WO1997004742A1

WO1997004742A1 - Oral compositions

Info

Publication number: WO1997004742A1
Application number: PCT/US1996/011809
Authority: WO
Inventors: Brian Anthony Brown
Original assignee: The Procter & Gamble Company
Priority date: 1995-07-29
Filing date: 1996-07-17
Publication date: 1997-02-13
Also published as: GB9515597D0; JPH11510161A

Abstract

An oral composition in the form of a dentifrice, mouthwash, chewing gum or the like comprising: a) from about 1 % to about 45 % by weight of a sugar alcohol consisting essentially of xylitol; b) from about 0.1 % to about 10 % potassium ions or strontium ions or mixtures thereof; c) from about 45 % to about 98.9 % orally acceptable carrier materials. The compositions have improved effectiveness in the desensitisation of teeth.

Description

Oral Compositions

Technical Field

The present invention relates to oral compositions. In particular, it relates to oral compositions which exhibit improved desensitisation of teeth and more particularly to compositions containing both xylitol and potassium ions or strontium ions which exhibit improved desensitisation and help retard the de- mineralisation of teeth.

Background

Many people suffer from hypersensitive teeth. People suffering from this condition find that exposure of the teeth to hot or, especially, cold stimuli causes pain. Even mechanical stimulation such as brushing the teeth can be an uncomfortable experience. Other problems within the oral cavity can exacerbate the condition. In particular, those diseases ofthe oral cavity which lead to increased exposure of the dentine often lead to increased suffering through hypersensitivity. Gingivitis can lead to recession of the gums, exposing more dentine at the base of the teeth and dental caries exposes dentine through attacking the tooth surface.

Hodosh, U.S. Patent 3,863,006 discloses that teeth may be desensitised by apphcation of a paste containing lithium, sodium or potassium nitrate, potassium nitrate being preferred.

EP-A-278,744 describes a tooth desensitising dentifrice composition comprising Triclosan in combination with a water-soluble source of potassium ions selected from the group consisting of potassium nitrate, potassium citrate and potassium bicarbonate. The composition was found to produce a synergistic desensitising effect.

EP-A-346,957 reports that a combination of potassium and / or strontium ions in combination with a hydroxyapatite abrasive is effective at desensitising teeth, each of the soluble and insoluble compounds having tooth desensitising activity.

Irish patent application no. 307/76 discloses that compositions for the therapy of dental caries in which xylitol is the active ingredient, the xylitol is said to cause a re-mineralisation of dental lesions. EP-A-405,682 claims an improved mineralising effect from the use of a combination of 10 - 20% xylitol together with 150 - 1800 ppm fluoride.

EP-A-529,212 claims a chewing gum comprising 0.01 to 5% of a water-soluble potassium salt, from 1 to 5% of a phosphate and at least 50% of xylitol or a mixture of xylitol and sorbitol. The chewing gum is for use in dental care.

Despite the aforementioned publications, a need for effective desensitisation of the teeth still exists. It has now suφrisingly been found that xylitol enhances the desensitising action of potassium and / or strontium ions. It is therefore an object of the present invention to provide compositions for improved desensitisation ofthe teeth.

It is a further object ofthe invention to provide oral compositions for improved desensitisation which are effective in retarding de-mineralisation ofthe teeth.

All percentages and ratios used herein are by weight, and all measurements are made at 25°C, unless otherwise specified.

Summarv ofthe Invention.

According to a first aspect of the invention, there is provided an oral composition in the form of a dentifrice, mouthwash, chewing gum or the like comprising: a) from about 1% to about 45% by weight of a sugar alcohol consisting essentially of xylitol; b) from about 0.1% to about 10% potassium ions or strontium ions or mixtures thereof; c) from about 45% to about 98.9% orally acceptable carrier materials.

The dentifrice compositions of the present invention may be in the form of pastes or gels. The term "toothpaste", as used herein, means paste and gel formulations unless otherwise specified.

The present compositions comprise some essential components and several optional components. A detailed description of these components follows.

Detailed Description ofthe invention

A) Xylitol

An essential component of the present invention is a sugar alcohol consisting essentially of xylitol. Xylitol is also useful as a humectant and / or a bulk sweetener in the present compositions and may be used successfully at levels of up to about 45%, though as little as about 1% can be effective in enhancing the desensitising action of the potassium and / or strontium salts. Preferably, however, xylitol will be used at levels of from about 3% to about 25%, more preferably from about 5% to about 10%.

B) Potassium and / or strontium ions

A further essential component ofthe present invention is a source of potassium and / or strontium ions, sufficient to provide at least 0.1% of the ions by weight. In general, the greater the amount of the potassium and / or strontium ions the greater will be the effect. At levels much above 10%, however, the increased effect is offset by other factors such as poor taste, problems of formulating and / or unacceptable cost.

A wide range of sources of the potassium and or strontium ions may be used, preferred sources are inorganic salts and the salts of orgamc acids. Suitable sources of strontium ions are the strontium fluoride, strontium chloride, strontium bromide, strontium nitrate and strontium acetate. Strontium nitrate is preferred. Potassium salts are preferred over strontium salts for reasons of weight efBciency, cost and greater compatibility with other formulation ingredients. Suitable potassium salts are potassium fluoride, potassium chloride, potassium bromide, potassium nitrate, potassium acetate, potassium carbonate, potassium bicarbonate, potassium citrate, potassium lactate, and the potassium or mixed sodium / potassium salts ofthe phosphates (particularly the oithophosphates, pyrophosphates, tripolyphosphates and monofluoro- phosphates) e.g. tetrapotassium pyrophosphate. Particularly preferred potassium sources are potassium nitrate, potassium citrate, potassium bicarbonate or mixtures thereof. Potassium nitrate is most preferred.

In general, the potassium and / or strontium ions are useful at levels of from about 0.1% to about 10%, preferably from about 0.5% to about 6%, more preferably from about 1% to about 4%.

C) Carrier materials

The oral compositions of the present invention are in the form of a dentifrice, mouthwash, chewing gum or the like, and further comprise various carrier materials, acceptable to the oral cavity and appropriate to the form and function ofthe compositions, as would be appreciated by the man skilled in the art of their manufacture. The term "carrier materials", as used herein, means any material safe and effective for use in the oral compositions prepared according to the present invention The carrier materials form the balance of the formulation, generally at a level of from about 50% to about 97% and will be described more fully below.

Dentifrice Carrier Materials

A preferred embodiment of the present invention is a dentifrice. In preparing the present dentifrice compositions, it is desirable to add one or more dentifrice carrier materials to the compositions. Such materials are well known in the art and are readily chosen by one skilled in the art based on the physical and aesthetic properties desired for the dentifrice composition being prepared. Dentifrice carrier materials typically comprise from about 50% to about 94%, preferably from about 60% to about 80% by weight of the present compositions.

The present dentifrice compositions typically comprise a soluble fluoride ion source. The soluble fluoride ion source, when used, is present in amounts sufficient to provide from about 10 to about 3500 ppm of the fluoride ion. Preferred fluorides are sodium fluoride, stannous fluoride, indium fluoride, and sodium monofluorophosphate. Norris et al., U.S. Patent 2,946,1735, issued July 26, 1960 and Widder et al., U.S. Patent 3,678,154, issued July 18, 1972 disclose such salts as well as others. Both patents are incoφorated herein by reference in their entirety.

The present compositions also typically contain a binder/thickening material to provide a desirable consistency. Preferred binder/thickening agents are carboxyvinyl polymers, carbomers, carrrageenan, hydroxyethyl cellulose and water soluble salts of cellulose ethers such as sodium carboxymethyl cellulose and sodium carboxymethyl hydroxyethyl cellulose. Natural gums such as gum karaya, xanthan gum, gum arabic, and gum tragacanth can also be used. Colloidal magnesium aluminium silicate or finely divided sihca can be used as part ofthe thickening agent to further improve texture. Thickening agents can be used in an amount from about 0.2% to about 5.0% by weight of the total composition. Preferred thickening sihca materials include those marketed by Rhone-Poulenc under the tradename, "Tixosil", particularly the sihca carrying the designation "Tixosil 43."

It is desirable to include some humectant material in a toothpaste to keep the composition from hardening upon exposure to air. Certain humectants can also impart a desirable sweetness or flavour to toothpaste compositions. The xylitol of the present invention is further useful for both humectancy and sweetening. Additional humectancy over and above that provided by the xylitol may be necessary however. Suitable additional humectants include glycerine, sorbitol, other edible polyhydric alcohols, and mixtures thereof, such that the total level of humectant is from about 15% to about 70% by weight ofthe composition.

Titanium dioxide can also be added to the present compositions. Titanium dioxide is a white powder which adds pigment to the compositions. Titanium dioxide generally comprises from about 0.25% to about 1% by weight of composition.

Water is also present in the dentifrice compositions of this invention. Water employed in the preparation of commercially suitable toothpastes should preferably be deionized and free of organic impurities. Water generally comprises from about 12% to about 50%, preferably from about 20% to about 45%, more preferably from about 25% to about 35% by weight of composition. These amounts of water include the free water which is added plus that which is introduced with other materials such as with sorbitol.

Sodium bicarbonate, also known as baking soda, is a household product with a variety of uses including use in dentifrices and mouthrinses, where it is often used to give a 'fresh' feeling to the teeth. It is a white powder that is soluble in water and unless stabilised, tends to release carbon dioxide in an aqueous system. If used in the present compositions, it will typically be at a level of from about 5% to about 50%, preferably from about 10% to about 30%.

The pH of the present compositions is adjusted through the use of buffering agents. Buffering agents, as used herein, refer to agents that can be used to increase the pH of the compositions to a range of above about pH 8 as preferred for sodium bicarbonate and tetrasodium pyrophosphate containing toothpastes. These agents include monosodium orthophosphate, trisodium orthophosphate, sodium hydroxide and sodium carbonate. Sodium carbonate is preferred at a level of from about 0.5% to about 2% by weight of composition.

An abrasive polishing material can also be included. The abrasive polishing material contemplated for use in the compositions of the present invention can be any material which does not excessively abrade dentine. These include, for example, silicas including gels and precipitates, calcium carbonate, dicalcium orthophosphate dihydrate, calcium pyrophosphate, tricalcium phosphate, calcium polymetaphosphate, insoluble sodium polymetaphosphate, hydrated alumina, and resinous abrasive materials such as particulate condensation products of urea and formaldehyde, and others such as disclosed by Cooley et al. in U.S. Patent 3,070,510, December 25, 1962, incoφorated herein by reference. Mixtures of abrasives can also be used.

Silica dental abrasives, of various types are preferred because of their unique benefits of exceptional dental cleaning and polishing performance without unduly abrading tooth enamel or dentine. The sihca abrasive pohshing materials, useful herein, as well as the other abrasives, generally have an average particle size ranging between about 0.1 and 30 microns, preferably 2 and 15 microns. The silica abrasive can be precipitated silica or sihca gels such as the sihca xerogels described in Pader et al., U.S. Patent 3,538,230, issued March 2, 1970 and DiGiulio, U.S. Patent 3,862,307, June 21, 1975, both incoφorated herein by reference. Preferred are the silica xerogels marketed under the tradename "Syloid" by W. R. Grace & Company, Davison Chemical Division. Preferred precipitated silica materials include those marketed by the J. M. Huber Coφoration under the tradename, "Zeodent", particularly the silicas carrying the designation "Zeodent 119", described in U.S. Patent 4,340,583, July 29, 1982, incoφorated herein by reference, and "Zeodent 128".

The abrasive is preferably present at a level of from about 6% to 70%, more preferably from about 20% to about 40% by weight.

The toothpaste compositions can also contain surfactants. Suitable surfactants are those which are reasonably stable and foam throughout a wide pH range, including non-soap anionic, nonionic, cationic, zwitterionic and amphoteric organic synthetic detergents. Many of these suitable agents are disclosed by Gieske et al. in U.S. Patent 4,051,234, September 27, 1977, incoφorated herein by reference. Preferred surfactants for use herein include sodium alkyl sulphate and polyethylene glycol, at levels of about 4% and about 3% by weight of compositions respectively. Also preferred for use herein are sodium and potassium salts of surfactants selected from the group consisting of sarcosinate surfactants, isethionate surfactants and taurate surfactants especially: lauroyl sarcosinate, myristoyl sarcosinate, palmitoyl sarcosinate, stearoyl sarcosinate and oleoyl sarcosinate. These surfactants can be present in the compositions of the present invention from about 0.1% to about 2.5%, preferably from about 0.3% to about 2.5% and most preferably from about 0.5% to about 2.0% by weight of the total composition. They can optionally be used in conjunction with a chelating agent such as alkali metal citrates or, preferably, tartrates as described, for example, in WO 93 14183.

Flavouring agents can also be added to the present compositions. Suitable flavouring agents include oil of wintergreen, oil of peppermint, oil of spear¬ mint, oil of sassafras, and oil of clove. Sweetening agents which can be used include aspartame, acesulphame, saccharin, dextrose, levulose and sodium cyclamate. Flavouring and sweetening agents are generally used in toothpastes at levels offrom about 0.005% to about 2% by weight of composition.

The present invention compositions can also contain optional pharmaceutical agents (e.g. triclosan) and other tartar control agents. Optional tartar control agents include such known materials as synthetic anionic polymers (including polyacrylates and copolymers of maleic anhydride or acid and methyl vinyl ether (e.g., Gantrez), as described for example in U.S. Patent 4,627,977 to Gaffar et al., the disclosures of which are incoφorated herein by reference in their entirety; as well as, e.g., polyamino propane sulphonic acid (AMPS)), polyphosphates (e.g. tripolyphosphate; hexametaphosphate), diphosphonates (e.g. EHDP; AHP), polypeptides (such as polyaspartic and polyglutamic acids), and mixtures thereof.

Also desirable for inclusion in the compositions of the present invention are zinc, copper and stannous salts such as zinc lactate, zinc citrate, stannous pyro¬ phosphate, stannous gluconate and copper bisglycinate. Antimicrobial quaternary ammonium salts, such as cetyl pyridinium chloride, tetradecylethyl pyridinium chloride, and bis-biguanide salts including chlorhexidine digluconate; nonionic antimicrobial salts and antimicrobial flavour oils such as thymol may also be used. Such agents are disclosed in U.S. Patent No. 2,946,725, July 26, 1960, to Norris et al. and U.S. Patent No. 4,051,234, September 27, 1977 to Gieske et al., incoφorated herein by reference. These agents, if present, are included at levels offrom about 0.01% to about 2%.

Preferred tartar control agents are pyrophosphate salts as described, for example, in U.S. Patent 4,999,184, to Parran, Jr. et al., issued March 12, 1991, the disclosure of which is incoφorated herein by reference in its entirety. Most preferred is tetrasodium pyrophosphate, although tetra alkali metal pyrophosphate other than tetrasodium pyrophosphate, such as dialkah metal diacid pyrophosphates, trialkali metal monoacid pyrophosphate and mixtures thereof may also be used, including those where the alkali metal is potassium as already described above. (Pyrophosphate salts are described in more detail in Kirk & Othmer, Encyclopedia of Chemical Technology. Second Edition, Volume 15, Interscience Publishers (1958), incoφorated herein by reference in its entirety). These salts are useful in both their hydrated and unhydrated forms.

The amount of pyrophosphate salt useful in these compositions is any tartar control effective amount, and is generally enough to provide at least about 1.0%, preferably from about 1.5% to about 10%, more preferably from about 3.0% to about 6% P2θγ"4, by weight of the compositions. It is to be appreciated that the level of P2O7-4 is that amoimt capable of being provided to the composition (i.e., the theoretical amount at an appropriate pH) and that other pyrophosphate forms (e.g., ΗP O^) may be present when a final product pH is estabhshed. The level of tetrasodium pyrophosphate salt preferably used in the present methods and compositions is therefore from about 1.5% to about 15%, and more preferably from about 2% to about 10%, by weight ofthe dentifrice composition.

The dentifrice compositions are prepared by mixing together the components described above according to methods known in the art.

Mouthwash Carrier Materials

Another preferred embodiment of the present invention is a mouthwash composition. Mouthwashes generally comprise from about 20:1 to about 2:1 of a water/ethyl alcohol solution and preferably other ingredients such as flavour, sweeteners, antimicrobials and humectants, as described above. Generally, on a weight basis, the mouthwash carrier materials of the invention comprise 5% to 60% (preferably 10% to 20%) ethyl alcohol, 0% to 20% (preferably 5% to 20%) of a humectant, 0% to 2% (preferably 0.01% to 0.15%) emulsifying agent, 0% to 0.5% (preferably 0.005% to 0.06%) sweetening agent such as saccharin, 0% to 0.3% (preferably 0.03% to 0.3%) flavouring agent, and the balance water. The amount of antimicrobial agent in mouthwashes is typically from about 0.01% to about 1.5% by weight.

Chewing Gum Carrier Materials

Chewing gums generally comprise an essentially tasteless, predominantly water-insoluble masticatory portion (the gum base) and one or more additives, which may be water-soluble or water-extractable whose piupose is usually to improve the organoleptic properties of the gum. Gum bases useful in the present invention generally comprise various ingredients well known in the art including; an elastomer, an elastomer solvent, a resin, a plasticiser, various fats and waxes, a filler, sweeteners, flavourants, colorants, pigments and anti¬ oxidants. Finished gum bases are available commercially from e.g. Cafosa SPA. A variety of gum base additives are typically added to the pre-prepared gum base to form the final consumer-acceptable chewing gum composition. These include bulk and high intensity sweeteners, flavourants, softeners, and fillers. Xyhtol itself is a suitable bulk sweetener and is useful in the chewing gum compositions of the present invention in amounts of from about 1% to about 45% by weight and most preferably about 10% to about 35% by weight. The potassium or strontium ions of the present invention are most readily incoφorated in the form of salts, as described above, with the other gum base additives.

EXAMPLES

The following examples further describe and demonstrate embodiments within the scope ofthe present invention.

Examples I, II and HI are suitable paste dentifrices, IV is a suitable gel dentifrice.

Ingredient I π m IV

% % % %

Sodium bicarbonate - 20 - -

Water 19.38 17.88 30.08 19.18

Zeodent 119 1 21 14.5 10 21

Tixosil 43 2 - - 10 -

Glycerin 8 8.5 15 15

Potassium nitrate 5 4 5 3.6

Xyhtol 9.7 13.2 8 12

Sorbitol (70%) 22 7 15 14.35

Tetrasodium pyrophosphate 5.05 3.8 - 5.05

Sodium alkyl sulphate (28%) 4 4 4 4

PEG-6 3 3 - 3

Sodium carbonate - 1.25 - -

Flavour 1 1 1 1

Carboxymethylcellulose 0.8 0.8 - 0.8

Xanthan gum - - 0.3 -

Carbomer 956 3 - - 0.5 -

Sodium saccharin 0.4 0.4 0.3 0.4

Titanium dioxide 0.35 0.35 0.5 0

Sodium fluoride 0.32 0.32 0.32 0.32

FD & C Blue No. 1 - - - 0.3

Total 100 100 100 100

1 Precipitated sihca abrasive from J. M. Huber Coφoration.

2 Thickening silica from Rhone-Poulenc.

3 Carbomer from B. F. Goodrich.

The paste compositions are prepared as follows. The jacket temperature of a mixing tank is set to about 150°F (65°C) to about 160°F (71°C). The humectants, xyhtol and water are added to the mixing tank and agitation is started. When the temperature reaches approximately 120°F (50°C) fluoride, potassium nitrate, sweetening agents, buffering agents, chelant, coloring agents and titanium dioxide are added. Thickening agents are added to the abrasive and the resulting mixture is added to the mixing tank with high agitation. The surfactant is added to the combination and mixing is continued. The tank is cooled to 120°F (50°C) and the flavoring agents are added. Mixing is continued for approximately 5 minutes.

Examples V and VI are mouthwash compositions within the scope of the present invention.

Ingredient V VI

% %

Undenatured Alcohol 16 11.2

Glycerine 5 8

Xyhtol 10 7

Polysorbate 80 0.10 0.08

Potassium nitrate 0.5 2.0

Sodium fluoride 0.05 0.05

Sodium saccharin 0.06 0.06

Sodium benzoate 0.05 0.05

Flavour 0.15 0.12

Water to 100% to 100%

Examples VI and Vu are suitable chewing gum compositions within the scope ofthe present invention.

Ingredient VI vπ

% %

Gum base 38.5 25.0

Potassium nitrate 0.50 1.00

Xylitol 36.8 40

Sorbitol 9.0 19.6

Mannitol 5.0 5.0

Maltitol syrup 5.0 5.0

Glycerine 3.0 3.0

Aspartame - 0.2

Liquid Flavour 2.2 1.2

Total 100 100

The oral compositions of the invention are effective in desensitisation of the teeth.

Claims

1. An oral composition in the form of a dentifrice, mouthwash, chewing gum or the like comprising: a) from about 1 % to about 45% by weight of a sugar alcohol consisting essentially of xyhtol; b) from about 0.1% to about 10% potassium ions or strontium ions or mixtures thereof; c) from about 45% to about 98.9% orally acceptable carrier materials.

2. A composition according to Claim 1 wherein the composition comprises from about 0.5% to about 8% potassium ions provided by potassium nitrate, potassium citrate, potassium bicarbonate or mixtures thereof.

3. A composition according to Claim 2 wherein the potassium ions are provided by potassium nitrate.

4. A composition according to any of Claims 1 to 3 wherein said composition comprises from about 3% to about 25%, more preferably from about 5% to about 10% of a sugar alcohol consisting essentially of xyhtol.

5. A composition according to any preceding claim wherein the oral composition is in the form of a dentifrice and the canier materials comprise one or more materials selected from binder/thickening agents, humectants, water, buffering agents, abrasive polishing materials, surfactants, sweetening agents, flavouring agents, titanium dioxide, and mixtures thereof.