NO136279B - - Google Patents

Description

The invention relates to a dental care agent containing a water-soluble monofluorophosphate salt as a fluorinating compound.

Various fluoridating compounds, including water-soluble monofluorophosphate salts, have been used in dental care

funds. The polishing materials that can be used in such dental care products vary partly depending on the particular fluoride

rewarding material used. Fluoridating materials and polishing materials have therefore been extensively investigated to find dental care products that contain such fluoridating materials and polishing materials and which retain a high

respective amount of soluble fluoride from the fluoridating material during storage and ageing.

The present invention provides a dentifrice which contains a monofluorophosphate salt as fluorine

yielding material and.which retains a desirable amount of fluoride on storage.

The invention relates to a dental care agent comprising an α-aluminium oxide trihydrate with an average particle size of 6-9 mm and a particle size distribution of 9^-99% below 30 μm, 85-93% below 20 μm, 56-67% below 10 μm and 28 ->+0% below 5 Mm, a water-soluble monofluorophosphate salt and as a polishing material together with the α-aluminium oxide trihydrate an insoluble alkali metal metaphosphate which is compatible with the monofluorophosphate salt, and the toothpaste is characterized by the content of insoluble alkaline metal metaphosphate and α-aluminium oxide trihydrate being 20-95% by weight of the dental care agent, that the amount of the alkali metal metaphosphate in relation to the amount of a-aluminium oxide trihydrate is between less than 1:1 and 1:500, and that the dental care agent in addition to the polishing material consisting of alkali metal metaphosphate and a-aluminum oxide trihydrate contains 0-5% of other polishing material such as alkaline earth metal phosphates .

The water-soluble monofluorophosphate used in the dentifrice according to the invention is preferably an alkali metal monofluorophosphate, such as sodium monofluorophosphate, lithium monofluorophosphate, potassium monofluorophosphate and ammonium monofluorophosphate. The preferred salt is sodium monofluorophosphate, Na 2 P 0 4 F, which in its commercially available form can have a highly varying degree of purity. It can be used with any suitable degree of purity, provided that any contamination will not adversely affect the desired properties. It is generally desirable to have a purity of at least 80% by weight, but to achieve the best results it should be at least 85% by weight, and preferably 90% by weight, of sodium monofluorine etc., the rest being mainly impurities or by-products from the manufacture, such as sodium fluoride and water-soluble sodium phosphate salt etc. Expressed in another way, the sodium monofluorophosphate used must have a total fluoride content of more than 12%, preferably more than 12.7%, a content of not more than 1.5%5 preferably not more than 1.2 %, free sodium fluoride and a sodium monofluorophosphate content of at least 12%, preferably at least 12.1%, all calculated as fluorine.

Other monofluorophosphate salts which have sufficient solubility in water to enable them to be used according to the invention include calcium monofluorophosphate, magnesium monofluorophosphate and aluminum monofluorophosphate. The term "monofluorophosphate" as used herein is also intended to include monofluoropolyphosphates, such as NaifP309F, KlfP309F, (NH^P^F, Na^P^F, (NH^)3NaP309F and LiIfP309F.

The monofluorophosphate is usually present in such an amount

that there is 0.01-1% fluoride in the dental care product. Sodium monofluorophosphate is therefore usually present in an amount of 0.05-7)6%.

The insoluble alkali metal metaphosphates used as polishing agents in the present dental care products are preferably the insoluble sodium and calcium salts of polymetaphosphoric acid. These materials are known in the art. The insoluble sodium metaphosphate is preferred. Such materials can be formed

in any suitable manner, as set forth in Thorpe's Dictionary of Applied Chemistry, Vol. 9> f+. edition), pp. 510-511. The forms of insoluble sodium metaphosphate known as Madrell's salt and Kurrol's salt are further examples of suitable materials. These metaphosphates only have a very low solubility in water and are therefore generally referred to as insoluble metaphosphates. A smaller amount of soluble phosphate material is present as impurities, usually in an amount of a few percent, such as e.g. up to h% by weight. The amount of soluble phosphate material, which in connection with insoluble sodium metaphosphate is assumed to be a soluble sodium trimetaphosphate, can be reduced if desired by washing with water. The insoluble alkali metal metaphosphate is usually used in powder form with particles of such a size that no more than approx. 1% of the material is larger than approx. 37 A^i.

The aluminum oxide which is used in the dental care agent according to the invention and which is also known in the art, is α-aluminium oxide trihydrate which is chemically generally indicated as A^<O->^^<H>^<O> or A1(OH)3. The average particle size is 6-9 mm with the following particle size distribution:

The ratio between insoluble alkali metal metaphosphate and aluminum oxide is below 1:1. Tooth care products containing these polishing ingredients and water-soluble monofluorophosphate salt be-

holds a desirable amount of soluble fluoride, e.g. at least h- 0%

of the original content of monofluorophosphate after accelerated aging of the dentifrice for 9 weeks at approx. h9°C. The relationship

■between insoluble alkali metal metaphosphate and aluminum oxide can vary from below 1:1 to 1:500 and is preferably 1:<1>+7.25.

Besides aluminum oxide and insoluble alkali metal metaphosphate, the polishing material may also contain 0-5%, preferably 1%, of an additional polishing component to facilitate the achievement of the desired polishing of the tooth enamel. Typical examples of such components include water-insoluble alkaline earth metal phosphates, such as anhydrous dicalcium phosphate, dicalcium phosphate dihydrate, tri-calcium phosphate and trimagnesium phosphate, etc.

The overall content of polishing agent in the dental care product can vary, but is usually up to 95% by weight of the overall mixture. For toothpastes, the amount of such polishing agents will usually be 20-75% by weight, preferably <*>fO-55% by weight, while the amount of polishing agents in tooth brushes will usually be larger, e.g. 70-95% by weight.

In the production of tooth powder, mechanical mixing is usually sufficient, e.g. when painting, of the various solid components in the appropriate quantities and with the appropriate particle sizes.

Any surface-active or cleansing material can be used in the dentifrices. Such compatible materials are desirable to achieve additional cleansing, foaming and antibacterial properties depending on the particular type of surfactant, and are selected on a similar basis.

These surface-active compounds are usually water-soluble organic compounds and may have an anionic structure. It is generally preferred to use the water-soluble non-soap or synthetic organic surface-active compounds.

The various surface-active materials can be used in any suitable amount of, as a rule, 0.05-10% by weight, preferably 0.5-5% by weight, of the dental care agent.

In the dentifrices according to the invention, the essentially saturated higher aliphatic acylamides of lower aliphatic aminocarboxylic acid compounds, such as those having 12-16 carbon atoms in the acyl radical, can also be used. The amino acid part is usually derived from the lower aliphatic saturated monoaminocarboxylic acids with 2-6 carbon atoms, usually the monocarboxylic acid compounds.

The amide compounds 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 alkylolamine salts.

Such materials are used in pure or substantially pure form. They should be as free as practicable of soap or similar higher fatty acid materials which tend to reduce the activity of these compounds. In normal practice, the amount of such higher fatty acid materials is less than 15% by weight

of the amide and insufficient to substantially adversely affect this, and preferably below 10% of the amide material. . The liquids in the toothpaste are usually mainly water, glycerol..., sorbitol and pylene glycol or suitable mixtures thereof. It is usually advantageous to use a mixture of both water and a wetting agent or binder, such as glycerol or sorbitol. 'It is preferred - to use glycerol.

The overall liquid content is usually 20-75% by weight of the mixture. It is also preferred to use a gelling agent in toothpastes, such as the natural and synthetic gums and rubber-like materials, e.g., Irish itnose, etc. ag ant gum., sodium carboxymethyl cellulose., .poly.lyvinylpyrr.olidone .and starch etc. Irish moss and sodium carboxymethyl cellulose are particularly compatible and are preferred gelling agents... fThe rubber content is usually up to 10% by weight , -preferably '0.5-'5 wt%, of the "mixture.

Various other materials can be used in the dentifrices according to the invention. Examples of these are coloring or whitening substances, preservatives, silicones, chlorophyll compounds and ammonia-containing materials, such as urea and diammonium phosphate and mixtures thereof.

It may also be desirable for certain purposes to use antibacterial agents in the dentifrices according to the invention.

In addition, any suitable flavoring or sooting agent can be used to provide a flavor in the present dentifrices.

Toothpastes must have a practical pH for use. A pH of 6-9 is particularly desirable. A reference to pH means the pH that is directly determined in the toothpaste. If desired, materials such as citric acid can be added to regulate the pH to e.g. 6.5-7 5 5. When citric acid is present,. As a rule, the toothpaste retains at least h0% of the original content of monoflupr-' phosphate after accelerated storage for 9 weeks at approx. 1+9°C. If the pH is not regulated with materials such as citric acid, the toothpaste usually retains at least half, and generally more than 50%, of the original content of monofluorophosphate after accelerated storage for 9 weeks at <k>^ °C.

The available dental care products provide a very good effect during use. When formulated in the form of toothpastes, they have desirable cosmetic and rheological properties and can be stored and dispensed from conventional squeezable tubes. The dental care agents according to the invention can e.g. are stored in unprepared. aluminum tubes.

In the examples, the dentifrices were prepared in the usual way, and all amounts of the various ingredients are based on weight if nothing else is stated.

EXAMPLE 1

The following dental care products were produced. The content of sodium monofluoride etc. in each of these corresponded to 0.1% fluoride ion:

Each of the dentifrices A, B and C had an original content of soluble monofluorophosphate? as fluoride, of 0.1%. Each dentifrice was stored for several weeks at <1>+9°C, and the soluble fluoride content was periodically determined. The results for dentifrices A and B, which contained a polishing material containing aluminum oxide and insoluble sodium metaphosphate, and for dentifrice C, which did not contain insoluble sodium metaphosphate, are given below:

It appears that the presence of insoluble metaphosphate strongly increases the ability of toothpastes A and B to retain soluble fluoride compared to toothpaste C.

After 9 weeks of storage at <!>+9°C, the percentage of soluble monofluorophosphate as fluoride was thus 0.0^1% for dentifrice B and only 0.030% for dentifrice C. It is true that dentifrice C contains 0.2% citric acid, while dentifrice B only contains 0.1% citric acid. The target is then whether it is this increase in citric acid content from 0.1% to 0.2% that quickly leads to the poor result for toothpaste C, and not the fact that toothpaste C does not contain insoluble sodium metaphosphate in addition to the hydrated aluminum oxide. In this connection, reference can be made to the penultimate paragraph, for example 1, where it is stated that when citric acid is present, the toothpaste usually retains at least ^+0% of the original content of monofluorine etc. that after accelerated storage for 9 weeks at approx. . <1>+9°C. This statement obviously applies to a toothpaste according to the invention which, in addition to the aluminum oxide trihydrate, also contains an insoluble alkali metal metaphase etc. It was then reasonable to expect that the dental care agent C according to example 1 would have retained at least approx. 0.0^0% of the soluble monofluorophosphate as fluoride if it had contained insoluble sodium urea metaphosphate. However, the results show that the dentifrice had only retained 0.030%. The sharp decrease in the percentage retained soluble monofluorophosphate as fluoride for the dental care agent C compared to that for the dental care agent B cannot therefore be solely attributed to the fact that the dental care agent C contains 0.2% citric acid,

while toothpaste B only contains 0.1% citric acid. The strong decrease in the percentage of soluble monofluorophosphate as fluoride for dentifrice C must also be due to the fact that insoluble sodium metaphosphate is not present in dentifrice c. It is therefore justified to claim that it is of decisive importance that insoluble alkali metal metaphosphate, with or without citric acid,

is present in the dentifrices according to the invention to greatly increase the amount of retained fluoride in the dentifrices. •

EXAMPLE 2

Dentifrices corresponding to dentifrice A according to Example 1 and containing a polishing material which was varied as indicated below, were prepared and stored for several weeks at 9°C. The dentifrices' content of soluble fluoride is also indicated.

Each of these dentifrices retained a high amount of soluble fluoride,

EXAMPLE 3

A dentifrice corresponding to dentifrice B according to Example 1 and containing a polishing material which was varied as indicated below, was prepared and stored for several weeks at -9°C. The dental care product's content of soluble fluoride is also indicated.

This dentifrice also retained a high amount of above-ground insoluble monofluorophosphate as fluoride even after accelerated storage for 9 weeks at <*>+9<0>C.

EXAMPLE h

Dental care agents corresponding to the dental care agent A according to example 1 and containing a wetting agent and polishing material which was varied as indicated below, were prepared and stored for several weeks at 1+9°C. Each of the toothpastes' content of soluble fluoride is also indicated belowj

Each of these dentifrices retained a h5y amount of soluble fluoride.

Example j?

Dental care agents corresponding to the dental care agent A according to example.1

and containing Irish moss in place of sodium carboxymethyl cellulose and a wetting agent and polishing material varied as indicated below, was prepared and stored for several weeks at ^9°C. Each of the dentifrices' soluble fluoride content is also listed below:

Each of these dentifrices retained a high amount of soluble fluoride.

Example 6

Dentifrices corresponding to dentifrice B according to example 1 and containing a wetting agent and polishing material which was varied as indicated below, were prepared and stored for several weeks at M-9°C. Each dentifrice's soluble fluoride content is also listed below:

Each of these dentifrices also retained a high amount of at least approx. ^0% soluble monofluorophosphate, as fluoride, even after accelerated storage for 9 weeks at <l>f9°C.

Example 7

. Dental care agents corresponding to the dental care agent B according to example 1 and containing a polishing material without anhydrous dicalcium phosphate, the polishing material being otherwise varied as indicated below, were prepared and stored for several weeks at 1+9°C. Each dentifrice's soluble fluoride content is also listed below:

Each of these dentifrices also retained a satisfactorily high amount of fluoride even after accelerated storage for 6-9 weeks at <1>*9°C.

Claims (1)

Dentifrice comprising an α-aluminum oxide trihydrate with an average particle size of 6-9 µm and a particle size distribution of 9^-99% below 30 μm, 85-93% below 20 μm, 56-67% below 10 μm and 28-^ 0% below 5 Mtn, a water-soluble monofluorophosphate salt and as a polishing material together with the a-aluminum oxide trihydrate an insoluble alkali metal metaphosphate which is compatible with the monofluorophosphate salt, characterized in that the content of insoluble alkali metal metaphosphate and a-aluminum oxide trihydrate is 20-95% by weight of the dentifrice, that the amount of the alkali metal metaphosphate in relation to the amount of the a-aluminium oxide trihydrate is between less than 1:1 and 1:500, and that the dental care agent in addition to the polishing material consisting of alkali metal metaphosphate and a-aluminium oxide trihydrate contains 0-5% of other polishing material such as alkaline earth metal phosphates.