WO2025031689A1 - Oral care composition - Google Patents

Abstract

An oral care composition comprising: a) xanthan gum having a molecular weight (Mw) from 5 to 15 million Daltons; b) a calcium based particulate having a particle size D50 from 0.05 to 10 microns.

Description

ORAL CARE COMPOSITION

Field of the Invention

The present invention relates an oral care composition. The invention particularly relates to a composition that deposits calcium particulates that can enhance the enamel.

Background of the Invention

The primary component of the enamel and dentin in teeth is calcium phosphate in the form of hydroxyapatite.

In the mouth, there is a natural equilibrium between hydroxyapatite being dissolved from the enamel of teeth and hydroxyapatite being formed on or in the teeth from substances occurring naturally in the saliva. This equilibrium is shifting continuously. Among other factors, it is determined by diet and physical condition.

The dentin of the tooth generally contains channels, called tubules. Tooth hypersensitivity may be related to the general increase in exposed root surfaces of teeth as a result of periodontal disease, toothbrush abrasion, or cyclic loading fatigue of the thin enamel near the dentinenamel junction. When root surfaces are exposed, dentinal tubules are also exposed.

The currently accepted theory for tooth hypersensitivity is based on the belief that open exposed dentinal tubules allow fluid flow through the tubules.

Dental erosion (i.e. , acid erosion or acid wear) is a surface phenomenon that involves demineralization, and ultimately complete dissolution of the tooth surface by acids that are not of bacterial origin. Most commonly the acid will be of dietary origin. Due to today's lifestyle which involves increasing consumption of acidic drinks and foods, tooth erosion is becoming more prevalent and common.

WO 2008/068149 discloses an oral care product comprising a first composition comprising an insoluble calcium salt that is not a calcium phosphate salt, a second independent composition comprising a source of phosphate ions, and a means for delivering each of the compositions to the surface of the teeth. The preferred insoluble calcium salt is calcium silicate. WO2020/212361 discloses non-aqueous toothpaste comprising polysaccharide, especially xanthan gum, and calcium carbonate to decrease relative dentin abrasivity (RDA) without reducing cleaning efficiency (PCR).

W02023/003940 discloses a method of reducing enamel erosion and repairing enamel damage by applying an oral care composition comprising a silica abrasive and hydroxyapatite.

The present invention relates to the enhanced deposition of calcium particulates onto the teeth thus enhancing the hardness of enamel and blocking the tubules.

Summary of the Invention

The present invention discloses an oral care composition comprising: a) xanthan gum having a weight average molecular weight (Mw) from 5 to 15 million Daltons; b) calcium hydoxy apatite, having a particle size D50 from 0.05 to 10 microns, in which the weight ration of a) xanthan gum to b) calcium hydroxy apatite is from 1:1 to 1:10.

The invention further relates to an oral care composition comprising xanthan gum having a weight average molecular weight (Mw) from 5 to 15 million Daltons for use in a method to deposit a calcium hydroxyapatite particulate onto an oral surface.

Detailed Description of the Invention

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”.

All amounts are by weight of the composition, unless otherwise specified.

The molecular weights referred to in the specification are weight average molecular weight and are measured Daltons. The weight average molecular weghts can be calculated using gel permeation chromatography (GPC).

It should be noted that in specifying any ranges of values, any upper value can be associated with any particular lower value. 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.

Any ingredients mentioned in this application that are natural or naturally derived have been sourced from Europe.

The term “oral care composition" 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, and a denture cleanser and the like.

The composition of the invention is used to preferably 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.

The composition of the invention is most preferably in the form of a dentifrice. The term "dentifrice" denotes 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.

Preferably the dentifrice/toothpaste is in the form of an extrudable semi-solid such as a cream, paste or gel (or mixture thereof). Toothpastes are preferred. The oral care composition includes xanthan gum having a weight average molecular weight from (Mw) from 5 to 15 million Daltons, preferably a (Mw) molecular weight from 5.5 to 10 million Daltons, more preferably from 6 to 8 million Daltons.

Preferably the xanthan gum has a viscosity ranging from 850 to 1,700 mPa.s (when measured at 25°C using a 1% solution of the gum in 1% KCI, on a viscometer of the Brookfield LV type, at 60 rpm using Spindle No.3).

Xanthan gum suitable for use in the present application is available from several commercial suppliers Keltrol® T plus, Keltrol® SF, and Keltrol T being particularly preferred.

Preferably the xanthan gum derivatives can be prepared by etherification, esterification, acetalation, amidation or oxidation of non-derivatized xanthan gum. Preferred xanthan gum derivatives are prepared by reacting non-derivatized gum with quaternary ammonium compounds in an amount equal to or greater than the stoichiometric amount required for complete derivatization. The quaternary ammonium compounds are preferably having a single alkyl or alkenyl substituent containing from 13 to 24 carbon atoms, and/or two alkyl or alkenyl substituents of 12 to 24 carbon atoms per substituent. Most preferably, the quaternary ammonium compound is alkyl dimethylbenzylammonium chloride with an alkyl group containing from 13 to 24 carbon atoms.

Preferred oral care composition includes from 0.1 wt.% to 5 wt% of the total composition of xanthan gum. Preferably the oral care composition includes at least 0.2 wt.% of xanthan wt.%, but typically not more than 4.5 wt.%, still preferably not more than 3.5 wt.%, still further preferably not more than 3.2 wt.%, and most preferably not more than 3 wt.% by weight of the total composition.

Compositions of the invention comprise a calcium hydroxy apatite having a particle size D50 from 0.05 to 10 microns, preferably a particle size from 0.1 to 10 microns, preferably 1 to 7 microns.

The level of calcium hydroxy apatite is preferably from 0.1 to 7 wt% of the total composition, preferably from 0.2 to 5wt%. A specific example of a suitable agent for the remineralisation of teeth is a mixture of the calcium source and a phosphate source which, when delivered to the teeth results in the in situ generation of hydroxyapatite on teeth.

In this instance the amount of remineralising calcium source(s) (e.g. calcium silicate) in the composition of the invention typically ranges from 1 to 30%, preferably from 5 to 20% by total weight remineralising calcium source based on the total weight of the oral care composition.

Illustrative examples of the types of phosphate source that may be used in this context (hereinafter termed “remineralising phosphate sources”) include, for example, monosodium dihydrogen phosphate, disodium hydrogen phosphate, sodium pyrophosphate, tetrasodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, potassium dihydrogenphosphate, trisodium phosphate, tripotassium phosphate and mixtures thereof. Preferably the remineralising phosphate source is a mixture of trisodium phosphate and sodium dihydrogen phosphate.

The amount of remineralising phosphate source(s) (e.g. trisodium phosphate and sodium dihydrogen phosphate) in the composition of this invention typically ranges from 2 to 15%, preferably from 4 to 10% by total weight remineralising phosphate source based on the total weight of the oral care composition.

Compositions of the invention may comprise a source of metal ions. Preferably the source of meta ions is a water-soluble or sparingly water-soluble metal salts. Preferred metal ions are zinc, stannous and copper ions.

Preferred sources of zinc ions are zinc chloride, zinc acetate, zinc fluoride, zinc monoglycerolate, zinc tartrate, zinc pyrophosphate zinc lactate, zinc gluconate, zinc oxide and zinc maleate, particularly preferred are zinc citate and zinc sulphate.

Preferred sources of stannous ions are stannous chloride, stannous fluoride or stannous oxide.

Preferably the level of source of meta ions is from 0.1 to 5 wt% of the total composition.

Preferably the oral care composition includes at least 0.2 wt.% of metal salt more preferably at least 0.3 wt.%, still preferably at least 0.5 wt.% and most preferably at least 0.8 wt.%, but typically not more than 4.5 wt.%, still preferably not more than 3.5 wt.%, still further preferably not more than 3.2 wt.%, and most preferably not more than 3 wt.% by weight of the total composition.

Compositions according to the invention comprises an anionic surfactant, preferably the anionic surfactant is sodium lauryl sulphate.

Preferably the level of anionic surfactant is from 1 to 10 wt% of the total composition.

Compositions according to the invention, particularly toothpastes, preferably comprise particulate abrasive materials such as silicas, aluminas, calcium carbonates, dicalciumphosphates, calcium pyrophosphates, hydroxyapatites, trimetaphosphates, insoluble hexametaphosphates and so on, including agglomerated particulate abrasive materials, usually in amounts between 3 and 60% by weight of the oral care composition.

In one embodiment of the invention the composition 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 - 1.47, preferably 1.435 - 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 about 70 - 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, 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 5-60% by weight, usually 5-20% by weight.

An alternative suitable abrasive is calcium carbonate. 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 wt%, preferably no more than 0.004 percent 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.

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.

In some embodiments, additional calcium-containing abrasives, for example calcium phosphate abrasive, e.g., tricalcium phosphate, hydroxyapatite or dicalcium phosphate dihydrate or calcium pyrophosphate, and/or silica abrasives, sodium metaphosphate, potassium metaphosphate, aluminum silicate, calcined alumina, or other siliceous materials, or combinations thereof are used.

The composition, particularly if a toothpaste preferably comprises an inorganic or a natural or synthetic thickener or gelling agent in proportions of about 0.10 to about 15% by weight depending on the material chosen. These proportions of thickeners in the dentifrice compositions of the present invention form an extrudable, shape-retaining product which can be squeezed from a tube onto a toothbrush and will not fall between the bristles of the brush but rather, will substantially maintain its shape thereon. Suitable thickeners or gelling agents useful in the practice of the present invention include inorganic thickening silicas such as amorphous silicas available from Huber Corporation under the trade designation Zeodent 165, Irish moss, iota-carrageenan, gum tragacanth, and polyvinylpyrrolidone.

Further suitable binders and thickeners can be present and include as sodium carboxy methylcellulose, hydroxyethyl cellulose (Natrosol®), gum arabic etc. as well as synthetic polymers such as polyacrylates and carboxyvinyl polymers such as Carbopol®.

Compositions according to the invention 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; Gantrez S-96: molecular weight 700,000; free acid;

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

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

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.

Compositions according to the invention 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.

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.

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

Preferably the total level of pigment in the composition is from 0.01 wt% to 3 wt, more preferably from 0.02 to 2 wt%.

If the composition is a toothpaste it may be a dual phase paste, with the whitening pigments present in one phase.

Compositions according to the invention 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.

Compositions of the invention may comprises fluoride sources such as sodium fluoride, stannous fluoride, sodium monofluorophosphate, zinc ammonium fluoride, tin ammonium fluoride, calcium fluoride, cobalt ammonium fluoride and mixtures thereof. Fluoride ion sources may be added to the compositions at a level of about 0.001 wt. percent to about 10 wt. percent, e.g., from about 0.003 wt. percent to about 5 wt. percent, 0.01 wt. percent to about 1 wt., or about 0.05 wt. percent. In some embodiment, the stannous fluoride is present in an amount of 0.1 wt. percent to 2 wt. percent (0.1 wt percent -0.6 wt. percent) of the total composition weight. Fluoride ion sources may be added to the compositions at a level of about 0.001 wt. percent to about 10 wt. percent, e.g., from about 0.003 wt. percent to about 5 wt. percent, 0.01 wt. percent to about 1 wt., or about 0.05 wt. percent. However, it is to be understood that the weights of fluoride salts to provide the appropriate level of fluoride ion will obviously vary based on the weight of the counter ion in the salt, and one of skill in the art may readily determine such amounts. In some embodiment, the fluoride source is a fluoride salt present in an amount of 0.1 wt. percent to 2 wt. percent (0.1 wt percent -0.6 wt. percent) of the total composition weight (e.g., sodium fluoride (e.g., about 0.32 wt. percent).

Some embodiments of the invention are free from fluoride sources, that is the composition comprises less than 0.01 wt% of a fluoride source.

In some embodiments, the oral care compositions comprise an effective amount of one or more antibacterial agents, for example comprising an antibacterial agent selected from halogenated diphenyl ether (e.g. triclosan), triclosan monophosphate, herbal extracts and essential oils (e.g., rosemary extract, tea extract, magnolia extract, thymol, menthol, eucalyptol, geraniol, carvacrol, citral, hinokitol, magnolol, ursolic acid, ursic acid, catechol, methyl salicylate, epigallocatechin gallate, epigallocatechin, gallic acid, miswak extract, sea-buckthorn extract), bisguanide antiseptics (e.g., chlorhexidine, alexidine or octenidine), quaternary ammonium compounds (e.g., cetylpyridinium chloride (CPC), CPC-claybenzalkonium chloride, tetradecylpyridinium chloride (TPC), N-tetradecyl-4-ethylpyridinium chloride (TDEPC)), phenolic antiseptics, hexetidine furanones, bacteriocins, ethyllauroyl arginate, arginine bicarbonate, a Camellia extract, a flavonoid, a flavan, halogenated diphenyl ether, creatine, sanguinarine, povidone iodine, delmopinol, salifluor, metal ions (e.g., zinc salts, stannous salts, copper salts, iron salts), propolis and oxygenating agents (e.g., hydrogen peroxide, buffered sodium peroxyborate or peroxycarbonate), phthalic acid and its salts, monoperthalic acid and its salts and esters, ascorbyl stearate, oleoyl sarcosine, alkyl sulfate, dioctyl sulfosuccinate, salicylanilide, domiphen bromide, delmopinol, octapinol and other piperidino derivatives, nisin preparations, chlorite salts; parabens such as methylparaben or propylparaben and mixtures of any of the foregoing. One or more additional antibacterial or preservative agents may optionally be present in the composition in a total amount of from about 0.01 wt. percent to about 0.5 wt. percent, optionally about 0.05 wt. percent to about 0.1 wt. percent or about 0.3 percent, by total weight of the composition.

In some embodiments, the oral care compositions also comprise at least one flavorant, useful for example to enhance taste of the composition. Any orally acceptable natural or synthetic flavorant can be used, including without limitation essential oils and various flavoring aldehydes, esters, alcohols, and similar materials, tea flavors, vanillin, sage, marjoram, parsley oil, spearmint oil, cinnamon oil, oil of Wintergreen, peppermint oil, clove oil, bay oil, anise oil, eucalyptus oil, citrus oils, fruit oils, sassafras and essences including those derived from lemon, orange, lime, grapefruit, apricot, banana, grape, apple, strawberry, cherry, pineapple, etc., bean-and nut-derived flavors such as coffee, cocoa, cola, peanut, almond, etc., adsorbed and encapsulated flavorants and the like. Also encompassed within flavorants herein are ingredients that provide fragrance and/or other sensory effect in the mouth, including cooling or warming effects. Such ingredients illustratively include menthol, carvone, menthyl acetate, menthyl lactate, camphor, eucalyptus oil, eucalyptol, anethole, eugenol, cassia, oxanone, a-irisone, , thymol, linalool, benzaldehyde, cinnamaldehyde, N-ethyl-p-menthan-3-carboxamine, N, 2, 3- trimethyl-2- isopropylbutanamide, 3- (1-menthoxy) -propane-1 , 2-diol, cinnamaldehyde glycerol acetal (CGA), menthone glycerol acetal (MGA) and the like. One or more flavorants are optionally present in a total amount of from about 0.01 wt. percent to about 5 wt. percent, for example, from about 0.03 wt. percent to about 2.5 wt. percent, optionally about 0.05 wt. percent to about 1.5 wt. percent, further optionally about 0.1 wt. percent to about 0.3 wt. percent and in some embodiments in various embodiments from about 0.01 wt. percent to about 1 wt. percent, from about 0.05 to about 2 percent, from about 0.1 percent to about 2.5 percent, and from about 0.1 to about 0.5 percent by total weight of the composition.

In some embodiments, the oral care compositions comprise at least one sweetener, useful for example to enhance taste of the composition. Sweetening agents among those useful herein include dextrose, polydextrose, sucrose, maltose, dextrin, dried invert sugar, mannose, xylose, ribose, fructose, levulose, galactose, corn syrup, partially hydrolyzed starch, hydrogenated starch hydrolysate, ethanol, sorbitol, mannitol, xylitol, maltitol, isomalt, aspartame, neotame, saccharin and salts thereof (e.g. sodium saccharin), sucralose, dipeptide-based intense sweeteners, cyclamates, dihydrochalcones.

One or more sweeteners are optionally present in a total amount depending strongly on the particular sweetener (s) selected, but typically 0.005 wt. percent to 5 wt. percent, by total weight of the composition, optionally 0.005 wt. percent to 0.2 wt. percent, further optionally 0.05 wt. percent to 0.1 wt. percent by total weight of the composition.

[0041] In some embodiments, the oral care compositions further comprise an agent that interferes with or prevents bacterial attachment, e.g., ethyl lauroyl arginiate (ELA), solbrol or chitosan, as well as plaque dispersing agents such as enzymes (papain, glucoamylase, etc.).

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

The composition according the invention will comprise further ingredients which are common in the art, 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 pharmaceutically acceptable carriers, e.g. starch, sucrose, water or water/alcohol systems etc.; further surfactants, such as anionic, nonionic, cationic and zwitterionic or amphoteric surfactants;

Humectants such as glycerol, sorbitol, propyleneglycol, xylitol, lactitol etc.; Glycerol and sorbitol are preferred. 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.

Examples

The invention will now be explained in detail with the help of the following non-limiting exemplary embodiments.

Example according to table 1 is listed below.

Table 1

Xanthan having differing molecular weights.

Testing procedure

5 mol of a 1:2 weight ratio of the above Example: water slurry was added to a single Pellicle Coated Artificial Skin Disk (PCASD) and vortexed The PCASD was removed from the slurry and rinsed in water thoroughly. The PCASD was then immersed in 5ml 70% HNO3 for 18 hours and 1ml aliquot of the solution was centrifuged for 1 minute. 0.1ml of the resulting solution was diluted (1 in 100) in 2% HNO3 to give a 10ml sample which was then measured for [Ca] by ICP- MS.

The ICP-MS results give [Ca] in ppb for each sample for two calcium isotopes (Ca43 & Ca44). An average of these Calcium levels was then calculated for each sample and the calcium delivery value in Ca/ppm calculated.

Table 2

Table 2 shows that xanthan having a high molecular weight are particularly beneficial in deposing calcium.

Table 3 describes a toothpaste according to the invention.

Table 3

Claims

1. An oral care composition comprising: a) xanthan gum having a weight average molecular weight (Mw) from 5 to 15 million Daltons; b) calcium hydroxy apatite, having a particle size D50 from 0.05 to 10 microns, in which the weight ration of a) xanthan gum to b) calcium hydroxy apatite is from 1:1 to 1:10.

2. An oral care composition according to any preceding claim in which the calcium hydroxy apatite has a particle size from 0.1 to 10 microns, preferably 1 to 7 microns.

3. An oral care composition according to any preceding claim in which the level of calcium based particulate is from 0.1 to 7 wt% of the total composition, preferably from 0.2 to

5 wt%.

4. An oral care composition according to any preceding claim that further comprises a sulphate based surfactant.

5. An oral care composition according to claim 1 in which the xanthan gum has a weight average (Mw) molecular weight from 5.5 to 10 million Daltons.

6. An oral care composition according to any preceding claim in which the level of xanthan is from 0.1 to 5 wt% of the total composition.

7. An oral care composition according to any preceding claim that further comprises a source of metal ions.

8. An oral care composition according to claim 7 in which the source of metal ions comprises at least one of zinc citrate, zinc sulphate, zinc lactate, zinc gluconate or zinc oxide, preferably zinc citrate.

9. An oral care composition according to any one of claims 7 to 8 in which the level of source of metal ions is from 0.1 to 5 wt% of the total composition.

10. An oral care composition according to any preceding claim in which the anionic surfactant is sodium lauryl sulphate.

11. An oral care composition according to any preceding claim in which the level of anionic surfactant is from 1 to 10 wt% of the total composition.

12. An oral care composition according to any preceding claim that further comprises a humectant selected from the group consisting of glycerol and sorbitol.

13. An oral care composition according to any preceding claim that is a toothpaste.

14. An oral care composition according to any preceding claim that comprises at least 20 wt% of the total composition of water.

15. An oral care composition comprising xanthan gum having a molecular weight (Mw) from 5 to 15 million Daltons for use in a method to deposit a calcium hydroxy apatiteonto an oral surface.