Dentifrice composition

Abstract

The present invention relates to a single-phase dentifrice composition that is capable of stabilizing two mutually incompatible oral care actives.

Description

[Technical Field]

[0001] The present invention relates to oral care compositions, and in particular to dentifrice (preferably toothpaste) formulations.The present invention relates to stable dentifrice compositions having two actives with different stability requirements. [Background technology]

[0002] Toothpaste formulations with potassium nitrate can provide everyday sensitivity protection.

[0003] Potassium is an ingredient that has been clinically proven to reduce dentin hypersensitivity. See Jeandot J et al., Clinic (French) 2007;28:379-384; Leight RS et al., J Clin Dent 2008;19:147-153; Nagata T et al., J Clin Periodontol 1994;21:217-221; Silverman G. Compend Contin Educ Dent 1985;6:131-133, 136 and Silverman G et al., Am J Dent 1994;7(1):9-12.

[0004] The potassium nitrate compound builds protection over time and helps to reduce the sensitivity of the nerves in the tooth pulp.

[0005] Potassium ions can migrate into the dentin tubules exposed from the tooth surface and reach the inner nerve. The accumulation of potassium ions over time reduces the sensitivity of the nerve in the pulp, helping the nerve to become less responsive to sensitive stimuli (e.g., cold water, hot coffee, etc.).

[0006] Stannous fluoride is also an active ingredient often used in toothpastes to achieve, among other benefits, reduced dentin sensitivity.

[0007] Stannous fluoride achieves reduced dentin sensitivity through a different mechanism of action than potassium nitrate. Stannous fluoride is thought to promote the occlusion of exposed dentinal tubules.

[0008] It has long been desirable to utilize a combination of these two actives in a single-phase toothpaste for superior sensitivity control.

[0009] However, this has not yet been satisfactorily achieved. The main reason for this is that the two active substances have very specific and conflicting formulation requirements. Potassium nitrate is an inorganic salt and therefore requires formulations that are typically highly polar, most preferably aqueous, to be stable. In contrast, stannous fluoride is typically unstable in (neutral) aqueous environments. Stannous fluoride is primarily marketed in non-aqueous formulations (e.g., various Sensodyne® toothpastes) to prevent unacceptable levels of decomposition during storage.

[0010] Until now, toothpaste compositions utilizing both of these actives at therapeutically useful levels have required the use of two-component pastes, often striped toothpastes, with one formulation optimized for one active and the other phase optimized for the other active, which are kept separate in a tube until applied to the brush. Summary of the Invention

[0011] It is an object of the present invention to solve this problem and provide an effective, stable, single-phase toothpaste that provides these benefits.

[0012] The present invention comprises a single-phase non-aqueous dentifrice composition; the composition comprises glycerol, potassium nitrate, stannous fluoride, fumed silica, and at least one hydroxyethyl cellulose polymer.

[0013] In a further embodiment of the present invention, the hydroxyethyl cellulose polymer has a formula weight average molecular weight (Da) of from about 500,000 to about 1,000,000 Da, preferably from about 600,000 to about 900,000 Da, more preferably from about 650,000 to about 800,000 Da, and most preferably from about 700,000 to about 750,000 Da.

[0014] In a further embodiment, the hydroxyethyl cellulose polymer comprises from about 0.05% to about 1% by weight, more preferably from about 0.1% to about 0.5% by weight, and most preferably from about 0.2% to about 0.4% by weight.

[0015] In a further embodiment, the fumed silica is present at about 1% to about 6% by weight, more preferably about 2% to about 4% by weight.

[0016] In a further embodiment, glycerol comprises at least about 50% by weight of the composition, more preferably at least about 60% by weight, and most preferably at least 70% by weight.

[0017] In a further embodiment, potassium nitrate comprises about 1% to about 8% by weight of the total formulation, more preferably about 3% to about 7% by weight, and most preferably about 5% by weight or so.

[0018] In a further embodiment, stannous fluoride comprises from about 0.1% to about 1%, preferably from about 0.3% to about 0.7%, and most preferably from about 0.4% to about 0.6% by weight of the formulation.

[0019] In a further embodiment, the composition further comprises one or more surfactants, wherein the one or more surfactants comprise from about 0.5% to about 5% by weight, preferably from 1.0% to 4.0% by weight, and most preferably from about 2.0% to about 3.0% by weight.

[0020] In a further embodiment, the one or more surfactants comprise an anionic surfactant.

[0021] In a further embodiment, the surfactant is sodium lauryl sulfate (SLS).

[0022] In a further embodiment, the composition further comprises from about 0.05% to about 5%, more preferably from about 0.075% to about 1%, and most preferably from about 0.1% to about 0.5%, by weight of the composition, of a thickening gum.

[0023] In a further embodiment, the thickening gum comprises carrageenan.

[0024] In a further embodiment of the present invention, the composition comprises one or more silicas, the total silica content being from about 1% to about 20% by weight, preferably from about 5% to about 15% by weight.

[0025] In a further embodiment, the composition further comprises from about 0.5% to about 10% by weight, preferably from about 2.5% to about 7.5% by weight, and most preferably about 5% by weight of one or more stain release ingredients.

[0026] In a further embodiment, the composition further comprises one or more additional ingredients selected from the categories of flavors, sweeteners, colors, and preservatives. DETAILED DESCRIPTION OF THE INVENTION

[0027] Applicants have surprisingly discovered a non-aqueous, single-phase dentifrice formulation that is stable to therapeutic levels of both potassium nitrate and stannous fluoride.

[0028] Dentifrice is a powder, paste or liquid composition for cleaning teeth. The most common form of dentifrice is toothpaste.

[0029] The formulations offer excellent storage stability and consumer acceptability.

[0030] Stannous fluoride is known to cause staining problems and can lead to yellowing in toothpaste. This is thought to be the result of chemical degradation and interactions, although the exact mechanism is not well understood. The formulations of the present invention offer significant resistance to this degradation effect and do not show discoloration even upon long-term storage.

[0031] For purposes of the present invention, non-aqueous means a total water content of less than about 5% by weight, preferably less than about 2.5% by weight, and most preferably less than about 1% by weight.

[0032] The dentifrice formulations of the present invention are based on glycerol as a solvent in combination with at least one hydroxyethyl cellulose polymer and fumed silica as thickeners.

[0033] Glycerol (also called glycerine or glycerin) is a simple polyol compound. It is a sweet-tasting, non-toxic, colorless, odorless, viscous liquid.

[0034] The dentifrice compositions of the present invention comprise at least about 50% by weight glycerol, preferably at least about 60% by weight glycerol, and most preferably at least about 70% by weight glycerol.

[0035] It is well known that commercially available glycerin may contain about 0.1% to about 2.0% by weight of water bound to the glycerin. Typically, this amount is less than 0.5% by weight of the glycerin, for example, about 0.1% to about 0.5% by weight. This small amount of water is bound to the glycerin and therefore is not available to other ingredients. Those skilled in the art would still consider a composition containing glycerin to be non-aqueous. In any case, the solvent should be as anhydrous as possible.

[0036] Hydroxyethyl cellulose is a gelling and thickening agent derived from the natural polymer cellulose.

[0037] Cellulose has the formula (CH 10 O5) n Cellulose is an organic compound with a molecular structure of 1 → 4, a polysaccharide consisting of linear chains of hundreds to thousands of β(1 → 4)-linked D-glucose units. Cellulose is an important structural component of the primary cell walls of green plants, many forms of algae, and oomycetes. It is the most abundant organic polymer on Earth.

[0038] Hydroxyethyl cellulose polymers are widely used in cosmetics, cleaning solutions, and other household products.

[0039] Hydroxyethyl cellulose polymers are commercially available products with a variety of different specifications. For the purposes of the present invention, hydroxyethyl cellulose polymers having a weight average molecular weight (Daltons or Da) of 500,000 to 1,000,000 Da are preferred.

[0040] More preferred is a hydroxyethyl cellulose polymer having a weight average molecular weight of 600,000 to 900,000 Da, and most preferred is 700,000 to 800,000 Da.

[0041] A particularly preferred hydroxyethyl cellulose polymer for use in the formulations of the present invention is Natrosol™ 250M Pharmaceutical Grade manufactured by Ashland. This polymer is approximately 720,000 Da.

[0042] Preferably, the hydroxyethyl cellulose polymer comprises 0.05% to 1% by weight of the total dentifrice composition, more preferably 0.1% to 0.5% by weight, and most preferably 0.2% to 0.4% by weight.

[0043] The weight ratio of glycerol to hydroxyethyl polymer in the dentifrice composition of the present invention is from about 2000:1 to about 60:1, preferably from about 1500:1 to about 120:1, most preferably from 750:1 to about 200:1, and most preferably from about 500:1 to about 250:1.

[0044] It is particularly preferred for the dentifrice compositions of the present invention to include a weight ratio of glycerol to hydroxyethylcellulose of about 300:1, which provides a single-phase base formulation capable of stabilizing a combination of both therapeutic levels of potassium nitrate and stannous fluoride.

[0045] The compositions of the present invention require fumed silica to achieve stability.

[0046] Fumed silica (also known as pyrogenic silica because it is produced in a flame) consists of minute droplets of amorphous silica that fuse into branched, chain-like, three-dimensional secondary particles, which then aggregate into tertiary particles. The resulting powder has an extremely low bulk density and a high surface area.

[0047] Preferably, the fumed silica of the present invention has a viscosity of at least 150 m 2 / g, more preferably at least 200m 2 / g specific surface area.

[0048] A particularly preferred fumed silica is Aerosil® 200 sold by Evonik chemical company. Aerosil® 200 has a viscosity of 200 ml 2 / g. Another preferred fumed silica is Aerosil® 300 sold by Evonik chemical company. Aerosil® 300 has a specific surface area of ​​300 m 2 It is a hydrophilic fumed silica with a specific surface area of ​​1.05g / g.

[0049] Other suitable sources of fumed silica include: Cabot Corporation (Cab-O-Sil®), Wacker Chemie (HDK®), Dow Corning, Heraeus (Zandosil®), Tokuyama Corporation (Reolosil®), OCI (Konasil®), Orisil (Orisil), and Xunyuchem (XYSIL®).

[0050] Preferably, the fumed silica is present at about 1% to about 6% by weight of the formulation, more preferably at about 2% to about 4% by weight.

[0051] Potassium nitrate may be used in a wide range of different concentrations.

[0052] Potassium nitrate may be found in the dentifrices of the present invention at about 1% to about 8% by weight, preferably about 3% to about 7% by weight.

[0053] The therapeutic clinical effect of potassium nitrate in dentifrice compositions is typically seen at about 5% by weight, an amount that is particularly preferred for the present invention.

[0054] Stannous fluoride may also be tolerated and stable in the compositions of the present invention at a wide range of different concentrations.

[0055] The amount of stannous fluoride that can be used in commercial toothpastes is highly regulated by law and varies in different jurisdictions, but the formulations of the present invention are stable in all of these, even at concentrations much higher than legally permitted.

[0056] Stannous fluoride may be used at about 0.1% to about 3% by weight, preferably about 0.2% to about 2.0% by weight, more preferably about 0.3% to about 1.0% by weight, and most preferably about 0.4% to 0.7% by weight.

[0057] A particularly preferred level of stannous fluoride for commercial toothpastes is 0.454% or 1100 ppm. Other preferred levels are 1450 ppm and 900 ppm.

[0058] An optional ingredient that can be used to provide additional stability is an aliphatic polyether. Preferred polyethers include polyethylene glycol (PEG) and polypropylene glycol (PPG) or combinations thereof.

[0059] When included in the formulations of the present invention, PEG or PPG preferably comprises from 1% to 25% by weight of the formulation, preferably from 5% to 15% by weight.

[0060] The formulations of the present invention may also include one or more additional thickeners and one or more additional solvents. Optionally, a dentally acceptable abrasive may be included in the non-aqueous carrier.

[0061] Advantageously, a thickener can be present in the formulation to adjust the rheology to be similar to that of a conventional tube-based dentifrice.

[0062] Preferably, the thickener comprises an additional polymer. One possible polymeric species is a carboxyvinyl polymer, such as a carbomer. Carbomers include synthetic, high-molecular-weight crosslinked polymers of acrylic acid. Polymer chains formed from repeating units of acrylic acid may be crosslinked, for example, with allyl sucrose to provide the carbomer commercially available under the name Carbopol™ 934; with an ether of pentaerythritol to provide the carbomer commercially available under the name Carbopol™ 974; or with divinyl glycol to provide the carbomer commercially available under the name Noveon™ AA-1. Carbopol™ polymers are manufactured by BFGoodrich Company. In one embodiment, the carboxyvinyl polymer comprises Carbopol™ 974. The carboxyvinyl polymer may be present in an amount ranging from about 0.1% to about 7.5% by weight of the non-aqueous composition. In one embodiment, the carboxyvinyl polymer is present in an amount ranging from about 0.3% to about 1.0% by weight of the composition.

[0063] Preferably, additionally or alternatively, the composition according to the invention may comprise at least one inorganic thickener, such as a thickening silica. Preferably, the thickener is a thickening silica, such as a colloidal hydrous silica, such as those commercially available as Sidet 22S or Syloid 244FP.

[0064] The compositions of the present invention may contain a mixture of two or more different grades of silica having different thickening and abrasive properties.

[0065] In one embodiment, the total amount of thickening silica and / or abrasive silica is present in the range of about 0% to about 15%, preferably about 5.0% to about 15.0%, by weight of the non-aqueous composition.

[0066] The toothpaste compositions of the present invention preferably contain at least one surfactant.

[0067] The at least one surfactant can be any surfactant known for use in oral care compositions.

[0068] A particularly preferred class of surfactants are anionic surfactants, more particularly C 10~20 It is of the alkyl sulfate surfactant class.

[0069] The alkyl sulfate surfactants for use in the present invention have the following structural formula: R 1 OSO3M R 1 represents a fatty alcohol moiety, and M represents sodium, potassium, ammonium, or triethanolamine. Fatty alcohols having a carbon chain length of about 10 to about 20 include those derived from coconut oil, palm oil, and tall oil. In one embodiment, the fatty alcohol is lauryl alcohol. In one embodiment, the sodium salt is used. In one embodiment, the alkyl sulfate is sodium lauryl sulfate.

[0070] The alkyl sulfate surfactant may be present in an amount of about 0.1% to about 10% of the non-aqueous composition. In one embodiment, the alkyl sulfate surfactant may be present in an amount of about 0.1% to about 5% by weight of the single-phase non-aqueous composition. In one embodiment, the alkyl sulfate surfactant is present in an amount of about 0.5% to about 2.0% by weight of the non-aqueous composition.

[0071] Of these, the most preferred surfactant is sodium lauryl sulfate.

[0072] Sodium lauryl sulfate may specifically be present at about 0.1% to about 3% by weight, preferably about 0.5% to about 2.5% by weight, and most preferably about 1% to about 2% by weight.

[0073] Another preferred surfactant for use in the compositions according to the present invention is a taurate surfactant. Taurate surfactants useful in the present invention are salts of fatty acid amides of N-methyl taurine. They generally have the structural formula: RC(O)N(CH3)CH2CH2SO3M where RC(O)- represents a fatty acid radical and M represents sodium, potassium, ammonium, or triethanolamine. Fatty acids having a carbon chain length of 10 to 20 are used, including those derived from coconut oil, palm oil, and tall oil. In one embodiment, the fatty acid is derived from coconut. In one embodiment, a sodium salt is used. In one embodiment, the taurate is sodium methyl cocoyl taurate. This taurate surfactant is sold under the trade name Adinol® CT by Croda.

[0074] The taurate surfactant may be present in an amount of about 0.1% to about 10% by weight of the non-aqueous composition. In one embodiment, the taurate surfactant is present in an amount of about 0.1% to about 5.0% by weight of the non-aqueous composition. In one embodiment, the taurate surfactant is present in an amount of about 0.5% to about 2.0% by weight of the non-aqueous composition.

[0075] Another class of surfactants suitable for use in the compositions of the present invention belongs to the class of compounds known as betaines. Structurally, betaine compounds contain an anionic functional group, such as a carboxylate functional group, and a cationic functional group, such as a quaternary nitrogen functional group, separated by a methylene moiety. Betaine compounds include n-alkyl betaines, such as cetyl betaine and behenyl betaine, and n-alkylamido betaines, such as cocamidopropyl betaine. In one embodiment, the betaine is cocamidopropyl betaine, commercially available under the trade name Tego Betaine. Preferably, the betaine is present in an amount ranging from about 0.05% to about 4% by weight of the non-aqueous composition, for example, from about 0.2% to about 2.0% by weight of the non-aqueous composition.

[0076] The composition according to the present invention may also comprise a surfactant system, which comprises a first surfactant and at least one second surfactant. In certain embodiments, the surfactant system comprises a first surfactant and a second surfactant, and the second surfactant comprises a mixture of two or more surfactants.

[0077] In a particular embodiment, the surfactant system consists of a mixture of at least two surfactants from the list of betaines, taurates and alkyl sulfates, and mixtures thereof.

[0078] The formulations of the present invention preferably include at least one anti-tartar ingredient or agent.

[0079] Polyphosphates are known to help retard tartar formation and are suitable examples of anti-tartar agents for use in the dentifrice compositions of the present invention.Polyphosphates are generally understood to consist of two or more phosphate groups arranged primarily in a linear configuration, although some cyclic derivatives may also be present.Polyphosphates used in the present invention include, among others, pyrophosphates, polyphosphates having three or more polyphosphate groups, such as sodium tripolyphosphate, and polyphosphates having four or more polyphosphate groups, such as tetrapolyphosphate and hexametaphosphate.

[0080] The polyphosphate may be used at about 1% to about 12% by weight of the composition, preferably about 2% to about 10% by weight, and more preferably about 3% to about 7% by weight.

[0081] A particularly preferred polyphosphate for use in the present invention is sodium tripolyphosphate.

[0082] Other chemical anti-tartar ingredients may be used as needed.

[0083] Other examples of such ingredients include sodium pyrophosphate and sodium hexametaphosphate.

[0084] The toothpaste compositions of the present invention may also include a bioactive glass component.

[0085] Examples of such additives are bioactive glasses of the type disclosed in WO 96 / 10985, WO 97 / 27158, and WO 99 / 13852. In an aqueous environment, such bioactive glasses release ions that cause a significant increase in pH, which can adversely affect the stability (especially over long-term storage) of any excipients contained in the dentifrice. The inclusion of silica-based bioactive glasses in the non-aqueous dentifrices of the present invention inhibits the release of ions within the dentifrice, thereby controlling the pH and improving the long-term storage stability of the dentifrice.

[0086] In one embodiment, a bioactive glass for use in the present invention has a composition by weight of about 45% silicon dioxide, about 24.5% sodium oxide, about 6% phosphorus oxide, and about 24.5% calcium oxide. One such bioactive glass is commercially available under the trade name NovaMin®, also known as 45S5 Bioglass®.

[0087] The bioactive glass may be present in an amount ranging from about 1% to about 20% by weight of the non-aqueous composition. In one embodiment, the bioactive glass is present in an amount of about 1% to about 15% by weight of the non-aqueous composition. In an alternative embodiment, the bioactive glass in the non-aqueous composition is present in an amount of about 1% to about 10% by weight of the non-aqueous composition. In a further alternative embodiment, the bioactive glass is present in an amount of about 2% to about 8% by weight of the non-aqueous composition.

[0088] Dentically acceptable abrasives may optionally be added to the non-aqueous compositions of the present invention. Advantageously, the presence or absence of dentally acceptable abrasives and the amount of such abrasives can be used to selectively control the abrasiveness of the dentifrice compositions prepared by the present invention. For example, bioactive glass, if present, can provide an acceptable level of abrasiveness for the non-aqueous composition depending on the final application. As a further example, a desired amount of dentally acceptable abrasives may be added to improve the overall abrasiveness of the non-aqueous composition.

[0089] Abrasives suitable for use in the non-aqueous compositions of the present invention include, for example, amorphous silica, gelled silica, precipitated or fumed silica, zinc orthophosphate, sodium bicarbonate (baking soda), plastic particles, alumina, hydrated alumina, calcium carbonate, calcium pyrophosphate, insoluble metaphosphates, or mixtures thereof.

[0090] Silica abrasives may be natural amorphous silicas, such as diatomaceous earth, or synthetic amorphous silicas, such as precipitated silica. Exemplary silica abrasives include those sold under the trade names Zeodent®, Sident®, Sorbosil®, or Tixosil® by Huber, Degussa, Ineos, and Rhodia, respectively.

[0091] Preferably, the silica abrasive is present in an amount up to about 25% by weight of the total composition, such as from about 2% to about 20% by weight, such as from about 5% to about 15% by weight of the total composition.

[0092] The formulations of the present invention contain stannous fluoride. An additional source of fluoride may also be included to adjust the fluoride to the required level. Suitable sources of fluoride ions for use in the compositions of the present invention include alkali metal fluorides, such as sodium fluoride, alkali metal monofluorophosphates, such as sodium monofluorophosphate, stannous fluoride, or amine fluorides in an amount to provide 25 ppm to 3500 ppm of fluoride ion, preferably 100 to 1500 ppm of fluoride ion.

[0093] The compositions of the present invention may further comprise an anti-erosion agent, such as a polymeric mineral surfactant as described in WO 04 / 054529 (Procter & Gamble).

[0094] The compositions of the present invention may contain additional ingredients, such as flavoring agents, sweetening agents, opacifying or coloring agents, and preservatives, selected from those conventionally used for such purposes in the field of oral hygiene compositions. Generally, these additional ingredients may be used in small amounts or in small proportions relative to the total formulation. For example, such ingredients are typically present in an amount of about 0.001% to about 5% by weight of the non-aqueous composition.

[0095] Dentifrice compositions typically have a viscosity suitable for application to the oral cavity. Viscosity can vary depending on the type of dentifrice composition prepared and its final use. From the teachings provided herein, those skilled in the art can easily prepare compositions having a viscosity suitable for use in the oral cavity.

[0096] Compositions according to the invention may be prepared by mixing the ingredients in the appropriate relative amounts in any convenient order. [Example]

[0097] The present invention is further illustrated by the following examples.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] [Table 4]

[0102] All examples demonstrated the required stability levels in terms of activity level and visible paste stability (no syneresis or obvious discoloration) in accelerated testing (3M, 40°C and 75% relative humidity).

Claims

1. A single-phase non-aqueous dentifrice composition comprising glycerol, potassium nitrate, stannous fluoride, fumed silica, and at least one hydroxyethyl cellulose polymer.

2. 2. The single-phase non-aqueous dentifrice composition of claim 1, wherein the hydroxyethyl cellulose polymer has a blend weight average molecular weight (Da) of 500,000 to 1,000,000 Da, preferably 600,000 to 900,0000 Da, more preferably 650,000 to 800,000 Da, and most preferably 700,000 to 750,000 Da.

3. 3. A single-phase non-aqueous dentifrice composition according to claim 1 or 2, wherein the hydroxyethyl cellulose polymer comprises from 0.05% to 1% by weight, more preferably from 0.1% to 0.5% by weight, most preferably from 0.2% to 0.4% by weight.

4. A dentifrice according to any one of claims 1 to 3, wherein the fumed silica is present at from 1% to 6% by weight, more preferably from 2% to 4% by weight.

5. A single-phase non-aqueous dentifrice composition according to any one of claims 1 to 4, wherein glycerol comprises at least 50% by weight of the composition, more preferably at least 60% by weight, and most preferably at least 70% by weight.

6. 6. A single-phase non-aqueous dentifrice composition according to any one of claims 1 to 5, wherein potassium nitrate comprises from 1% to 8% by weight of the total formulation, more preferably from 3% to 7% by weight, and most preferably around 5% by weight.

7. 7. A single-phase non-aqueous dentifrice composition according to any one of claims 1 to 6, wherein stannous fluoride comprises from 0.1% to 1%, preferably from 0.3% to 0.7%, most preferably from 0.4% to 0.6% by weight of the formulation.

8. 8. A single-phase non-aqueous dentifrice composition according to any one of claims 1 to 7, wherein the composition further comprises at least one surfactant, the at least one surfactant comprising from 0.5% to 5% by weight, preferably from 1.0% to 4.0% by weight, most preferably from 2.0% to 3.0% by weight.

9. 9. The single-phase, non-aqueous dentifrice composition of claim 8, wherein the at least one surfactant comprises an anionic surfactant.

10. 10. The single-phase non-aqueous dentifrice composition of claim 8 or 9, wherein the one or more surfactants is sodium lauryl sulfate (SLS).

11. 11. A single-phase, non-aqueous dentifrice composition according to any one of claims 1 to 10, further comprising from 0.05% to 5%, more preferably from 0.075% to 1%, most preferably from 0.1% to 0.5% by weight of the composition of a thickening gum.

12. 12. The single-phase, non-aqueous dentifrice composition of claim 11, wherein the thickening gum comprises carrageenan.

13. 13. A single-phase non-aqueous dentifrice composition according to any one of claims 1 to 12, further comprising one or more additional silicas, the total silica content being between 1% and 20% by weight, preferably between 5% and 15% by weight.

14. 14. A single-phase non-aqueous dentifrice composition according to any one of claims 1 to 13, additionally comprising one or more additional fluoride sources.

15. 15. A dentifrice composition according to any one of claims 1 to 14, further comprising one or more additional ingredients selected from the categories of flavourings, sweeteners, colourings, whitening agents, pH adjusters, rheology modifiers, antimicrobial agents, preservatives and mixtures thereof.

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