GB1560913A - Dentifrices - Google Patents

Description

(54) DENTIFRICES (71) We, UNILEVER LIMITED, a British company, of Unilever House, Blackfriars, London EC4, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to dentifrices and more particularly to those containing an anti-caries agent.

It is well known to include an anti-caries agent in a toothpaste and such agents that have found commerical application include the ionic fluorides sodium fluoride and stannous fluoride, sodium monofluorophosphate and sodium trimetaphosphate. These materials react with tooth mineral reducing its solubility in an acidic medium.

We have now discovered that further materials useful for inclusion in dentifrices as a means of inhibiting acidic attack on dental enamel are alkali metal salts of cyclic tetrametaphosphoric acid, such as the sodium and potassium salts.

Accordingly the invention relates to a dentifrice containing from 0.5% to 5010, preferably l No to 4%, by weight of an alkali metal tetrametaphosphate.

The dentifrice of the invention may be in the form of a powder, paste or tablet, mouthwash or rinse, liquid dentifrice or chewing gum.

In dentifrice compositions in the form of a paste, powder or tablet, a dentally acceptable water-insoluble abrasive or polishing agent is usually the major ingredient and is present in amounts of from about 20% to 95% in toothpowders and 20% to 75% in tablets and toothpaste or cream. Examples of suitable abrasive cleaning agents are silicia xerogels, insoluble sodium metaphosphate, dicalcium phosphate, tricalcium phosphate, hydrated alumina, calcium carbonate and synthetic resins. These materials usually have an average particle size in the range 0.1 to 30 microns.

Preferred abrasives are the silica xerogels, insoluble sodium metaphosphate and synthetic resins, and mixtures thereof. The silica xerogels, which have relatively recently found commerical application in dentifrices, are described in US Patent Specifications Nos. 3,538,230 and 3,689,637, and UK Patent Specification No. 1,419,692.

Suitable resin abrasives are also described in UK Patent Specification No. 1,419,692.

Dentifrices in paste form will include a liquid medium usually comprising a mixture of water and a humectant material such as glycerine or sorbitol syrup. The liquid medium amounts to 20% to 70% by weight of the toothpaste, the humectant amounting to about 15% to 40% by weight of the toothpaste. Gelling or thickening agents, for example from 0.5% to 10% by weight, such as Irish moss, gum tragacanth, sodium carboxymethylcellulose and synthetic clays, are usually included in dentifrice pastes.

In addition to the tetrametaphosphate, the dentifrice of the invention may include other anti-caries agents such as sodium fluoride, stannous fluoride, sodium monofluorophosphate, these being preferably in a amounts corresponding to 500 to 1,500 ppm of fluorine by weight of the dentifrice, or sodium trimetaphosphate, the latter being used in an amount of from about 0.5% to 6% by weight The pH of the dentifrice is desirably 5.5 to 8.0, preferably 6.0 to 7.5.

Dentifrice pastes may contain other optional ingredients such as surface active agent, flavouring agent, sweetening agent, as is well known in the art.

Table 1 gives examples of toothpastes according to the invention. Percentages are by weight.

TABLE 1 Ingredient % Example I II III IV V VI VII VIII IX X XI Silica xerogel 13.0 13.0 10.0 10.0 - - 13.0 - - - 10.3 Silica aerogel 6.0 6.0 11.0 11.0 - - 6.0 - - - 11.0 Hydrated alumina - - - - 50.0 50.0 - 45.0 - - Dicalcium phosphate dihydrate - - - - - - - - 31.0 31.0 Chalk - - - - - - - - 12.0 12.0 Sodium dihydrogen phosphate - - - - 0.5 0.5 - 0.5 - - Sorbitol (70%) - - 27.0 27.0 27.0 27.0 - 27.0 27.0 - 27.0 Glycerol 40.0 35.0 - - - - 40.0 - - 30.0 Titanium dioxide 0.5 0.5 0.5 0.5 1.0 1.0 0.5 1.0 1.0 1.0 0.5 Sodium carboxymethylcellulose 0.4 0.4 0.4 - 0.4 0.4 - - - - 0.4 Sodium caragheenate - - - 1.6 - - 1.5 0.9 0.9 1.5 Sodium lauryl sulphate 1.5 1.0 1.5 1.0 1.5 1.5 - 1.5 1.5 1.5 1.5 Sodium benzene dodecyl sulphate - 0.5 - 0.5 - - - - - - Polyethylene glycol - - - - - - 5.0 - - - Saccharin 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Flavour 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Sodium tetrametaphosphate 3.0 1.0 3.0 3.0 3.0 3.0 1.0 1.0 3.0 3.0 3.0 Sodium monofluorophosphate - - - - - - - - - - 0.8

Water # to 100.0 # The effect on the solubility of the material of tooth enamel by acid by pretreatment thereof with sodium tetrametaphosphate was determined in the following manner.

Calcium hydroxyapatite (referred hereafter as HAP) having a molar Ca/P ratio of 1.614 was treated with a 5 mM solution of sodium tetrametaphosphate for 17 hours (1 g of HAP to 200 ml of solution) after which the solid was drained, washed with water and dried in a vacuum desiccator. The pretreated HAP was agitated in acetate buffer solution at pH 4.7 for 16 hours and after filtration the filtrate was analysed for calcium and phosphate content. The exeriment was repeated using water as a pretreatment medium instead of the solution of sodium tetrametaphosphate.

The results are given in Table 2 below.

TABLE 2.

Dissolved in Buffer Treatment ,ug Ca/ml ,ug P/ml 5 mM sodium tetrametaphosphate 449.4 169.0 Water 666.0 284.0 This experiment clearly shows the inhibiting effect that treatment with sodium tetrametaphosphate has on the solubility of tooth mineral by acid.

Claims (4)

WHAT WE CLAIM IS:

1. A dentifrice containing from 0.5% to 5% by weight of an alkali metal salt of a cyclic tetrametaphosphate.

2. A dentifrice as claimed in claim 1 containing from 1% to 4% by weight of the tetrametaphosphate.

3. A dentifrice as claimed in claim 1 or claim 2, wherein the salt is the sodium or potassium salt.

4. A dentifrice substantially as herein described with reference to any of the Examples.