DK165821B - TOOTHPASTE - Google Patents

Description

in

DK 165821 B

Sodium carboxymethyl cellulose has usually been used as the commercially selected gelling agent in toothpastes because of its availability and the generally satisfactory rheological properties it imparts to toothpastes, especially when prepared and used under temperate climatic conditions. In tropical climatic conditions, it may be prone to degradation with ce11u1 ase.

A tendency can be observed for toothpastes formulated with many grades of sodium carboxymethyl cellulose to become uneven in appearance (formation of soft lumps or thickening) even at room temperature, especially when subjected to dynamic aging, which consists of extruding a 2 cm toothpaste strip from a tube twice a day for two weeks, a condition that simulates normal toothpaste use for a single person.

Even grades of sodium carboxymethyl cellulose, which do not undergo such unevenness in dynamic aging, may exhibit other rheological problems, e.g. poor form-strength properties, i.e., rapid collapse of the extruded paste into a flat strip, or thickening with time.

It is noteworthy that irregularities in dynamic aging can be observed especially when the toothpaste contains a compound which provides fluoride and a calcium phosphate is present as a polishing agent. Thus, the problem is not quite great when fluorine is provided with sodium monofluorophosphate or a mixture of sodium monofluorophosphate and sodium fluoride and the polishing agent is a siliceous material. However, the problem can be readily observed when fluorine is provided with sodium monofluorophosphate or a mixture of sodium monofluorophosphate and sodium fluoride in a toothpaste containing at least 35% by weight of calcium phosphate polish, such as dicalcium phosphate.

Attempts to overcome the problem of unevenness without other problems, such as poor form strength, arising from

DK 165821 B

mixing various grades of sodium carboxymethylcellulose or mixing sodium carboxymethylcellulose with other gelling agents such as synthetic, inorganic silicic acid (e.g. materials obtainable under the trademarks Laponite® and "Vee-5 gum"), thickeners, such as silica dioxide thickeners, available from Huber under the trademark Laponite® as Zeo-syl 200 and from Rhone Poulenc as Tixosil® and as Tixosil ® 33J or available from Wacker under the designation "HDK N20", and liquid phase material such as polyethylene glycol 600 has not been satisfactory.

Hydroxyethyl cellulose has been proposed as an alternative gelling agent for sodium carboxymethyl cellulose, and qualities of hydroxyethyl cellulose such as Natrosol M have been used in commercial toothpastes, and grades have been mentioned, e.g. in U.S. Patents 3,862,307 (Natrosol® G) and 3,070,510 (viscosity of 75-125 cps-Brookfield, 20 ° C, 2% in water) and 4,022,881 (Natrosol® 250 H, a high viscosity material). Such grades of hydroxyethyl cellulose, which are generally satisfactory, may be prone to cause toothpastes to undergo widespread changes in rheological properties by forming a visible "tail" during container filling and pressing on a toothbrush. Such viscous flow properties were e.g. disclosed in U.S. Patent 4,022,881 to toothpastes containing a thickener mixture consisting of 30% hydroxyethyl cellulose and 70% sodium carboxymethyl cellulose. A non-viscous toothpaste containing calcium carbonate abrasive together with a thickener mixture consisting of 10% hydroxyethyl cellulose and 90% sodium carboxymethyl cellulose were also disclosed.

In the present invention there is disclosed a gelling agent composition which has little tendency to unevenness by aging as well as other desirable rheological properties such as good mold strength, lack of "tail formation" on an extruded toothpaste strip and good shine of the strip. Further, toothpaste can easily be made with this 3

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mixing without substantially altering the methods used when sodium carboxymethyl cellulose is the only gelling agent. The gelling agent with which sodium carboxymethyl cellulose is preferably mixed in a specific weight ratio is hydroxyethyl cellulose. This material, although generally good, has also not been fully satisfactory from rheological considerations when used alone or in admixture with thickening or gelling agents other than sodium carboxymethyl cellulose. In fact, toothpastes containing hydroxyethyl cellulose grades such as Natrosol® 250 M, dicalcium phosphate and a compound which provides fluorine, "tail formation" and / or low mold strength exhibit qualities such as Natrosol® 250 M being the only gelling agent or present. together with sodium carboxymethyl cellulose in a 15 weight ratio of sodium carboxymethyl cellulose to hydroxyethyl cellulose (Natrosol® 250 M and the like) of less than approx. 2: 3, e.g. ca. 1:10 and 3: 7.

U5 patent 4,022,881 discloses a toothpaste which contains as a thickener 5-30% high viscous hydroxyethyl cellulose (e.g. Natrosol® 250 H) and 70-95% sodium carboxymethyl cellulose to stabilize the sodium carboxymethyl cellulose against degradation. However, such relative amounts (e.g., 10: 1 and 7: 3) are not satisfactory, as they do not prevent the surface irregularities overcome by the present invention.

It is an advantage of the invention that a gelling agent system is provided for a toothpaste which remains smooth at dynamic aging and has other generally desirable rheological properties.

It is a particular advantage of the invention that toothpaste tail formation is avoided and mold strength is improved even when hydroxyethyl cellulose is prevalent in the gelling agent system. Such an advantage can be particularly evident when toothpaste is filled into or squeezed out of a pressure differential or mechanically driven container or toothpaste tube, especially when the toothpaste contains hydrated polished alumina hydrate.

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The above advantages can be obtained with a gelling agent mixture of sodium carboxymethyl cellulose and hydroxyethyl cellulose in a special weight ratio when the toothpaste contains a fluorine source, e.g. a binary fluorine source of sodium monofluorophosphate and sodium fluoride, and a polishing agent containing a calcium phosphate.

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Other advantages will be apparent from the following description.

The invention relates to a toothpaste, characterized in that it comprises a fluorine source which provides at least 100 ppm of 15 fluorine onions, selected from sodium monophosphorus phosphate and a mixture of sodium monophosphorus phosphate and sodium fluoride in which 30-40% by weight of the fluorine content is obtained. of the sodium fluoride in the mixture, 40-75% by weight of a polishing agent containing a calcium phosphate in an amount of at least 35% by weight of the toothpaste, at least 20% by weight, based on the weight of the toothpaste, of a liquid phase containing water, wetting agent or a mixture thereof and 0.5-5% by weight, based on the weight of the toothpaste, of a gelling agent containing sodium carboxymethylcellulose and hydroxyethylcellulose present in a weight ratio of 25: 3: 2 to 2: 3.

The above numerical references to viscosity in the present specification refer to viscosities measured with a Brookfield viscometer in 2% by weight aqueous solution at 25 ° C.

The gelling agent is present in the toothpaste in an amount of 0.5-5% by weight, preferably 0.8-2%, and most preferably 0.9-1.1%, where the ratio of sodium carboxymethylcellulose to hydroxyethylcellulose 35 is 3: 2 to 2: 3. , typically 1: 1, and preferably less than 1: 1 to 2: 3 (e.g., 49:51, 9:11, or 2: 3).

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Sodium carboxymethylcellulose may be commercially available from Hercules as CMC-7MXF and 7MFD, which are preferred qualities in the practice of the present invention. The grades may have a degree of polymerization in the vicinity of 500 corresponding to a molecular weight in the vicinity of 100,000. The viscosity is medium to high, e.g. 300-3000 cps or more, typically 300-1200 cps, preferably 300-500 cps (Brookfield, 2%, 25 ° C). The CMC-7MXF contains approx. 0.7 sodium carboxymethyl groups per anhydroglycose unit.

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The following table shows desirable commercial grades of sodium carboxymethyl cellulose (CMC) (when viscosity is measured with anything other than a Brookfield viscometer in 2% by weight aqueous solution at 25 ° C, the differences are noted): 15 20 25 1 35

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6 T A B E L 1 CMC-

Supplier qualitative viscosity (cps) 5 Hercules 7MXF 300-500 "7MFD 300-500 9M31F 900-1200" 9M31XF 900-1200 "12M31XF 900-1200 10" 7MF 300-500 "12M31PD 900-1200" 7M8SXF 200-800

Wolff Walsrode Walocel®CRT 1000 PA 07 700-1200

Nyma Nymcel ZMF.33 * 50-80 15 Enka Akucell AC 1642 * 80-120 "Akucell AC 1632 * 60-120

Cros Cellogen HP-SA 700-900

Uddeholm Cekol MVEP 500-800

Hoechst Tylose®CB 200 ** 120-260 20 * 1% solution (Brookfield; 25 ° C) ** Hoeppler viscometer (2%; 20 ° C)

Hydroxyethyl cellulose is commercially available from Hercules as Na-trosol® 250 M, which is a preferred quality in the practice of the present invention.

The grades may have a degree of polymerization in the vicinity of 750 corresponding to a molecular weight in the vicinity of 190,000. The viscosity is medium to high, e.g. 3000-12,000 cps or more, typically 3000-7000 cps, and preferably 4500-6500 cps (Brookfield, 2%, 25 ° C). When the viscosity is measured with anything other than a Brookfield viscometer in 2% by weight aqueous solution at 25 ° C, the differences are noted.

The following table shows desirable commercial grades of hydroxyethyl cellulose (HEC): 35 7

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T A B E L 2 HEC-

Provides quality viscosity (cos) 5 Hercules Natrosol® 250M and MR 4500-6500

Natrosol® 250 HR * and 250H * 1500-2500

Natroso1® 250 HHR * and 250 3400-5000

HH

B.P. Chemicals Ce11obond®5000A 4200-5600 10 "Cellobond®7000A 6000-7000

Hoechst Ty 1ose®H 4000P ** 3000-5000

Tylose® H10000P * 7000-12000 * 1% solution (Brookfield; 25eC) 15 ** Hoeppler viscometer (2%; 20eC)

The sodium carboxymethyl cellulose and hydroxyethyl cellulose may be mechanically mixed prior to mixing with the liquid phase of the toothpaste primer or may be separately mixed with the liquid phase.

The rheological advantages of the present invention are evident when the toothpaste contains a source of fluorine which provides at least approx. 100 ppm fluorine, typically 100-10,000 ppm (eg 750-25 2000 ppm). As mentioned, in accordance with the present invention, sodium monofluorophosphate or a mixture of sodium monofluorophosphate and sodium fluoride is used. The rheological advantages are also evident when, as mentioned, a calcium phosphate polish, especially dicalcium phosphate, is present in an amount of at least about 35% by weight relative to the toothpaste.

Such a toothpaste typically contains 40-75% by weight, preferably 40-55%, of a dental acceptable water-insoluble polishing agent consisting essentially of a calcium phosphate, such as di-calcium phosphate, in its dihydrated or anhydrous form, or as mixtures thereof. in any desired ratio, tricalcium phosphate and calcium pyrophosphate. Most typically, s

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dicalcium phosphate, commonly used as the dihydrate, is used. Di-calcium phosphate is typically the only polishing agent, but if desired, smaller amounts (e.g., up to 5% by weight of the toothpaste and up to 12% by weight of the polish) can be of other then acceptable water-insoluble polishes, as in substantially, the ability of the present invention to promote oral hygiene is not present. Typical polishes are alumina, silica, sodium aluminum silicate, etc.

A smaller amount of hydrated alumina (e.g., 1%) inhibits 10 or even eliminates the tendency of some toothpastes to separate or "soft" in their tubes.

The toothpaste typically contains sodium monofluorophosphate or a mixture of sodium monofluorophosphate and sodium fluoride in an amount to provide 100-10,000 ppm fluorine, e.g. 750-2000 ppm, especially 1400-2000, such as 1400-1670 ppm. A binary fluoride system of sodium monofluorophosphate and sodium fluoride, in which 30-40% of the fluorine amount (e.g., 30-35%, i.e. 300-580 ppm) is provided with sodium fluoride, is most preferably used.

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The mixed gelling agent system is particularly desirable as the gelling ingredient in toothpastes containing the binary fluorine mixture and the dicalcium phosphate polishing agent disclosed in published British Patent Publication 20 25 68 727 A (Application 79/43642). Thus, in a typical toothpaste, sodium monofluorophosphate is typically used in the binary system in an amount providing 700-1090 ppm of fluorine in the toothpaste, wherein the total fluorine amount is 1000-1670 ppm with 30-35% by weight of the total fluorine amount provided with sodium fluorine. rid (300-580 ppm). This corresponds to 0.5-1.2 wt% sodium monofluorophosphate and 0.05-0.11 wt% sodium fluoride. Preferably, the toothpaste contains 1000-1500 ppm fluorine, most preferably 950-1000 ppm fluorine provided with sodium monofluorophosphate and 450-500 ppm provided with sodium fluoride.

Sodium monofluorophosphate, Na2 PO3F, as commercially available, can vary substantially in purity. It can be used in a 35 9

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any suitable degree of purity, provided that any impurities do not significantly adversely affect the desired properties. In general, the purity is preferably at least 80%. For best results, it should be at least 85% and preferably at least 590% by weight sodium monophosphate, the remainder being primarily impurities or by-products of the preparation such as sodium fluoride and water-soluble sodium phosphate salt. Put another way, the sodium monophosphorus phosphate used should have a total fluoride content greater than 12%, preferably more than 10 12.7%, a free sodium fluoride content of not more than 1.5%, preferably no more than 1.2%, and a sodium monofluorophosphate content of at least 12%, preferably at least 12.1%, all calculated as fluoride.

As stated above, sodium fluoride in the binary mixture is a separate fluorine-containing component relative to sodium monofluorophosphate. The toothpaste is preferably applied to approx. 300-580 ppm fluorine from sodium fluoride.

In the toothpaste compositions, the toothpaste matrix comprises a liquid phase adapted to the gelling agents to form an extensible, creamy mass of the desired consistency. Generally, the fluids in the toothpaste will comprise primarily water, glycerol, sorbitol, polyethylene glycol 400, propylene glycol or the like, including appropriate mixtures thereof.

It is usually advantageous to use a mixture of both water and a wetting agent or binder, such as glycerol or sorbitol, typically approx. 10-30% by weight water and approx. 15-50 wt% wetting agent. Use of glycerol or sorbitol is preferred. The total liquid content will be at least 20% by weight of the composition.

Any suitable surfactant or cleanser may be incorporated into the toothpaste compositions. Such compatible materials are desirable to provide additional cleansing, foaming and antibacterial properties depending on the type of surfactant concerned and selected from 10

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same way. These detergents are usually water-soluble compounds and may be anionic, nonionic or cationic in structure. It is usually preferred to use the water-soluble "non-soaps" or synthetic organic detergents. Suitable cleaning materials are known and include e.g. the water-soluble salts of higher fatty acid monoglyceride monosulfate detergents (e.g., sodium coconut fatty acid monoglyceride monosulfate), higher alkyl sulfates (e.g., sodium lauryl sulfate), all kylaryl aryl sulfonates (e.g., sodium dodecylbenzene sulfonate), higher 1.2 dihydroxypropane sulfonate) and the like.

Additional surfactants include the substantially saturated higher aliphatic acyl amides of lower aliphatic aminocarboxylic acid compounds such as those having 12-16 carbon atoms in the acyl group. The amino acid moiety is generally derived from the lower aliphatic saturated monoaminocarboxylic acids having about 2-6 carbon atoms, usually the monocarboxylic acid compounds. Suitable compounds are the fatty acid amides 20 of glycine, sarcosine, alanine, 3-aminopropionic acid and valine, which have approx. 12-16 carbon atoms in the acyl group. However, to obtain the best effects, the use of the N-lauro-yl, myristoyl and palmitoyl sarcoside compounds is preferred.

The amide compound can be used in the form of the free acid or preferably as the water-soluble salts thereof, such as the alkali metal, ammonium, amine and alkylamine salts. Specific examples thereof are the sodium and potassium N-lauroyl, myristoyl and palmitoyl sarcosides, ammonium and ethanolamine N-laurolyl glycide and alanine. For convenience, reference herein to "aminocarboxylic acid compound", "sarcoside" and the like will refer to such compounds having a free carboxy group or the water-soluble carboxylate salts.1 Such materials are used in pure or substantially pure form. They should be as free as practically possible for soap or similar higher fatty acid materials which are prone to

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π reduce the activity of these compounds. In conventional practice, the amount of such higher fatty acid material is less than 15% by weight of the amide and insufficient to adversely affect it, and preferably less than about 10% by weight. 10% of the 5 amide material.

Various other materials can be incorporated into the toothpaste of the invention. Examples thereof are coloring or bleaching agents, preservatives, stabilizers, tetrasodium pyrophosphate, silicones, chlorophyll compounds and ammonia derivatives such as urea, diammonium phosphate and mixtures thereof. These additives are incorporated into the present compositions in amounts which do not substantially counteract the desired properties and characteristics and are suitably selected and used in conventional amounts.

For certain purposes, it may be desirable to include antibacterial agents in the compositions of the present invention. Typical antibacterial agents which can be used in amounts of about 0.01% by weight to approx. 5% by weight, preferably approx. 0.05% by weight to approx. 1.0 wt.% Relative to the toothpaste composition includes: N1-4- (chlorobenzyl) -N5- (2,4-dichlorobenzyl) bi guanide, 25 p-chlorophenylbiguanide, 4-chlorobenzyhydrylbiguanide, 4-chlorobenzyhydrylguanylurea, N-3 -lauroxypropyl-N5-p-chlorobenzylbiguanide, 1,6-di-p-chlorophenylbiguanide hexane, 1- (lauryldimethyl ammonium) -8- (p-chlorobenzyl di methyl ammonium) - octane dichloride, 5.6-dichloro-2-guanidine benzimidazole, -chloro-phenyl-N5-lauryl bi-guanide, 5-amine no-1,3-bis (2-ethyl hexyl) -5-methylhexahydropyrimidine, and their non-toxic acid addition salts.

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Any suitable flavoring or sweetening agent may be used to formulate a taste for the dentifrices of the invention. Examples of suitable flavoring ingredients include flavoring oils, e.g. green mint oil, peppermint oil, winter vegetable oil, 5 sassafras oil, clove oil, sage oil, eucalyptus oil, marjoram oil, cinnamon oil, lemon oil and orange oil as well as methyl salicylate.

Suitable sweeteners include sucrose, lactose, maltose, sorbitol, sodium cyclamate, sodium saccharin dipeptides of U.S. Patent No. 3,939,261 and oxathiazine salts of U.S. Patent No. 3,932,606. The flavoring and sweetening agents may together constitute approx. 0.01 to approx. 5% or more of the composition.

15 The toothpastes should have a pH value that is practically applicable. A pH range from 5 to 9 is particularly desirable. When the major part of the polish is hydrated alumina, the pH may be 3-10.5. The reference to the pH value must mean the pH determination directly on the toothpastes. If desired, 20 materials such as benzoic acid or citric acid can be added to adjust the pH to generally 5.5-6.5 or 4-7.5 for toothpaste containing hydrated alumina.

The toothpaste is typically packaged in an extruding tube, such as an aluminum or lead lined or unlined tube, or laminated tubes in general, and in particular in mechanical dispensers for toothpaste containing hydrated alumina.

The following examples further illustrate the present invention. The compositions are prepared in the usual manner and all amounts of the various ingredients are by weight unless otherwise stated.

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EXAMPLES 1-3

Mixed gelling agent, calcium phosphate, single and binary liquid source.

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Example 1

The following toothpastes are prepared by conventional tooth paste molding technique in which the sodium carboxymethyl cellulose and hydroxyethyl cellulose ingredients are separately added to a premix of glycerol and water. They are placed in aluminum standpipe tubes and age dynamically by extruding 2 cm toothpaste strip twice a day, five days a week for two weeks.

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PARTS

A B

Glycerol 22.00 22.00 Sodium Carboxymethyl Cellulose 20 (Hercules 7MFD) 0.44 0.45

Hydroxyethyl cellulose (Hercules Natrosol 250 M) 0.46 0.50

Dicalcium phosphate dihydrate 48.00 48.00

Sodium lauryl sulfate 1.50 1.50 Sodium saccharin 0.20 0.20

Sodium monofluorophosphate 0.76 0.76

Sodium fluoride 0.10 0.10

Flavor 0.90 0.90

Demineralized water until 100 to 100.

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After dynamic aging for 2 weeks, the surfaces of the toothpastes are smooth and rheologically acceptable. The pastes do not form a tail when extruded from the tube, and they hold the strip shape well on toothbrushes.

Similar rheological effects occur at a weight ratio of sodium carboxymethyl cellulose to hydroxyethyl cellulose of 3: 2.

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When the compositions are modified such that the weight ratio between the sodium carboxymethyl cellulose and the hydroxyethyl cellulose is greater than 3: 2 (7: 3 and 10: 1), surface irregularities are observed by dynamic aging; When only sodium carboxymethyl cellulose is present as a gelling agent (0.90 parts), the surface may be lumped towards the end of 2 weeks of dynamic aging.

When the relative amount of sodium carboxymethyl cellulose in relation to hydroxyethyl cellulose is less than 2: 3, the toothpastes do not hold the mold well, but settle down quickly as flat strips. Further, when the extortion is completed, the stripes form tails. Tail formation is also evident when hydroxyethyl cellulose is the only gelling agent.

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Example 2

Toothpaste A of Example 1 is modified to contain 0.36 parts of sodium carboxymethyl cellulose and 0.54 parts of hydroxyethyl cellulose. The surface is smooth and the toothpaste does not form the tail and holds the mold well.

Example 3 Toothpaste A from Example 1 is modified to contain 0.45 parts of sodium carboxymethyl cellulose (Hercules 7MFD) and 0.45 parts of hydroxyethyl cellulose (Hercules 250 M). The surface is smooth, the toothpaste does not form tail and it holds the shape well.

Similarly, desired rheological properties are observed when toothpaste A of Example 1 is modified to contain 0.50 parts of sodium carboxymethyl cellulose (Hercules 7MF) and 0.50 parts of hydroxyethyl cellulose (Hercules 250 MR), with 0.25 parts of tetrasodium pyrophosphate also present.

Effects similar to those described in Examples 1-3 are obtained when other grades of sodium carboxymethyl cellulose 35

Claims (7)

10 Patent Claims. A toothpaste, characterized in that it comprises a fluorine source which provides at least 100 ppm fluorine ions selected from sodium monofluorophosphate and a mixture of sodium monofluorophosphate and sodium fluoride, wherein 30 to 40% by weight of the fluorine content is provided by the sodium fluoride. 40-75% by weight of a polishing agent containing a calcium phosphate in an amount of at least 35% by weight of the toothpaste, at least 20% by weight, based on the weight of the toothpaste, of a liquid phase containing water, wetting agent or a mixture thereof, and 0.5 to 5% by weight, based on the weight of the toothpaste, of a gelling agent containing sodium carboxymethyl cellulose and hydroxyethyl cellulose present in a weight ratio of 3: 2 to 2: 3. Toothpaste according to claim 1, characterized in that the sodium carboxymethyl cellulose and hydroxyethyl cellulose of the gelling agent are present in a weight ratio of 49:51 to 2: 3. Toothpaste according to any one of the preceding claims, characterized in that it contains 750-2000 ppm fluorine ions. Tooth paste according to any one of the preceding claims, characterized in that the fluorine source is a mixture of sodium monofluorophosphate and sodium fluoride, wherein 30 - 35% by weight of the fluorine content is provided by the sodium fluoride. Toothpaste according to any one of the preceding claims, characterized in that dicalcium phosphate is present as 10 polish in an amount of 40 - 50% by weight. A toothpaste according to any one of the preceding claims, characterized in that the sodium carboxymethyl cellulose has a viscosity of 300-500 cps and that the hydroxyethyl cellulose has a viscosity of 4500-6500 cps, each viscosity based on a measurement on a Brookfield viscometer at 25 ° C with a 2% aqueous solution. A toothpaste according to any one of claims 1-6, characterized in that the gelling agent is present in an amount of 0.8 - 2% by weight. 25 1 35