WO2021047997A1 - Oral care water-in-oil emulsions - Google Patents

Abstract

Disclosed is an oral care water-in-oil emulsion composition comprising: (a) at least 40 wt% edible oil or fat; (b) at least one kind of wax; (c) a hydrophilic inorganic thickener which swells by intercalating water; and, (d) a high molecular weight polymer suitable for oral and mucosal contact application, wherein said molecular weight of the polymer is at least 50,000 g/mol.

Description

ORAL CARE WATER-IN-OIL EMULSIONS

Field of the Invention

The present invention relates an oral care gel composition, especially for overnight application.

Background and Prior Art

Oral care products are available in a variety of format such as opaque toothpastes, gel toothpastes, mouthwashes, breath freshening strips, serums and pain-relieving gels, and even chewing gums and lozenges.

This variety of products is available for meeting the changing and evolving needs of consumers, which in turn ranges from basic oral hygiene, extended or prolonged hygiene, whiter teeth, shiny teeth, gum care, relief from pain, hypersensitivity, fresh breath and many more.

One of the formats discussed earlier is oral care gels and serums, which may also be called mousse or balms.

US2004037789 A1 (P&G) discloses a monophasic aqueous overnight leave-on gel that provides a pleasant mouth feel acceptable for long term use in the oral cavity. The composition is substantive, for long-lasting contact and efficacy. The composition is dissolvable within the oral cavity such that after waking up the user does not feel the presence of the applied product, and the product does not require mechanical means of removal such as brushing or rinsing. The gel comprises an oral care benefit agent, a thickener, less than 5% abrasive, less than 18% C1 to C6 monohydric alcohols, less than 10% silicone. The gel’s viscosity is greater than about 10 Pa. s at a shear rate of 0. 1 s' and from about 0. 1 Pa. s to about 300 Pa. s. at a shear rate of 1 s'.

US20060280700 A1 (Isler Stuart) discloses a system comprising a daytime composition and an overnight gel for daily application to the mouth, gums and teeth. The day and night-time compositions are applied by a special applicator to deliver a precise quantity. These compositions have xylitol and menthol. The overnight gel has eucalyptol. GB2423251 A (Hagan Louise) discloses a tooth balm in the form of an aqueous perfumed/flavoured gel for coating the teeth, contains fluoride and an odour suppressant such as eugenol. It may be applied after brushing at night so that breath is fresher in the morning or applied in the day to keep breath fresher for longer and may be formulated for separate male/female use. The tooth mousse comprises such an aqueous gel together with foaming agent and air and constitutes an easily applied alternative toothpaste.

Summary of the Invention

Usually such compositions contain at least one active or benefit agent such as breath- freshening agent, anti-hypersensitivity agent and it would be useful to formulate the compositions in such a way that the concerned active is retained for as long as possible before the product is rinsed out. We have determined that combination of edible oil or fat, a wax, a hydrophilic inorganic thickener and a certain kind of polymer provides a stable product to control the release of actives and to allow the actives to be retained longer.

In accordance with a first aspect of the invention is disclosed an oral care water-in-oil emulsion composition comprising: a) at least 40 wt% edible oil or fat; b) at least one kind of wax; c) a hydrophilic inorganic thickener which swells by intercalating water; and, d) a high molecular weight polymer suitable for oral and mucosal contact application, wherein said molecular weight of the polymer is at least 50,000 g/mol".

In accordance with a second aspect is disclosed a method of treating the oral cavity comprising the steps of: a) application of an oral care composition of the first aspect to the oral cavity such that at least 75% of the gingival margin or at least 75% of the buccal portion of the hard tissue is coated with the composition; b) leaving said composition overnight in contact with the oral cavity; and, c) rinsing the oral cavity without necessarily using a toothbrush.

In accordance with a third aspect is disclosed use of an oral care composition of the first aspect for the treatment of the oral cavity. 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 cosmetic 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.

Compositions of the invention are for oral care. The term oral care includes care of the teeth, gums or the oral cavity. Preferably oral care means any one or more of the following benefits such as anti-microbial, breath-freshening, desensitising, teeth whitening, antistain, probiotic, anti-tartar, anti-plaque, tooth strengthening, nutrition or antioxidant.

The composition of the invention is a water-in-oil emulsion. Such emulsions have oil as the continuous phase. Edible oil

The oral care water-in-oil emulsion composition of the invention comprises at least 40 wt% edible oil or fat. This oil or fat forms large part of oil phase of the emulsion. Preferably the composition comprises 40 to 70wt% edible oil or fat.

The edible oil or fat is preferably from a plant source. In such cases it could be derived from any part of the plant such as seeds. Alternatively, the edible oil or fat is from an animal source such as fish oil or lard. However, it is preferred that the edible oil or fat is from a plant source.

It is preferred that the edible oil is at least one of groundnut, soybean, sunflower, rapeseed, linseed, safflower, sesame, palm corn, canola, cottonseed, almond, beech, brazil nut, cashew, hazelnut, macademia, pecan, pine nut, pistachio, walnut, pumpkin seed, bottle gourd, flaxseed, coconut, olive, rice bran, fish, hydrogenated vegetable, amaranth, apricot, argan, avocado, babassu, cocoa butter or mustard. The edible oil could be a mixture of one or more of the oils listed above in any combination so long as the oils or fats are not grossly incompatible.

Wax

The wax is at least one of microcrystalline wax, hard paraffin wax, bees wax, emulsifying wax, carnauba wax, sugar cane wax, montan wax, rice bran wax, hydrogenated rice bran wax or lanolin. Preferably the wax is a combination of an emulsifying wax and at least one of microcrystalline wax, hard paraffin wax, bees wax, emulsifying wax, carnauba wax, sugar cane wax, montan wax, rice bran wax, hydrogenated rice bran wax or lanolin.

Preferably the compositions of the invention comprise 2 to 30 wt% wax. In this case it is the sum total of all waxes present. When the compositions comprise an emulsifying wax it is preferred that the amount is 1 to 10 wt%. When the compositions comprise an emulsifying wax and at least one of microcrystalline wax, hard paraffin wax, bees wax, carnauba wax, sugar cane wax, montan wax, rice bran wax, hydrogenated rice bran wax or lanolin, it is preferred that the amount of each wax individually is from 1 to 10 wt%. It is particularly preferred that the compositions of the invention comprise an emulsifying wax and at least one of microcrystalline wax, hard paraffin wax or bees wax. More particularly it is preferred that the compositions of the invention comprise an emulsifying wax and microcrystalline wax, hard paraffin wax and bees wax.

Thickener

It is preferred that the inorganic thickener is at least one of magnesium-aluminium silicate, a layered silicate, smectite, hectorite, bentonite, montmorillonite or phyllosilicate.

Preferably the compositions of the invention comprise 0.1 to 10 wt% of the hydrophilic inorganic thickener. More preferably the compositions of this invention comprise 0.3 to 5 wt%, most preferably 0.4 to 3 wt% of the non-silica hydrophilic inorganic. It is preferred that the inorganic thickener is at least one of magnesium-aluminium silicate, a layered silicate, smectite, hectorite, bentonite, montmorillonite or phyllosilicate. More preferably the inorganic thickener is smectite or magnesium-aluminium silicate.

Several grades of magnesium-aluminium silicates are commercially available, for example, the VEEGUM® range of thickeners such as Normal Fast Ultra, VEEGUM® K, VEEGUM® HV, VEEGUM® PURE, VEEGUM® CH, VEEGUM® HS, VEEGUM® D, VEEGUM® Ultra and the VANATURAL range of thickeners such as VANATURAL® MC. The VANATURAL® range is of the bentonite clay type.

While not necessary, the magnesium-aluminium silicate or smectite may be used in the form of combination or blend of the thickener with a natural organic gum or natural organic thickener. An example thereof is VANATURAL® XGB (Bentonite and Xanthan Gum). Other examples include VAN GEL SX (smectite clay and xanthan gum) and VEEGUM CER (smectite clay and cellulose gum). Other such blends could include polyacrylates, carbomers, cellulose, sodium, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, methylcellulose, xanthan gum, sodium carrageenan, sodium alginate, hydroxypropyl guar, gum arabic (acacia) or gum tragacanth.

Other preferred forms of smectite include sodium magnesium silicates, organically modified smectites including tetra alkyl and/or trialkyl ammonium smectites (organically modified montmorillonite clays) such as quaternium-18 bentonite, quaternium-18 hectorite, stearalkonium bentonite and stearalkonium hectorite; and mixtures thereof. Montmorillonites represent clay minerals, which belong to the dioctahedral smectites, and are materials which swell in water but do not become plastic. The layer packets in the 3- layer structure of the montmorillonites can swell as the result of reversible incorporation of water (in a 2-7 fold amount).

As montmorillonites have a large capacity for ion exchange, aluminum can be replaced by Mg, Fe(ll), Fe(lll), Zn, Pb, Cr, Cu and others. The resulting negative charge of the octahedral layers is balanced by cations, such as Na⁺ (sodium montmorillonite) and Ca⁺² (calcium montmorillonite) in interlayer positions.

Smectites are characterized by a 2:1 layer structure in which two tetrahedral sheets form on either side of an octahedral sheet through sharing of apical oxygens. As the apical oxygens from the tetrahedral sheet form ditrigonal or hexagonal rings, one oxygen from the octahedral sheet is located on the centre of each ring and is protonated to yield a structural hydroxyl. In 2:1 phyllosilicates, isomorphous substitution of cations having different valencies can lead to charge imbalances within a sheet. These may be partly balanced by the opposite type of charge imbalance in the adjacent sheet (e.g. a positively charged octahedral sheet may offset some of the negative charge associated with a tetrahedral sheet).

The compounds/clay materials belonging to the class of smectites is quite large, and especially the Cs exchanged classes of smectites includes hectorite, saponite, and montmorillonite in addition to vermiculite, and several non-exchangeable phyllosilicates.

Other preferred thickener as per this invention is sodium and calcium montmorillonite, which are part of the smectite group of natural aluminosilicate minerals, and are the most common members. Montmorillonite is the major phase in a type of clays called bentonites. Amongst the calcium and sodium bentonites, sodium bentonite is more preferred.

Montmorillonite is characterized by the substitution of a limited number of octahedral Al³⁺ with Mg²⁺ which accounts for its negative charge. This is naturally balanced by Na⁺ between the clay platelets, partially sunk in the hexagonal openings of the silica layer. Because the sodium ions are not structural they can be easily replaced by other positively charged elements or molecules, and are called exchangeable cations. In addition to the charge balancing cations, a tightly held layer of oriented water, about 0.29 nanometers thick, occupies the space between individual flakes. This water requires temperatures well in excess of 100°C for removal. A single VEEGUM® Magnesium Aluminum Silicate or VANATURAL® Bentonite Clay particle is composed of thousands of these sandwiched platelets with exchangeable cations and a layer of water between each.

The trioctahedral analogues of montmorillonite are saponite and hectorite.

The binding effect of inter-platelet water and counterions makes mechanical delamination of smectite clays very difficult but swelling by intercalation with polar liquids and solutions is quite easy. Likewise, in cases where the full surface area of the clay needs to be exposed and/or its rheological properties exploited, hydraulic delamination is relatively simple. When such an inorganic thickener and water are mixed, water penetrates between platelets forcing them further apart. The cations begin to diffuse away from platelet faces. Diffusion (the movement of cations from between platelets out into the water) and osmosis (the movement of water into the space between platelets) then promote delamination until platelets are completely separated.

High molecular weight polymer

The compositions of the invention comprise a high molecular weight polymer suitable for oral and mucosal contact application. The term “high molecular weight” in this particular context means that molecular weight of the polymer is at least 50,000 g/mol, more preferably at least 500,000 g/mol. A suitable method to determine the molecular weight is gel permeation chromatography against a polyethylene glycol standard.

It is preferred that the high molecular weight polymer is a crosslinked poly(meth)acrylic acid polymer, PVP polymer, maleic anhydride polymer, vinyl ethyl polymer or cellulosic polymer.

It is further preferred that the compositions of the invention comprise from 0.05 to 4 wt% polymer. Further preferably the polymer is crosslinked poly(meth)acrylic acid polymer. Suitable examples include polymers of the Carbopol® or the Pemulen® trade name.

Emulsifier

Preferably the composition comprises a first emulsifier whose HLB value is 3 to 6. More preferably this emulsifier is sorbitan oleate or sorbitan stearate but alternatively or additionally any equivalent emulsifier may be used. Preferably the compositions of the invention comprise 1 to 10 wt% of this emulsifier. Examples of suitable low HLB emulsifiers include Glycol Distearate HLB=1, Sorbitan Trioleate HLB=1.8, Propylene Glycol Isostearate HLB=2.5, Glycol Stearate HLB=2.9, Sorbitan Sesquioleate HLB=3.7, Glyceryl Stearate HLB=3.8, Lecithin HLB=4, Sorbitan Oleate HLB=4.3, Sorbitan Monostearate NF HLB=4.7, Sorbitan Stearate HLB=4.7, Sorbitan Isostearate HLB=4.7, Steareth-2 HLB=4.9, Oleth-2 HLB=4.9, Glyceryl Laurate HLB=5.2, Ceteth-2 HLB=5.3, PEG-30 Dipolyhydroxystearate HLB=5.5, Glyceryl Stearate SE HLB=5.8, PPG-1 -PEG-9 Lauryl Glycol Ether, (HLB ca. 6), Sorbitan Stearate (and) Sucrose Cocoate HLB=6 or PEG-4 Dilaurate HLB=6.

Preferably the composition comprises a second emulsifier whose HLB value is 8 to 20. More preferably this emulsifier is polyoxyethylene sorbitan monooleate or polyoxyethylene sorbitan stearate but alternatively or additionally any equivalent emulsifier may be used. Preferably the compositions of the invention comprise 1 to 10 wt% of this emulsifier.

Preferred high HLB emulsifiers include PEG-7 Glyceryl Cocoate HLB=10, PEG-20 Almond Glycerides HLB=10, PEG-7 Glyceryl Cocoate (HLB 10), Coceth-7 (HLB ca. 10) PEG-25 Hydrogenated Castor Oil HLB=10.8, Stearamide MEA HLB=11, Glyceryl Stearate (and) PEG-100 Stearate HLB=11, Polysorbate 85 HLB=11, PEG-7 Olivate HLB=11, Cetearyl Glucoside HLB=11 , PEG-8 Oleate HLB=11.6, Polyglyceryl-3 Methyglucose Distearate=12, Oleth-10 HLB=12.4, Oleth-10/Polyoxyl 10 Oleyl Ether NF HLB=12.4, Ceteth-10 HLB=12.9, PEG-8 Laurate HLB=13, Cocamide MEA HLB=13.5, PEG 40 Hydrogenated Castor Oil (HLB 14-16), Polysorbate 60 NF HLB=14.9, Polysorbate 60 HLB=14.9, Polysorbate 80 HLB=15, lsosteareth-20 HLB=15, PEG-60 Almond Glycerides HLB=15, Polysorbate 80 NF HLB=15, PEG-20 Methyl Glucose Sesquistearate HLB=15, Ceteareth-20 HLB=15.2, Oleth-20 HLB=15.3, Steareth-20 HLB=15.3, Steareth-21 HLB=15.5, Ceteth-20 HLB=15.7, Isoceteth- 20 HLB=15.7, Polysorbate 20 HLB=16.7, Polysorbate 20 NF HLB=16.7, Laureth-23 HLB=16.9, PEG-100 Stearate HLB=18.8, Steareth-100 HLB=18.8, PEG-80 Sorbitan Laurate HLB=19.1

Actives

Preferably the oral care water-in-oil emulsion composition of the invention comprises at least one active agent which is an anti-microbial agents, breath-freshening active, desensitising agent, teeth whitening active, antistain agent, probiotic, anti-tartar agent, anti-plaque agent, fluoride ion source, tooth strengthening agent, nutrient or an antioxidant.

The actives suitable for whitening include peroxides, metal chlorites, perborates, percarbonates, peroxyacids, and combinations thereof. Suitable peroxide compounds include hydrogen peroxide, calcium peroxide, carbamide peroxide, and mixtures thereof. Suitable metal chlorites include calcium chlorite, barium chlorite, magnesium chlorite, lithium chlorite, sodium chlorite, and potassium chlorite. Additional whitening actives may be the hypochlorite salts and chlorine dioxide.

Anti-tartar agents known for use in dental care products include pyrophosphates, linear polyphosphates with 4 or more repeat units, polyphosphonates and mixtures thereof. Pyrophosphate ions delivered to the teeth are derived from pyrophosphate salts. The pyrophosphate salts are described in more detail in Kirk & Othmer, Encyclopedia of Chemical Technology, Third Edition, Volume 17, Wiley-lnterscience Publishers (1982).

Fluoride ion sources are well known for use in oral care compositions as anticaries agents. A wide variety of fluoride ion-yielding materials can be employed as sources of soluble fluoride Examples include sodium fluoride, stannous fluoride and sodium monofluorophosphate.

Preferred oral care benefit agents herein are anti-microbial agents. Antimicrobial agents are known to those skilled in the art and include cationic agents, non-cationic agents and metal ion salts. Such agents may include, but are not limited to, 5-chloro-2-(2,4-dichloropheno- xy)- phenol, commonly referred to as triclosan, and described in The Merck Index, 11th ed. (1989), pp. 1529 (entry no. 9573); phthalic acid and its salts, substituted monoperthalic acid and its salts and esters, preferably magnesium monoperoxy phthalate, chlorhexidine (Merck Index, no. 2090), alexidine (Merck Index, no. 222; hexetidine (Merck Index, no. 4624); sanguinarine (Merck Index, no. 8320) and benzalkonium chloride (Merck Index, no. 1066) and cetylpyridinium chloride (CPC) (Merck Index, no. 2024).

Anti-inflammatory agents include non-steroidal anti-inflammatory agents (or NSAIDs) such as ketorolac, flurbiprofen, ibuprofen, naproxen, indomethacin, aspirin, ketoprofen, piroxicam and meclofenamic acid. Nutrients may improve the condition of the oral cavity and can be included in the aqueous gels of the present invention. Nutrients include minerals, vitamins, nutritional supplements, and mixtures thereof.

Minerals that can be included with the aqueous gels of the present invention include calcium, phosphorus, fluoride, zinc, manganese, potassium and mixtures thereof.

Vitamins can be included with minerals or used separately. Vitamins include Vitamins C and

D, thiamine, riboflavin, calcium pantothenate, niacin, folic acid, nicotinamide, pyridoxine, cyanocobalamin, para-aminobenzoic acid, bioflavonoids, and mixtures thereof.

Enzymes useful in the present invention include any of the commercially available proteases, glucanohydrolases, endoglycosidases, amylases, mutanases, lipases and mucinases or compatible mixtures thereof. Preferred are the proteases, dextranases, endoglycosidases and mutanases, most preferred being papain, endoglycosidase or a mixture of dextranase and mutanase.

Antioxidants are generally recognized as useful in aqueous gels such as those of the present invention. Antioxidants are disclosed in texts such as Cadenas and Packer, The Handbook of Antioxidants, 1996 by Marcel Dekker, Inc. Antioxidants that may be included in the aqueous gel or substance of the present invention include, but are not limited to Vitamin

E, ascorbic acid, Uric acid, carotenoids, Vitamin A, flavonoids and polyphenols, herbal antioxidants, melatonin, aminoindoles, lipoic acids and mixtures thereof.

Compositions of the invention preferably have a viscosity of from 10,000 to 60,000 cps at 25°C, more preferably 15,000 to 45,000 cps at 25°C, more preferably from 19,000 to 35,000 cps at 25°C.

In the context of the present invention viscosity is measured at 25°C, using a Brookfield viscometer with Helipath Stand and a T-bar, TB spindle, rotating at 5 rpm. The measurement jar has a minimum diameter of 5 cm and a minimum height of 10 cm. The viscosity value is recorded 60 seconds from the start of the measurement. Compositions according to the invention will usually contain an aqueous dispersed phase. The amount of water preferably ranges from 10 to 35 wt%, more preferably from 10 to 20 wt%.

Compositions of the invention may comprise a preservative. A preferred preservative is sodium benzoate, more preferably a system formed from ethylhexyl glycerin, phenoxyethanol and benzyl alcohol. Preferably the level of preservative in the case of the mixed system described is from 0.5 to 2 wt% of the total composition. This level refers to the total level of preservative system.

It is preferable if the pH of the composition at 25°C is from 5 to 8.0, more preferably from 6.0 to 7.5.

The invention will now be illustrated by the following non-limiting Examples. Examples of the invention will be illustrated by a number, comparative Examples by a letter.

In accordance with a second aspect of the invention is disclosed a non-therapeutic method of treating the oral cavity comprising the steps of:

(a) application of an oral care composition of the first aspect to the oral cavity such that at least 75% of the gingival margin or at least at least 75% of the buccal portion of the hard tissue is coated with the composition;

(b) leaving said composition overnight in contact with the oral cavity; and,

(c) rinsing the oral cavity without necessarily using a toothbrush.

More preferably the method is a cosmetic method. Alternatively it is a therapeutic method.

In accordance with yet another aspect of the invention is disclosed the non-therapeutic use of an oral care composition of the first aspect of the invention for the treatment of the oral cavity. Preferably this use is for cosmetic purposes. Alternatively the use is for therapeutic purpose.

In accordance with yet another aspect is disclosed an oral care water-in-oil emulsion composition for use in a method for the treatment of the oral cavity, comprising:

(a) at least 40 wt% edible oil or fat; (b) at least one kind of wax;

(c) a hydrophilic inorganic thickener which swells by intercalating water; and,

(d) a high molecular weight polymer suitable for oral and mucosal contact application, wherein said molecular weight of the polymer is at least 50,000 g/mol.

Examples

Four (4) water-in-oil emulsion compositions as shown in Table 1 were prepared. The compositions were given a reference number for ease of identification. Three out of the four compositions were labelled as comparative compositions (A, B and C) because they were outside the scope of the present invention. Formulation Ref 1 was inside the scope of the present invention because it comprised at least 40 wt% edible oil or fat (50 wt% sesame oil), at least one kind of wax (refer the oil phase), a hydrophilic inorganic thickener (Veegum Ultra) and a high molecular weight, crosslinked poly(meth)acrylic acid polymer suitable for oral and mucosal contact application (Carbopol® 971 P NF).

Table 1

Note:

Carbopol® 971P NF is Acrylic Acid Resin; 2-Propenic Acid Homopolymer; Acrylic Acid Polymer Carbopol® 974P is 2-Propenic Acid Homopolymer; Acrylic Acid Polymer.

All the compositions were kept at room temperature (25°C) and their physical state was checked after every seven days to find out whether they were stable or not. If the phases had separated or if the oil has oozed out from the mass, the compositions were considered unstable.

The observations were as follows: A - Phase separation in 7 days B - Phase separation in 30 days C - Phase separation in 7 days 1 - Stable even after 30 days The observations indicate that only the formulation ref. 1 was stable enough. Observations concerning the rest of the compositions clearly indicate that having just a wax (or waxes) or any of the Carbopol® polymers was not enough to stabilise the compositions.

Claims

1. An oral care water-in-oil emulsion composition comprising:

(a) at least 40 wt% edible oil or fat;

(b) at least one kind of wax;

(c) a hydrophilic inorganic thickener which swells by intercalating water; and,

(d) a high molecular weight polymer suitable for oral and mucosal contact application, wherein said molecular weight of the polymer is at least 50,000 g/mol.

2. An oral care composition as claimed in claim 1 wherein said composition comprises 40 to 70wt% edible oil or fat.

3. An oral care composition as claimed in claim 1 wherein said edible oil is at least one of groundnut, soybean, sunflower, rapeseed, linseed, safflower, sesame, palm oil, corn, canola, cottonseed, almond, beech, brazil nut, cashew, hazelnut, macademia, pecan oil, pine nut, pistachio, walnut, pumpkin seed, bottle gourd, flaxseed, coconut, olive, rice bran I, fish, hydrogenated vegetable, amaranth, apricot, argan, avocado, babassu, cocoa butter or mustard.

4. An oral care composition as claimed in any of claims 1 to 3 wherein said inorganic thickener is at least one of magnesium-aluminium silicate, a layered silicate, smectite, hectorite, bentonite, montmorillonite or phyllosilicate.

5. An oral care composition as claimed in any of claims 1 to 4 wherein said wax is at least one of microcrystalline wax, hard paraffin wax, bees wax, emulsifying wax, camauba wax, sugar cane wax, montan wax, rice bran wax, hydrogenated rice bran wax or lanolin.

6. An oral care composition as claimed in claim 5 wherein said wax is a combination of an emulsifying wax and at least one of microcrystalline wax, hard paraffin wax, bees wax, camauba wax, sugar cane wax, montan wax, rice bran wax, hydrogenated rice bran wax or lanolin.

7. An oral care composition as claimed in any of claims 1 to 6 wherein said high molecular weight polymer is a crosslinked poly(meth)acrylic acid polymer, PVP polymer, maleic anhydride polymer, vinyl ethyl polymer or cellulosic polymer.

8. An oral care composition as claimed in any of claims 1 to 7 wherein said composition comprises a first emulsifier whose HLB value is 3 to 6.

9. An oral care composition as claimed in claim 8 wherein said first emulsifier is sorbitan stearate or sorbitan oleate.

10. An oral care composition as claimed in any of claims 1 to 9 wherein said composition comprises a second emulsifier whose HLB is from 8 to 20.

11. An oral care composition as claimed in claim 10 wherein said second emulsifier is polyoxyethylene sorbitan monooleate or polyoxyethylene sorbitan stearate.

12. An oral care composition as claimed in any of claims 1 to 11 wherein said composition comprises at least one active agent which is an anti-microbial agent, breath-freshening active, desensitising agent, teeth whitening active, antistain agent, probiotic, anti-tartar agent, anti-plaque agent, fluoride ion source, tooth strengthening agent, nutrient or an antioxidant.

13. A non-therapeutic method of treating the oral cavity comprising the steps of: a) application of an oral care composition as claimed in any of claims 1 to 12 to the oral cavity such that at least 75% of the gingival margin or at least 75% of the buccal portion of the hard tissue is coated with the composition; b) leaving said composition overnight in contact with the oral cavity; and, c) rinsing the oral cavity without necessarily using a toothbrush.

14. Non-therapeutic use of an oral care composition as claimed in any of claims 1 to 12 for the treatment of the oral cavity.

15. An oral care water-in-oil emulsion composition for use in a method for the treatment of the oral cavity, comprising: (a) at least 40 wt% edible oil or fat;

(b) at least one kind of wax;

(c) a hydrophilic inorganic thickener which swells by intercalating water; and,

(d) a high molecular weight polymer suitable for oral and mucosal contact application, wherein said molecular weight of the polymer is at least 50,000 g/mol.