Oral care composition

Abstract

The present invention relates to an oral care composition. which provides for a specific foam profile maintained during the brushing. The good foam in turn provides surprisingly good mouth feel, flavour impact and overall freshness benefits.

Description

[0001] ORAL CARE COMPOSITION

[0002] Field of the Invention

[0003] The present invention relates to an oral care composition. The invention particularly relates to oral care composition having improved foam stability and foam characteristics. of the Invention

[0004] In oral care composition, foaming plays a vital role in consumer acceptance. Improved foaming is often perceived by consumers as being directly related to improved mouthfeel, cleaning, and freshness. Desired foaming also includes specific structure, density, and the stability of the foam.

[0005] In addition to foaming, flavor impact and the taste of the composition, may often be of more importance to consumers. It is highly desirable that oral care composition imparts a fresh and clean feeling as this provides consumers with a signal of continued freshness and cleanliness. In addition to the feeling of cleanliness, consumers also want to experience the benefits of oral care actives like anti-microbial agents, for example, through their oral care regimen. Since many efficacious oral care components have undesirable taste, color, odor or clarity, efforts to improve these characteristics are common in the art.

[0006] The ability to formulate a consumer acceptable oral care composition, however, raises challenges as many of the components used to impart a flavor, deliver a benefit, or that are part of the base for the oral care composition add unwanted tastes and / or sensations along with the targeted benefit for which they are added. Thus, formulating oral care compositions can be a balancing act between acceptable sensorial, such as foaming, flavor, and acceptable oral care benefits.

[0007] It is thus an object of the present invention to provide desired foam quality and improved foam stability while also maintaining good mouthfeel and flavour impact in the oral care composition.

[0008] Summary of the Invention

[0009] The present inventors have found oral care composition which provides for a specific foam profile maintained during the brushing provides surprisingly good mouth feel and flavour impact and overall freshness benefits. According to a first aspect of the present invention provided is an oral care composition comprising: i 1.5- 3 wt% anionic sulphated surfactant; ii less than 10 wt.% thickening system comprising xanthan gum; wherein the oral care composition has a rate of change in bubble count of 25% or less when measured from about 20 seconds to about 7 minutes using a dynamic foam analyzer, wherein the thickening system comprises a combination of xanthan gum, carboxymethyl cellulose and thickening silica.

[0010] Detailed Description of the Invention

[0011] Oral care

[0012] The term “oral care composition" refers to a composition that is delivered to the oral surfaces. The composition may be a product which, during the normal course of usage, is not for the purpose of systemic administration or intentionally swallowed but is rather retained in the oral cavity for a time sufficient to contact substantially all of the dental surfaces and / or oral tissues for the purposes of oral activity.

[0013] Examples of the oral composition include a toothpaste or a dentifrice, a mouthwash or a mouth rinse, powder (e.g., tooth powder), lozenge, mint, cream, strip, or gum (e.g., chewing gum), a film a topical oral gel, and a denture cleanser and the like.

[0014] The composition of the invention is used to preferably used to clean the surfaces of the oral cavity. Accordingly, preferred product forms for compositions of the invention are those which are suitable for brushing and / or rinsing the surfaces of the oral cavity.

[0015] The composition of the invention is most preferably in the form of a dentifrice. The term "dentifrice" denotes an oral composition which is used to clean the surfaces of the oral cavity. Such a composition is not intentionally swallowed for purposes of systemic administration of therapeutic agents, but is applied to the oral cavity, used to treat the oral cavity, and then expectorated. Typically, such a composition is used in conjunction with a cleaning implement such as a toothbrush, usually by applying it to the bristles of the toothbrush and then brushing the accessible surfaces of the oral cavity.

[0016] Preferably the oral care composition is an aqueous oral care composition. The term aqueous implies that the compositions in accordance with the invention comprises water. The water includes any that may come along with some other ingredients such as humectants, in particular, sorbitol.

[0017] The oral care composition is preferably alcohol-free. The term alcohol-free refers to a composition which has not more than 1 wt.%, still more preferably not more than 0.5 wt.% alcohol.

[0018] Preferably the oral care composition is a gel type composition. Preferably the oral care composition is a gel type dentifrice composition, more preferably gel type toothpaste composition. The term gel indicates physical appearance of the compositions of the invention. The gel compositions of the invention are transparent to light, i.e. , they allow visible light to pass through. Clear gel toothpastes are popular with consumers. Undoubtedly, this is due, at least in part, to their appearance. On the other hand, there are some other types of dentifrice compositions that are not gels but are opaque. That is because such compositions usually contain opacifying ingredients such as chalk or other calcium-based abrasives. Therefore, it is preferred that the composition according to the invention do not comprise more than 5 wt.%, preferably not more than 2 wt.% and more preferably not more than 1 wt.% calcium-based abrasive.

[0019] Bubble form and structure:

[0020] According to the first aspect of the present invention the oral care composition has a rate of change in bubble count of 20% or less when measured using a dynamic foam analyzer as described herein below.

[0021] Preferably the oral care composition provides an initial bubble count of greater than 170 / mm2, still preferably 180 / mm2, further preferably greater than 190 / mm2, still preferably an initial bubble count per mm2ranging from 170 / mm2to 200 / mm2. Preferably the oral care composition provides a final bubble count of not less than 120 / mm2, still preferably not less than 130 / mm2, further preferably greater than 150 / mm2. Preferably the oral care composition has a final bubble count ranging from 120 / mm2to 170 / mm2, still preferably from 140 / mm2to 160 / mm2when measured using a dynamic foam analyzer as described herein below.

[0022] Preferably the oral care composition provides an initial mean bubble area of not more than 6000 pm2, still preferably not more than 5200 pm2. Preferably the oral care composition provides an initial mean bubble area ranging from 4900 pm2to 6000 pm2, still preferably from 5000 to pm2to 6000 pm2, still more preferably from 5100 pm2to 5800 pm2. Preferably the oral care composition provides a final mean bubble area of not more than 6500 pm2, still preferably less than 6400 pm2. Preferably the oral care composition provides final mean bubble area ranging from 6000 pm2to 6500 pm2.

[0023] Preferably the oral care composition provides an initial average bubble radius of less than 40 pm, still preferably less than 39 pm. Preferably the oral care composition provides a final initial average bubble radius of less than 45, still preferably less than 44pm.

[0024] Bubble measurement:

[0025] The bubble count, mean bubble area and the average bubble radius is measured on a Dynamic foam analyzer (DFA100) instrument from Kruss.

[0026] Three measurement modes were used to collect the maximal amount of information on foam stability: foam and liquid level height (measured via light scattering), structure (measured via image analysis of time lapse images of foam), and liquid content (measured via conductivity measured along a string of electrodes placed at different heights throughout the sample). The dynamic foam analyzer was used to obtain the structure of the bubble with advance software which was used for data analysis. The following instrument settings were used: air flow rate of 0.2 L / min, with light illumination of 12 % for height measurements and light illumination of 20% for structure measurements. Height illumination was conducted using infrared light of 850 nm. 50 mL of solution (solution was prepared by mixing 5 grams of gel toothpaste with 50 mL of water with a hardness of 28.9 FH at 25°C) was used and twice that volume (90 mL) of air was mechanically purged through the liquid. Air was passed through a 16 - 40 urn sintered glass frit in the DFA100. The foam was generated by using a stirrer at a speed of 4000 rpm and an oscillation period of 0 seconds. The stability of the foam was evaluated over a time period of 7 minutes 25 seconds, which began immediately after the stirrer was started through the sample and the foaming was stopped after 25 seconds and then measurement was stopped after 7 minutes. The data was exported.

[0027] A data sampling interval as provided in table below were included, resulting in images that were analyzed for bubble structure.

[0028] *fph refers to frames per hour and#fps refers to frames per second.

[0029] The camera was positioned at a height of 55 mm above the bottom of the measurement vessel.

[0030] The oral care composition according to the present invention has an initial bubble count preferably ranging from 180 / mm2to 200 / mm2, more preferably from 185 / mm2to 195 / mm2. The decrease in the bubble count at the end of the time period of 7 minutes 25 seconds was less than 25%. More preferably the decrease in the bubble count ranges from 15% to 25%, 15% to 20%. The oral care composition according to the present invention has a rate of change in bubble count of 20% or less, more preferably 19% or less. The rate of change in bubble count is calculated using the formula:

[0031] Rate of change in bubble count (%) = BCinitiai - BCfinai X 100 BCinitiai where,

[0032] BCinitiai (count / mm2) = bubble count immediately after forming the foam (count / mm2) BCfinai (count / mm2) = bubble count at the end of 7 minutes 25 seconds

[0033] The oral care composition according to the present invention preferably has an initial mean bubble area ranging from 5000 pm2to 6000 pm2, more preferably from 5100 pm2to 5500 pm2. The increase in the mean bubble area at the end of the time period of 7 minutes 25 seconds was preferably not more than 30%, still preferably not more than 25%, preferably ranging from 20% to 30%, still preferably ranging from 20% to 28%, further preferably 20% to 25%.

[0034] The rate of change in mean bubble area is calculated using the formula: Rate of change in mean bubble area (%) = M BA final - M BA initial X 100 M BA initial

[0035] MBA initial (pm2) = bubble area immediately after forming the foam MBA final (pm2) = bubble area at the end of 7 minutes 25 seconds

[0036] The oral care composition according to the present invention preferably has a rate of change in the mean bubble area which is not more than 30% was found to provide bubble which were more uniform at the time of generation and smaller in size and provide good foam structure and stability. The oral care composition according to the present invention preferably has a rate of change of mean bubble area ranging from 20% to 30%, still preferably ranging from 20% to 28%, further preferably 20% to 25%.

[0037] The oral care composition according to the present invention has an initial average bubble radius preferably ranging from 35 pm to 45 pm, more preferably from 35 pm to 40 pm. The increase in the average bubble radius at the end of the time period of 7 minutes 25 seconds was preferably not more than 15%, still preferably not more than 14%, preferably ranging from 11% to 13.5%.

[0038] The rate of change in mean bubble radius is calculated using the formula: Rate of change in mean bubble radius (%) = R final - R initial X 100 R initial

[0039] R initial (pm) = average bubble radius immediately after forming the foam R final (pm) = average bubble area at the end of 7 minutes 25 seconds

[0040] The oral care composition according to the present invention has a rate of change of average bubble radius ranging from 11% to 13.5%.

[0041] The oral care composition according to the first aspect of the present invention comprises less than 10 wt.% thickening system comprising xanthan gum. The thickening system preferably comprises further thickening agent selected from thickening silica, cellulose thickener, and mixtures thereof. More preferably the thickening system comprises a combination of thickening silica, xanthan gum, and cellulose thickener.

[0042] Preferably the oral care composition comprises a thickening system where the combined amount of all thickening agent is less than 10 wt.%. Still more preferably it is less than 9.5 wt.%. Preferably the weight ratio of the xanthan gum to the cellulose thickener in the oral care composition ranges from 1 :2.3 to 1 :3, more preferably from 1 :2.3 to 1 :2.6.

[0043] Xanthan gum:

[0044] According to a first aspect of the present invention disclosed oral care composition includes xanthan gum. Preferably the xanthan gum has a weight average molecular weight (Mw) ranging from 5 to 15 million Daltons, preferably ranging from 5.5 million Daltons to 10 million Daltons, more preferably form 6 million Daltons to 8 million Daltons.

[0045] Preferably the xanthan gum has a viscosity ranging from 850 mPa.s to 1 ,700 mPa.s (when measured at 25°C using a 1% solution of the gum in 1 % KCI, on a viscometer of the Brookfield LV type, at 60 rpm using Spindle No.3).

[0046] Xanthan gum suitable for use in the present application is available from several commercial suppliers Keltrol® T plus, Keltrol® SF, and Keltrol T being particularly preferred.

[0047] Preferably the xanthan gum derivatives can be prepared by etherification, esterification, acetylation, amidation, or oxidation of non-derivatized xanthan gum. Preferred xanthan gum derivatives are prepared by reacting non-derivatized gum with quaternary ammonium compounds in an amount equal to or greater than the stoichiometric amount required for complete derivatization. The quaternary ammonium compounds are preferably having a single alkyl or alkenyl substituent containing from 13 to 24 carbon atoms, and / or two alkyl or alkenyl substituents of 12 to 24 carbon atoms per substituent. Most preferably, the quaternary ammonium compound is alkyl dimethylbenzylammonium chloride with an alkyl group containing from 13 to 24 carbon atoms.

[0048] Xanthan gum has a primary structure consisting of regular repeating units, each containing five sugars: two glucose, two mannose, and one glucuronic acid. The main chain is built up of -D- glucose units linked through the 1- and 4-positions, i.e. , a chemical structure the same as cellulose. A three-sugar side chain is linked to the 3-position of every other glucose residue in the main chain. About half of the terminal D-mannose residues contain a pyruvic acid residue linked to the 4- and 6-positions. Preferably the xanthan gum, has a degree of substitution of less than 0.4 carboxylate groups per sugar residue.

[0049] Preferably the oral care composition includes from 0.1 wt.% to 5 wt.% xanthan gum, more preferably from 0.1 to 1 wt.% still preferably from 0.1 to 0.75 wt.%, further preferably from 0.1 wt.% to 0.5 wt.% xanthan gum. Preferably the oral care composition comprises at least 0.15 wt.%, still preferably at least 0.2 wt.%, still preferably at least 0.25 wt.%, still preferably at least 0.28 wt.%, most preferably at least 0.3 wt.% of xanthan gum, but typically not more than 4 wt.%, still preferably not more than 3 wt.%, still further preferably not more than 2.5 wt.%, still more preferably not more than 1 wt.% and most preferably not more than 0.75 wt.%, still more preferably not more than 0.5 wt.% of xanthan gum based on the weight of the oral care composition.

[0050] Preferred oral care composition includes from 0.1 wt.% to 1 wt.% xanthan gum. Preferably the oral care composition includes at least 0.15 wt.%, preferably at least 0.16 wt.%, still preferably at least 0.17 wt.% and most preferably at least 0.18 wt.%, but typically not more than 1 wt.%, still preferably not more than 0.8 wt.%, still further preferably not more than 0.6 wt.%, and most preferably not more than 0.3 wt.% by weight of xanthan gum.

[0051] Thickening silica:

[0052] The oral care composition according to the first aspect of the present invention preferably includes a thickening system which comprises thickening silica.

[0053] The thickening silica preferably has a weight average particle size ranging from 45 micrometers to 250 micrometers.

[0054] Preferably the surface area of the thickening silica (BET) ranges from 125 g / m2to 190 g / m2, still preferably from 140 g / m2to 185 g / m2.

[0055] Preferably the thickening silica is present in an amount ranging from 5 wt.% to 9 wt.% by weight of the oral care composition, preferably from 6 wt.% to 9 wt.%, still more preferably from 7.5 wt.% to 9 wt.% by weight of the oral care composition.

[0056] Cellulose thickener:

[0057] Preferably the oral care composition includes a cellulose thickener. Preferably the cellulose thickener is a substituted carboxymethyl cellulose. Still preferably the carboxymethyl cellulose has an average degree of substitution (DS) per anhydroglucose unit more than 0.7, still preferably the average degree of substitution (DS) per anhydroglucose unit ranging from 0.8 to 1. As used herein, the term "degree of substitution (DS)" generally refers to carboxymethyl cellulose with the average number of carboxymethyl groups substituted per unit of anhydroglucose. Preferably the carboxymethyl cellulose may comprise a backbone ranging from 8 to 12 cellulose units, more preferably 9 cellulose units. CMC is a biodegradable, highly compatible anionic polymer obtained from cellulose by substitution of at least a portion of the hydroxyl groups in cellulose molecule for carboxymethyl ether groups.

[0058] Preferably the oral care composition includes from 0.1 wt.% to 0.8 wt.% carboxymethyl cellulose, more preferably from 0.1 wt.% to 0.75 wt.% still preferably from 0.5 wt.% to 0.7 wt.%, further preferably from 0.55 wt.% to 0.7 wt.% carboxymethyl cellulose. Preferably the oral care composition comprises at least 0.2 wt.%, still preferably at least 0.3 wt.%, still preferably at least 0.4 wt.%, most preferably at least 0.5 wt.% of carboxymethyl cellulose, but typically not more than 0.75 wt.%, still preferably not more than 0.73 wt.%, still further preferably not more than 0.7 wt.% carboxymethyl cellulose based on the weight of the oral care composition.

[0059] Surfactant

[0060] The oral care composition according to the first aspect of the invention comprises an anionic sulphated surfactant. Preferably the anionic surfactant is a water-soluble salt of Cs to C20 alkyl sulphate. More preferably the sulphated surfactant is a primary alcohol sulphate surfactant. Preferably the surfactant is a sodium lauryl sulphate surfactant.

[0061] Preferably the surfactant is present in an amount ranging from 0.5 wt.% to 3 wt.%. still preferably from 1.5 wt.% to 3 wt.%, still more preferably 2 wt.% to 2.7 wt.%.

[0062] Preferably the composition comprises less than 1 wt.% surfactants selected from nonionic surfactant, amphoteric surfactant, and mixtures thereof.

[0063] Water

[0064] According to the first aspect, the present invention preferably comprises less than 21 wt.% added water.

[0065] The oral care composition according to the invention comprises less than 21 wt.% added water. Preferably the composition comprises less than 20 wt.% added water. Still preferably the composition comprises from 10 wt.% to 20 wt.% added water.

[0066] Preferably the oral care composition includes from 5 wt.% to 20 wt.% added water, more preferably from 5 wt.% to 18 wt.% still preferably from 10 to 18 wt.%, further preferably from 12 wt.% to 18 wt.% added water. Preferably the oral care composition comprises at least 8 wt.%, still preferably at least 9 wt.%, still preferably at least 10 wt.%, most preferably at least 12 wt.% of added water, but typically not more than 20 wt.%, still preferably not more than

[0067] 19.5 wt.%, still further preferably not more than 19 wt.%, still more preferably not more than

[0068] 18.5 wt.% and most preferably not more than 18 wt.%, still more preferably not more than

[0069] 17.5 wt.% of added water based on the weight of the oral care composition.

[0070] Preferably the oral care composition may include some water which is present contained in other ingredients added to the composition. Preferably the “total water content” in the composition includes the added water added to the composition along with the water which is contained in any ingredient which ingredient is incorporated in the composition. As an example, water present with ingredient includes those which may be added in the form of an aqueous solution. One example includes sorbitol, which may be added to the composition in the form of a 70% sorbitol solution. Accordingly, in a 70% sorbitol solution, about 30% comprises water. The water content present in the sorbitol solution contributes to the total water content.

[0071] Purely by way of illustration, a composition may comprise 20 wt.% added water and 56% of a 70% sorbitol solution (i.e. , about 16.8 wt.% water). Assuming no other ingredients in the formulation contain water, such a formulation would contain about 36.8% total water content (20 wt.% free water + 16.8 wt.% water contained in all ingredients).

[0072] Preferably the water is employed in the preparation of oral care composition is deionized and free of organic impurities.

[0073] Preferably the total water content present in the composition ranges from 17 wt.% to 37 wt.%, still more preferably from 20 wt.% 37 wt.%, furthermore preferably from 20 wt.% to 35 wt.%.

[0074] Silica based abrasive

[0075] According to the first aspect of the present invention the oral care composition preferably comprises a silica-based abrasive. Preferably the oral care composition comprises a silica- based abrasive, or a mixture of two different types of silica-based abrasive as defined hereinbelow in amounts which provides for effective cleaning and whitening, while minimizing abrasive damage.

[0076] Preferably the oral care composition has a high pellicle cleaning ratio (PCR), but a low degree of dental abrasion, which is measured as radioactive dental abrasion (RDA). Preferably the oral care composition has a PCR value of at least 90, still more preferably a PCR value ranging from 90 to 102. Preferably the oral care composition has RDA value of less than 200, still more preferably the RDA value ranges from less than 150, still preferably less than 130, still more preferably less than 125, and even more preferably less than 120. Preferably the silica-based abrasive has an average particle size ranging from 0.1 micrometers to 30 micrometers, more preferably from 1 micrometers to 20 micrometers, still more preferably from 5 micrometers to 15 micrometers.

[0077] Preferably the silica-based abrasive comprises a combination of a first silica abrasive and a second silica abrasive. Preferably the first silica abrasive includes a hydrated silica with RDA (Radioactive dentine Abrasion) ranging from 130 to 180, more preferably an RDA ranging from 130 to 160. Preferably the PCR value (Pellican cleaning ratio) ranges from 85 to 100%, still more preferably from 85% to 95%. Preferably weight average particle size of the abrasive silica D90 is not more than 30 micrometers. Preferably the first silica-based abrasive is present in the oral care composition in an amount ranging from 8 wt.% to 10 wt.%. Preferably the silica abrasive has a refractive index ranging from 1.441 to 1.445.

[0078] Preferably the second silica abrasive includes a hydrated silica with RDA ranging from 160 to 330, more preferably from 160 to 220. Preferably the PCR value (Pellican cleaning ratio) ranges from 110 to 115%. Preferably weight average particle size of the abrasive silica is D90 is not more than 12.2 micrometers. Preferably the silica-based abrasive is present in the oral care composition in an amount ranging from 0.5 wt.% to 3 wt.%, more preferably from 1 wt.% to 2.5 wt.%. Preferably the second silica abrasive has a weight average particle size (D50) ranging from 7 micrometers to 11 micrometers. Preferably the silica abrasive has a refractive index ranging from 1.435 to 1.445.

[0079] Preferably the oral care composition according to the first aspect of the present invention comprises from 9 wt.% to 12.5 wt.% silica-based abrasive, still preferably from 9 wt.% to 11 wt.% silica-based abrasive.

[0080] Preferably the abrasive silica has a low refractive index silica with an apparent refractive index in the range of 1.41 to 1.47, preferably 1.435 to 1.445. Examples of suitable low refractive index abrasive silicas having an R.l. of between 1.435 and 1.445 are Tixosil 63 and 73 ex Rhone Poulenc; Sident 10 ex Degussa; Zeodent 113 ex Zeofinn; Sorbosil AC 77 ex Ineos having an R.l. of approximately 1.440. Humectant

[0081] Preferably the transparent oral care composition comprises a humectant. Preferably the humectant is selected from the sugar alcohol, still more the sugar alcohol that are soluble in an amount of from 150 to 250 g in 100 mL aqueous solution at 20°C. Preferably the oral care composition includes from 35 wt.% to 70 wt.% humectant.

[0082] Non-limiting examples of humectant includes glycerin, propylene glycol polyethylene glycol, sorbitol, xylitol, and mixtures thereof. More preferably the humectant is sorbitol, still more preferably the sorbitol is in the form of an aqueous solution.

[0083] More preferably the humectant includes sorbitol. Preferably the sorbitol is a 70% aqueous sorbitol solution. More preferably the composition comprises from 45 wt.% to 70 wt.% sorbitol solution, still preferably from 45 wt.% to 65 wt.% sorbitol solution, still more preferably from 45 wt.% to 60 wt.% sorbitol solution.

[0084] Preferably the composition disclosed herein is substantially free of glycerin. As used herein, the term "substantially free of glycerin" means that the composition comprises no added glycerol, more preferably it means that the oral care composition comprises 0 wt.% by weight of glycerin.

[0085] Preferably the oral care composition includes from 50 wt.% to 65 wt.% sorbitol, more preferably from 52 wt.% to 65 wt.% still preferably from 55 wt.% to 60 wt.%, further preferably from

[0086] 58 wt.% to 60 wt.% sorbitol, wherein the sorbitol is in the form of a 70% solution. Preferably the oral care composition comprises at least 52 wt.%, still preferably at least 55 wt.%, still preferably at least 56 wt.%, most preferably at least 58 wt.% of sorbitol, but typically not more than 65 wt.%, still preferably not more than 63 wt.%, still further preferably not more than 62 wt.%, still more preferably not more than 61 wt.% and most preferably not more than 60.5 wt.%, still more preferably not more than 60 wt.% of sorbitol based on the weight of the oral care composition, wherein the sorbitol is in the form of a 70% solution.

[0087] Zinc compound

[0088] Preferably the oral care composition according to the first aspect of the present invention includes a zinc compound.

[0089] Preferably the oral care composition may include zinc compound which is a source of zinc ions. Preferably the zinc compound is a zinc salt. Zinc ions have been found to help in the reduction of gingivitis, plaque, sensitivity, and improved breath benefits. Many zinc compounds, however, are sparingly soluble and hence must be used in relatively large amounts to provide an effective amount of zinc ions. Unfortunately, many zinc compounds also have an unpleasant consumer astringency, especially when used in relatively high concentration. The compositions disclosed herein allow for an effective incorporation of zinc ions into an oral care composition. Examples of suitable zinc compounds that may serve as zinc ion sources include, for example, zinc oxide, zinc citrate, zinc sulfate, zinc chloride, zinc lactate, zinc gluconate, zinc malate, zinc tartrate, zinc carbonate, zinc phosphate, and other zinc salts. Preferably, the zinc ion source is zinc citrate. Preferably the zinc salt is selected from the group consisting of zinc lactate, zinc oxide, zinc chloride, zinc phosphate, and zinc citrate. Preferably, the zinc ion source is zinc sulphate, still preferably zinc sulphate heptahydrate. In yet another embodiment the zinc ion source is zinc citrate, preferably zinc citrate trihydrate.

[0090] Zinc ions are derived from the zinc compound, i.e. , zinc ion source, present in the oral care composition in an effective amount. An effective amount of zinc ions is defined as from at least 1000 ppm zinc ion, preferably 2,000 ppm to 15,000 ppm. More preferably, zinc ions are present in an amount from 3,000 ppm to 13,000 ppm and even more preferably from 4,000 ppm to 10,000 ppm. This is the total amount of zinc ions that is present in the compositions for delivery to the tooth surface.

[0091] The amount of zinc compound (zinc ion source) employed in the oral composition of the invention can vary from 0.01 wt.% to 8 wt.%, based on the total weight of the composition, typically from 0.1 wt.% to 5 wt.%, or 1 wt.% to 4 wt.%, or 1.5 wt.%, based on the total weight of the oral care composition. Preferably the zinc ion source / zinc salt is present in an amount ranging from 0.01 wt.% to 5 wt.%, more preferably 0.1 wt.% to 4 wt.%, still preferably 0.1 wt.% to 3 wt.%, further preferably 0.1 wt.% to 1 wt.% and most preferably from 0.1 wt.% to 0.5 wt.% by weight of the oral care composition.

[0092] Preferably the oral care composition may include a water-soluble compound of zinc, preferably those with a water-solubility of at least 10 grams in 100 mL of water at 20°C. Preferably the oral care composition comprises a zinc compound selected from zinc sulphate, zinc chloride, zinc nitrate and mixtures thereof. Preferably the zinc compound is selected from the group consisting of zinc sulphate. Still more preferably zinc sulphate heptahydrate. Zinc sulphate has a water solubility of 57.7 g / 100 g water at 25 °C as per Lide, D.R. CRC Handbook of Chemistry and Physics 86TH Edition 2005- 2006. CRC Press, Taylor & Francis, Boca Raton, FL 2005, p. 4-96. Preferably the zinc compound is a sparingly water-soluble compound. Preferably the sparingly soluble salt of zinc has a solubility of 1 to 8 grams in 100 mL of water. Preferably the zinc compound is selected from the group consisting of zinc is at least one of zinc citrate, zinc oxide, zinc lactate, zinc gluconate, zinc glycinate, zinc oleate, zinc hydroxide and zinc peroxide. More preferably the salt is zinc citrate. A combination of two or more such compounds may also be used.

[0093] In one embodiment of the present invention, it is preferred that oral care composition comprise less than 0.1 wt.% of water-soluble compound of zinc whose solubility at 20°C is greater than 10 g / 100 g water.

[0094] Fluoride ion source

[0095] Preferably the oral care composition comprises a fluoride ion source. The fluoride ion source may be either an inorganic compound or an organic compound. Specific examples include but are not limited to sodium fluoride, potassium fluoride, tin fluoride, sodium silicon fluoride, ammonium fluoride, aluminum fluoride, silver fluoride, hexylamine hydro fluoride, decanol amine hydro fluoride, octadecenyl amine hydro fluoride and mixtures thereof. Sodium fluoride and ammonium fluoride are preferable and from a viewpoint that the amount of fluoride ion uptake into tooth enamel and the like is large, sodium fluoride is more preferable. One kind or a combination of two or more kinds of these fluoride ion source may be contained in the dentifrice composition of the present invention. In addition, the dentifrice composition of the present invention may contain other fluorides such as sodium monofluorophosphate as a fluorine compound other than the fluoride ion source, which do not supply fluoride ion directly.

[0096] Preferably the composition contains from 0.002 wt.% to 5 wt.%, more preferably from 0.01 wt.% to 1 wt.% and even more preferably from 0.05 wt.% to 1 wt.%, still more preferably 0.05 wt.% to 0.5 wt.% of the fluoride ion source.

[0097] Optional ingredients

[0098] Tooth whitening agent:

[0099] Preferably the oral care composition according to the invention may comprise a tooth whitening agent. The whitening agent preferably comprises a green and / or a blue pigment. In the context of the present invention a pigment is generally understood to be a shade / material which is insoluble in the relevant medium, at the relevant temperature. This contrasts with dyes which are soluble. In the context of this invention, the "relevant medium" is human saliva, the liquid medium in which the composition is used, at the temperature of the oral cavity during brushing of the teeth, i.e., up to 37°C. As a reasonable approximation, the relevant medium may be considered to be water and the relevant temperature to be 25°C. Preferably the blue pigment is Pigment Blue 15, more preferably Pigment Blue 15:1, 15:2, 15:3, 15:4, 15:5 or 15:6, most preferably 15:1. A preferred pigment is blue pigment is Phthalocyanine Blue Pigment, Cl No. 74160, blue covarine. The preferred green pigment is Phthalocyanine Green, preferably Phthalocyanine Green CI-74260.

[0100] Preferably the total level of pigment in the composition is from 0.01 wt% to 3 wt, more preferably from 0.02 to 2 wt%.

[0101] Preferably the oral care composition according to the invention may comprise oral care enzyme systems such as hydrogen peroxide producing enzyme systems (e.g., the oxidoreductase enzyme glucose oxidase), amyloglucosidase, dextranase and / or mutanase, (optionally in the presence of zinc ion providing compounds and / or 8- hydroxyquinoline derivatives), lactoperoxidase, lactoferrin, lysozyme and mixtures thereof.

[0102] Flavour:

[0103] Preferably the oral care composition according to the invention may comprise at least one flavour, useful for example to enhance taste of the composition. Any orally acceptable natural or synthetic flavour can be used. Flavours may be added in the oil form, or they may be in the adsorbed and encapsulated flavour form. Also encompassed within flavour herein are ingredients that provide fragrance and / or other sensory effect in the mouth, including cooling or warming effects.

[0104] Any orally acceptable natural or synthetic flavour can be used, including without limitation essential oils and various flavoring aldehydes, esters, alcohols, and similar materials, tea flavors, vanillin, sage, marjoram, parsley oil, spearmint oil, cinnamon oil, oil of Wintergreen, peppermint oil, clove oil, bay oil, anise oil, eucalyptus oil, citrus oils, fruit oils, sassafras and essences including those derived from lemon, orange, lime, grapefruit, apricot, banana, grape, apple, strawberry, cherry, pineapple, etc., bean-and nut-derived flavours such as coffee, cocoa, cola, peanut, almond, etc., adsorbed and encapsulated flavour and the like. Also encompassed within flavours herein are ingredients that provide fragrance and / or other sensory effect in the mouth, including cooling or warming effects. Such ingredients illustratively include menthol, carvone, menthyl acetate, menthyl lactate, camphor, eucalyptus oil, eucalyptol, anethole, eugenol, cassia, oxanone, a-irisone, thymol, linalool, benzaldehyde, cinnamaldehyde, N-ethyl- p-menthan-3-carboxamine, N, 2, 3-trimethyl-2- isopropylbutanamide, 3- (1-menthoxy) -propane- 1, 2-diol, cinnamaldehyde glycerol acetal (CGA), menthone glycerol acetal (MGA) and the like. One or more flavorants are optionally present in a total amount of from about 0.01 wt. percent to about 5 wt. percent, for example, from about 0.03 wt. percent to about 2.5 wt. percent, optionally about 0.05 wt. percent to about 1.5 wt. percent, further optionally about 0.1 wt. percent to about 0.3 wt. percent and in some embodiments in various embodiments from about 0.01 wt. percent to about 1 wt. percent, from about 0.05 to about 2 percent, from about 0.1 percent to about 2.5 percent, and from about 0.1 to about 0.5 percent by total weight of the composition.

[0105] Preferably the oral care composition according to the invention may comprise at least one sweetener, useful for example to enhance taste of the composition. Sweetening agents among those useful herein include dextrose, polydextrose, sucrose, maltose, dextrin, dried invert sugar, mannose, xylose, ribose, fructose, levulose, galactose, corn syrup, partially hydrolyzed starch, hydrogenated starch hydrolysate, ethanol, sorbitol, mannitol, xylitol, maltitol, isomalt, aspartame, neotame, saccharin and salts thereof (e.g., sodium saccharin), sucralose, dipeptide- based intense sweeteners, cyclamates, dihydrochalcones. One or more sweeteners are optionally present in a total amount depending strongly on the particular sweetener (s) selected, but typically 0.005 wt. percent to 5 wt. percent, by total weight of the composition, optionally 0.005 wt. percent to 0.25 wt. percent, further optionally 0.05 wt. percent to 0.23 wt. percent by total weight of the composition.

[0106] Binders:

[0107] Preferably the binders include synthetic polymers such as polyacrylates and carboxyvinyl polymers such as Carbopol®.

[0108] Cosmetically acceptable carrier:

[0109] Preferably the oral care composition may include a cosmetically acceptable carrier. Preferably the carrier includes starch, sucrose, or mixtures thereof.

[0110] Vitamins:

[0111] Preferably the oral care composition may include a optional ingredients include vitamins such as Vitamin C, and plant extracts.

[0112] Desensitizing agents:

[0113] Preferably the oral care composition may include desensitizing agents such as potassium bicarbonate, potassium oxalate, potassium nitrate as well as strontium salts may also be included. Anti-calculus agents:

[0114] Preferably the oral care composition may include an anti-calculus agent. The anti-calculus agent may be selected from alkali metal pyrophosphates, hypophosphite-containing polymers, organic phosphonates, and phosphor-citrates.

[0115] Bleaching agents:

[0116] Preferably the composition may include at least one tooth whitening or tooth bleaching agent. Suitable bleaching agents include at least one of peroxides, metal chlorites, and persulfates. Peroxides may include at least one of hydroperoxides, hydrogen peroxide, peroxides of alkali and alkaline earth metals, organic peroxy compounds, and peroxy acids. Peroxides of alkali and alkaline earth metals include lithium peroxide, potassium peroxide, sodium peroxide, magnesium peroxide, calcium peroxide, barium peroxide, and mixtures thereof. Other peroxides include perborate, urea peroxide, and mixtures thereof. Suitable metal chlorites may include calcium chlorite, barium chlorite, magnesium chlorite, sodium chlorite, lithium chlorite, and potassium chlorite. Preferably the tooth whitening and the tooth bleaching agent may be present in the oral care composition in an amount ranging from 1 wt.% to 20 wt.% by weight of the composition.

[0117] Other optional ingredients that may be included are effervescing systems such as sodium bicarbonate / citric acid systems and colour change systems. pH modifying agent:

[0118] Preferably the oral care composition comprises at least one pH modifying agent. pH modifying agents may include acidifying agents to lower pH, basifying agents to raise pH, and buffering agents to control pH within a desired range. Any orally acceptable pH modifying agent can be used, including without limitation carboxylic, phosphoric, and sulfonic acids, acid salts (such as monosodium citrate, disodium citrate, and monosodium malate), alkali metal hydroxides such as sodium hydroxide, carbonates such as sodium carbonate, bicarbonates, sesquicarbonates, borates, silicates, phosphates (such as monosodium phosphate, trisodium phosphate, and pyrophosphate salts), imidazole and the like. The at least one pH modifying agent may be optionally present in a total amount effective to maintain the composition in an orally acceptable pH range.

[0119] Preferably the oral care composition according to the present invention comprises a hydroxide ion source. Preferably the hydroxide ion source is an alkali metal hydroxide. Still more preferably it is selected from sodium hydroxide, potassium hydroxide or mixtures thereof. More, preferably the hydroxide ion source is sodium hydroxide. Preferably the oral care composition comprises 0.05 wt.% to 0.5 wt.% hydroxide ion source. The amount of the hydroxide ion source is such that the composition comprises 0.6 to 1.5 moles of hydroxide ions per mole of zinc ions in the sparingly water-soluble compound.

[0120] Preferably the composition comprises from 0.1 wt.% to 5 wt.% pH modifying agent, more preferably from 0.1 wt.% to 0.5 wt.% alkali metal hydroxide, still further preferably sodium hydroxide.

[0121] Preferably the oral care composition has a pH ranging from 6 to 9, more preferably 6 to 7.5 when measured using a 1% solution in distilled water at 25°C.

[0122] Sweetener:

[0123] Preferably the oral care composition may include a sweetener. The sweetener preferably provides for enhancing the taste of the composition. Any orally acceptable natural or artificial sweetener can be used, including without limitation dextrose, sucrose, maltose, dextrin, dried invert sugar, mannose, xylose, ribose, fructose, levulose, galactose, corn syrup (including high fructose corn syrup and corn syrup solids), partially hydrolyzed starch, hydrogenated starch hydrolysate, sorbitol, mannitol, xylitol, isomalt, acesulfame potassium, glycyrrhizin, perillartine, thaumatin, aspartame, neotame, saccharin and salts thereof, dipeptide-based intense sweeteners, cyclamates and the like. The amount of the sweetener present in the composition depends on the sweetener selected, but typically it may range from 0.005 wt.% to 5 wt.% by weight of the composition. Preferably the sweetener is saccharin.

[0124] Antibacterial agent:

[0125] Preferably the oral care composition may include antibacterial agents other than zinc compounds. Non-limiting examples of the antibacterial agents includes halogenated diphenyl ether compounds, cetyl pyridinium chloride, polyphenols, phenolic compounds, stannous ions, and mixtures thereof. A non-limiting example of a halogenated diphenyl ether compound is triclosan.

[0126] Colorant:

[0127] Preferably the oral care compositions disclosed herein comprises a colorant. Colorants may include pigments, dyes, lakes, strips, and agents imparting a particular luster or reflectivity such as pearling agents. A colorant can serve a number of functions, including, for example, to provide a white or light-colored coating on a dental surface, to act as an indicator of locations on a dental surface that have been effectively contacted by oral care composition and / or to modify appearance, in particular color and / or opacity, of the composition to enhance attractiveness to the consumer. Any orally acceptable colorant can be used, including without limitation talc, mica, magnesium carbonate, calcium carbonate, magnesium silicate, magnesium aluminum silicate, silica, titanium dioxide, zinc oxide, red, yellow, brown, and black iron oxides, ferric ammonium ferrocyanide, manganese violet, ultramarine, titaniated mica, bismuth oxychloride and mixtures thereof. Preferably the colorant may be present in oral care composition in an amount ranging from 0.001 wt.% to 20 wt.%, such as from 0.01 wt.% to 10 wt.%, or from 0.1 wt.% to 5 wt.%, by weight of the composition.

[0128] Oral care composition according to the present invention may also contain coloured particles suspended therein, e.g., coloured silica agglomerates or other coloured particles to impart a "speckled" appearance to the oral care composition, preferably a dentifrice composition.

[0129] Dentifrice composition may also contain stripes of a coloured paste, to provide for a visually clear gel-type dentifrice with coloured stripes or a separate-coloured phase.

[0130] Benefit agents:

[0131] Preferably the oral care compositions may also be formulated with additional optional ingredients, such as, for example anticaries agents, antibacterial agents, anticalculus, tartar control agents, anti-plaque agents, breath freshening agents, anti-inflammatory agents, enzymes, vitamins, and anti-adhesion agents.

[0132] Preferred other optional ingredients include but is not limited to antibacterial agents, fluoride ion sources, anti-calculus agents, buffers, flavouring agents, sources of peroxide (e.g., hydroxide peroxide), alkali metal bicarbonate salts, thickening agents, antimicrobial agents, titanium dioxide, cooling agents, coloring agents, visual cues, and mixtures thereof.

[0133] Preferably the oral care compositions may comprise an orally acceptable antiplaque agent, including plaque disrupting agent, present in an antiplaque effective total amount. Suitable antiplaque agents include without limitation stannous, copper, magnesium, and strontium salts, dimethicone copolyols such as cetyl dimethicone copolyol, papain, glucoamylase, glucose oxidase, urea, calcium lactate, calcium glycerophosphate, strontium polyacrylates and chelating agents such as citric and tartaric acids and alkali metal salts thereof. Preservative agent:

[0134] Preferably the oral care compositions may comprise a preservative agents. Non-limiting examples of the preservative agents may include, for example, parabens such as methylparaben and propylparaben. Still preferably the oral care composition according to the invention is paraben free.

[0135] Oral care composition according to the present invention may be prepared using known conventional methods.

[0136] Preferably the dentifrice composition is prepared using methods which include mixing the ingredients under moderate shear and atmospheric pressure.

[0137] Refractive index

[0138] The oral care composition according to the first aspect of the invention provides particles having a refractive index ranging from 1.4 to 1 .46. Preferably the refractive index is achieved by a careful management of the amount of water, refractive particles in the composition and the levels of the humectant and thickening system.

[0139] Package:

[0140] Typically, the oral care composition will be packaged.

[0141] Preferably the oral care composition in the gel form, still more preferably when the oral care composition is a gel type transparent toothpaste composition, the composition may be packaged in a conventional plastic laminate, metal tube, or a single compartment dispenser.

[0142] Preferably the dispenser for the dentifrice composition may be a tube, pump, or any other container suitable for dispensing toothpaste.

[0143] Method of use:

[0144] The oral care composition may be applied to dental surfaces by any physical means, such as a toothbrush, fingertip or by an applicator directly to the sensitive area. 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 seconds to 10 hours, more preferably still from 10 seconds to 1 hour and most preferably from 30 seconds 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.

[0145] 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.

[0146] Examples

[0147] Example 1-

[0148] Transparent oral care composition according to the present invention was prepared by following the well-known method known in the art. The composition detail is provided in the table 1 below. Analysis of the bubble structure using a composition as provided in table 1 was performed using a Dynamic foam analyzer (DFA100) instrument from Kruss. The setting and the measurement protocol was followed as provided in accordance to the invention.

[0149] Table 1 As can be seen from the data provided in table 1 the oral care composition according to the present invention having a rate of change in the bubble count less than 25% and which composition comprises a thickening system comprising xanthan gum and a sulphated surfactant provides improved foam profile (good foam density, small bubble size and good stability) which enhances the mouthfeel and flavour impact of the composition.

[0150] Example 2- Comparative evaluation of foam formation and stability

[0151] A comparison of the claimed formulation was made with a comparative formulation and analysis of various bubble parameters was done as in Example 1. All bubble parameters (bubble count, mean bubble area, average bubble radius) were measured continuously upto 7 minutes. The initial bubble parameters are recorded at 20 seconds and final bubble parameters are recorded at 444 sec (~7 minutes). The results are shown in table 3 below. Table 2

[0152] Table 3

[0153] As seen from above data, the composition according to the invention has better foam stability (lower bubble count reduction and lower rate of change of bubble radius) as compared to the comparative formulation A.

Claims

CLAIMS1. An oral care composition comprising: i 1.5- 3 wt% anionic sulphated surfactant; ii less than 10 wt.% thickening system comprising xanthan gum; wherein the oral care composition has a rate of change in bubble count of 25% or less when measured from about 20 seconds to about 7 minutes using a dynamic foam analyzer, and wherein the thickening system comprises a combination of xanthan gum, carboxymethyl cellulose and thickening silica.

2. A composition according to claim 1 wherein the rate of change in bubble count is 20% or less.

3. A composition according to claim 1 or 2 wherein the sulphated surfactant is a water- soluble salt of C12 to C20 alkyl sulphate surfactant, preferably sodium lauryl sulphate.

4. A composition according to any one of the preceding claims wherein the sulphated surfactant is present in an amount ranging from 2 to 3 wt.% by weight of the composition.

5. A composition according to any one of the preceding claims wherein the rate of change of the average bubble radius ranges from 11% to 13.5% when measured from about20 seconds to about 7 minutes using a dynamic foam analyzer.

6. A composition according to any one of the preceding claims wherein the xanthan gum has a weight average molecular weight (Mw) ranging from 5 to 15 million Daltons.

7. A composition according to any one of the preceding claims wherein the composition comprises a fluoride ion source.

8. A composition according to any one of the preceding claims wherein the composition comprises a zinc salt.

9. A composition according to any one of the preceding claims wherein the weight ratio of the xanthan gum to the cellulose thickener ranges from 1:2.3 to 1:2.6.

10. A composition according to any one of the preceding claims wherein the composition comprises a humectant, preferably sorbitol.

11. A composition according to any one of the preceding claims wherein the composition comprises less than 21 wt.% added water.

12. A composition according to any one of the preceding claims wherein the xanthan gum is present in an amount ranging from 0.1 wt.% to 5 wt.%, still preferably in an amount ranging from 0.1 wt.% to 0.8 wt.%.

13. A composition according to any one of the preceding claims wherein the cellulose thickener is present in an amount ranging from 0.1 wt.% to 0.8 wt.%.

14. A composition according to any one of the preceding claims wherein the composition comprises a silica abrasive, preferably a silica abrasive having a weight average particle size ranging from 0.1 micrometers to 30 micrometers, more preferably from 5 micrometers to 15 micrometers.

15. A composition according to any one of the preceding claims wherein the thickening silica has a weight average particle size ranging from 45 micrometers to 250 micrometers.

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