WO2020099068A1

WO2020099068A1 - Oral care composition

Info

Publication number: WO2020099068A1
Application number: PCT/EP2019/078507
Authority: WO
Inventors: Xiaohong Wang; Meili Zhang; Huanjun ZHOU
Original assignee: Unilever N.V.; Unilever Plc; Conopco, Inc., D/B/A Unilever
Priority date: 2018-11-15
Filing date: 2019-10-21
Publication date: 2020-05-22

Abstract

An oral care composition is disclosed comprising from 0.25 to 60% by weight of composite particles, from 0.1 to 20% by weight of a water soluble calcium source and a physiologically acceptable carrier, wherein the composite particle comprises a first component core comprising a water insoluble and/or slightly soluble calcium source, and a second component coating comprising a biomineralization agent, wherein the water insoluble and/or slightly soluble calcium source comprises calcium carbonate, calcium aluminate, calcium oxalate, calcium oxide, calcium carboxymethyl cellulose, calcium alginate, calcium hydroxide, calcium sulfate, calcium salts of citric acid or mixtures thereof, wherein the biomineralization agent comprises amorphous calcium phosphate, α- tricalcium phosphate, β-tricalcium phosphate, calcium deficient hydroxyapatite (Ca₉(HPO₄)(PO₄)₅OH), dicalcium phosphate (CaHPO₄), dicalcium phosphate dehydrate (CaHPO₄·2H₂O), hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂), octacalcium phosphate (Ca₈H₂(PO₄)₆·5H₂O), tetracalcium phosphate (Ca₄(PO₄)₂O) or mixtures thereof, and wherein the composite particle has a specific surface area of from 15 m²/g to 200 m²/g, measured using nitrogen via the BET method according to ISO 9277.

Description

ORAL CARE COMPOSITION

Technical Field of the Invention

The present invention relates to oral care compositions such as tooth pastes, powders, gums, mouthwashes and the like. It particularly relates to an oral care composition comprising composite particles and a water soluble calcium source. It also relates to the use of such compositions for treating tooth hypersensitivity and/or remineralizing and/or whitening of teeth of an individual.

Background of the Invention

Tooth hypersensitivity is a temporary induced pain sensation that affects up to 20% of the adult population. Hypersensitive teeth may be sensitive to temperature, pressure or chemical action.

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. 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 dentin-enamel junction. When root surfaces are exposed, dentinal tubules are also exposed.

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.

There are different approaches 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. 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.

Therefore, there is still a need for more efficacious methods for treating tooth

hypersensitivity. The present inventors have found unexpected that an oral care composition comprising a composite particle and a soluble calcium source is more efficient for treating tooth hypersensitivity in that it provides excellent tubule blockage efficacy to reduce tooth sensitivity. It has also been found that such compositions can enhance the tooth remineralization efficacy and may even help deposit benefit agents on tooth surfaces.

Tests and Definitions

Tooth Paste

“Tooth paste” for the purpose of the present invention means a paste or gel dentifrice for use with a toothbrush. Especially preferred are tooth pastes suitable for cleaning teeth by brushing for about two minutes.

Composite Particle

“Composite particle” for the purpose of the present invention means a particle comprising a first component core and a second component coating wherein the core and coating are composed of different materials.

Refractive Index

Refractive index is quoted at a temperature of 25°C and a wavelength of 589 nm. JDH

pH is quoted at atmospheric pressure and a temperature of 25°C. When referring to the pH of an oral care composition, this means the pH 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 oral care composition with 20 ml. water for 30 s, then immediately testing the pH with indicator or a pH meter. Solubility

“Soluble” and“insoluble” for the purpose of the present invention means the solubility of a source (e.g., like calcium salts) in water at 25°C and atmospheric pressure.“Soluble” means a source that dissolves in water to give a solution with a concentration of at least 0.1 moles per litre.“Insoluble” means a source that dissolves in water to give a solution with a concentration of less than 0.001 moles per litre.“Slightly soluble”, therefore, is defined to mean a source that dissolves in water to give a solution with a concentration of greater than 0.001 moles per litre and less than 0.1 moles per litre.

Substantially Free

“Substantially free of” for the purpose of the present invention means less than 1.5%, and preferably less than 1.0%, and more preferably less than 0.75% and more preferably still less than 0.5%, and even more preferably less than 0.1% and most preferably from 0.0 to 0.01% by weight, based on total weight of the oral care composition, including all ranges subsumed therein.

Dual-Phase

“Dual-Phase” for the purpose of the present invention means a composition having two independent phases which are physically separate.

Anhydrous Composition

“Anhydrous composition” for the purpose of the present invention means the water content of the composition is less than 3.0%, and preferably less than 2.0%, and more preferably less than 1.0% and most preferably less than 0.5% by total weight of the oral care composition.

Viscosity

Viscosity of a tooth paste is the value taken at room temperature (25 °C) with a Brookfield Viscometer, Spindle No.4 and at a speed of 5 rpm. Values are quoted in centipoises (cP=mPa.s) unless otherwise specified.

Remineralization

“Remineralization” for the purpose of the present invention means in situ (i.e. in the oral cavity) generation of calcium phosphate on teeth (including layers on teeth from 10 nm to 20 microns, and preferably from 75 nm to 10 microns, and most preferably, from 150 nm to 5 microns thick including all ranges subsumed therein) 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.

Miscellaneous

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 final oral care 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.

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.

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.

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.

Summary of the Invention

In a first aspect, the present invention is directed to an oral care composition comprising:

(a) from 0.25 to 60% by weight of composite particles;

(b) from 0.1 to 20% by weight of a water soluble calcium source; and

(c) a physiologically acceptable carrier;

wherein the composite particle comprises:

(i) a first component core comprises a water insoluble and/or slightly soluble calcium source; and

(ii) a second component coating comprises a biomineralization agent;

wherein the water insoluble and/or slightly soluble calcium source comprises calcium carbonate, calcium aluminate, calcium oxalate, calcium oxide, calcium carboxymethyl cellulose, calcium alginate, calcium hydroxide, calcium sulfate, calcium salts of citric acid or mixtures thereof;

wherein the biomineralization agent comprises amorphous calcium phosphate, o tricalcium phosphate, b-tricalcium phosphate, calcium deficient hydroxyapatite

(Ca₉(HP0₄)(P0₄)₅0H), dicalcium phosphate (CaHPCU), dicalcium phosphate dehydrate (CaHPC>₄-2H₂0), hydroxyapatite (Caio(P0₄)₆(OH)₂), octacalcium phosphate

(Ca₈H₂(PC>₄)₆-5H₂0), tetracalcium phosphate (Ca₄(PC>₄)₂0) or mixtures thereof; and wherein the composite particle has a specific surface area of from 15 m²/g to 200 m²/g, measured using nitrogen via the BET method according to ISO 9277.

In a second aspect, the present invention is directed to a method for reducing sensitivity and/or remineralization and/or whitening of teeth of an individual comprising the step of applying the oral care composition of any embodiment of the first aspect to at least one surface of the teeth of the individual.

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

All other aspects of the present invention will more readily become apparent upon considering the detailed description and examples which follow.

Detailed Description

The only limitation with respect to the composite particles that may be used in this invention is that the same is suitable for use in the mouth. The composite particle comprises a first component core and a second component coating. The first component core comprises a water insoluble and/or slightly soluble calcium source. Illustrative yet non-limiting examples of the types of the water insoluble and/or slightly soluble calcium source that may be used in the invention include, for example, calcium carbonate, calcium aluminate, calcium oxalate, calcium oxide, calcium carboxymethyl cellulose, calcium alginate, calcium hydroxide, calcium sulfate, calcium salts of citric acid or mixtures thereof. Preferably, the first component core comprises the water insoluble and/or slightly soluble calcium source in an amount of at least 50% by weight of the core, more preferably at least 70% and most preferably from 80 to 100%. In an especially preferred embodiment, the core comprises at least 80% by weight of calcium carbonate, more preferably from 90 to 100% by weight of calcium carbonate, based on total weight of the first component core, and most preferably the first component core of the composite particle is calcium carbonate. Typically, the composite particle comprises the first component core in an amount of at least 3%, preferably from 3% to 50%, more preferably from 5% to 30% and most preferably from 8% to 25% by weight of the composite particle, based on total weight of the composite particle and including all ranges subsumed therein.

The second component coating of the composite particle comprises a biomineralization agent that is suitable to improve the remineralization of teeth. Suitable biomineralization agent that may be used in the invention include, for example, amorphous calcium phosphate, otricalcium phosphate, b-tricalcium phosphate, calcium deficient

hydroxyapatite (Ca₉(HP0₄)(P0₄)₅0H), dicalcium phosphate (CaHPCU), dicalcium phosphate dehydrate (CaHPCU^hhO), hydroxyapatite (Caio(P0₄)₆(OH)₂), octacalcium phosphate (CasH^PCU ShhO), tetracalcium phosphate (Ca₄(PC>₄)₂0) or mixtures thereof. The second component coating preferably comprises the biomineralization agent in an amount of at least 50% by weight of the second component coating, more preferably at least 70% and most preferably from 80 to 100%. In an especially preferred embodiment, the second component coating comprises at least 60% by weight of hydroxyapatite, more preferably from 90 to 100% by weight of hydroxyapatite, based on total weight of the second component coating, and most preferably the second component coating of the composite particle is hydroxyapatite.

The second component coating typically forms the majority of the composite particle and so preferably the particle comprises the first component core and the second component coating in a weight ratio (first component core: second component coating) of at least 1 :30, more preferably from 1 :20 to 10:1 , more preferably still from 1 :15 to 1 :1 , and most preferably from 1 :10 to 1 :3.

Preferably, the composite particle has a volume determined median particle size D50 from 100 nm to 75 microns, more preferably from 500 nm to 50 microns, more preferably still from 1 micron to 20 microns and most preferably from 2 microns to 10 microns. The volume determined median particle size D50 can be measured, for example, by using Malvern Mastersizer 2000 Laser Diffraction System.

The composite particle has a porous surface as this allows for maximum surface area for contact with dental tissue. The composite particle has a specific surface area of from 15 m²/g to 200 m²/g, preferably from 30 m²/g to 180 m²/g, more preferably from 50 m²/g to 150 m²/g and most preferably from 80 m²/g to 130 m²/g. The specific surface area, as used herein, can be measured by the Brunauer Emmett Teller (BET) method with nitrogen as adsorbing gas and by use of an ASAP 2460 instrument from Micromeritics according to ISO 9277.

In a preferred embodiment, the composite particle is calcium carbonate coated with hydroxyapatite and is made commercially available, for example, from suppliers like Omya International AG under the trade name Omyadent® 100-OG, which has a specific surface area 1 10 m²/g measured by the BET method according to ISO 9277.

The oral care composition of the present invention comprises from 0.25 to 60% by weight of the composite particles, preferably from 0.5 to 40% and more preferably from 1 to 30%, based on total weight of the oral care composition and including all ranges subsumed therein.

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 water soluble calcium source is calcium salts in addition to the composite particles which are included in the composition. Suitable water soluble calcium source that may be used in this invention include, for example, calcium chloride, calcium nitrate, calcium acetate, calcium lactate, calcium formate, calcium malate, calcium propionate, calcium butyrate, calcium bicarbonate, calcium gluconate, calcium ascorbate or mixtures thereof or the like. Calcium chloride, calcium nitrate or mixtures thereof is particularly preferred.

The oral care composition of the present invention comprises from 0.1 to 20% by weight of the water soluble calcium source, preferably from 1 to 15%, more preferably from 2 to 10%, based on total weight of the oral care composition and including all ranges subsumed therein. The oral care composition typically comprises the composite particle and the water soluble calcium source in a weight ratio of from 1 :5 to 20:1 , more preferably from 1 :3 to 10:1 , more preferably still from 1 :1.5 to 8:1 and most preferably from 1 :1 to 5:1.

The composition of the present invention is an oral care composition and comprises a physiologically acceptable carrier. The carrier preferably comprises at least surfactant, thickener, humectant or a combination thereof.

Preferably the oral care 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 Ce to Ci₈ 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 and is limited only to the extent that the same may be added to a composition suitable for use in the mouth. 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. 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.

In an especially 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.

In another especially 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.

In another especially preferred embodiment, the thickener is xanthan gum.

Thickener typically makes up from 0.01 to about 10%, more preferably from 0.1 to 9%, and most preferably, from 0.1 to 5% by weight of the oral care composition, based on total weight of the composition and including all ranges subsumed therein.

When the oral care composition of this invention is a toothpaste or gel, the same typically has a viscosity from about 30,000 to 180,000 centipoise, and preferably, from 60,000 to 170,000 centipoise, and most preferably, from 65,000 to 165,000 centipoise.

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.

The humectant may be present in the range of from 10 to 90% by weight of the oral care 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.

Typically, the oral care composition has a pH from 4.0 to 10.0, more preferably from 5.0 to 8.0, and most preferably from 5.5 to 7.5.

In one embodiment, the oral care composition may be substantially free of phosphate source. This is especially preferred when the composition is a monophase hydrous composition (i.e. comprises greater than 1.5% water, preferably greater than 5% water, more preferably greater than 10% water and most preferably from 20 to 90% water by weight of the composition). Presence of water soluble calcium sources and phosphate sources in a monophase hydrous formulation can lead to premature reaction of the calcium and phosphate and instability of the product.

For certain compositions, especially anhydrous compositions (i.e. compositions substantially free of water) or dual-phase hydrous compositions, it is preferable to compound a phosphate source in the oral composition. 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.

The phosphate source that may be used in this invention is limited only to the extent that the same may be used in a composition suitable for use in the mouth. Illustrative examples of the types of phosphate source suitable for use in this invention include trisodium phosphate, monosodium dihydrogen phosphate, disodium hydrogen phosphate, tripotassium phosphate, monopotassium dihydrogen phosphate, dipotassium hydrogen phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, mixtures thereof or the like. The phosphate source is preferably one which is water soluble.

When used, the phosphate source typically makes up from 0.5 to 40%, and more preferably, from 1 to 30%, and most preferably, from 2 to 20% by weight of the oral care composition, based on total weight of the oral care composition and including all ranges subsumed therein. In a preferred embodiment, the phosphate source used is trisodium phosphate and monosodium dihydrogen phosphate at a trisodium phosphate to monosodium dihydrogen phosphate weight ratio of 1 :4 to 4:1 , preferably 1 :3 to 3:1 , and most preferably, from 1 :2 to 2:1 , including all ratios subsumed therein. In another preferred embodiment, the phosphate source used is or at least comprises monosodium dihydrogen phosphate. In another preferred embodiment, the phosphate source is monopotassium dihydrogen phosphate, dipotassium hydrogen phosphate or a mixture thereof.

The oral care composition may further comprise benefit agents that are typically delivered to human teeth and/or the oral cavity including the gums to enhance or improve a characteristic of those dental tissues. The only limitation with respect to the benefit agents that may be used in this invention is that the same is suitable for use in the mouth. The benefit agents are present in the oral care composition in addition to the composite particles and the water soluble calcium source that are included in the composition.

Typically the benefit agent is selected from optical agents, antibacterial agents, gum health agents, desensitizing agents, anti-calculus agents, freshness agents or mixtures thereof. Preferably, the benefit agent is selected from optical agents, antibacterial agents, gum health agents, freshness agents or mixtures thereof.

For example, optical agents such as coloring agents like whitening agents and pigments. Preferably, the pigment, when used, is violet or blue having a hue angle, h, in the CIELAB system of from 220 to 320 degrees. These pigments may be selected from one or more of those listed in the Colour Index International, listed as pigment blue 1 through to pigment blue 83, and pigment violet 1 through to pigment violet 56. In another preferred embodiment, the optical agents may be selected from one or more of mica, interference mica, boron nitride, poly(methyl methacrylate) flake, composite microspheres, titanium dioxide coated glass flake, inverse opal, cholesteric liquid crystal, photonic sphere, hollow sphere and zinc oxide. Antibacterial agents may be selected from one or more of metal salts where the metal is selected from zinc, copper, silver or a mixture thereof, triclosan, triclosan monophosphate, triclocarban, curcumin, quaternary ammonium compounds, bisbiguanides and long chain tertiary amines, preferably zinc salts including zinc oxide, zinc chloride, zinc acetate, zinc ascorbate, zinc sulphate, zinc nitrate, zinc citrate, zinc lactate, zinc peroxide, zinc fluoride, zinc ammonium sulfate, zinc bromide, zinc iodide, zinc gluconate, zinc tartarate, zinc succinate, zinc formate, zinc phenol sulfonate, zinc salicylate, zinc glycerophosphate or a mixture thereof. Gum health agents may be selected from one or more of anti-inflammatory agents, plaque buffers, biomolecules, proteinaceous materials, vitamin, plant extracts and curcumin. Freshness agents may be flavors selected from one or more of peppermint, spearmint, menthol, flora oil, clove oil and citrus oil.

The benefit agent is preferably particulate. In a preferred embodiment, the benefit agent is a particulate whitening agent for tooth whitening.

Typically, the particulate whitening agent comprises a material suitable to physically and immediately improve characteristics of teeth and especially whiten teeth. In order to provide excellent whitening effect, the material is preferred to have a high refractive index of at least 1.9, more preferably at least 2.0, even more preferably at least 2.2, even more preferably still at least 2.4 and most preferably at least 2.5. The maximum refractive index of the material is not particularly limited but preferably up to 4.0. Preferably, the material has a refractive index ranging from 1.9 to 4.0.

Particularly suitable materials are metal compounds and preferred are compounds where the metal is selected from zinc (Zn), titanium (Ti), zirconium (Zr) or a combination thereof. Preferably, the metal compound is (or at least comprises) a metal oxide such as titanium dioxide (T1O2), zinc oxide (ZnO), zirconium dioxide (ZrC>2) or a combination thereof. In addition, the particulate whitening agent can also comprise non-metal oxides such as strontium titanate and zinc sulfide.

In a preferred embodiment, the particulate whitening agent comprises metal oxides, non- metal oxides or a combination thereof in an amount of at least 50% by weight of the whitening agent and more preferably at least 70%, more preferably still from 80 to 100% and most preferably from 85 to 95%. In an especially preferred embodiment, the particulate whitening agent is at least 50% by weight titanium dioxide, and most preferably, from 60 to 100% by weight titanium dioxide, based on total weight of the whitening agent and including all ranges subsumed therein. In another especially preferred embodiment, the particulate whitening agents are slightly soluble or insoluble in water, but most preferably, insoluble in water.

In a preferred embodiment, the particulate whitening agents are core-shell particulates. The refractive index of a core-shell particulate comprising more than one material can be calculated based on the refractive indices and volume fractions of the constituents using effective medium theory, as is described for example in WO 2009/023353.

The core-shell particulate comprises a first component core and a second component shell. Typically, the core of the core-shell particulate comprises a material suitable to physically and immediately improve characteristics of teeth and especially whiten teeth. In order to provide excellent whitening effect, the material is preferred to have a high refractive index of at least 1.9, more preferably at least 2.0, even more preferably at least 2.2, even more preferably still at least 2.4 and most preferably at least 2.5. The maximum refractive index of the material is not particularly limited but preferably up to 4.0.

Preferably, the material has a refractive index ranging from 1.9 to 4.0.

Particular suitable materials are metal compounds and preferred are compounds where the metal is selected from zinc (Zn), titanium (Ti), zirconium (Zr) or a combination thereof. Preferably, the metal compound is (or at least comprises) a metal oxide such as titanium dioxide (T1O2), zinc oxide (ZnO), zirconium dioxide (ZrC>2) or a combination thereof. In addition, the core of the core-shell particulate can also comprise non-metal oxides such as strontium titanate and zinc sulfide.

The core of the core-shell particulate typically makes up from 3 to 98%, and preferably from 6 to 65%, and most preferably from 10 to 55% by weight of the core-shell particulate, based on total weight of the core-shell particulate and including all ranges subsumed therein. In a preferred embodiment, the core comprises metal oxides, non- metal oxides or a combination thereof in an amount of at least 50% by weight of the core and more preferably at least 70%, more preferably still from 80 to 100% and most preferably from 85 to 95%. In an especially preferred embodiment, the core is at least 50% by weight titanium dioxide, and most preferably, from 60 to 100% by weight titanium dioxide, based on total weight of the first component core.

The second component shell comprises material suitable to adhere to tooth enamel, dentin or both. In a preferred embodiment, the second component shell is suitable to interact with phosphate ions to produce calcium and phosphate in situ reaction products that adhere well to tooth enamel, dentin or both. Typically the shell material comprises the element calcium, and optionally, other metals like potassium, sodium, aluminium, magnesium as well as mixtures thereof whereby such optional metals are provided as, for example, sulphates, lactates, oxides, carbonates or silicates. Optionally, the shell material may be aluminium oxide or silica. In a preferred embodiment, the shell material is suitable to provide a biological or chemical

improvement to teeth which is long term (e.g., results in hydroxyapatite formation).

Preferably, the shell employed comprises at least 50% by weight elemental calcium, and most preferably, at least 65% by weight elemental calcium based on total weight of metal in the shell. In an especially preferred embodiment, the metal in the shell is from 80 to 100% by weight of elemental calcium, based on total weight of metal in the second component shell and including all ranges subsumed therein. In another especially preferred embodiment, the core and the shell are slightly soluble or insoluble in water, but most preferably, insoluble in water.

In an especially desired embodiment, the second component shell can comprise, for example, calcium phosphate, calcium oxide, calcium carbonate, calcium hydroxide, calcium sulphate, calcium carboxymethyl cellulose, calcium alginate, calcium salts of citric acid, calcium silicate, mixture thereof or the like. In another desired embodiment, the calcium source in the shell comprises calcium silicate.

In yet another preferred embodiment, the shell can comprise the element calcium which originates from insoluble calcium silicate, present as the composite material calcium oxide-silica (CaO-SiC>2) as described in international patent applications published as WO 2008/015117 and WO 2008/068248.

When a calcium silicate composite material is employed as shell, the ratio of calcium to silicon (Ca:Si) may be from 1 :10 to 3:1. The Ca:Si ratio is preferably from 1 :5 to 3:1 , and more preferably, from 1 :3 to 3:1 , and most preferably, from about 1 :2 to 3:1. The calcium silicate may comprise mono-calcium silicate, bi-calcium silicate, or tri-calcium silicate whereby ratios of calcium to silicon (Ca:Si) should be understood to be atom ratios

Usually, at least 30% of the outer surface area of the first component core is coated with the second component shell, preferably at least 50% of the core is coated with the shell, most preferably, from 70 to 100% of the outer surface area of the first component core is coated with the second component shell. In an especially preferred embodiment, the particulate whitening agent is titanium dioxide coated with calcium silicate.

The particulate whitening agent according to the present invention can be of different sizes and shapes. The particles may be of spherical, platelet or irregular shape form. The diameter of the particulate whitening agent is often from 10 nm to less than 50 microns, and preferably, from 75 nm to less than 10 microns. In an especially preferred

embodiment, the diameter of particles is from 100 nm to 5 microns, including all ranges subsumed therein. Particle size can be measured, for example, by dynamic light scattering (DLS). For core-shell particulates, in a preferred embodiment, at least 40%, and preferably, at least 60%, and most preferably, from 75 to 99.5% of the diameter of the core-shell particulate is the core, including all ranges subsumed therein.

The oral care composition of the present invention may comprise a single benefit agent or a mixture of two or more benefit agents. Typically, the benefit agent is present in an amount from 0.25 to 60%, and more preferably, from 0.5 to 40%, and most preferably, from 1 to 30% by total weight of the oral care composition and including all ranges subsumed therein.

The oral care composition of the present invention may contain a variety of other ingredients which are common in the art to enhance physical properties and performance. These ingredients include preservatives, pH-adjusting agents, sweetening agents, particulate abrasive materials, polymeric compounds, buffers and salts to buffer the pH and ionic strength of the compositions, and mixtures thereof. 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.

The oral care composition of this invention can be used in a method for benefiting teeth of an individual comprising applying in the composition to at least one surface of the teeth of an individual, said benefits includes reduced sensitivity, remineralization, whitening and combinations thereof. The oral care composition of this invention may additionally or alternatively be for use as a medicament and/or used in the manufacture of a

medicament for providing an oral care benefit as described herein, such as for reducing sensitivity and/or remineralizing and/or whitening of the teeth of an individual.

Alternatively and preferably, the use is non-therapeutic.

The oral care composition of the present invention is prepared by conventional methods of making oral care compositions. Such methods include mixing the ingredients under moderate shear and atmospheric pressure.

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.

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. When the oral care composition is a dual-phase composition, the two phases of the composition are mixed during application. The mixed phases are typically left on the teeth for from 3 minutes to 10 hours, more preferably from 3 minutes to 8 hours. The application may be carried out one to five times monthly.

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.

Examples

Example 1

This example demonstrates the deposition on tooth surfaces. All ingredients are expressed by amount of the total formulation, and as level of active ingredient. TABLE 1

a. Commercial available calcium carbonate coated with hydroxyapatite under the trade name Omyadent® 100-OG from Omya International AG.

Methods

To evaluate the deposition on tooth surfaces, fresh slurries were prepared by mixing samples with water for 20 seconds on a mini-shaker and used immediately. Six bovine enamel blocks were separated into three groups (n=2). The enamel blocks 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 min, the enamel blocks were soaked in toothpaste slurry for another 1 min. Then the enamel blocks were rinsed with 50 ml. de-ionised (Dl) water and agitated on a flatbed shaker at 150 rpm for 10 strokes. The enamel blocks were then soaked in simulated oral fluid (SOF) for 6 hours under the condition of a shaking water bath at 37°C and 60.0 rpm. The enamel blocks were characterized by scanning electron microscopy (SEM, Hitachi S-4800, Japan). Simulated oral fluid was made by combining the ingredients in Table 2:

TABLE 2

Results

SEM images of the enamel block surfaces were taken after one brushing. From the top view of the SEM images, it was apparent that sample 2 gave better and denser deposition on tooth surfaces than samples 1 and 3.

Example 2

This example demonstrates the deposition on tooth surfaces by using full formulations. All ingredients are expressed by weight percent of the total formulation, and as level of active ingredient.

TABLE 3

b. Commercially available titanium dioxide coated with alumina under the trade name

HOMBITAN AFDC300 from Sachtleben.

c. Commercially available silica under the trade name Sorbosil AC77 from PQ Corporation.

Methods

To evaluate the deposition on tooth surfaces, fresh slurries were prepared by mixing samples with water at a weight ratio of 1 :2 under vortex for 20 to 30 seconds.

Human dentine discs were eroded by 6% citric acid for 2 mins, then they were treated with different slurries via brushing following the same protocol. Four dentine discs were separated into two 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 +1-5 g and the automatic brushing operated at a speed of 150 rpm. After brushing for 1 min, the dentine discs were soaked in toothpaste slurry for another 1 min. The dentine discs were then rinsed with 50 ml. de-ionised (Dl) water and agitated on a flatbed shaker at 150 rpm for 10 strokes. After that, the dentine discs were soaked in SOF for 6 to 16 hours under the condition of a shaking water bath at 37°C and 60.0 rpm. The brushing was repeated twice for one day. After two days of brushings, the dentine discs were characterized by scanning electron microscopy (SEM, Hitachi S-4800, Japan).

Scoring Standard for Tubules Blockage

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 50x 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 assessed following the standards described in Table 4. The measurement is carried out for the two dentine discs of each test group.

TABLE 4

Results

SEM images of the dentine discs were taken after two days of brushings. The images were analyzed and scored. The results are summarized in Table 5 (error represents standard deviation for duplicate measurements).

TABLE 5

Sample 5 comprising additional calcium chloride showed significantly better (p<0.01 ) tubule blockage efficacy than sample 4. SEM images clearly showed that all dentinal tubules of the dentine discs were blocked after treated with sample 5.

Claims

1. An oral care composition comprising:

(a) from 0.25 to 60% by weight of composite particles;

(b) from 0.1 to 20% by weight of a water soluble calcium source; and

(c) a physiologically acceptable carrier;

wherein the composite particle comprises:

(ii) a second component coating comprises a biomineralization agent;

wherein the biomineralization agent comprises amorphous calcium phosphate, o tricalcium phosphate, b-tricalcium phosphate, calcium deficient hydroxyapatite (Ca₉(HP0₄)(P0₄)₅0H), dicalcium phosphate (CaHPCU), dicalcium phosphate dehydrate (CaHP0₄-2H₂0), hydroxyapatite (Caio(P0₄)₆(OH)₂), octacalcium phosphate (CasH^PCU ShhO), tetracalcium phosphate (Ca₄(PC>₄)₂0) or mixtures thereof; and

wherein the composite particle has a specific surface area of from 15 m²/g to 200 m²/g, measured using nitrogen via the BET method according to ISO 9277.

2. The oral care composition according to claim 1 , wherein the first component core comprises at least 80% by weight of calcium carbonate, preferably is calcium carbonate.

3. The oral care composition according to claim 1 or claim 2, wherein the second component coating comprises at least 60% by weight of hydroxyapatite, preferably is hydroxyapatite.

4. The oral care composition according to any of the preceding claims, wherein the composite particle is calcium carbonate coated with hydroxyapatite.

5. The oral care composition according to any of the preceding claims, wherein the composite particle comprises the first component core in an amount of from 3% to 50%, preferably from 5% to 30% by weight of the composite particle.

6. The oral care composition according to any of the preceding claims, wherein the composite particle has a volume determined median particle size D50 in the range from 100 nm to 75 microns, preferably from 500 nm to 50 microns.

7. The oral care composition according to any of the preceding claims, wherein the composite particle has a specific surface area of from 30 m²/g to 180 m²/g, more preferably from 50 m²/g to 150 m²/g, measured using nitrogen via the BET method according to ISO 9277.

8. The oral care composition according to any of the preceding claims, wherein the composite particle is present in an amount of from 1 to 30% by weight of the composition.

9. The oral care composition according to any of the preceding claims, 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 gluconate, calcium ascorbate or mixtures thereof, preferably calcium chloride, calcium nitrate or mixtures thereof.

10. The oral care composition according to any of the preceding claims, wherein the composite particle and the water soluble calcium source are present in a weight ratio from 1 :5 to 20:1 , preferably from 1 :3 to 10:1.

1 1. The oral care composition according to any of the preceding claims, wherein the oral care composition is a monophase hydrous composition.

12. The oral care composition according to claim 1 1 , wherein the oral care composition is substantially free of phosphate source, and wherein the phosphate source comprises trisodium phosphate, monosodium dihydrogen phosphate, disodium hydrogen phosphate, tripotassium phosphate, monopotassium dihydrogen phosphate, dipotassium hydrogen phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate or mixtures thereof.

13. The oral care composition according to any of the preceding claims, wherein the composition further comprises a benefit agent, preferably a particulate whitening agent.

14. The oral care composition according to claim 13, wherein the particulate whitening agent is titanium dioxide coated with calcium silicate.

15. A method for reducing sensitivity and/or remineralizing and/or whitening of teeth of an individual comprising applying the composition according to any one of claims 1 to 14 to at least one surface of the teeth of the individual.