GB2095694A - Tooth cleaning compositions - Google Patents

Abstract

Solids compositions comprising a diphosphonic acid, or a salt thereof, and a compound which releases oxygen with effervescence on contact with water, can be formulated as powders or tablets for cleaning teeth and, in particular, dentures.

Description

SPECIFICATION Tooth cleaning compositions This invention relates to compositions which can be used for cleaning teeth and, in particular, dentures.

Denture-cleaning compositions are often provided in tablet or powder form, for addition to water in which dentures are stored, e.g. overnight. Known denture-cleaning compositions may be alkaline or acidic. Known acidic compositions comprise, for example, potassium monopersulphate and sodium monohydrate perborate. Such composition are effective in removing tartar and plaque deposits.

However, the reaction of a monopersulphate with an alkali metal chloride causes the evolution of chlorine. The compositions may therefore leave an acidic or evolved chlorine after-taste, and may cause exposed metal parts to corrode, A further disadvantage of such compositions is that they may cause rapid restain.

Known alkaline denture-cleaning compositions comprise oxidising agents which effectively bleach stains and film which form on dentures, and components which provide active effervescent oxygen which agitates and sterilises the dentures. Such compositions may comprise, for example, an alkali metal monohydrate perborate and an alkali metal orthophosphate. However, such compositions do not readily dissolve tartar and plaque deposits.

It is known to add sequestering agents to alkaline compositions of the type described. Calgon (registered Trade Mark) and ethylenediaminetetraacetic acid and its salts have been used for this purpose. Such agents have the advantage that they render the composition clear when added to water.

This may make the compositions more acceptable to consumers, and may prevent deposition of calcium salts, but the known sequestering agents do not generally dissolve such salts.

British Patent Specification No. 1,1 10,987 discloses ethane-1 -hydroxy-1 ,1 diphosphonic acid as an anti-calculus agent. British Patent Specification Nos. 1,160,640 and 1,263,934 disclose other diphosphonic acids, and salts thereof, for use in tooth cleaning, i.e. toothpaste, compositions.

Ethane-1-hydroxy-1,1-diphosphonic acid (also known as acetyldiphosphonic acid) and its salts have been used, in solution, to remove lime scale from boilers and pipes. US Federal Drug Administration (tDA) regulations may allow the use of such compounds in live steam for contact with foodstuffs. However, there has been no previous indication that such compounds could be successfully used In solid form for cleaning dentures, nor has there been any denture cleaning composition which satisfactorily removes the predominantly calcium phosphate-containing plaque/tartar/calculus on dentures, which is usually mixed in a crystal-type latice with desquamated epithelial cells, food debris and microorganisms.

A solid composition according to the present invention comprises a diphosphonic acid, or a salt thereof, and a compound which releases oxygen with effervescence on contact with water, The compositions of the invention may be formulated, for example, as tablets or powders. On addition to water, oxygen is evolved with effervescence, causing bleaching of stains and films on dentures in the water and the diphosphonic acid of its salt provides tartar/plaque removal. The effervescence promotes rapid dissolution of soluble ingredients in the composition and rapid and uniform distribution of dissolved materials in water. If the composition is in tablet form, the tablet disintegrates quickly. The evolved oxygen has beneficial bactericidal proprties. The compositions are usually alkaline and this assists their bactericidal properties.

The diphosphonic acid, or salt thereof, may be any of those described in British Patent Specifications Nos, 1,1 10,987, 1,160,640 and 1,263,934. Preferably, acetyldiphosphonic acid, or an alkali metal, e.g. the sodium, salt, thereof, is used. The amount of this component in a composition of the invention is usually from 1 to 50, and more preferably from 2 to 30, e.g. about 10, 96 by weight.

The oxygen-releasing compound may be of the type which has previously been used in alkaline denture-cleaning compositions. This compound preferably comprises a perborate. Hydrated perborates, suitably of alkali metals, e.g. sodium perborate monohydrate, may suitably be used. However, if an anhydrous perborate is included in the composition, then this will react and break up faster in an aqueous environment, providing more rapid dispersal of the disphonate. Most preferably, the oxygenreleasing compound comprises a mixture of hydrated and anhydrous perborate, e.g. sodium perborate monohydrate and anhydrous sodium perborate.

The weight of the oxygen-releasing compound or compounds in the composition is usually from 30 to 90, and most preferably from 40 to 85, 96 by weight of the composition. The amount of anhydrous perborate is usually from 20 to 100, and preferably from 30 to 60, 96 by weight of the total perborate content.

A composition of the invention is preferably such that it can provide a pH of at least 9, e.g. 10 to 12, when dissolved in water. The recommended amount of the composition for such purpose may be from 5 to 30 g/l, and this may comprise one or two tablets of the composition. It has been found that the disodium salt of acetyl-diphosphonic acid actively attacks calcium salts at a pH of 10 to 12, e.g. 1 g of the salt dissolves 0.8 g calcium carbonate. It is this property which causes marked dissolution and softening of tartar/plaque build-up on contaminated dentures. This effect allows, not only actual dissolution, but easier removal on light brushing and rinsing, owing to softening.

A composition of the invention may comprise materials further to those described above. Such additional materials may be, for example, buffers to ensure long-term storage stability and/or bulking agents. A suitable material which serves both purposes is tri-sodium orthophosphate. Such a material may be included in the composition of the invention in an amount of, for example, 5 to 6 96 by weight.

P articularly when a composition of the invention is provided in tablet form, the composition may comprise a binding agent. Suitable binding agents are talc and mineral oil. The total amount of such a material will not usually exceed 5 % by weight; the amount may be, for example, 1 96 by weight The following Example illustrates a table formulation of the present invention.

% w/w Trisodium Orthophosphate 34.00 Sodium Perborate Anhydrous 20.0 Sodium Perborate Monohydrate 32.0 Sodium Lauryl Sulphate 0.14 Sodium Carbonate Anhydrous 2.12 Disodium Salt of Acetyldiphosphonic acid 9.74 Colour 0.025 Flavour 0.10 Pressing Aids 1.875 The given compounds were compounded into tablets.

Claims (9)

1. A solid composition which comprises a diphosphonic acid, or a salt thereof, and a compound.

which releases oxygen with effervescence on contact with water.

2. A composition according to claim 1 which comprises acetyldiphosphonic acid or an alkali metal salt thereof.

3. A composition according to claim 1 or claim 2, which comprises from 1 to 50 96 by weight of the diphosphonic acid or salt.

4. A composition according to any preceding claim, in which the oxygen-releasing compound is a perborate.

5. A composition according to claim 4, in which the oxygen-releasing compound comprises a mixture of hydrated and anhydrous perborates.

6. A composition according to any preceding claim, which comprises from 30 to 90 96 by weight of the oxygen-releasing compound.

7. A composition according to any preceding claim, which, when dissolved in water provides a pH of at least 9.

8. A composition according to any preceding claim, in tablet form.

9. A composition according to claim 1, substantially as described in the Example.