WO1993025184A1

WO1993025184A1 - Dentifrice compositions

Info

Publication number: WO1993025184A1
Application number: PCT/US1993/005159
Authority: WO
Inventors: Thomas Edward Huetter; Donald James White, Jr.
Original assignee: The Procter & Gamble Company
Priority date: 1992-06-10
Filing date: 1993-06-01
Publication date: 1993-12-23
Also published as: AU4398893A; CN1085776A; MX9303461A

Abstract

Disclosed are dentifrice compositions containing potassium nitrate which are improved in performance. Also disclosed are improved methods for treating sensitive teeth.

Description

DENTIFRICE COMPOSITIONS

₅ TECHNICAL FIELD

The present invention relates to compositions and methods which eliminate or reduce discomfort and pain caused by tooth hypersensitivity or exposed ce entum and/or dentin.

It is becoming increasingly apparent that the problem of tooth ₁₀ hypersensitivity affects a far greater number of people than previously suspected. People suffering from this annoying condition may react painfully to heated or chilled foods, citric acid or sweets, or other every-day stimuli, including toothbrush contact. The problem is especially prevalent in adults who have lost some of the ₁₅ normal protective enamel sheathing on tooth surfaces because of erosion, abrasion, caries, chipping of the enamel, or in whom recession of the gingiva has exposed tooth dentin and/or cementum.

Attempts have been made to develop products which alleviate sensitivity. Such attempts have included looking at materials such as

2_Q strontium salts and nitrate salts including potassium nitrate. The latter are disclosed in U.S. Patent 3,863,006, January 28, 1975 incorporated herein by reference.

The present inventors have found that the performance of potassium nitrate in a toothpaste can be improved by controlling the _Z5 level of surfactant and eliminating other components from the compositions.

It is therefore an object of this invention to provide improved potassium-nitrate toothpaste products for treating tooth sensitivity. It is a further object to provide improved methods for treating ,_Q tooth sensitivity through the use of the products herein.

These and other objects will become readily apparent from the disclosure which follows.

All percentages and ratios used herein are by weight unless otherwise specified. Also, all measurements referred to herein are ,r made at 25°C in the composition unless otherwise specified. SUMMARY OF THE INVENTION

The present invention, in certain aspects, embraces toothpaste compositions containing specified surfactants, potassium nitrate, an abrasive and water.

The present invention also encompasses a method for treating sensitive teeth using the compositions of this invention.

By the term "comprising", as used herein, is meant that various additional components can be conjointly employed in the compositions of this invention as long as the listed materials perform their intended functions.

By the term "carrier", as used herein, is meant a suitable vehicle which is pharmaceutically acceptable and can be used to apply the present compositions in the oral cavity.

DETAILED DESCRIPTION OF THE INVENTION

The present invention in certain aspects involves toothpaste compositions containing potassium nitrate and specified surfactants.

Given below are the essential and optional components of the present invention. Potassium Nitrate:

Potassium nitrate is the first essential component of this invention and is a stable item of commerce. The material is present at a level of from about 1% to about 20%, preferably from about 2% to about 10%, most preferably about 5%. Surfactants:

The surfactants useful in the present invention are sodium lauryl sulfate and synthetic sodium alkyl sulfate, with the preferred being synthetic sodium alkyl sulfate. By "alkyl" is meant alkyl chain lengths of from about C-8 to about C-14.

The surfactant is present in the compositions of the present invention at a level of from about 1.8% to about 3%, preferably from about 2 to about 2.5. Water:

Water is also present in the compositions of this invention. Water employed in the preparation of commercially suitable compositions should preferably be deionized and free of organic impurities. Water generally comprises from about 20% to about 60%, preferably from about 35% to about 50%, by weight of the toothpaste compositions. These amounts of water include the free water which is added plus that which is introduced with other materials as with sorbitol . Abrasive:

Toothpastes contain as a major component an abrasive. The abrasive polishing material contemplated for use in the present invention can be any material which does not excessively abrade dentin. These include, for example, silicas including gels and precipitates, calcium carbonate, dicalcium orthophosphate dihydrate, calcium pyrophosphate, tricalcium phosphate, calcium poly etaphosphate, 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, incorporated herein by reference. Mixtures of abrasives may also be used.

Silica dental abrasives, of various types, can provide the unique benefits of exceptional dental cleaning and polishing performance without unduly abrading tooth enamel or dentin. Silica abrasive materials are also exceptionally compatible with sources of soluble fluoride and other ion sources. For these reasons they are preferred for use herein.

The silica abrasive polishing materials useful herein, as well as the other abrasives, generally have an average particle size ranging between about 0.1 and 30 microns, preferably 5 and 15 microns. The silica abrasive can be precipitated silica or silica gels such as the silica 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 incorporated herein by reference. Preferred are the silica xerogels marketed under the tradename "Syloid" by the W. R. Grace & Company, Davison Chemical Division. Preferred precipitated silica materials include those marketed by the J. M. Huber Corporation under the tradename, "Zeodent", particularly the silica carrying the designation "Zeodent 119". These silica abrasive are described in U.S. Patent 4.340.583. July 29, 1982, incorporated herein by reference. The abrasive in the dentifrice compositions described herein is present at a level of from about 6% to about 70%, preferably from about 15% to about 30% when the dentifrice is a toothpaste.

_ Optional Components in Toothpaste Carrier: b

Flavoring agents can also be added to the dentifrice compositions of the present invention. Suitable flavoring agents include oil of wintergreen, oil of peppermint, oil of spearmint, oil of sassafras, and oil of clove. Sweetening agents are also useful and include aspartame, acesulfa e, saccharin, dextrose, levulose and sodium

10 cyclamate. Flavoring and sweetening agents are generally used in the compositions herein at levels of from about 0.005% to about 2% by weight and may be used as a solvent for the antibacterials hereinbefore indicated.

In preparing toothpastes, it is necessary to add some thickening

15 material to provide a desirable consistency. Preferred thickening agents are carboxyvinyl polymers, carrageenan, hydroxyethyl cellulose and water soluble salts of cellulose ethers such as sodium carboxymethyl cellulose and sodium carboxy ethyl hydroxyethyl

20 cellulose. Natural gums such as gum karaya, gum arabic, and gum tragacanth and polysaccharide gums such as xanthan gum can also be used. Colloidal magnesium aluminum silicate or finely divided silica can be used as part of the thickening agent to further improve texture. Thickening agents in a combined amount from 0.5% to 5.0% by weight of the total composition may be used.

25

It is also desirable to include a humectant in a toothpaste to keep it from hardening. Suitable hu ectants include glycerin, sorbitol, and other edible polyhydric alcohols at a level of from about 15% to about 70%.

It is preferred that the compositions herein contain no more

30 humectant than is necessary to prevent drying out of the product since it tends to interfere with product performance. Additionally, materials such as polyethylene glycols should be excluded from the present compositions.

Another optional component is an anionic polycarboxylate. 35

The anionic polymeric polycarboxylates optionally but preferably employed herein are well known, being employed in the form of their free acids or partially or preferably fully neutralized water soluble alkali metal (e.g. potassium and preferably sodium) or ammonium salts. Preferred are 1:4 to 4:1 copolymers of maleic anhydride or acid with

5 another polymerizable ethylenically unsaturated monomer, preferably methyl vinyl ether (methoxyethylene) having a molecular weight (M.W.) of about 30,000 to about 1,000,000. These copolymers are available for example as Gantrez (AN 139(M.W. 500,000), A.N. 119 (M.W. 250,000) and preferably S-97 Pharmaceutical Grade (M.W. 70,000), of GAF i_Q Corporation.

Other operative polymeric polycarboxylates include such as the 1:1 copolymers of maleic anhydride with ethyl acrylate, hydroxyethyl methacrylate, N-vinyl-2-pyrollidone, or ethylene, the latter being available for example as Monsanto EMA No. 1103, M.W. 10,000 and EMA

,r Grade 61, and 1:1 copolymers of acrylic acid with methyl or hydroxyethyl methacrylate, methyl or ethyl acrylate, isobutyl vinyl ether or N-vinyl-2-pyrrolidone.

Additional operative polymeric polycarboxylates disclosed in above referred to U.S. Patent Nos. 4.138.477 and 4.183.914.

2Q incorporated herein by reference, include copolymers of maleic anhydride with styrene, isobutylene or ethyl vinyl ether, poly-acrylic, polyitaconic and polymaleic acids, and sulfoacrylic oligomers of M.W. as low as 1,000 available as Uniroyal ND-2.

Suitable generally are polymerized olefinically or ethylenically

25 unsaturated carboxylic acids containing an activated carbon-to-carbon olefinic double bond and at least one carboxyl group, that is, an acid containing an olefinic double bond which readily function sin polymerization because of its presence in the monomer molecule either in the alpha-beta position with respect to a carboxyl group or as part

₃₀ of a terminal methylene grouping. Illustrative of such acids are acrylic, methacrylic, ethacrylic, alpha-chloroacrylic, crotonic, beta-acryloxy propionic, sorbic, alpha-chlorsorbic, cinnamic, beta-styrylacrylic, muconic, itaconic, citraconic, mesaconic, glutaconic, aconitic, alpha-phenyl-acrylic, 2-benzyl acrylic,

,52-cyclohexylacrylic, angelic, umbellic, fumaric, maleic acids and anhydrides. Other different olefinic monomers copolymerizable with such carboxylic monomers include vinylacetate, vinyl chloride, dimethyl maleate and the like. Copolymers contain sufficient carboxylic salt groups for water-solubility.

Also useful herein are carboxyvinyl polymers, referred to herein

₅ earlier as suitable binders, disclosed as toothpaste components in U.S. Patent No. 3.980,767 issued Sept. 14, 1976 to Choun et al . , U.S. Patent No. 3.935.306 issued Jan. 27, 1976 to Roberts et al . , U.S. Patent No. 3.919.409 issued Nov. 11, 1975 to Peria et al . , U.S. Patent No. 3.911.904 issued Oct. 7, 1975 to Harrison, and U.S. Patent

₁₀3.711,604 issued Jan. 16, 1973 to Colodney et al . They are commercially available for example under the trademarks Carbopol 934, 940, 941, and 956 of B. F. Goodrich, these products consisting essentially of a colloidally water-soluble polymer of polyacrylic acid crosslinked with from about 0.75% to about 2.0% of polyallyl sucrose

,5 or polyallyl pentaerythritol as crosslinking agent.

The synthetic anionic polymeric polycarboxylate component is mainly a hydrocarbon with optional halogen and 0-containing substituents and linkages as present in for example ester, ether and OH groups, and when present is generally employed in the instant

2_Q compositions in approximate weight amounts of 0.05 to 3%, preferably 0.05 to 2%, more preferably 0.1 to 2%.

Another optional component is a fluoride ion source. The sources of fluoride ions, or fluoride-providing compounds, required according to this invention as an essential acid phosphatase and pyrophosphatase

25 enzyme inhibitor component are well known in the art as anticaries agents and also act as such agents in the practice of this invention. These compounds may be slightly soluble in water or may be fully water-soluble. They are characterized by their ability to release fluoride ions in water and by freedom from undesired reaction with

-₀ other compounds of the oral preparation. Among these materials are inorganic fluoride salts, such as soluble alkali metal, alkaline earth metal salts, for example, sodium fluoride, barium fluoride, sodium fluor-silicate, ammonium fluorosilicate, sodium fluorozirconate, sodium monofluorophosphate, aluminum mono- and di-fluorophosphate, and

-c fluorinated sodium calcium pyrophosphate. Alkali metal and tin fluorides, such as sodium and stannous fluorides, sodium mono-fluorophosphate (MFP) and mixtures thereof, are preferred. The amount of fluoride-providing compound is dependent to some extent upon the type of compound, its solubility, and the type of oral preparation, but it must be a nontoxic amount, generally about 0.005 _c to about 3.0% in the preparation. In a dentifrice preparation, e.g. dental gel, toothpaste (including cream), an amount of such compound which releases up to about 5,000 ppm of F ion by weight of the preparation is considered satisfactory. Any suitable minimum amount of such compound may be used, but it is preferable to employ

₁₀ sufficient compound to release about 300 to 2,000 ppm, more preferably about 800 to about 1,500 ppm of fluoride ion. Typically, in the cases of alkali metal fluorides and stannous fluoride, this component is present in an amount up to about 2% by weight, based on the weight of the preparation, and preferably in the range of about 0.05% to 1%. In

_]ς the case of sodium monofluorophosphate, the compound may be present in an amount of about 0.1-3%, more typically about 0.76%.

Still another optional component for use in the compositions is an anticalculus agent. These agents include any which are effective against calculus such as pyrophosphate salts as disclosed in U.S.

20 Patent 4,515,772, May 7, 1985 incorporated herein by reference. The preferred agents are mono, di, tri and tetra alkali metal and ammonium pyrophosphates.

The compositions of this invention are preferably put into tubes or pumps which are compatible with the composition components. Such

_?5 containers preferably have polyethylene or polyethyl terephthalate contacting the compositions.

Given below are non-limiting examples which illustrate the compositions of the present invention.

EXAMPLES I - IV

_3Q Given below are four examples of compositions which are made using the processes of the present invention. Component Wei ht %

Water

35 ^Sili" Glycerin

Sorbitol (70%)

Sodium alkyl sulfate (27.

Potassium nitrate

Sodium lauryl sulfate 5 Trisodium phosphate

Thickening silica

Carboxymethyleel1ulose

Flavor

Xanthan gum ₁₀ Titanium dioxide

Monosodium phosphate

Saccharin

Carbomer 956

Sodium fluoride

15 FD&C Blue #1 Total

Given below is a method by which the compositions of the present invention can be prepared. 2o 1. Add liquids (water, sorbitol, glycerin). Heat to 120-160^βF.

2. Add salts (fluoride, potassium nitrate, phosphate buffers, saccharin) and mix until dissolved.

3. Add titanium dioxide and mix until dispersed.

4. Disperse binders in silica and add to other components. Mix 2₅ until dispersed and lump-free.

5. Add flavor and mix.

6. Add sodium alkyl sulfate and mix. When using sodium lauryl sulfate, disperse it in glycerin (leave out of step 1) before adding to facilitate dissolution.

30 7. Mill, deaerate, cool and pack product in tubes. The performance of the above compositions of this invention are superior due to the amount of surfactant employed.

35

Claims

CLAIMS:

1. A dentifrice composition capable of reducing the pain due to sensitive teeth comprising:

(a) from about 1% to about 20% of potassium nitrate;

(b) from about 1.8% to about 3.0% of a surfactant selected from the group consisting of sodium lauryl sulfate, sodium alkyl sulfate and mixtures thereof;

(c) from about 6% to about 70% of a silica dentifrice abrasive; and

(d) from about 20% to about 60% of water.

2. A dentifrice composition according to Claim 1 wherein the surfactant is synthetic sodium alkyl sulfate.

3. A dentifrice composition according to either of Claims 1 or 2 wherein the concentration of potassium nitrate is from about

2% to about 10%.

4. A dentifrice composition according to any of Claims 1-3 wherein the dentifrice abrasive is selected from the group consisting of silica, calcium carbonate and mixtures thereof.

5. A dentifrice composition according to any of Claims 1-4 wherein said composition also contains a fluoride ion source.

6. A dentifrice composition according to any of Claims 1-5 wherein the abrasive is a silica abrasive and the fluoride ion source is sodium fluoride.

7. A dentifrice composition according to any of Claims 1-6 wherein said composition also contains an anticalculus agent.

8. A dentifrice composition according to any of Claims 1-7 wherein said anticalculus agent is a soluble pyrophosphate salt.

9. A dentifrice composition according to any of Cl aims 1-8 which in addition contains a synthetic anionic polymer.