DK166257B - Abrasive silica compsn. for dentifrice paste - contains amorphous silica pptd. by acidulation of a soln. of alkaline earth metal silicate in soft water - Google Patents

Abstract

An abrasive compsn. contains an amorphous silica, pptd. by acidulation of a soln. of an alkaline earth metal silicate in soft water, this being intimately reacted with an alkaline earth, pref. Ca, Sr or Mg, partic. Ca, salt to give 10-300, pref. 10-100, ppm. alkaline earth ions. The amorphous silica has a radioactive abrasion value >=40, a compressed mass of 0.24-0.55 g/ml, an oil absorption of 70-95 cm3/100g, a BET specific surface of 100-250 m2/g, and a heat loss of 4-6%. This specially prepd. silica is used as an abrasive in dentifrice pastes, partic. those contg. soluble fluorides and phosphates. Such compsns. combine compatibility with fluoride (i.e. high levels of soluble fluoride are maintained even after storage) with high cleaning power.

Description

in

DK 166257B

The present invention relates to a fluoride-containing toothpaste containing improved dentifrice abrasives. More particularly, the invention relates to toothpastes containing novel alkaline earth metal ion precipitated precipitated silicon dioxide abrasives suitable for use in dentifrices containing both soluble fluorides as agents for reducing enamel solubility and soluble phosphates as tooth penetration. These toothpastes exhibit both high compatibility with fluoride and high purity.

The function of an abrasive in preparations intended for use in the oral cavity is to remove various deposits, including membrane films from the surface of the teeth. Membrane films are firmly adherent and often contain brown or yellow pigments and therefore give the teeth an unappealing appearance. An advantageous toothpaste abrasive should maximize film removal without causing too much grinding of the hard gum tissue. Dental scientists are constantly working to develop toothpaste abrasives that exhibit a satisfactory degree of cleansing and which are not too abrasive and harmful to the oral tissue.

In addition to abrasives, toothpastes typically contain sources of fluoride ion. The beneficial reduction in the incidence of dental caries by topical application to teeth enamel surfaces of solutions containing fluoride ions is well known. Especially at pH values of the solution between ca. 4 and 8, fluoride ions are assumed to react with the enamel and decrease the acid solubility of this enamel. Thus, enamel treated with fluoride is more resistant to caries formation. Therefore, toothpastes are formulated to provide available fluoride ion in tooth brushing solutions which form in the oral cavity during use.

It has been postulated that the efficacy of fluoride treatment to provide anticariogenic advantages and advantages with respect to the insolubility of the enamel depends on the amount of fluoride ion available for uptake of the enamel being treated.

Of course, it is therefore desirable to formulate toothpaste.

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2, which provides maximum availability of fluoride ion in brush solutions formed therefrom. However, efforts to utilize such ionic anticarogenic fluoride agents in toothpaste suitable for home use have been unable to provide the theoretically maximum soluble fluoride due to the tendency of ionic fluoride to be inactivated and thereby rendered inaccessible to enamel. . That is, upon storage (with rates increasing with temperature) the toothpaste loses the ability to provide the theoretically maximum amount of soluble fluoride. For the purposes of the present invention, "soluble fluoride" content of a given toothpaste composition refers to the concentration in ppm of fluoride ion found in a sample of the supernatant centrifuged from a 1: 3 wt% solution of the toothpaste in water (1-3). = toothpaste: water).

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Sources of fluoride ion tend to react with toothpaste units and with such toothpaste components as abrasives, buffers and so on. This reaction diminishes the ability of the fluoride source to provide "soluble fluoride" upon use. The propensity of the toothpastes referred to herein to maintain their level of soluble fluoride after storage is hereinafter expressed as "toothpaste fluoride compatibility". Thus, the toothpaste fluoride compatibility of a given toothpaste is the percentage of the theoretically maximum amount of fluoride source that is actually measured as soluble fluoride after storage for a specified time and at a specified temperature (e.g., a week at 49 ° C ). The propensity for such a dentifrice component, such as the abrasive, to react with the fluoride source to decrease the measured soluble fluoride level from the theoretically maximum amount of fluoride source (especially in the presence of membrane penetration agents described in detail below) is expressed. in a manner similar to "in the case of fluoride compatibility". The test methods used in the present specification to determine 35 "toothpaste fluoride compatibility" values and "sieve agent fluoride compatibility" values are described in more detail below.

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A toothpaste component that may cause particular difficulties in the composition of fluoride toothpaste is a precipitated silica as abrasive component. Precipitated silica abrasives are desirable for use in toothpastes because they have desirable low dentin values. Certain known precipitated Si 1 dioxide abrasives are generally compatible with soluble fluoride sources but have insufficiently high abrasiveness to provide effective cleaning. Certain other known precipitated si 1 icium dioxide abrasives provide acceptable purification, but have low abrasive agent 10 compatibility as measured by the method described below. It is believed that no hitherto precipitated silicon dioxide abrasive provides both high "sealant fluoride compatibility" and acceptable cleaning performance (as shown by standard radioactive dentin sieve values). Thus, there is a clear need to assemble precipitated silicon dioxide abrasives that exhibit high " sealant fluoride compatibility ”and acceptable purity. It is therefore an object of the invention to provide a toothpaste with a content of precipitated sialcium dioxide abrasives which abrasives exhibit high "sieve agent fluoride compatibility" and acceptable cleaning performance.

Another toothpaste component that can be particularly damaging to the soluble fluoride content of certain toothpaste compositions is soluble phosphate. Soluble phosphates serve in toothpaste use to enhance the ability of fluoride ions to permeate the dental film. For this reason, soluble phosphates are conveniently included in fluoride toothpastes. However, especially in combination with silicon dioxide tooth abrasives, soluble phosphate as a membrane penetration agent tends to promote the loss of soluble fluoride in toothpastes containing these materials, and the toothpastes therefore exhibit low fluoride compatibility values. Thus, there is a clear need to assemble precipitated silicon dioxide abrasives which provide high toothpaste fluoride compatibility when used in fluoride toothpastes containing soluble phosphates as film penetration agents.

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Thus, there is a further need to provide fluoride toothpastes which may contain precipitated silicon dioxide abrasives in combination with soluble phosphates. It is therefore an object of the invention to provide fluoride toothpastes which contain soluble phosphates and precipitated in 1 dioxide sludge agents, and yet retain relatively high degrees of soluble fluoride, even after storage times.

Surprisingly, it has been found that the above object can be realized with the toothpaste of the invention, which contains a novel precipitated silicon dioxide abrasive that has been treated with an alkaline earth metal material, especially calcium. Using the present tooth abrasives, fluoride toothpastes, especially those embodiments containing soluble phosphates, can be prepared which have high toothpaste fluoride compatibility and excellent cleaning performance.

Of course, it is well known that dentifrices contain calcium phosphate materials as abrasives, but these calcium materials are present in large quantities as described above and illustrated e.g. in U.S. Patent Nos. 3,624,199 and 3,864,471. Also known are dentifrices which contain small amounts of alkaline earth metal ions, such as calcium ions, and compositions of this type are illustrated by U.S. Patent No. 3,991,177. This patent discloses dental agents containing a stabilizer activator for a dextranase enzyme agent, wherein the stabilizer activator is a salt such as calcium chloride present in an amount of 0.001 to 0.3% by weight. This agent may also contain therapeutic fluoride and the abrasive is calcium carbonate.

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Other prior art disclosing dentifrices containing alkaline earth metal compounds or ions are U.S. Patents 3,095,356, 3,122,483, 3,669,221, 3,782,466, 3,842,168, and 3,689,537. However, none of these patents disclose tooth pastes which contain as abrasive a precipitated low-structure silicon dioxide containing approx. 10 to 300 parts per million alkaline earth metal ion as described below.

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Thus, the present invention relates to a toothpaste which is characterized in that it contains: A. from 6 to 35% by weight of a precipitated silica dioxide abrasive, 5 which is a precipitated amorphous silica dioxide made from fresh water salt potassium metal 1 in cat solution by acidification , which has been caused to react intimately with a solution of a salt of an alkaline earth metal, so that there are about 10-300 parts per million of alkaline earth metal ions in the amorphous silicon dioxide, which amorphous silicon dioxide exhibits a radioactive dentin wear value of at least 40, an average particle size of 5 to 15 microns in diameter, a packed bulk weight of 0.24 to 0.55 g per meter. ml, an oil absorption of 70-95 cm 2/100 g, a BET surface area of 100-250 m2 / g and a glow loss of 4-6%; B. from 0.01 to 3.0% by weight of a water-soluble fluorine-containing material which gives off fluoride ions in aqueous solution; C. from 3 to 55% by weight of a moisture binder; D. from 0.2 to 2.0% by weight of a binder, and E. from 15 to 80% by weight of water; 25 which toothpaste gives a pH of 4 to 8 when suspended in water in a weight ratio of 3: 1 between water and the toothpaste.

The abrasives contained in the toothpaste of the invention may be prepared by a process which generally comprises the formation of a precipitated low structure silica, by acidifying certain freshwater sodium silicate solutions with a mineral acid and subsequently treating the resulting wet cake with the required amount of alkaline earth metal ions.

Thus, the invention relates to fluoride-containing toothpastes which exhibit minimal loss of soluble fluoride upon storage at normal levels.

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6 paint temperatures, which provide excellent cleaning performance. These toothpastes thus contain as essential constituents an amorphous, precipitated silica dioxide abrasive, a source of fluoride ions, a binder, a moisture-binding agent and water. · Each of these components as well as optional ingredients, the use and preparation of the toothpaste are described in detail in the following.

Thus, the toothpaste of the invention includes low-structure precipitated silicon dioxide materials suitable for use as dental abrasives. These abrasives are associated with approx. 10 to 300 parts per million, preferably 10 to 100 parts per million. million, of alkaline earth metal, preferably calcium, based on the amount of recoverable dry material. This dentifrice material is further characterized by having a percent wear-mediated fluoride compatibility in the range of at least 90%, an RDA of at least 40, preferably from about 40%. 70 to 120, a glow loss (hereafter referred to as L0I) in the range of 4-6%; 0.24 to 0.55 grams per milliliters, an oil absorption in the range of approx. 70 to 95 cm 2/100 grams and 20 a BET surface area in the range of approx. 100 to 250 m 2 / g and an average particle size in the range of 5 to 15 microns. When the tooth abrasives are incorporated into a toothpaste, they provide high fluoride compatibility and excellent cleaning performance. The definition of low structure silicon dioxide materials is disclosed in the aforementioned U.S. Patent No. 3,893,840.

The dental materials used in the toothpaste of the invention are precipitated silica produced by the general methods described e.g. in U.S. Patent Nos. 30, 3,893,840, 3,988,162, and 4,067,746. Abrasives prepared by such methods are then treated with alkaline earth metal ions in the manner described below. The process for preparing sieve in the silica generally comprises acidifying an aqueous alkali metal silicate solution with a 35-mineral acid to effect precipitation of silica. The acid addition is continued to an acidic pH and the result is obtained

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7 precipitated Si silica is then removed, e.g. by filtration and washed to remove any by-products such as alkali metal sulfate to form a wet cake. The resulting wet cake is then resuspended in its own water or with additional water and then treated with the required amount of 5 alkaline earth metal ions in the form of a soluble salt to provide the abrasive materials.

The abrasive products differ from the precipitated silica materials which have been treated with alkaline earth ethanol 10 and described in US Patent No. 4,340,584 and DK

Patent Application No. 4103/77, corresponding to U.S. Patent No. 4,159,280. The silicon dioxides treated with alkaline earth metals described in U.S. Patent No. 4,159,280 are abrasives useful for incorporation into dentifrices to prevent corrosion of unlined aluminum toothpastes. These corrosion-prevented precipitated silicon dioxides, described in U.S. Patent No. 4,159,280, are silicon dioxides prepared by the so-called sulphate liquid method. In this method, an electrolyte such as alkali metal sulfate is mixed with alkali metal silicate liquid during acidification with mineral acid, described e.g. in U.S. Patent Nos. 3,960,586 and 3,928,541. The products of U.S. Patent No. 4,159,280 can be described as precipitated silica, which thoroughly mixes an amount of alkaline earth ions that are within the range of the present invention, but the toothpaste of the invention has properties other than s. The silica produced by the sulphate liquid method. Si lium dioxide mats in the alms prepared by the sulphate liquid method do not, when used in certain fluoride-containing dentifrices, provide the better fluoride compatibility obtained in accordance with the present invention. The better values for fluoride compatibility of these dental abrasives are obtained only with silicon dioxides prepared by the so-called freshwater alkali metal I1 cat method described below.

The silicon dioxide abrasives in the toothpaste of the present invention are treated with alkaline earth metal, precipitated

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8 silica made from fresh water silicate solutions. Such a process does not use any electrolyte, such as sodium sulfate, to prepare the untreated precipitated silica. In addition, in the products used for use in the toothpastes of the present invention, it has been found that the presence of alkaline earth metal ions blinded intimately with the resulting silicon dioxide must be present within a particularly narrow range to give the fluoride compatibility necessary for use in the toothpastes of the invention. Thus, the abrasive products herein have fluoride compatibility values of at least 90%, whereas the abrasives disclosed in U.S. Patent No. 4,159,280 generally provide compatibility values of 89% or less as determined by the toothpaste fluoride compatibility test, described in the present application.

It is believed that the improved fluoride compatibility of the present dental abrasives is based on the manner in which the silanol groups therein are bonded to the surface of the silica product. Thus, in the silicon dioxide produced by the fresh water silicate method, the silanol groups on the surface of the material are assumed to be more accessible than in the silicon dioxide obtained by the sulfate liquid method as described in U.S. Patent No. 25,159,280. Furthermore, due to the silanol groups, the surface acidity of the freshwater silica is higher than the corresponding acidity of the silica, obtained by the sulphate liquid method. Because the silanol groups are different in these two materials, the actual surface acidity does not react well with calcium treatment for fluoride compatibility in products made by the sulfate liquid method. The products of U.S. Patent No. 4,159,280 also have higher abrasive values than the silica used in the toothpastes of the present invention. The present abrasives are therefore distinguishable from the silicon dioxide-treated silica disclosed in U.S. Patent No. 4,159,280.

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The present precipitated silicon dioxide abrasives are preferably prepared by filling an aqueous solution of an alkali metal silicate solution, preferably a sodium silicate solution, in a reactor for acidification. The aqueous sodium silicate solution is a freshwater solution having a sodium sieve 1 in the cat concentrate in the range of from about 10 to 17 wt * and preferably 12.5 to 15.5 wt * and a composition of the sodium silicate of Na220.2.6 S in O2 to get the best results. The aqueous sodium sulfate solution is then raised to a temperature of approx. 50 to 10 95 ° C, and with still stirring, the solution is acidified by the addition of an aqueous solution of a mineral acid with a concentration of approx. 10 to 20 wt * to a substantially constant pH in the range of approx. 8.5 to 10.5. The mineral acid is preferably sulfuric acid, since sulfuric acid gives the best results, but as is known (see U.S. Patent Nos. 3,988,162, 3,893,840, and 4,067,746), other acidifying agents such as nitric acid may also be used. phosphoric acid, hydrochloric acid, carbonic acid and the like. These prior patents describe processes for producing silicon dioxides of the type in question here.

In the most preferred embodiment, only a portion of the alkali metal silicate solution is charged to the reactor, brought to the desired temperature with stirring, and the sulfuric acid and the remainder of the alkali metal silicate solution are simultaneously added to the first added silicate solution at the reaction temperature. Preferably, approx. 8 to 12 weight * of the metal silicate from the beginning added to the reactor. The remaining part is then added together with the sulfuric acid. The period during which the alkali metal leachate and the sulfuric acid are added to the alkali metal leachate in the reactor can be predetermined and are generally based on the volume of the reactor and the difficulties in controlling the temperature and stirring. After completion of the addition of the alkali metal silicate solution, the acidifying agent is continuously added until the pH of the reaction slurry drops below approx. 6.0 and preferably in the range of approx. 4.6 to 5.0. The resulting slurry is the precipitated silica contained in the reaction medium.

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After reaching the pH below 6.0, the slurry is then heated for a ripening period to a temperature of 10 to 30 ° C above the reaction temperature and the pH of the reaction mixture is adjusted again if necessary. The resulting slurry is then filtered and washed with additional water to remove any reaction by-products, such as sodium sulfate, which may be contained in the silica product. The moisture of the wet cake in the resulting filter cake is in the range of approx. 60 to 66% and the material is of low structure. The above reaction to this point is generally the same as described in U.S. Patents Nos. 3,893,840, 3,988,162, and 4,067,746 for the preparation of silicon dioxide of freshwater alkali metal aliquot.

In the process described, the material, after filtration and washing of the wet cake of silica, is then subjected to treatment with alkaline earth metal ions to prepare the novel toothpaste of the invention. In the process, the wet washed filter cake is then resuspended in its own water or with the addition of fresh water at ambient temperature with stirring. While stirring, the slurry is then treated with a sufficient amount of alkaline earth metal ion, preferably calcium ions in the form of a salt which is sufficiently soluble to give an amount of alkaline earth metal ion corresponding to approx. 10 to 300 parts per

25 million or 0.001 to 0.03% by weight (based on the weight of the dry extractable silicon dioxide), alkaline earth metal ions intimately linked to the silicon dioxide.

The alkaline earth metal ion added at this point is preferably 30 calcium ion because it is readily available, inexpensive and easy to incorporate into the silica. The calcium ions can be incorporated into the silicon dioxide at this stage in any sufficiently water-soluble form (i.e., soluble in water to at least 0.07 g / 100 cm 3 H 2 O at 20 ° C), such as solutions of calcium nitrate, calcium oxide, calcium hydroxide or calcium chloride. . Lime or calcium hydroxide is preferred. Solutions of organic salts such as calcium acetate, calcium formate and the like

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11 may also be used. The corresponding strontium and magnesium salts of the class of alkaline earth metals can also be used. Food-grade salts should be used.

After treatment with the alkaline earth metal ion, the slurry of the cake is stirred vigorously for 10 to 20 minutes, preferably 15 minutes, to provide the effective amount of alkaline earth metal for treatment on the surface of the abrasive of silica. The resulting product is then dried. Preferably, the drying in 10 is carried out by a spray dryer having an inlet temperature of 483 ° C and an outlet temperature of 1220 ° C, as is known in the art, and then ground to the desired degree of fineness.

A. Fluoride ion source.

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The present toothpastes further contain from 0.01 to 3%, preferably from 0.1 to 1.0% by weight of a water-soluble fluorine-containing material which gives off fluoride ions in aqueous solutions. These fluoride ions interact with the tooth enamel, thereby reducing the solubility of the enamel in acid. The use of fluoride ions for tooth enamel serves to protect teeth from destruction.

Many different materials which give off fluoride ion can be used as sources of soluble fluoride in the present agents. Examples of suitable fluoride ion-releasing materials can be found in U.S. Patent No. 3,535,422 and U.S. Patent No. 3,678,154. Preferred sources of fluoride ion for use in the toothpastes of the invention include sodium fluoride (NaF), stannous fluoride (SnF2), potassium fluoride (KF), potassium stannofluoride (SnF2-KF), indium fluoride (InF3), zinc fluoride (ZF), zinc fluoride ( and stannous chlorofluoride (SnCIF). Sodium fluoride and stannous fluoride are particularly preferred as well as mixtures thereof.

Preferably, the present toothpastes provide from ca. 50 ppm to 500 ppm and especially from approx. 100 to 400 ppm fluoride ions in the aqueous solutions which come into contact with tooth surfaces.

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12 when the toothpastes of the invention are used in the mouth. As further described below, such solutions are mimicked by preparing 3: 1 water / toothpaste slurries (by weight) of the toothpastes of the invention and then centrifuging these slurries to obtain an overlying aqueous liquid. The fluoride ion concentration in such a supernatant is taken as a measure of the soluble fluoride that a given fluoride toothpaste can deliver.

B. Binder.

A binder is used essentially to prevent the separation of the solid and liquid phases in the toothpastes. Such binders are well known in the art of toothpaste.

The most conveniently used binders are seaweed colloids such as Carragen (Irish moss or Viscarin®), and derivatives of cellulose such as sodium carboxymethyl cellulose and hydroxyethyl cellulose. Another type of binder suitable for use in the toothpastes of the invention are gums such as 1) vegetable gums, e.g. guar gums and 2) fermentation products, e.g. xanthan gum. The binder component is usually from 0.1 to 5%, preferably 0.2 to 2% by weight of the dentifrice. Since the natural and synthetic water dispersions of water binders are subject to microbial or fungal attack, the toothpastes of the invention may optionally contain a relatively small amount of a preservative. Examples of preservatives typically used are esters of parahydroxybenzoates.

30 Toothpaste binders of the specifics of U.S. Patent Nos. 2,839,448 and 3,862,307.

C. Moisturizing agent.

Another essential component of the present toothpastes is a moisture-binding agent. Suitable moisture-binding materials are also well known in the art of toothpaste. The moisture-binding agent

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13 serves to maintain moisture, thereby preventing the toothpastes from hardening when exposed to air. Certain moisture-binding idols can also impart desirable sweetness or aroma. The moisture binder is usually from 5 to 55%, preferably from 20 to 36% by weight of the toothpastes.

Suitable moisture binders for use in the toothpastes of the invention include edible polyhydric alcohols such as glycerol, sorbitol, xylitol and propylene glycol. Sorbitol is frequently used as a 70% aqueous solution known by the name Sorbo®. Mixtures of glycerol and sorbitol are particularly preferred as the moisture-binding component of the present toothpastes.

D. Water.

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Water is another essential component of the toothpastes of the invention. Water used to make commercially suitable toothpastes must be deionized and free of organic impurities. Water constitutes from 15 to 80%, preferably from 20 to 40% by weight of the present toothpastes.

E. Optional ingredients.

In addition to the essential components described above, the toothpastes of the invention may contain various optional dental care ingredients known per se. These optional ingredients include (1) foaming agents, (2) film permeation agents, (3) flavoring and sweetening agents, (4) anti-tartar and plaque agents, and (5) pigments and coloring agents.

1) Foam agents.

A preferred optional ingredient is a foaming agent. Suitable foaming agents are those which are suitably stable and form foams within a wide pH range, i.e. anionic non-soap synthetic cleansers, non-ionic, cationic, zwitterio-

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14 niche and amphoteric organic synthetic cleansers. Foam agents of these types are further described in U.S. Patent No. 3,959,458 and U.S. Patent No. 3,937,807.

Anionic foaming agents useful in the toothpastes of the invention include the water-soluble salts of alkyl sulfates having from 8 to 18 carbon atoms in the alkyl radical, and the water-soluble salts of sulfonated monoglycerides of fatty acids having from 10 to 18 carbon atoms. Sodium sulphate and sodium coconut monoglyceride sulfonates are examples of anionic surfactants of this type. Mixtures of anionic surfactants may also be used.

The nonionic foaming agents which can be used in toothpastes 15 of the invention can be broadly defined as compounds prepared by condensation of alkylene oxide groups (of hydrophilic nature) with an organic hydrophobic compound which may be aliphatic or alkylaromatic in character. Examples of suitable nonionic foaming agents include Pluronics, polyethylene oxide condensates of alkyl phenols, products obtained by condensation of ethylene oxide with the reaction product of propylene oxide and ethylenediamine, ethylene oxide condensates of aliphatic alcohols, long chain tertiary alkoxide 25 these materials.

The zwitterionic synthetic foams useful in the toothpastes of the invention can be broadly described as derivatives of aliphatic, quaternary ammonium, phosphonium and sulfonium compounds, wherein the aliphatic radicals may be straight or branched, and wherein one of the aliphatic substituents contains from approx. 8 to 18 carbon atoms and one contains an anionic water-solubilizing group, e.g. carboxy, sulfonate, sulfate, phosphate or phosphonate.

The cationic foaming agents useful in toothpastes of the invention can be broadly defined as quaternary ammonium compounds.

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15 compounds having one long alkyl chain containing from ca. 8 to approx. 18 carbon atoms such as lauryltrimethylammonium chloride, cetyl pyridinium chloride, cetyltrimethylammonium bromide, diisobutylphenoxyethoxyethyl dimethyl benzyl ammonium chloride d, coconut alkyltrimethylammonium nitrite, cetylpyridinium fluoride

Particularly preferred are the quaternary ammonium fluorides disclosed in U.S. Patent No. 3,535,421, wherein the quaternary ammonium fluorides have purifying properties. The cationic foaming agents may also act as germicides in some of the toothpastes.

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The amphoteric foaming agents useful in the toothpastes of the invention can be broadly described as derivatives of aliphatic, secondary and tertiary amines in which the aliphatic radical may be straight or branched, and wherein one of the aliphatic substituents contains from ca. 8 to approx. 18 carbon atoms and one contains an anionic water solution comprising, e.g. carboxylate, sulfonate, sulfate, phosphate or phosphonate.

The foaming agent can be found in the toothpastes of the invention in an amount of 0.1 to 6% by weight of the total agent.

2) Phosphate permeability agent.

The toothpastes according to the invention contain as a highly preferred optional component from ca. 5 to 12%, preferably from ca. 7 to 11% by weight of a water-soluble phosphate as "membrane penetrant" These soluble phosphates serve to promote the transfer of fluoride ions through the naturally occurring salivary membrane formed on the teeth. Fluoride-containing toothpastes using the amounts of phosphate described herein exhibit increased fluoride diffusion through the brain and fluoride uptake of tooth enamel compared to fluoride toothpastes which do not contain such phosphates as membrane penetrants.

Relatively large amounts of soluble phosphates can provide advantages with respect to the permeation of the fluoride in the

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16 fluoride toothpastes, but the presence of these salts can also diminish the stability of soluble fluoride in such toothpastes during storage. Surprisingly, it has been found that such soluble phosphates can be included in the silica-containing fluoride toothpastes of the invention with particularly good results in terms of fluoride compatibility if the special precipitated silica dioxide abrasives described herein are used.

Phosphates optionally found in toothpastes of the invention are water soluble. For the purposes of the invention, a water-soluble phosphate is one which is soluble in water to an extent of at least 3.0 g / 100 cm 3 H 2 O at 20 ° C.

The phosphates are the phosphorus compounds in which anions each phosphorus atom is surrounded by four oxygen atoms placed in the corners of a tetrahedron. By dividing oxygen atoms between tetrahedra, chains, rings and branched polymers of interconnected PO 1 tetrahedrons can be formed. Simple phosphates are ortho-20 phosphates. Polymeric phosphates include the polyphosphates, such as the pyrophosphates and tripolyphosphates. Ring phosphates are the methaphosphates.

Examples of suitable water-soluble polyphosphates for use in the toothpastes of the invention are tetras potassium pyrophosphate, tetrasodium pyrophosphate, sodium pyrophosphate, sodium tripolyphosphate and potassium tripolyphosphate. Examples of suitable water-soluble metaphosphates are mono-potassium metaphosphate, sodium trimetaphosphate, sodium hexametaphosphate, and sodium heptamethosphate. Many of these water-soluble polyphosphates and metaphosphates are used in the form of hydrated salts.

The most preferred phosphates for use in the toothpastes of the invention are the simple orthophosphates. Orthophosphates are derived from tribasic orthophosphoric acid of formula H3PO4. Water-soluble sodium, potassium and ammonium salts can be used.

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It's about. ten different crystalline sodium orthophosphates, including various hydrates. These include e.g. NaH2 PO4, NaH2PO, H2O, NaH2PO4.2H20, Na2HPO4, Na2HPO4.2H20,

Na2HPO4.7H2O, Na2HPO4.12H2O, Na3PO4.6H2O, Na3PO4.8H2O and 5 mixtures thereof. Preferred sodium orthophosphates include NaH2 PO4, H2O, Na2HPO4.2H2O and mixtures thereof. Particularly preferred are mixtures of NaH2PO4, H2O and Na2HPO4.2H2O in a weight ratio of monosodium salt to disodium salt in the range of about 1: 3 to 1: 5.

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Potassium and ammonium orthophosphates can also be used as membrane penetrants. Examples of such potassium and ammonium salts are KH2PO4, K2HPO4, K2HPO4,2H salts.

A particularly preferred phosphate composition for use in the toothpastes of the invention is a mixture of NaH2 PO4, H2O and K2HPO4.2H2O in a weight ratio of sodium to potassium salt in the range of about 1: 3 to 1: 5.

The soluble phosphates are industrially available materials. A more detailed description of these phosphates useful in the toothpastes of the invention can be found in Kirk & Othmer, Encyclopedia of Chemical Technology, 2nd Edition, Volume 15, Interscience Publishers, Incorporated (1968), pages 232-276.

Preferably, the present toothpastes provide concentrations of 30 0.5 mol / 1000 g H2 O to 2.0 mol / 1000 g H2 O of phosphate salts in the aqueous solutions which come into contact with tooth surfaces when the toothpastes of the invention are used in the mouth. In this case, the supernatant liquid from 3: 1 slurries of water and toothpaste is also used to mimic these utility solutions.

Additional membrane penetration agents may optionally also be added to the fluoride-containing toothpastes of the invention.

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These optional ingredients further promote the benefits of the fluoride penetration of the membrane created by the phosphates. These agents include, e.g. hydroxy acids and salts thereof, such as citric acid, tri sodium citrate, malic acid and tartaric acid. If such additional permeability agents are present, they constitute from ca. 0.2 to 5.0% by weight of the dentifrice.

3) Aromatization agents.

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Flavoring agents can also be added to the present toothpastes. Suitable flavoring agents include winter vegetable oil, peppermint oil, garden mint oil, sassafras oil and clove oil. Suitable sweeteners include saccharin, dextrose, levulose, aspartame, D-tryptophan, acetosulpham, dihydrochalcones and sodium cyclamate. Flavoring agents are generally used in toothpastes in amounts ranging from approx. 0.01 to 2% by weight and sweeteners in amounts from about 0.05 to approx. 3% by weight.

4) Anti-tartar / plague remedies.

Phosphorus-containing antifouling agents and / or bis-biguanidant plaque agents may optionally also be added to the toothpastes of the invention. Phosphorus-containing anti-tartar agents such as disodium ethane-1-hydroxy-1,1-diphosphonate and related materials are described in more detail in U.S. Patent No. 3,488,419. Bis-biguanide anti-plaque agents such as chlorhexidine (1,6-bis- [N5-p-chlorophenyl-N1-biguanido] hexane), the soluble and insoluble salts thereof, and related materials, such as 1,2-bis (N5-p -trifluoromethylphenyl-N1-biguanido) ethane is described in greater detail in U.S. Patent No. 3,934,002, U.S. Patent No. 3,937,807, U.S. Patent No. 843,244, and U.S. Patent No. 844,764.

The anti-toothpaste and / or anti-plaque agents, if present, generally constitute, if present, from ca. 0.01 to 2.5% by weight of the toothpastes.

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19 5) Pigments and dyes.

Various other optional components well known in the art may be added to the toothpastes of the invention 5 to improve the usual aesthetic properties. These include pigments, dyes, marbling agents and the like. When present, these optional components generally comprise from ca. 0.001 to approx. 2% by weight of the toothpastes.

The toothpastes of the invention are prepared by simply blending in any order and by known means the essential and optional components therein. Once prepared, the agents have a pH value of approx. 4.0 to 8.0, preferably 6.5 to 7.5, when slurried with water in a 3: 1 weight ratio of water to the agent. Fluoride toothpastes which provide pH values between 4.0 and 8.0 provide special advantages in effective anti-solubility of tooth enamel, compared to toothpastes with pH values outside this range. Aromatization of dentifrices within this pH-20 range is also relatively easy.

Toothpaste according to the invention is used in the usual manner. Toothpastes or slurries thereof are brushed onto the tooth surfaces and then rinsed off.

25

During the use of the toothpaste according to the invention in the usual manner, pastes or slurries are generally in contact with tooth surfaces for at least approx. 30 sec. More preferably, these pastes or slurries are in contact with tooth surfaces 30 for at least approx. 60 sec.

The following examples are given to illustrate the invention. In the examples, the parts are by weight, unless otherwise stated.

35

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20

Example 1.

Into a 30,000 liter stainless steel reactor with steam heating jacket was placed 1794 liters of sodium silicate solution 5 (3.78% Na 2 O, 9.53% SiO 2) having a density of 1.121 and containing 42 g Na 2 O per liter. liter. The reaction medium was heated to 88 ° C with still stirring. At this time, 10% sulfuric acid solution (density 1.066) and sodium silicate solution were added simultaneously to the reaction medium at a rate of 151.4 10 l / min acid and 351 l / min sodium silicate while maintaining the reaction temperature at 88 ° C ± 1 ° C. These two solutions were added to the reaction medium for a predetermined period. The silicate addition was discontinued after 47 min, but the acid addition was continued until the pH of the slurry was between 4.8 and 5.0. The reaction slurry was boiled at 100 ° C for 20 minutes and the pH of the reaction mixture was adjusted again to between 4.8 and 5.0. The resulting slurry of silica was filtered and washed to remove most of the reaction by-product (sodium sulfate) and the filter cake was dried and the dry product ground to the desired degree of fineness. The dry silicon dioxide was subjected to various physicochemical tests, the analyzes of which are listed below (see Table I). This example is the preparation of a control product to which no alkaline earth metal is added.

25

Example 2.

To a 30,000 liter stainless steel reactor with steam heating sheath was added 1794 liters of sodium silicate solution 30 (3.78% Na 2 O, 9.53% SiO 2) with a density of 1.121 and containing 42 g Na 2 O per liter. liter. The reaction medium was heated to 88 ° C with still stirring. At this point, 10% sulfuric acid solution (density 1.066) and sodium silicate solution were added simultaneously to the reaction medium at a rate of 151.4 l / min 35 acid and 351 l / min sodium silicate while maintaining the reaction temperature at 88 ° C ± 1 ° C. These two solutions were added to the reaction medium for a predetermined period. The silicate

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21 was discontinued after 47 min, but acid loading was continued until the slurry pH was between 4.8 and 5.0. The reaction slurry was boiled at 100 ° C for 20 minutes and the pH of the reaction mixture was adjusted again to between 4.8 and 5.0. The resulting sialcium dioxide slurry was filtered and washed to remove most of the reaction by-product (sodium sulfate).

The washed filter cake was then resuspended without water addition at ambient temperature with stirring. While stirring, the slurry was treated with 102 g of Codex grade (American Food Grade) hydrated lime (calcium hydroxide) to give 25 ppm of calcium ion based on the total weight of dry recoverable solid product in the slurry form. After treatment with the calcium ion, the slurry of the cake was stirred vigorously for 15 min. to provide the effective amount of calcium ion on the surface of the abrasive of si 1 icium dioxide. The resulting product is then spray dried at an inlet temperature of 483 ° C and an outlet temperature of 122 ° C, ground and characterized in terms of abrasive properties and physical properties in the same manner as the abrasive of Example 1.

Example 3

25

The procedure in this example was the same as in Example 2 except that the rate of addition of sulfuric acid was 162.7 liters per liter. and the calcium addition was 204 g of calcium hydroxide to give 50 ppm of calcium ion. The product was then characterized.

Example 4

This example was the same as Example 2 except that the rate of addition of sulfuric acid was 166.5 liters per liter. and the calcium addition was 408 g of calcium hydroxide to form 100 ppm of calcium ion in the silica. The product was then characterized.

22

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Example 5

In this example, a silica gel abrasive for toothpastes was prepared by first adding 1420 liters of sodium silicate-5 solution (4.09% Na 2 O, 10.31% SiO 2) having a density of 1.131 and containing 46.3 g Na 2 O per liter. liter to the reactor as reaction medium. The reactor was heated to 91 ° C with still stirring. At this point, 12% sulfuric acid (density 1.08) and sodium silicate solution were added simultaneously to the reaction medium 10 at a rate of 162.7 l / min acid and 315.7 l / min sodium silicate while maintaining the reaction temperature at 91 ± leC. The silicate addition was discontinued after 47 minutes, but the acid addition was continued until the pH of the slurry was between 4.6 and 4.8. The reaction slurry was boiled at 100 ° C for 20 minutes and the pH of the reaction mixture was again adjusted to between 4.6 and 4.8. The resulting slurry of silica. was filtered and washed to remove the by-product sodium sulfate.

The washed filter cake was then resuspended without water addition at ambient temperature with stirring. While stirring, the slurry was treated with 510 g of Codex grade (US food grade) hydrated lime (calcium hydroxide) to give 125 ppm of calcium ion based on the total weight of the dry extractable silica present in the slurry form. After treatment with calcium ion, the slurry of the cake was stirred vigorously for 15 min. to provide the effective amount of calcium ion on the surface of the silica abrasive. The resulting product was then spray dried at an inlet temperature of 483 ° C and an outlet temperature of 122 ° C, ground and then characterized.

Example 6

This example was the same as Example 5 except that from the beginning 1608 liters of sodium sulfate solution was added.

DK 166257 B

to the reactor as reaction medium, and the rate of acid addition was increased to 170.3 liters / minute, while the rate of silicate addition was maintained at 315.7 liters / minute.

The washed filter cake was treated with 816 g of calcium hydroxide to form 200 ppm of calcium ion on the surface of the abrasive of silica. The product was then characterized.

Example 7.

This example was the same as Example 2 except that the addition of calcium ion was 2.040 g of calcium hydroxide to form 500 ppm of calcium ion. The product was then characterized.

After preparing the products of Examples 1 to 7, they were characterized in terms of physical properties and the results are set forth in the following Table I.

20 25 30 35

DK 166257B

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DK 166257 B

25

Several representative toothpastes according to the invention are mentioned in the following examples, in which the precipitated silica dioxide sealants are used herein.

Example 8.

A toothpaste is prepared using the precipitated silica dioxide abrasive of Example 2, which toothpaste has the following composition:

Component Amount (wt%) Precipitated in silica abrasive (Example 2) 16.0

Sodium Fluoride (NaF) 0.28 15

Sorbitol solution (70%) 32.0

Glycerol 13.0

Sodium Carrageenan 0.75 9n Monosodium Orthophosphate Monohydrate * (NaH 2 PO 4, H 2 O) 2.15

Disodium orthophosphate dihydrate (Na2HPO4.2H2O) 8.34

Sodium alkyl sulfate solution (28.8%) 6.0 Coconut monoglyceride sodium sulfonate 0.9

Aroma 1.22

Sodium saccharin 0.3

Color (FD&G Blue no. 1 solution 1%) 0.35 30

Titanium Dioxide (TiO 2) 0.5

Trisodium citrate dihydrate 0.25 (C6H5Na307.2H2O)

Distilled water e.g.

Total 100.0

The above toothpastes are prepared by mixing the components in a normal way for toothpaste making. Preferably%

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26, the water component is first added to a suitable container, to which is then added, under moderate stirring, in order of the permeability agents, the aroma, the moisture binder and then the remaining components.

5

A 3: 1 slurry by weight of the above freshly prepared agent with water (3: 1 water / agent) gives a pH of approx.

7.1. This toothpaste provides beneficial fluoride treatment of toothed tissue which is brushed therewith, due to the high compatibility between toothpaste and fluoride. The toothpaste also provides good cleansing and an RDA of 100. When stored for a long time at 27 ° C, such toothpaste exhibits minimal loss of soluble fluoride.

Toothpastes which provide substantially the same advantages with regard to fluoride treatment, compatibility between toothpaste and fluoride and purity can be realized when the sodium fluoride in the composition of Example 8 is replaced by an equivalent amount of stannofluoride, sodium chlorofluoride, potassium fluoride, potassium fluoride, potassium fluoride, potassium fluoride, potassium fluoride, potassium fluoride. ammonium fluoride.

20

Toothpastes which give substantially the same benefits in terms of fluoride treatment and substantially the same purity are obtained when the mixture of phosphate in the composition of Example 8 is substituted with an equivalent amount of NaH2PO4, NaH2PO4, H2O, NaH2PO4.2H20, Na2HPO4, Na2HPO4 , 2h20, Na2HP04,7H20, Na3P04,6H20,

Na3PO4,8H20, KH2PO4, K2HPO4, K2HPO4.2H20, Κ2ΗΡθ4.5Η20, K3PO4 »3H20, K3PO4,7H20, K3PO4,9H2Q, (NH4) Η2Ρ04, (NH4) 2HPO4, (NH4} H04, (NH4} 3PO4, Na2HPO4.2H2O in weight ratio of monosodium to disodium from about 1: 3 to 30 1: 5, mixtures of NaH2PO4, H2O and K2HPO4.2H2O in weight ratio of sodium to potassium salt from about 1: 3 to 1: 5, umpyrophosphate, tetrasodium pyrophosphate, disodium pyrophosphate, sodium tripolyphosphate, potassium tripolyphosphate, monocal potassium metaphosphate, sodium trimetaphosphate, sodium hexametaphosphate or sodium heptametaphosphate, provided these agents in a pH of 4.0 to a pH of 4.0:

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27

Example 9

A high abrasive toothpaste is formulated using the precipitated si 1 cesium dioxide sizing agent of Example 3, which 5 toothpaste has the following composition:

Component. Amount (wt * l Precipitated silica dioxide softener (Example 3) 35.0

Sodium fluoride (NaF) 0.22

Glycerol 5.0

Sorbitol solution (70%) 20.0

Carboxynethyl cellulose (0.7 D.S.) 0.5 15

Magnesium Aluminum Silicate (Veegum Flakes) 0.3

Mononatri umorthophosphate monohydrate (NaH2 PO4, H2O) 0.3

The sodium morphophosphate dihydrate (Na2HPO4.2H2O) 0.3

Sodium alkyl sulfate solution (28.8%) 2.3

Coconut monoglyceride sodium sulfonate 0.7

Flavor 0.9 Sodium saccharin 0.2

Titanium Dioxide (TiO 2) 0.5

Spot staining material 0.5

Distilled water e.g.

30

Total 100.0.

Toothpastes which provide substantially similar advantages with respect to fluoride treatment, compatibility between toothpaste and fluoride, and cleaning ability are obtained when the abrasive component of precipitated silicon dioxide, prepared as in Example 3, is replaced by an equivalent amount of abrasives prepared in Examples 2, 4, 5 and 6.

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28

Toothpastes which give substantially the same benefits in terms of fluoride treatment and substantially similar purity are obtained when in the composition of Example 9 the phosphate mixture is replaced by an equivalent amount of NaH2PO4'NaH2PO4'NaH2PO4 , Na2HP04,7H20, Na3P04,6H20,

Na3PO4,8H2O, KH2PO4, K2HPO4, K2HPO4.2H2O, K2HPO4.6H2O, K3PO4.3H2O, K3PO4.7H2O, K3PO4.9H2O, (NH4) H2PO4, (NH4) 2HPO4, (NH4) HPO4, (NH4) 3PO4, Na2HPO4.2H2O in a weight ratio of monosodium to disodium salt from ca. 10: 1: 3 to 1: 5, mixtures of NaH2 PO4, H2O and K2HPO4.2H2O in a weight ratio of sodium to potassium salt from ca. 1: 3 to 1: 5, tetras potassium pyrophosphate, tetrasodium pyrophosphate, disodium pyrophosphate, sodium tripolyphosphate, potassium tripolyphosphate, monocal potassium metaphosphate, sodium trimetaphosphate, sodium hexamex taphosphate, or sodium phosphate 3 to 8.0.

Example 10.

A clear toothpaste is prepared using the precipitated silica dioxide abrasive of Example 4, which toothpaste has the following composition:

Component Amount (% by weight) Precipitated Si silica abrasive (Example 4) 20.0

Sodium fluoride (NaF) 0.24

Sorbitol Solution (70¾) 57.0 Glycerol 15.0

Sodium carrageenin 0.5

Phosphoric acid (85¾) 0.10

Sodium alkyl sulfate solution (28.8¾) 4.0 Aroma 1 »0

Sodium saccharin 0.2

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29

Color (FD&C Blue no. 1 solution 1%) 0.05

Distilled water e.g.

Total 100.0 g

Example 11.

A mild abrasive toothpaste is formulated using the precipitated silica dioxide abrasive of Example 3, which toothpaste has the following composition:

Component Amount (% by weight) Precipitated Si silica abrasive (Example 3) 6.0

Stannous fluoride (SnF2) 0.40

Sorbitol solution (70%) 51.0

Glycerol 25.6

Sodium carboxymethyl cellulose (0.7 DS) 1.0 Sorbitan monoisostearate 2.00

Sodium alkyl sulfate solution (28.8%) 6.0

Aroma 1.20

Sodium Saccharin 0.28 25 Color (FD&C Blue # 1 Solution 1%) 0.25

Pyrogenic Tcolloids are 1 icium dioxide (Aerosil 200V) * 5.00

Distilled water e.g.

30 Total 100.0 ★ Negotiated by Degussa, Inc.

Toothpastes which provide substantially the same advantages with regard to fluoride treatment, the same compatibility between toothpaste and fluoride, and the same cleaning performance are obtained when the precipitated silica-9 oxide abrasive in the composition of Example 10 is replaced by an equivalent amount of abrasives prepared in Examples 2, 3, 5 and 6.

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30

A toothpaste which provides substantially the same benefits in terms of fluoride treatment and improved anti-tooth effect is obtained when the composition of Example 10 further contains approx.

1.0 wt.% Disodium ethane-1-hydroxy-1,1-diphosphonate.

5

The precipitated silicon dioxide abrasives described herein can be used to prepare particularly desirable toothpastes containing soluble phosphate as membrane penetrants. These agents provide both high compatibility between abrasive and fluoride and yet have good dental cleanliness. The following tests and assessments serve to show the excellent fluoride compatibility afforded by the precipitated silicon dioxide tooth abrasives in toothpastes of the invention. It is also shown below that the abrasives provide higher compatibility between abrasive and fluoride than abrasives prepared in a similar manner that have not been treated to contain the substantial amounts of alkaline earth metal. The excellent cleaning performance of the toothpastes according to the invention is also demonstrated. Finally, it is shown that abrasives produced by a process of acidifying 20 sulphate liquids, although containing an alkaline earth metal, cannot give the high values of fluoride compatibility as the fresh water precipitated silica dioxide abrasives.

Compatibility between abrasive and fluoride.

25 Precipitated silica tooth abrasives can be sorted by their relative compatibility with fluoride materials by means of a 24 hour slurry test. Such a sample can be used to obtain data that can predict the availability of soluble fluoride in certain types of fluoride toothpastes after storage for a period of approx. 4 weeks at 27 ° C.

The 24-hour abrasive slurry sample is used to develop fluoride compatibility values, defined as the 35 percent of the theoretical maximum available fluoride, which is actually measured after 24 hours as soluble fluoride by the following test method. By this method (Orion Specific Ion

DK 166257 B

31

Electrode Method) prepared a standard sodium fluoride stock solution containing 1624 ppm of fluoride by dissolving 2.80 g of sodium fluoride, 21.5 g of NaH 2 PO 4 and 83.4 g of Na 2 HPPO 4,2H 2 O in 672.5 g of deionized distilled water and storing it in a polyethylene. 5 bottle. Weigh 30 g of this solution then. 7 g of the silica abrasive being tested is then dispersed in the solution and contacted for 24 hours at a temperature of 37.8 ° C. After 24 hours, the mixture of precipitated sialcium dioxide abrasive and fluoride solution is centrifuged for 20 minutes.

10 at 15000 rpm or until the overlying liquid is clear. Then pipette 10 ml of the overlying liquid into a plastic bottle. Then pipette 10 ml of EDTA / THAM solution into the plastic bottle. (The EDTA / THAM solution is 0.2 molar with respect to EDTA (ethylenediaminetetraacetic acid, disodium salt) and 0.2 molar with respect to THAM (2-amino-2-hydroxymethyl-1,2-propanediol) and adjusted to pH 8.0 with sodium hydroxide). A magnetic stir bar is added and gentle stirring is initiated. The fluoride ion concentration is determined by direct potentiometry with the Orion fluoride electrode (model 20 95-09). Emk is converted into parts per million (ppm) of fluoride in the supernatant using a logarithmic equation. The fluoride compatibility value is then calculated by expressing the measured ppm of soluble fluoride as a percentage of the theoretically available soluble fluoride.

25

Using this method, the relative compatibility values of abrasive and fluoride for the various abrasives prepared according to Examples 1 to 7. are determined. The results of these determinations are given in the following Table II.

30 35 32

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Table II

Compatibility of abrasive and fluoride 5 Ex. No. Calcium Treatment Siibentant Fluoride Compatibility __ (ppm) ____ 1 (Control) 0 76% 2 25 93% 10 3 50 94% 4 100 93% 5 125 91% 6 200 90% 7 500 88% 15

The data in Table II shows that the precipitated silicon dioxide abrasives used in the toothpaste of the invention containing certain amounts of an alkaline earth metal give significantly better compatibility of abrasives and fluoride compared to that obtained with an alkaline earth metal-free abrasive material which is otherwise manufactured in the same way. Therefore, the precipitated silicon dioxide slurries prepared in Examples 2 to 6 would be suitable for the preparation of toothpastes containing fluoride and membrane penetration agents which exhibit high compatibility between abrasive and fluoride.

Compatibility of abrasive and fluoride in toothpastes.

Preferred toothpastes of the invention containing precipitated 30 silica abrasives and membrane penetrants are assessed for abrasive / uride compatibility. The toothpastes prepared for evaluation have the same composition as the toothpaste of Example 8 and differ only in a variation in the sealant component.

To determine fluoride compatibility values for the tested toothpastes, a method of determining solubility is used.

DK 166257B

33 is similar to the method described above for determining abrasive and fluoride compatibility values. In this method, the toothpastes are stored in a laminated tube for a given time. Then 15.0 g of the agent is placed in a 100 ml beaker and then 45.0 g of distilled water is added. The mixture is then stirred to form a slurry in which the toothpaste is uniformly distributed. The slurry is then centrifuged for 20 minutes. at 15000 rpm. or until the overlying liquid is clear.

10

The overlying liquid is then treated as by the method described above for determining abrasive-fluoride compatibility. The concentration of soluble fluoride is similarly measured, and a similarity value for abrasive and fluoride compatibility is calculated for each toothpaste. The compatibility values for toothpaste and fluoride for the respective toothpastes examined are shown in Table III. The abrasives tested are those prepared as described in Examples 1 to 7 and characterized in Table I.

20

Table III

Compatibility of toothpaste and fluoride.

25 Abrasive Calcium Treatment Toothpaste Fluoride Compatibility (Ex. No.) _ (ppm) _ (1 week 27 ° C) _ 1 (control) 0 76% 2 25 99% 30 3 50 98% 4 100 99% 5 125 97% 6 200 94 % 7 500 90%

The data in Table III shows that the preferred toothpastes of the invention utilizing the present precipitated silicon

DK 166257B

34 dioxide abrasives, provide better values for abrasive and fluoride compatibility than a similar dentifrice containing the precipitated silica dioxide abrasive prepared by the method of Example 1 which has not been treated with alkaline earth metal. The data in Table III further shows that the availability of the soluble fluoride from the source of fluoride ion is not appreciably diminished by storage when the silicon dioxide / l agents are used in the toothpastes of the invention.

Of course, it should be recognized that the amount of soluble fluoride available, even in the toothpastes of the invention, will decrease to some extent as a function of increasing time and temperature upon storage. The values for toothpaste compatibility and fluoride for toothpastes stored for longer periods or, thus, at more demanding temperatures are generally lower than those exemplified above.

Additional data on abrasive and fluoride compatibility for several toothpastes showing prolonged storage and at 20 higher temperatures are shown in Table IV.

25 30 35

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DK 166257 B

36

The data in Table IV shows that the preferred toothpastes of the invention retain their relatively high fluoride and abrasive compatibility, even under longer storage or under more demanding storage conditions.

5 Cleanability.

The dental cleanliness of the described silica dioxide abrasives can be assessed by the radioactive dentin grinding (RDA) test. RDA values can be used to judge the relative cleanliness of various abrasives for a given type of dental abrasive. Thus, for precipitated silicon dioxide abrasives, an RDA value (measured by the method described below) of at least 40, preferably between 70 and 120, is required to ensure that the abrasive has sufficient abrasiveness to be an effective toothpaste agent. Prior art precipitated silica abrasives which exhibit high fluoride and toothpaste compatibility are generally poor oral hygiene cleaners, as demonstrated by low RDA values. The abrasives treated with alkaline earth metal, on the other hand, provide both effective tooth cleaning and high fluoride compatibility.

Several commercially precipitated silica abrasives exhibiting relatively high compatibility of toothpaste and fluoride, as measured in the present application, are selected for evaluation for RDA values. The test is carried out in a standard toothpaste matrix having the same composition as the toothpaste of Example 8 and differs only by variation in the sealant component.

The procedure used to determine toothpaste RDA values listed in Table V is described below. This study method is described in detail in the Journal of Dental Research, July-August 1976 by Hefferren, pages 563-573. The individual steps for determining RDA values are as follows: 35

DK 166257B

37 A. Selection and preparation of teeth.

Healthy, permanent teeth with a single root, which are free of variety and vital at extraction, are selected. The teeth are then scraped clean with a scalpel. The crown and root tip of each tooth are removed using a grinding wheel to make a dentine specimen 14 mm long and at least 2 mm wide at the narrow end. Cut pieces of root (dentin shavings) or, alternatively, a further tooth are also prepared for later use to determine a correction factor for radiation self-absorption.

B. Radiation of dentin.

The prepared roots and dentin chips described in step 15A are subjected to a neutron flow of 2 x 10 5 neutrons per second. cm 2 for 3 hours.

C. Mounting of roots.

After irradiation, the irradiated roots are embedded in a cold-hardening dental methacrylate resin support and mounted on a cross-brushing machine. Toothbrushes used throughout the sample are "Pepsodent" toothbrushes with 50 brush strokes, which are of medium size and flat.

D. Pre-treatment of the dentin surfaces · Before the first experiment, the freshly mounted irradiated roots are brushed with a reference slurry (10 g calcium pyro-phosphate + 50 ml of a 0.5% CMC-10% glycerol solution) with 6,000 brush strokes. At the beginning of each subsequent day's trial, the roots are brushed with 1,000 strokes.

35

DK 166257B

38 E. Proceedings of trials.

After pretreatment, the dentin samples are then conditioned with the reference slurry (same slurry as in step D) with 1500 brush strokes at the beginning during and at the end of each 5 trials. The course of the experiment consists of brushing dentine samples with 1500 brush strokes with a slurry of the test product (25 g of dentifrice + 40 ml of deionized distilled water).

F. Preparation of correction factors.

10

The correction factors are prepared by dissolving the dentine shavings or, alternatively, an additional tooth from step B in 5 ml of concentrated HCl, which is filled with distilled water to a volume of 250 ml. One ml of this solution is added to the test bases and the reference slurries, prepared in a similar manner to those in Step E, and then neutralized with 0.1 N NaOH.

Radioactive tracer count.

20

The radioactivity of the slurry samples (1.0 ml) is determined with an Interteknik SL-30 liquid scintillation counter. Alternative counting method: 3 ml portions of each slurry are transferred to small flat bottom stainless steel cans with dimensions 2.5 25 cm x 0.8 cm and counted using Nuclear Chicago Geiger

Counting System.

Calculations.

30 The radioactive dentine wear value (RDA) for a given condition will be the ratio of the average corrected number of this paste to the average number of the reference multiplied by 100. The reference abrasive is given in an arbitrary dentine wear value of 100 units.

The results of these RDA valuations are listed in the following Table V.

35

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39

Table V.

Radioactive dentin wear values

Toothpaste 1uoride compound- 5 Abrasive_RDA_quality 1 week (27 ° C) _ A. (Ex. No.) 1 control 75 ± 7 76% 2 80 ± 21 99% 10 3 6718 98% 4 8011 99% 5 10315 97% 6 111+ 5 94% 15 7 5614 90% B. Industrial precipitated silica 8 Occident 3 1 * 1412 92% 20 9 Neosyl 2 * 2512 78% 10 QUSO G-30 1 2 · 22 + 2 87% 11 Neosyl ET * · 2614 * 84% 1. A precipitated Si silica marketed by Degussa, Incorporated (NY).

2. A precipitated Si silica marketed by Joseph Crosfield & Sons, Limited (London, England).

A precipitated Si silica sold by the Philadelphia Quartz Company (Valley Forge, Pennsylvania).

30 2

A precipitated si 1 icium dioxide sold by Joseph Crosfield & Sons, Limited.

The data in Table V shows that the industrial precipitated silica abrasives may well exhibit high compatibility between abrasive and fluoride, but are not sufficiently abrasive to be useful as toothpaste abrasives. Surprisingly giving

DK 166257 B

40 the present novel precipitated s in 1 icium dioxide 1 agents excellent compatibility between abrasive and fluoride and at the same time excellent RDA abrasive values, which values can be used as an indicator of relative tooth cleaning performance.

5 "Fresh water" versus "sulfate liquid" slides.

As mentioned above, the abrasive products used in the toothpaste of the present invention are related to, but different from, the calcium-treated silicon dioxides of U.S. Patent No. 4,159,280. In order to demonstrate such a difference, the following assessment is made to compare the fluoride compatibility of the products of U.S. Patent

4,159,280 with the fluoride compatibility of the abrasive products used in the toothpaste of the present invention.

The tested "sulfate liquid" silica materials are prepared by the process described in U.S. Pat.

No. 4,159,280 and U.S. Patent No. 3,960,586 as follows: Dry sodium sulfate was added to 38 liters of water in a 760 liter of 20 reactor so that the sodium sulfate concentration in the reaction medium was 10%. The pH of the reaction medium was then adjusted to 9.0 by the addition of sodium silicate. The reaction temperature was 65 ° C. The sodium silicate solution had a molar ratio of SiO 2 / Na 2 O of 2.5 and a concentration of 0.24 kg / l. Sodium silicate was added to the reaction medium for 4 minutes. At this point, the addition of sodium silicate was stopped and sulfuric acid with a concentration of 11.4% was added to the reaction medium until a pH of 9.0 was reached. At this point, the sodium filtrate solution and sulfuric acid solution were added simultaneously for a period of 35 minutes. After the period of 35 min. the silicate addition was discontinued and the acid addition continued until a slurry having a pH of 5.5 was obtained. The portion was left to ripen at 77 ° C for 20 minutes, and the resulting wet cake was recovered and washed.

DK 166257 B

41

The wet cake was then treated in the manner described in Example 2, divided into 6 portions, and treated with 50, 100, 200, 400 and 800 parts, respectively. million calcium from aqueous solutions of calcium hydroxide. Each wet cake was then dried and processed as described in Example 2 and characterized in the following Table VI, the first abrasive being a control in which no calcium was added. Table VI indicates the results of the assessment.

Table VI.

10 "Sulfate Liquid" - Ca-additive Abrasive Fluoride-Sl Adhesive (ppm) - Unite! iqhed * _ A 0 (control) 88 B 50 89 15 C 100 88 D 200 88 E 400 86 F 800 82 20 * Determined by the test described in connection with Table II.

As will be seen from the data in Table VI, the calcium-treated "sulfate liquid" abrasives of U.S. Pat.

4,159,280 abrasive and fluoride compatibility values generally lower than those obtained with "fresh water" silica dioxide abrasives used in the toothpaste of the present invention (see Table II). Furthermore, addition of alkaline earth metal to abrasives prepared by the "sulphate liquid" method does not result in a dramatic improvement in the compatibility of abrasive and fluoride. As will be seen in a comparison with Table II, the addition of equivalent amounts of alkaline earth metal to silica dioxide abrasives used in the toothpaste of the invention produced by the "fresh water" method, conversely results in dramatic improvements in the compatibility of abrasive and fluoride.

Claims (8)

1. Toothpaste, characterized in that it contains: 5 A. from 6 to 35% by weight of a precipitated sieve silica abrasive which is a precipitated amorphous sieve dioxide made from freshwater alkali metal silicate solution by acidification which has been made to react intimately with a solution of a salt of an alkaline earth metal, such that there are approx. 10-300 parts per 10 million alkaline earth metal ions in the amorphous silicon dioxide, which amorphous silicon dioxide exhibits a radioactive dentin removal value of at least 40, an average particle size of 5 to 15 microns in diameter, a packed bulk weight of 0.24 to 0.55 g per meter. ml, an oil absorption of 70-95 cm1 / 100 g, a BET-15 surface area of 100-250 m2 / g and a glow loss of 4-6%; B. from 0.01 to 3.0% by weight of a water-soluble fluorine-containing material which gives off fluoride ions in aqueous solution; 20 c * from 3 to 55% by weight of a moisture binder; D. from 0.2 to 2.0% by weight of a binder, and E. from 15 to 80% by weight of water; 25 which toothpaste gives a pH of 4 to 8 when suspended in water in a weight ratio of 3: 1 between water and the toothpaste. A toothpaste according to claim 1, characterized in that it further contains from 5 to 12% by weight of a water-soluble phosphate as a dental penetrant selected by the group consisting of orthophosphates, pyrophosphates, tripolyphosphates and metaphosphates. Toothpaste according to claim 2, characterized in that the precipitated silica dioxide abrasive constitutes from 10 to 20% by weight of the toothpaste; B. the fluorine-containing material constitutes from 0.1 to 1.0% by weight of the toothpaste; 5 C. the moisture-binding agent constitutes from 20 to 35% by weight of the toothpaste; D. the water component is from 15 to 40% and 10 E. The pH of a 3: 1 water / toothpaste slurry is from 6.5 to 7.5. The toothpaste according to claim 3, characterized in that it further contains from 0.1 to 6% by weight, based on the toothpaste, of a foaming agent, wherein A. the fluorine-containing material is selected from the group consisting of sodium fluoride and stannous fluoride; B. the phosphate as a tooth permeation agent is an ortho-phosphate and the C. moisture binding agent is of the group consisting of glycerol, sorbitol, xylitol and mixtures thereof. Toothpaste according to claim 4, characterized in that A. the fluorine-containing material is sodium fluoride and B. the foaming agent is selected from the group consisting of: 1 2 the water-soluble salts of alkyl sulfates having from 8 to 18 carbon atoms in the alkyl radical, 2 water-soluble salts of sulfonated fatty acids monoglycerides having from 8 to 18 carbon atoms in the fatty acid moiety, and DK mixtures thereof. Toothpaste according to claim 3, characterized in that the binder is carrageenan. A toothpaste according to claim 4, characterized in that it further contains from 0.2 to 5% by weight, calculated on the toothpaste, of another dental penetrant selected by the group consisting of citric acid, trisatriacrylate, malic acid and tartaric acid, wherein A. the fluorine-containing material is sodium fluoride, and B. the phosphate as a tooth penetrant is a mixture of sodium dihydrogen phosphate monohydrate and disodium hydrogen phosphate dihydrate in a weight ratio of the monosodium to disodium salt of 1: 3 to 1: 5. The toothpaste according to claim 3, characterized in that it contains an additional component selected by the group consisting of: A. from 0.01 to 2% by weight of an aromatizer; B. from 0.05 to 3% by weight of a sweetener; From 0.01 to 2.5% by weight of an ant in tartar which is disodium methane-1-hydroxy-1,1-diphosphonate; D. from 0.01 to 2.5% by weight of a bisbiguanide antiplaque agent, 30 09 E. blends of these additional toothpaste components. 35