluconate or mixtures thereof.

[0028] The oral care composition of the present invention preferably comprises from 0.001 to 20% by weight of the water-soluble calcium source, more preferably from 0.01 to 15%, even more preferably from 0.05 to 10% and most preferably from 0.1 to 5%, based on total weight of the oral care composition and including all ranges subsumed therein.

[0029] Preferably, the tetracalcium phosphate and the water-soluble calcium source are present in the oral care composition in a weight ratio from 1:20 to 80:1, more preferably from 1:10 to 50:1 and most preferably from 1:1 to 40: 1.

[0030] The composition may comprise a phosphate source. The phosphate source is able to provide phosphate ions to react with the calcium source to produce a calcium phosphate in situ reaction product that is a precursor for hydroxyapatite formation. Preferably the phosphate source dissolves in water to give a phosphate ion concentration of at least 0.1 moles per liter at room temperature and atmospheric pressure. Examples of phosphate source suitable for use in this invention include trisodium phosphate, monosodium dihydrogen phosphate, disodium hydrogen phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, tripotassium phosphate, monopotassium dihydrogen phosphate, dipotassium hydrogen phosphate, mixtures thereof or the like.

[0031] The phosphate source may be present in the range of from 0.1 to 30%, preferably from 0.5 to 20%, more preferably from 1 to 15% by weight of the composition, based on total weight of the composition and including all ranges subsumed therein. The composition is an aqueous composition. The water content is at least 1.5% by weight of the composition, preferably at least 5%, more preferably at least 10%, even more preferably at least 15% and most preferably at least 20% by weight of the composition. It is preferable that the water content is from 1.5 to 95% by weight of the composition, more preferably from 5 to 80%, even more preferably from 10 to 60%, more preferably still preferably from 15 to 50%, most preferably from 20 to 40%, based on total weight of the composition and including all ranges subsumed therein.

[0032] Typically, the composition has a pH from 5.5 to 10.5, more preferably from 6.0 to 10, and most preferably from 6.5 to 9.5. The pH of composition may be measured when 5 parts by weight of the composition is uniformly dispersed and / or dissolved in 20 parts by weight pure water at 25°C. In particular, the pH may be measured by manually mixing 5 g composition with 20 mL water for 30 s, then immediately testing the pH with indicator or a pH meter, or the pH of composition may be measured directly with a pH meter.

[0033] The composition of the present invention may also comprise a physiologically acceptable carrier. The carrier preferably comprises at least surfactant, thickener, humectant or a combination thereof.

[0034] Preferably the composition comprises a surfactant. Preferably the composition comprises at least 0.01% surfactant by weight of the composition, more preferably at least 0.1% and most preferably from 0.5 to 7%. Suitable surfactants include anionic surfactants, such as the sodium, magnesium, ammonium or ethanolamine salts of Cs to Cis alkyl sulphates (for example sodium lauryl sulphate), Cs to Cis alkyl sulphosuccinates (for example dioctyl sodium sulphosuccinate), Cs to Cis alkyl sulphoacetates (such as sodium lauryl sulphoacetate), Cs to Cis alkyl sarcosinates (such as sodium lauryl sarcosinate), Cs to Cis alkyl phosphates (which can optionally comprise up to 10 ethylene oxide and / or propylene oxide units) and sulphated monoglycerides. Other suitable surfactants include nonionic surfactants, such as optionally polyethoxylated fatty acid sorbitan esters, ethoxylated fatty acids, esters of polyethylene glycol, ethoxylates of fatty acid monoglycerides and diglycerides, and ethylene oxide / propylene oxide block polymers. Other suitable surfactants include amphoteric surfactants, such as betaines or sulphobetaines. Mixtures of any of the above described materials may also be used. More preferably the surfactant comprises or is anionic surfactant. The preferred anionic surfactants are sodium lauryl sulphate and / or sodium dodecylbenzene sulfonate. Most preferably the surfactant is sodium lauryl sulphate, sodium coco sulfate, cocamidopropyl betaine, sodium methyl cocoyl taurate or mixtures thereof. Thickener may also be used in this invention. Illustrative examples of the types of thickeners that may be used in this invention include, sodium carboxymethyl cellulose (SCMC), hydroxyl ethyl cellulose, methyl cellulose, ethyl cellulose, gum tragacanth, gum arabic, gum karaya, sodium alginate, carrageenan, guar, xanthan gum, Irish moss, starch, modified starch, silica based thickeners including silica aerogels, magnesium aluminum silicate (e.g., Veegum), Carbomers (cross-linked acrylates) and mixtures thereof.

[0035] Typically, xanthan gum and / or sodium carboxymethyl cellulose and / or a Carbomer is / are preferred. When a Carbomer is employed, those having a weight-average molecular weight of at least 700,000 are desired, and preferably, those having a molecular weight of at least 1 ,200,000, and most preferably, those having a molecular weight of at least about 2,500,000 are desired. Mixtures of Carbomers may also be used herein.

[0036] In a preferred embodiment, the Carbomer is Synthalen PNC, Synthalen KP or a mixture thereof. It has been described as a high molecular weight and cross-linked polyacrylic acid and identified via CAS number 9063-87-0. These types of materials are available commercially from suppliers like Sigma.

[0037] In another preferred embodiment, the sodium carboxymethyl cellulose (SCMC) used is SCMC 9H. It has been described as a sodium salt of a cellulose derivative with carboxymethyl groups bound to hydroxy groups of glucopyranose backbone monomers and identified via CAS number 9004-32-4. The same is available from suppliers like Alfa Chem.

[0038] In another preferred embodiment, the thickener is xanthan gum.

[0039] In another especially preferred embodiment, the thickener is carrageenan. Suitable carrageenan includes iota and kappa carrageenan. Preferably the iota carrageenan and the kappa carrageenan are present in a weight ratio of from 1:2 to 2:1. Preferably the carrageenan present in the composition of the invention consists from 33 to 66% by weight of iota carrageenan and 33 to 66% by weight of kappa carrageenan. The total level of carrageenan is preferably from 0.05 to 1% by weight of the composition, more preferably 0.08 to 0.5%, and most preferably 0.08 to 0.25% by weight of the composition, lota carrageenan or kappa carrageenan is commercially available, for example, from CP Kelco. Thickener preferably makes up from 0.01 to 10%, more preferably from 0.1 to 9%, and most preferably, from 0.1 to 5% by weight of the composition, based on total weight of the composition and including all ranges subsumed therein.

[0040] Suitable humectants are preferably used in the oral care composition of the present invention and they include, for example, glycerin, sorbitol, propylene glycol, dipropylene glycol, diglycerol, triacetin, mineral oil, polyethylene glycol (preferably, PEG-400), alkane diols like butane diol and hexanediol, ethanol, pentylene glycol, or a mixture thereof. Glycerin, polyethylene glycol, sorbitol or mixtures thereof are the preferred humectants.

[0041] The humectant may be present in the range of from 10 to 90% by weight of the composition. More preferably, the carrier humectant makes up from 25 to 80%, and most preferably, from 30 to 60% by weight of the composition, based on total weight of the composition and including all ranges subsumed therein.

[0042] The composition may comprise a fluoride source. Preferred fluoride source includes sodium fluoride, stannous fluoride, potassium fluoride, sodium monofluorophosphate, sodium fluorosilicate, ammonium fluorosilicate, amine fluoride, ammonium fluoride or mixtures thereof. Preferably, the fluoride source is stannous fluoride, sodium fluoride, sodium monofluorophosphate or mixtures thereof. Sodium monofluorophosphate is particularly preferred. The fluoride source may be present at a level from 0.01 to 10%, more preferably from 0.03 to 5% and most preferably from 0.1 to 2% by weight of the composition, based on total weight of the composition and including all ranges subsumed therein.

[0043] The composition may comprise particulate abrasive materials such as silicas, aluminas, calcium carbonates, trimetaphosphates, insoluble hexametaphosphates and so on, including agglomerated particulate abrasive materials. The abrasives may be present in the range of from 0.01 to 60%, more preferably from 0.1 to 30%, and most preferably from 1 to 15% by weight of the composition, based on total weight of the composition and including all ranges subsumed therein.

[0044] Preferably the composition, particularly a toothpaste, comprises a silica-based abrasive. The preferred abrasive silicas used in the present invention is a silica with a low refractive index. It may be used as the sole abrasive silica, or in conjunction with a low level of other abrasive silicas, e.g. those according to EP 236070. The low refractive index silicas, used as abrasives in the present invention are preferably silicas with an apparent refractive index (R.l.) in the range of 1.41 to 1.47, preferably 1.435 to 1.445, preferably having a weight mean particle size of between 5 and 15 mm, a BET (nitrogen) surface area of between 10 and 100 m2 / g and an oil absorption of 70 to 150 cm3 / 100 g, but abrasive silicas with a lower apparent refractive index may also be used. Typical examples of suitable low refractive index abrasive silicas (e.g. having an R.l. of between 1.435 and 1.445) are Tixosil 63 and 73 ex Rhone Poulenc; Sident 10 ex Degussa; Zeodent 113 ex Zeofinn; Zeodent 124 ex Evonik, Zeodent 120 ex Evonik, Sorbosil AC 77 ex PQ Corporation (having an R.l. of approximately 1.440). The amount of these silicas in the composition generally ranges from 5 to 60% by weight, usually 5 to 20% by weight.

[0045] In another preferred embodiment, the composition comprises a calcium carbonate abrasive. Natural calcium carbonate abrasive is typically a finely ground limestone which may optionally be refined or partially refined to remove impurities. The material preferably has an average particle size of less than 10 microns, e.g., 3-7 microns, e.g., about 5.5 microns. For example, a small particle silica may have an average particle size (D50) of 2.5 -4.5 microns. Because natural calcium carbonate may contain a high proportion of relatively large particles of not carefully controlled, which may unacceptably increase the abrasivity, preferably no more than 0.01 %, preferably no more than 0.004% by weight of particles would not pass through a 325 mesh. The material has strong crystal structure, and is thus much harder and more abrasive than precipitated calcium carbonate. The tapped density for the natural calcium carbonate is for example between 1 and 1.5 g / cc, e.g., about 1.2 for example about 1.19 g / cc. There are different polymorphs of natural calcium carbonate, e.g., calcite, aragonite and vaterite, calcite being preferred for purposes of this invention.

[0046] Precipitated calcium carbonate has a different crystal structure from natural calcium carbonate. It is generally more friable and more porous, thus having lower abrasivity and higher water absorption. For use in the present invention, the particles are small, e.g., having an average particle size of 1-5 microns, and e.g., no more than 0.1 %, preferably no more than 0.05% by weight of particles which would not pass through a 325 mesh. The particles may for example have a D50 of 3-6 microns, for example 3.8-4.9, e.g., about 4.3; a D50 of 1-4 microns, e.g., 2.2- 2.6 microns, e.g., about 2.4 microns, and a D10 of 1-2 microns, e.g., 1.2-1.4, e.g., about 1.3 microns. The particles have relatively high water absorption, e.g., at least 25 g / 100 g, e.g., 30- 70 g / 100 g.

[0047] The composition may comprise water-soluble or sparingly water-soluble sources of metal salts, preferably a zinc source. Examples of suitable zinc source include zinc chloride, zinc acetate, zinc gluconate, zinc sulphate, zinc fluoride, zinc citrate, zinc lactate, zinc oxide, zinc monoglycerolate, zinc tartrate, zinc pyrophosphate zinc maleate or mixtures thereof; also preferred are stannous source such as stannous fluoride and stannous chloride.

[0048] The composition may comprise a polymeric deposition aid. Preferably the composition comprises acid anhydride polymers, particularly preferred are co-polymers of maleic anhydride with methyl vinylether, in which the anhydride moiety may be in a partially or fully hydrolysed or alcoholysed form. Preferred copolymers include Gantrez(R) polymers such as: Gantrez S-95: molecular weight 216,000; free acid;

[0049] Gantrez S-96: molecular weight 700,000; free acid;

[0050] Gantrez S-97: molecular weight 1,500,000; free acid; and

[0051] Gantrez MS-955: molecular weight 1,060,000; calcium / sodium salt.

[0052] Particularly preferred co-polymers of maleic acid and methyl vinylether have a molecular weight of 1,000,000 or greater and an especially preferred material is Gantrez S-97.

[0053] The composition may comprise a tooth whitening agent. The whitening agent preferably comprises a green and / or a blue pigment. In the context of the present invention a pigment is generally understood to be a shade / material which is insoluble in the relevant medium, at the relevant temperature. This is in contrast to dyes which are soluble. In the context of this invention, the "relevant medium" is human saliva, the liquid medium in which the composition is used, at the temperature of the oral cavity during brushing of the teeth, i.e. up to 37 Degrees C. As a reasonable approximation, the relevant medium may be considered to be water and the relevant temperature to be 25 Degrees C.

[0054] Preferably the blue pigment is Pigment Blue 15, more preferably Pigment Blue 15:1, 15:2, 15:3, 15:4, 15:5 or 15:6, most preferably 15:1. A preferred pigment is blue pigment is Phthalocyanine Blue Pigment, Cl No. 74160, blue covarine.

[0055] The preferred Green pigment is Phthalocyanine Green, preferably Phthalocyanine Green CI- 74260.

[0056] Preferably the total level of pigment in the composition is from 0.01 to 3% by weight of the composition, more preferably from 0.02 to 2%.

[0057] The composition may comprise oral care enzyme systems such as hydrogen peroxide producing enzyme systems (e.g. the oxidoreductase enzyme glucose oxidase), amyloglucosidase, dextranase and / or mutanase, (optionally in the presence of zinc ion providing compounds and / or 8- hydroxyquinoline derivatives), lactoperoxidase, lactoferrin, lysozyme and mixtures thereof;

[0058] Mixtures of any of the above described materials may also be used.

[0059] The composition of the present invention may contain a variety of other ingredients which are common in the art to enhance physical properties and performance in addition to the ingredients specified above, such as: antimicrobial agents, e.g. chlorhexidine, sanguinarine extract, metronidazole, quaternary ammonium compounds, such as cetylpyridinium chloride; cetylpyridium chloride clay complex bis-guanides, such as chlorhexidine digluconate, hexetidine, octenidine, alexidine; and halogenated bisphenolic compounds, such as 2,2' methylenebis-(4-chloro-6-bromophenol); anti-inflammatory agents such as ibuprofen, flurbiprofen, aspirin, indomethacin etc.; anti-caries agents such as sodium- and stannous fluoride, aminefluorides, sodium monofluorophosphate, sodium trimeta phosphate and casein; plaque buffers such as urea, calcium lactate, calcium glycerophosphate and strontium polyacrylates; vitamins such as Vitamins A, C, D, B (preferably B3) and E; plant extracts; plant-derivable antioxidants such as flavonoid, catechin, polyphenol, and tannin compounds and mixtures thereof; desensitising agents, e.g. potassium citrate, potassium chloride, potassium tartrate, potassium bicarbonate, potassium oxalate, potassium nitrate and strontium salts; anti-calculus agents, e.g. alkali-metal pyrophosphates, hypophosphite-containing polymers, organic phosphonates and phosphocitrates etc.; biomolecules, e.g. bacteriocins, antibodies, enzymes, etc.; flavours, e.g. peppermint and spearmint oils; proteinaceous materials such as collagen; preservatives; opacifying agents; hyaluronic acid; amino acids such as arginine; colouring agents; pH-adjusting agents; sweetening agents; mouth feel agents; polymeric compounds which can enhance the delivery of active ingredients such as antimicrobial agents can also be included; buffers and salts to buffer the pH and ionic strength of the oral care composition; and other optional ingredients that may be included are e.g. bleaching agents such as peroxy compounds e.g. potassium peroxydiphosphate, effervescing systems such as sodium bicarbonate / citric acid systems, colour change systems, and so on.

[0060] Such ingredients typically and collectively make up less than 20% by weight of the composition, and preferably, from 0.0 to 15% by weight, and most preferably, from 0.01 to 12% by weight of the composition, including all ranges subsumed therein.

[0061] The oral care composition of this invention can be used in a method for remineralizing and / or reducing sensitivity and / or combating dental erosion or dental caries of teeth of an individual. The method comprises applying the oral care composition of this invention to the oral cavity of the individual in need thereof, e.g., by brusing, for example, one or more times per day. Preferably, the method is non-therapeutic.

[0062] Additionally or alternatively, the present invention is directed to an oral care composition for use in remineralizing and / or reducing sensitivity and / or combating dental erosion or dental caries of teeth of an individual. Additionally or alternatively, the present invention is directed to use of an oral care composition for remineralizing and / or reducing sensitivity and / or combating dental erosion or dental caries of teeth of an individual, the use is preferably non-therapeutic.

[0063] Additionally or alternatively, the present invention is directed to use of an oral care composition in the manufacture of a medicament in remineralizing and / or reducing sensitivity and / or combating dental erosion or dental caries of teeth of an individual.

[0064] Additionally, application of the composition of the present invention to the oral cavity of an individual may provide one or more of the following benefits: reduce plaque accumulation; inhibit microbial biofilm formation in the oral cavity; reduce or inhibit gingivitis; promote healing of sores or cuts in the mouth; reduce levels of acid producing bacteria; increase relative levels of non-cariogenic and / or non-plaque forming bacterial; reduce, repair or inhibit pre-carious lesions of the enamel; treat, relieve or reduce dry mouth; clean the teeth and oral cavity; reduce erosion; whiten teeth; reduce tartar build-up; and / or promote systemic health, including cardiovascular health, e.g., by reducing potential for systemic infection via the oral tissues. The disclosure further provides compositions for use in any of the above methods. The composition can be effective even when used in an individual’s daily oral hygiene routine. For example, the composition may be brushed onto the teeth. The composition may, for example, be contacted with the teeth for a time period of one second to 20 hours. More preferably from 1 s to 10 hours, more preferably still from 10 s to 1 hour and most preferably from 30 s to 5 minutes. The composition may be used daily, for example for use by an individual once, twice or three times per day.

[0065] The following examples are provided to facilitate an understanding of the present invention. The examples are not provided to limit the scope of the claims.

[0066] Examples

[0067] Example 1

[0068] This example demonstrates the blockage of dentinal tubules. Compositions were prepared as shown in table 1. All ingredients are expressed by amount of the total formulation, and as level of active ingredients.

[0069] Table 1

[0070] Methods

[0071] Fresh toothpaste slurries were prepared by mixing toothpaste samples with water and used immediately.

[0072] Human dentine discs were eroded by 6% citric acid for 2 minutes, then they were treated with different slurries via brushing following the same protocol. Ten human dentine discs were separated into five groups (n=2). The dentine discs were brushed with the slurry under a tooth brushing machine equipped with toothbrushes. The load of the tooth brushing was 170 g + / -5 g and the automatic brushing operated at a speed of 150 rpm. After brushing for 1 minute, the dentine discs were soaked in slurry for 1 minute. Then the dentine discs were placed in 50 mL DI water and agitated on a flatbed shaker at 150 rpm for 10 strokes. The discs were then soaked in simulated oral fluid (SOF) for at least 3 hours under the condition of a shaking water bath at 37°C and 60.0 rpm. After that, the dentine discs were brushed with the slurry by machine using the same procedure as in the first step. The brushing was repeated 3 times for one day, then the dentine discs were kept in SOF overnight (>12 hours) in a shaking water bath at 37°C to mimic oral environment. The dentine samples were characterized by scanning electron microscopy (SEM, Hitachi S-4800, Japan) after one day.

[0073] Simulated oral fluid was made by combining the ingredients in table 2:

[0074] Table 2

[0075] Regardless of the original shape of the dentine discs, a square (with a size of 4mm x 4mm) is selected and one image is captured under 30x magnification. Within this square, five spots (each with a size of 150 pm x 150 pm, one in the middle, and one in every corner) are selected and observed under 1000x magnification. The blockage of tubules is accessed following the standards described in Table 3. The measurement is carried out for the two dentine discs of each test group.

[0076] Table 3

[0077] SEM images of the dentine discs were taken after one day (3 brushings). The images were analyzed and scored. The results are reported in table 4. Table 4

[0078] The results showed that sample 1 had higher efficacy in blocking the tubules compared to samples A, B, C and D.

[0079] Example 2

[0080] This example demonstrates microhardness change of tooth enamels. Compositions were prepared as shown in table 5. All ingredients are expressed by weight percent of the total formulation.

[0081] Table 5

[0082] Evaluation of surface microhardness (SMH) reduction of tooth enamels

[0083] Fresh toothpaste slurries were prepared by mixing 4 g toothpaste sample with 8 mL de-ionised (DI) water for 40 seconds and used immediately.

[0084] The enamel surface microhardness (SMH) was measured by a microhardness tester (Struers Durascan) using a Knoop indenter at 50gf load for 10 seconds. Five indentations were made per test point for each enamel block in different regions to avoid residual stress. To evaluate the microhardness of tooth enamel, well-polished human enamel blocks were divided into five groups (n=5 per group) with similar baseline values of SMH. The SMH of the human enamel blocks were measured and recorded as SMH baseline- The human enamel blocks were soaked in freshly prepared toothpaste slurry for 3 minutes and then placed in demineralization solution (Demin solution) for 4 hours at 37°C with mild shaking, followed by rinsing with water. After that, the enamel blocks were soaked in remineralization solution (Remin solution) for 4 hours at 37°C with mild shaking. The whole treatment within one day was called one-day treatment cycle. The treatment was repeated for 7 days and the SMH of the enamel blocks were measured and recorded as SM Htreated.

[0085] Demin solution consisted of 2 mM CaCh, 2 mM KH2PO4, 75 mM acetic acid, 0.1 mM Tris buffer, pH adjusted to 4.6 using 1 M KOH.

[0086] Remin solution consisted of 1.5 mM CaCh, 0.9 mM KH2PO4, 150 mM KOI, and 20 mM H EPES adjusted to pH 7.0 with NaOH.

[0087] The surface microhardness (SMH) reduction of tooth enamels was calculated as: SMH Reduction (%)= (SMHtreated-SMHbaseiine) x 100 / SMHbaseiine

[0088] The results are shown in table 6.

[0089] Table 6

[0090] As shown in table 6, the enamel blocks treated with sample 2 had higher acid resistance, suggesting improved protection of enamel from acid erosion.

Claims

CLAIMS1. An oral care composition comprising: a) tetracalcium phosphate; b) a water-soluble calcium source; wherein the water-soluble calcium source comprises calcium chloride, calcium nitrate, calcium acetate, calcium lactate, calcium formate, calcium malate, calcium propionate, calcium butyrate, calcium bicarbonate, calcium glycerophosphate, calcium gluconate, calcium ascorbate, calcium glycinate or mixtures thereof; and wherein the composition is an aqueous composition and the water content is at least 5% by weight of the composition.

2. The oral care composition according to claim 1, wherein the water-soluble calcium source comprises calcium chloride, calcium nitrate, calcium glycinate, calcium glycerophosphate, calcium gluconate or mixtures thereof.

3. The oral care composition according to claim 1 or claim 2, wherein the tetracalcium phosphate is present in an amount of from 0.1 to 80% by weight of the composition, preferably from 0.5 to 50% by weight of the composition.

4. The oral care composition according to any of the preceding claims, wherein the tetracalcium phosphate and the water-soluble calcium source are present in a weight ratio from 1 :20 to 80: 1 , preferably from 1 : 10 to 50: 1.

5. The oral care composition according to any of the preceding claims, wherein the water- soluble calcium source is present in an amount of from 0.001 to 20% by weight of the composition, preferably from 0.01 to 15% by weight of the composition.

6. The oral care composition according to any of the preceding claims, wherein the composition additionally comprises a phosphate source.

7. The oral care composition according to any of the preceding claims, wherein the composition additionally comprises a silica-based abrasive or a calcium carbonate abrasive.

8. The oral care composition according to any of the preceding claims, wherein the composition additionally comprises a fluoride source.

9. The oral care composition according to any of the preceding claims, wherein the composition additionally comprises a zinc source.

10. The oral care composition according to any of the preceding claims, wherein the water content is at least 10% by weight of the composition, preferably at least 15%.

11. A method for remineralizing and / or reducing sensitivity and / or combating dental erosion or dental caries of teeth of an individual comprising the step of applying the composition according to any of the preceding claims to the oral cavity of the individual.

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