WO2006005420A1

WO2006005420A1 - Tooth whitening composition

Info

Publication number: WO2006005420A1
Application number: PCT/EP2005/006759
Authority: WO
Inventors: Stephane Lefort
Original assignee: Unilever N.V.; Unilever Plc; Hindustan Lever Limited
Priority date: 2004-07-15
Filing date: 2005-06-22
Publication date: 2006-01-19

Abstract

Tooth whitening composition comprising water, a polycarboxylic acid structurant and a tooth whitening agent, characterised by a monofluorophosphate salt.

Description

TOOTH WHITENING COMPOSITION

The present invention relates to a composition for whitening the teeth.

WO 91/14650 (Ultradent) discloses a dental composition for treating teeth surfaces. The compositions disclosed therein aarree hhiigghh vviissccoossiittyy ccoommppoossiittiioo:ns which comprise either bleaching agents or fluoride.

WO 00/28955 (3M) discloses dental whitening compositions of high viscosity optionally comprising adjuvants such as fluoride.

US 2002/0155070 Al (Chen) discloses dental bleaches which may comprise, as desensitizing agent, sodium fluoride.

US 4 687 663 (Schaeffer) discloses an oral composition comprising sorbitol, water, Veegum^® and sodium fluoride. The disclosure also includes several other formulations comprising Carbopol^® instead of Veegum^®. However, none of these also comprises sodium fluoride.

US 5 217 710 (Williams) discloses an oral composition for whitening the teeth comprising Lutrol F127^® as structurant and sodium monofluorophosphate as flouride ion source. In Table III is shown how a formulation comprising sodium monofluorophosphate, hydrogen peroxide and Pluronic F127 is inherently unstable with no peroxide being recovered in stability trials. Despite the prior art their remains a need to provide superior, stable whitening compositions for the teeth and the inventor has found that monofluorophosphate salts have an unexpected stabilising effect in whitening compositions according to the invention.

The present invention provides a tooth whitening product according to claim 1.

Suitable fluoride salts include the monofluorophosphates, especially the alkali-metal monofluorophosphates such as sodium monofluorophosphate. Preferably, from 500 to 2000 ppm, more preferably from 700 to 1700 ppm and most preferably 800 to 1600 ppm of a free fluoride ion is added as a monofluorophosphate salt. Typically, 1450 ppm is generated by sodium monofluorophosphate at 1.11% by weight of the composition.

The composition of the invention preferably comprises water at from 10 to 70% by weight, preferably from 25 to 60% by weight and especially preferably from 35 to 45% by weight.

The composition also comprises a tooth whitening agent which is preferably a bleaching material. Preferred bleaching materials include those which are capable of generating peroxyl radicals in water. Examples include hydrogen peroxide and carbamide peroxide. Other examples include N- phthalimido hexanoic peroxy acid (PAP) . Preferably, and where the tooth whitening agent is a bleaching agent selected from hydrogen peroxide or carbamide peroxide, it is present at from 1 to 30% by weight of the invention, preferably from 10 to 20% by weight and more preferably from 13 to 18% by weight.

The composition also comprises a polycarboxylic acid structurant. The structurant is preferably present at from 1 to 30% by weight depending on the material used. The most preferred structurant is Carbopol^® 980 because it provides a tackiness to the product which improves its stickiness to the oral hard surfaces and retains the bleaching agent at the surface for up to three minutes after application. It also provides the most optimal conditions for monofluorophosphate to exert its stabilising benefit.

The composition may also comprise a humectant. Preferably, such humectant is compatible with a peroxide generating species. Examples include glycerine, propylene glycol and short chain polyethylene glycols. Such short chain polyethylene glycols include those with a chain length comprising 400 repeating units or less, e.g. PEG 200 and PEG 400. The most preferred humectant is glycerine. The humectant is present at from 20 to 65%, more preferably from 30 to 50% and especially preferably 40% by weight of the composition. In a most preferred embodiment the humectant and water together comprise from 60 to 90%, preferably from 75 to 85% by weight of the composition.

Preferably, said composition has a viscosity of from 40 000 to 300 000 centipoise measured on a Brookfield viscometer at 25°C, at 5 rpm and with a TA spindle. More preferably the viscosity as measured in the same way is from 140 000 to 220 000 cps. Preferably, the composition according to the invention has a pH preferably ranging from 4.5 to 7.5, preferably from 4.5 to 6 and especially from 5 to 5.5. A pH of from 5 to 5.5 is particularly preferable where the composition comprises as structurant Carbopol^® at from 0.5 to 2% by weight of the composition. This careful balancing of the pH enables the composition to have just the right viscosity to allow for

•if-" optimal application to the surfaces in the oral cavity without being too sticky and without being too fluid.

The composition may also comprise a buffering agent such as ammonium or sodium hydroxide. These may be present at from 0.15 to 0.6 % by weight of the composition in order to maintain the pH accordingly.

The composition is preferably visually clear by which is meant that it scores-3 or more on a font card, i.e. that through a 1 ml cuvette a font of size -3 can be read.

The composition is also preferably colourless. This is beneficial since the product is gradually washed away within a few minutes of application and it would be undesirable for a coloured product to remain visible between the teeth thereafter.

Preferably, the oral composition according to the invention is a leave-on product, i.e. one which is intended to be applied to the teeth and then left for a period of time before being rinsed by salivation and mechanical discruption. This is in contrast to most of the prior art compositions which are to be applied to the teeth as part of a brushing regime and are rinsed off shortly after.

The oral composition according to the invention may also comprise further ingredients which are common in the art, such as:

antimicrobial agents, e.g. Triclosan, chlorhexidine, copper-, zinc- and stannous salts such as zinc citrate, zinc sulphate, zinc glycinate, sodium zinc citrate and stannous pyrophosphate, sanguinarine extract, metronidazole, quaternary ammonium compounds, such as cetylpyridinium chloride; bis-guanides, such as chlorhexidine digluconate, hexetidine, octenidine, alexidine; and halogenated bisphenolic compounds, such as 2,2' methylenebis- (4-chloro- 6-bromophenol) ;

anti-inflammatory agents such as ibuprofen, flurbiprofen, aspirin, indomethacin etc.;

plaque buffers such as urea, calcium lactate, calcium glycerophosphate and strontium polyacrylates;

vitamins such as Vitamins A, C and E;

plant extracts;

desensitising agents, e.g. potassium citrate, potassium chloride, potassium tartrate, potassium bicarbonate, potassium oxalate, potassium nitrate and strontium salts; - S -

anti-calculus agents, e.g. alkali-metal pyrophosphates, hypophosphite-containing polymers, organic phosphonates and phosphocitrates etc. ;

biomolecules, e.g. bacteriocins, antibodies, enzymes, etc.;

flavours, e.g. peppermint and spearmint oils;

proteinaceous materials such as collagen;

preservatives;

opacifying agents;

colouring agents;

pH-adjusting agents;

sweetening agents;

pharmaceutically acceptable carriers, e.g. starch, sucrose, water or water/alcohol systems etc.;

surfactants, such as anionic, nonionic, cationic and zwitterionic or amphoteric surfactants;

particulate abrasive materials such as silicas, aluminas, calcium carbonates, dicalciumphosphates, calcium pyrophosphates, hydroxyapatites, trimetaphosphates, insoluble hexametaphosphates and so on, including agglomerated particulate abrasive materials, usually in amounts between 3 and 60% by weight of the oral care composition.

humectants such as glycerol, sorbitol, propyleneglycol, xylitol, lactitol etc.;

binders and thickeners such as sodium carboxymethyl- cellulose, xanthan gum, gum arabic etc. as well as synthetic polymers such as polyacrylates and carboxyvinyl polymers such as Carbopol^®;

polymeric compounds which can enhance the delivery of active ingredients such as antimicrobial agents can also be included;

buffers and salts to buffer the pH and ionic strength of the oral care composition; and

other optional ingredients that may be included are e.g. bleaching agents such as peroxy compounds e.g. potassium peroxydiphosphate, effervescing systems such as sodium bicarbonate/citric acid systems, colour change systems, and so on.

Liposomes may also be used to improve delivery or stability of active ingredients.

The composition may be in any form common in the art, e.g. toothpaste, gel, mousse, aerosol, gum, lozenge, powder, cream, etc. and may also be formulated into systems for use in dual-compartment type dispensers. A second aspect of the invention provides for a kit comprising a composition according to the first aspect and an applicator for applying said composition to the surfaces of the tooth.

The kit preferably comprises a single container and a plurality of applicators, preferably from 5 to 50 applicators. The most preferred number is applicati corresponding to a four week application schedule.

The container according to the kit of the invention is typically a jar or plastic receptacle of between 5 and 50 ml in volume.

Preferably the applicator is made from a natural material such as wood pulp, paper or cotton.

A third aspect of the invention provides for a method of whitening the teeth using a kit according to the second aspect of the invention, said method characterised by the following steps:

(a) taking said applicator and composition from said kit and applying said composition to the surface of the area of the teeth to be whitened;

(b) maintaining the mouth open for from 20 to 50 seconds such that the composition only remains in touch with the tooth surface to which it was applied;

(c) closing the mouth. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material ought to be understood as modified by the word 'about' .

The term 'comprising' is meant not to be limiting to any subsequently stated elements but rather to encompass non- specified elements of major or minor functional importance. In other words the listed steps, elements or options need not be exhaustive. Whenever the words 'including' or

'having' are used, these terms are meant to be equivalent to 'comprising' as defined above.

Embodiments according to the invention shall now be discussed with reference to the following non-limiting examples.

EXAMPLE

A formulation is provided according to the composition of the invention. It is made by normal processes.

EXAMPLE 2

To measure the inherent stability in the leave-on whitening gel product we analysed the time to liquefaction at 90⁰C.

A leave-on gel product according to Example 1 comprising 1000 ppm sodium monofluorophosphate took 18 hours to liquefaction at 90⁰C while the same formulation with 1000 ppm sodium fluoride instead of sodium monofluorophosphate took 12 hours.

Accordingly, the improved stability of the leave-one gel is due to the surprising effect of SMFP.

Claims

1. Tooth whitening composition comprising water, a polycarboxylic acid structurant and a tooth whitening agent, characterised by a monofluorophosphate salt.

2. Tooth whitening composition according to claim 1, wherein the composition comprises from 500 to 2000 ppm of a free fluoride ion added as a monofluorophosphate salt.

3. Tooth whitening composition according to claim 1 or 2, wherein the monofluorophosphate salt is an alkali-metal monofluorophosphate salt.

4. Tooth whitening composition according to any preceding claim, wherein the monofluorophosphate salt is sodium

. monofluorophosphate.

5. Tooth whitening composition according to any preceding claim, wherein the composition comprises from 10 to 70% by weight water.

6. Tooth whitening composition according to any preceding claim, wherein the composition has a pH. of from 4.5 to

7.

7. Tooth whitening composition according to any preceding claim, wherein the composition comprises a buffering agent selected from ammonium hydroxide and sodium hydroxide.

8. Tooth whitening composition according to any preceding claim, wherein the composition is visually clear.

9. Tooth whitening composition according to any preceding claim, wherein the composition comprises a humectant selected from glycerine, propylene glycol and short chain polyethylene glycols.