ORAL COMPOSITION WITH AN IMPROVED TEETH WHITENING EFFECT

Abstract: The invention provides an improved teeth whitening oral care composition containing a peroxy compound and a catalyst which is an iron compound containing pentadentate nitrogen-containing ligands in which the H-atom of the C-H group of the methylamine moiety, present in the ligands is substituted by other groups. A typical example is FeMeN4Py.

Description: "ORAL COMPOSITION WITH AN IMPROVED TEETH WHITENING EFFECT" The present invention relates to an oral composition with an improved teeth whitening effect. More particularly, it relates to an oral composition with an improved teeth whitening effect comprising, in addition to particulate abrasive cleaning agents, a safe and effective amount of peroxy compounds and certain catalysts . The use of peroxy compounds in oral care compostions has already been proposed in the prior art. Many peroxy compounds have been suggested for whitening/bleaching human teeth, and representative examples of such peroxy compounds are hydrogen peroxide, urea peroxide, organic peracids such as perphthalic acid, diperoxycarboxylic acids, 1,12- dodecanedioic peroxy acid, peroxy acetic acid and systems comprising a peroxy compound and a peroxy acid precursor which generate peroxy acetic acid in situ, such as sodium perborate and tetraacetylethylene diamine (TAED) . The use of peroxy acetic acid is suggested in particular in e.g. EP-A- 0545,594 (Colgate), which also sets out the various prior proposals, made in the art for several peroxy compounds as bleaching/whitening agent for human teeth. In our WO-A-96/05802 we have described the use of various organic peroxyacids as teethwhitening agents. We have now found that oral care compositions containing particulate abrasive cleaning agents and peroxy compounds, together with certain catalysts, defined hereinafter, provide for an improved teeth whitening effect. In our co-pending European patent application EP-A-0 909 809, filed 30 September 1998, we have described and claimed fabric bleaching systems comprising a peroxy compound and a catalyst which is an iron compound containing pentadentate nitrogen-containing ligands, in which the H-atom of the C-H group of the methylamine moiety present in the ligands are substituted by other groups. The catalyst according to the present invention provides a bleach and oxidation catalyst comprising an Fe-complex having formula (A) : [LFeX z Y q (A) or precursors thereof, in which Fe is iron in the II, III, IV or V oxidation state; X represents a coordinating species such as H 2 0, ROH, NR 3 , RCN, OH " , OOH " , OOR " , RS " , RO " , RCOO " , OCN " , SCN " , N 3 ~ , CN " , F " , Cl " , Br " , I " , O 2" , N0 3 " , N0 2 " , S0 4 2" , S0 3 2" , P0 4 3" or aromatic N donors such as pyridines, pyrazines, pyrazoles, i idazoles, benzimidazoles, pyrimidines, triazoles and thiazoles with R being H, optionally substituted alkyl or optionally substituted aryl ; n is an integer ranging from 0-3; Y is a counter ion, the type of which is dependent on the charge of the complex; q = z/ [charge Y] ; z denotes the charge of the complex and is an integer which can be positive, zero or negative; if z is positive, Y is an anion such as F " , Cl " , Br " , I " , N0 3 " , BPh 4 " , C10 4 " , BF 4 " , PF 6 " , RSO3 " , RS0 4 " , S0 4 2" , CF 3 S0 3 " or RCOO " ; if z is negative, Y is a common cation such as an alkali metal, alkaline earth metal or (alkyl) ammonium cation; and L represents a ligand of general formula (B) : R R I I R-i C N (B) R 3 R 5 which contains at least five nitrogen atoms and in which the substituent groups Rι-R 5 are independently selected from hydrogen, hydroxy, halogen, nitroso, formyl , carboxyl, and esters and salts thereof, carbamoyl, sulfo, and esters and salts hereof, sulfamoyl, nitro, amino, C 0 -C 20 - alkyl -hydroxy, C 0 -C 0 -alkyl-halogen, C 0 -C 20 -alkyl-nitroso, C 0 -C 2 o-alkyl- formyl , C 0 -C 20 -alkyl -carboxyl, and esters and salts thereof, Co -C 20 - alkyl -carbamoyl, C 0 -C 20 -alkyl-sulfo, and esters and salts hereof, C 0 -C 20 -alkyl-sulfamoyl , C 0 -C 20 -alkyl-amino, C 0 - C 20 -alkylaryl, C 0 -C 20 -alkylheteroaryl , C 0 -C 20 alkyl, C 0 -C 8 alkoxy, carbonyl-C 0 -C 6 -alkoxy, and aryl -C 0 -C 6 - alkyl , provided that Ri does not represent hydrogen. Preferably, the peroxy compound bleach is selected from hydrogen peroxide, hydrogen peroxide-liberating or - generating compounds, peroxyacids and their salts, and mixtures thereof, optionally together with peroxyacid bleach precursors, and a catalyst according to the present invention. An advantage of the Fe-complex catalysts according to the present invention is that they exhibit a remarkably high oxidation activity in alkaline aqueous media in the presence of peroxy compounds . A second advantage of the new Fe-complex catalysts of the invention is that they show good bleaching activity at a broader pH range (generally pH 6-11) than those observed for the previously disclosed iron complexes. Their performance was especially improved at a more alkaline pH. This advantage may be particularly beneficial in view of the current chalk toothpaste formulations that employ rather alkaline conditions, as well as the tendency to shift the pH during brushing from alkaline (typically, a pH of 9) to more neutral values. Another advantage is that the catalysts of the invention have a relatively low molecular weight and, consequently, are very weight-effective. Precursors of the active Fe-complex catalysts of the invention can be any iron co-ordination complex, which, during brushing, is transformed into the active iron complex of general formula (A) . Alternatively, the precursor of the Fe-complex of the invention can be a mixture of an iron salt, such as Fe(N0 3 ) 3 , and the ligand L. It is also possible that the catalyst is present mainly in the ligand for, i.e. without complexed Fe, as this also exhibits catalytic activity since any iron present in the oral cavity e.g. in the stain can complex with the ligand. A preferred class of ligands is that of compounds of general formula (B) , in which R 2 , R 3 , R 4 , R 5 are independently chosen from C 0 -C 5 alkyl substituted with nitrogen-containing heterocyclic aromatic groups, such as pyridines, pyrazines, pyrazoles, imidazoles, benzimidazoles, thiazoles, triazoles and pyrimidines, in particular pyridines, and in which the substituent group Ri represents any group other than hydrogen, e.g. hydroxy, halogen, nitroso, formyl , carboxyl, and esters and salts thereof, carbamoyl, sulfo, and esters and salts hereof, sulfamoyl, nitro, amino, C 0 -C 20 -alkyl- hydroxy, C 0 -C 2 o-alkyl-halogen, C 0 -C 20 -alkyl-nitroso, C 0 -C 20 - alkyl-formyl, C 0 -C 20 -alkyl-carboxyl , and esters and salts thereof, C 0 -C 2 o-alkyl-carbamoyl , C 0 -C 2 o-alkyl-sulfo, and esters and salts hereof, C 0 -C 2 o-alkyl -sulfamoyl , C 0 -C 2 o-alkyl- amino, C 0 -C 2 o-alkylaryl , C 0 -C 20 -alkylheteroaryl , C 0 -C 2 o alkyl, C 0 -C 8 alkoxy, carbonyl-C 0 -C 6 -alkoxy, aryl -C 0 -C 6 -alkyl , whereby the carbamoyl, sulfamoyl and amino groups are optionally further substituted by any other group. A more preferred class of ligands is that of compounds of general formula (B) , in which the substituent group Ri is selected from C 0 -C 20 alkylaryl, C 0 -C 2 o alkylheteroaryl , and C 0 - C 2 o alkyl, and in which the substituent groups R 2 , R 3 , R 4 , and R 5 are independently chosen from C 0 -C 5 alkyl substituted with a pyridine ring. Examples of preferred ligands in their simplest forms are: N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (pyridin-2 -yl) -1- aminoethane ; N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (pyridin-2 -yl) -2-phenyl - 1 -aminoethane ; N,N-bis (pyrazol-1-yl -methyl) -1, 1-bis (pyridin-2 -yl) -1- aminoethane; N,N-bis (pyrazol-1-yl -methyl) -1, 1-bis (pyridin-2 -yl) -2-phenyl - 1-aminoethane ; N,N-bis (imidazol-2 -yl -methyl) -1, 1-bis (pyridin-2 -yl) -1- aminoethane; N,N-bis (imidazol-2 -yl -methyl) -1, 1-bis (pyridin-2 -yl) -2- phenyl - 1 -aminoethane ; N,N-bis (1,2, 4-triazol-l-yl -methyl) -1, 1-bis (pyridin-2 -yl) -1- aminoethane; N,N-bis (1,2, 4-triazol-l-yl -methyl) -1, 1-bis (pyridin-2-yl) -2- phenyl - 1 -aminoethane ; N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (pyrazol-1-yl) -1- aminoethane; N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (pyrazol-1-yl) -2-phenyl* 1 -aminoethane; N,N-bis (pyridin-2-yl -methyl) -1, 1-bis (imidazol -2 -yl) -1- aminoethane; N,N-bis (pyridin-2-yl -methyl) -1, 1-bis (imidazol-2 -yl) -2- phenyl -1 -aminoethane ; N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (1, 2 , 4-triazol-l-yl) -1- aminoethane ; N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (1 , 2 , 4-triazol-l-yl) -1- aminoethane; More preferred ligands are: N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (pyridin-2 -yl) -1- aminoethane, N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (pyridin-2 -yl) -1- aminohexane , N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (pyridin-2 -yl) -2-phenyl - 1-aminoethane , N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (pyridin-2 -yl) -2- (4- sulfonic acid-phenyl) -1 -aminoethane, N,N-bis (pyridin-2 -yl -methyl) -1, 1-bis (pyridin-2 -yl) -2- (pyridin-2-yl) -1 -aminoethane, N,N-bis (pyridin-2 -yl -methyl) -1 , 1-bis (pyridin-2 -yl) -2- (pyridin-3-yl) -1 -aminoethane, N,N-bis (pyridin-2 -yl -methyl) -1 , 1-bis (pyridin-2-yl) -2- (pyridin-4-yl) -1 -aminoethane, N,N-bis (pyridin-2-yl -methyl) -1, 1-bis (pyridin-2-yl) -2- (1- alkyl-pyridinium-4 -yl ) - 1 -aminoethane , N,N-bis (pyridin-2 -yl -methyl) -1 , 1-bis (pyridin-2 -yl) -2- (1- alkyl -pyridinium-3 -yl ) - 1-aminoethane , N,N-bis (pyridin-2-yl -methyl) -1, 1-bis (pyridin-2 -yl) -2- (1- alkyl -pyridinium-2 -yl ) - 1 -aminoethane . The most preferred ligands are: N,N-bis (pyridin-2 -yl -methyl) -1 , 1-bis (pyridin-2 -yl) -1- aminoethane, hereafter referred to as MeN 4 Py, N,N-bis (pyridin-2 -yl-methyl) -1, 1-bis (pyridin-2 -yl) -2-phenyl - 1-aminoethane, hereafter referred to as BzNPy. Suitable counter ions are those which give rise to the formation of storage-stable solids. Combination of the preferred iron complexes with the counter ion Y preferably involves counter ions selected from RCOO " , BPh 4 " , C10 4 " , BF 4 " , PF 6 " , RS0 3 " , RS0 4 " , S0 4 2" , N0 3 " , F " , Cl " , Br " , I " wherein R=H, optionally substituted phenyl , naphthyl or Cι-C 4 alkyl. Preferred co-ordinating species X are selected from CH 3 CN, pyridine, H 2 0, Cl " , OR " , and OOH " , wherein R=H, optionally substituted phenyl , naphthyl or Cι-C alkyl. The composition of the invention has particular application in toothpaste formulations, to form a new and improved composition within the purview of the invention comprising a peroxy compound bleach as defined above, the aforesaid Fe- complex catalyst having general formula (A) , particulate abrasive cleaning agents. The Fe-complex catalyst will be present in the oral care composition according to the invention in amounts so as to provide the required level in the mouth. Generally, the Fe- complex catalyst level in the composition corresponds to an iron content of from 0.0005% to 0.5% by weight. When the dosage of toothpaste is relatively low, e . g. about 1-2 g/1, the Fe content in the formulation is suitably 0.0025 to 0.5%, preferably 0.005 to 0.25% by weight. At higher product dosages, the Fe content in the formulation is suitably 0.0005 to 0.1%, preferably 0.001 to 0.05% by weight. Compositions of the invention are effective over a wide pH- range of between 7 and 13, with optimal pH-range lying between 8 and 10. The peroxy compound is preferably hydrogen peroxide but it may also be a compound which is capable of yielding hydrogen peroxide in aqueous solution. Hydrogen peroxide sources are well known in the art. They include the alkali metal peroxides, organic peroxides such as urea peroxide, and inorganic persalts, such as the alkali metal perborates, percarbonates, perphosphates persilicates and persulphates . Mixtures of two or more such compounds may also be suitable. Another suitable hydrogen peroxide generating system is a combination of a Cι-C 4 alkanol oxidase and a Cι-C 4 alkanol, especially a combination of methanol oxidase (MOX) and ethanol or even a similar system such as glucose oxidase and glucose. Such combinations are disclosed in WO-A-9507972 , which is incorporated herein by reference. Organic peroxyacids may also be suitable as the peroxy bleaching compound. Such materials normally have the general formula : 0 II Y-R-C-O-OH wherein R is an alkyl- or alkylidene- or substituted alkylene group containing from 1 to about 20 carbon atoms, optionally having an internal amide linkage; or a phenylene or substituted phenylene group; and Y is hydrogen, halogen, alkyl, aryl, an imido-aromatic or non-aromatic group, a COOH or COOOH group or a quaternary ammonium group . Typical monoperoxy acids useful herein include, for example: (i) peroxybenzoic acid and ring-substituted peroxybenzoic acids, e.g. peroxy-α-naphthoic acid; (ii) aliphatic, substituted aliphatic and arylalkyl monoperoxyacids, e.g. peroxylauric acid, peroxystearic acid and N, N-phthaloylaminoperoxy caproic acid (PAP) ; and (iii) 6-octylamino-6-oxo-peroxyhexanoic acid. Typical diperoxyacids useful herein include, for example (iv) 1, 12-diperoxydodecanedioic acid (DPDA) ; (v) 1, 9-diperoxyazelaic acid; (vi) diperoxybrassylic acid; diperoxysebacic acid and diperoxyisophthalic acid; (vii) 2-decyldiperoxybutane-l , 4-dioic acid; and (viii) 4 , 4 ' -sulphonylbisperoxybenzoic acid. Also inorganic peroxyacid compounds are suitable, such as for example potassium monopersulphate (MPS) . If organic or inorganic peroxyacids are used as the peroxygen compound, the amount thereof will normally be within the range of about 2-10 % by weight, preferably from 4-8 % by weight. All these peroxy compounds may be utilized alone or in conjunction with a peroxyacid bleach precursor and/or an organic bleach catalyst not containing a transition metal . Generally, the bleaching composition of the invention can be suitably formulated to contain from 0.001 to 15% , preferably from 0.01 to 5% by weight, of the peroxy bleaching agent . Peroxyacid bleach precursors are known and amply described in literature, such as in GB-A-836988 ; GB-A-86 , 798 ; GB-A- 907,356; GB-A-1 , 003 , 310 and GB-A-1 , 519 , 351 ; DE-A-3 , 337 , 921 ; EP-A-0,185,522; EP-A-0 , 174 , 132 ; EP-A- 0 , 120 , 591 ; and US-A- 1,246,339; US-A-3 , 332 , 882 ; US-A-4 , 128 , 494 ; US-A-4 , 412 , 934 and US-A-4, 675, 393. Another useful class of peroxyacid bleach precursors is that of the cationic i.e. quaternary ammonium substituted peroxyacid precursors as disclosed in US-A-4 , 751 , 015 and US- A-4, 397, 757, in EP-A-0,284,292 and EP-A-331 , 229. Examples of peroxyacid bleach precursors of this class are: 2- (N,N,N-trimethyl ammonium) ethyl sodium-4 -sulphophenyl carbonate chloride - (SPCC) ; N-octyl ,N,N-dimethyl-Nι 0 -carbophenoxy decyl ammonium chloride - (ODC) ; 3 - (N,N,N-trimethyl ammonium) propyl sodium-4 -sulphophenyl carboxylate; and N,N,N-trimethyl ammonium toluyloxy benzene sulphonate. Any one of these peroxyacid bleach precursors can be used in the present invention, although some may be more preferred than others . Of the above classes of bleach precursors, the preferred classes are the esters, including acyl phenol sulphonates and acyl alkyl phenol sulphonates; the acyl -amides; and the quaternary ammonium substituted peroxyacid precursors. Examples of said preferred peroxyacid bleach precursors or activators are sodium-4-benzoyloxy benzene sulphonate (SBOBS) ; N, N, N 'N' -tetraacetyl ethylene diamine (TAED) ; sodium- 1 -methyl -2 -benzoyloxy benzene-4-sulphonate; sodium-4- methyl-3-benzoloxy benzoate; 2- (N,N,N-trimethyl ammonium) ethyl sodium-4 -sulphophenyl carbonate chloride (SPCC) ; trimethyl ammonium toluyloxy-benzene sulphonate; sodium nonanoyloxybenzene sulphonate (SNOBS); and sodium 3,5,5- trimethyl hexanoyl-oxybenzene sulphonate (STHOBS) . The precursors may be used in an amount of up to 12 %, preferably from 1-10 % by weight, of the composition. The preferred peroxy compound is hydrogen peroxide, and the preferred catalyst is Fe N,N-bis (pyridin-2 -yl -methyl ) -1, 1 - bis (pyridin-2-yl) -1 -aminoethane ( FeMeN4Py ) The catalyst is used generally in an amount of 0.0001 to 5 % by weight, preferably 0.025 to 1.5 % by weight, and particulary preferably 0.005 to 1 % by weight of the oral care composition. The oral compositions can be formulated in any suitable application form, such as gels, mouthwashes, toothpowders and toothpastes. An alternative product form may be an adhesive patch which fits over the tooth surface and keeps the bleaching agents in contact with the tooth surface for a short period of time, e.g. over-night. They may be formulated into a single formulation or they may be formulated for multi compartment containers into different formulations, e.g. one containing the peroxy compound and ingredients compatible therewith, and another containing the remaining ingredients. The oral care compositions of the present invention may furthermore comprise optional, conventional ingredients such as pharmaceutically acceptable carriers like starch, sucrose, water or water/alcohol systems etc.. Small amounts of surfactants may also be included, such as anionic, nonionic and amphoteric surfactants. When formulated into a dentifrice, such formulation may contain all the usual dentifrice ingredients. Thus, they comprise particulate abrasive materials such as silicas, aluminas, calcium carbonates, dicalciumphosphates, calcium pyrophosphates hydroxyapatites , trimetaphosphates, insoluble hexametaphosphates, agglomerated particulate abrasive materials and so on, usually in amounts between 5 and 60 % by weight. Furthermore, the dentifrice formulations may comprise humectants such as glycerol, sorbitol, propyleneglycol , xylitol, lactitol and so on. Binders and thickeners such as sodium carboxymethyl- cellulose, xanthan gum, gum arabic etc. may also be included, as well as synthetic polymers such as polyacrylates and carboxyvinyl polymers such as Carbopol ® . Flavours such as peppermint and spearmint oils may also be included, as well as preservatives, opacifying agents, colouring agents, pH-adjusting agents, sweetening agents and so on. Stabilising agents for the organic peroxy compounds such as dipicolinic acid or sodium stannate may also be usefully included. Anti -bacterial agents may also be included such as Triclosan, chlorhexidine, copper-, zinc- and stannous salts such as zinc citrate, sodium zinc citrate and stannous pyrophosphate, sanguinarine extract, metronidazole. Further examples of anti -bacterial agents are quaternary ammonium compounds such as cetylpyridinium chloride; bis-guanides such as chlorhexidine digluconate, hexetidine, octenidine, alexidine; halogenated bisphenolic compounds such as 2,2' methylenebis- (4-chloro-6-bromophenol) . Polymeric compounds which can enhance the delivery of active ingredients such as anti -bacterial agents can also be included. Examples of such polymers are copolymers of polyvinylmethylether with maleic anhydride and other similar delivery enhancing polymers, e.g. those described in DE-A- 3,942,643 (Colgate) Furthermore anti- inflammatory agents such as ibuprofen, flurbiprofen, aspirin, indomethacin etc. may also be included. Anti -caries agents such as sodium- and stannous fluoride, aminefluorides, monosodiumfluorophosphate, casein, plaque buffers such as urea, calcium lactate, calcium glycerophosphate, strontium polyacrylates may also be included. Other optional ingredients include vitamins such as Vitamin C, and plant extracts. Desensitising agents such as potassium citrate, potassium chloride, potasium tartrate, potassium bicarbonate, potassium oxalate, potassium nitrate as well as strontium salts may also be included. Buffers and salts to buffer the pH and ionic strength of the compositions may also be included. The pH of the compositions usually ranges from 5-10, preferably 6-9 and especially preferably 7-8.5. Liposomes and other encapsulates may also be used to improve delivery or stability of active ingredients. Furthermore, the oral compositions may comprise anti- calculus agents such as alkalimetal pyrophosphates, hypophosphite-containing polymers, organic phosphonates, alkalimetal tripolyphosphates, phosphocitrates etc.. In addition, the compositions may comprise functional biomolecules such as bacteriocins , antibodies, enzymes and so on. Other optional ingredients that may be included are e.g. effervescing systems such as sodium bicarbonate/citric acid systems, colour change systems, and so on. The compositions may also contain a bleach precursor. When formulated as a mouthwash, the oral care composition usually comprises a water/alcohol solution, flavour, humectant, sweetener and colorant. The invention also includes the use of the combination of a peroxy compound and a catalyst according to the invention as teeth whitening effect. The present invention will further be illustrated by way of Example . Example I Tea-stained and saliva-coated cotton (to mimic a tooth surface) were treated with 1 part of composition A,B, or C, and sterile saliva (2 parts) for 30 seconds. The colour of the cotton was measured before and after treatment using a flat bed scanner and image analysis software. The changes in colour were expressed as follows: Delta L* = L* (post treatment) L* (Pre treatment) The following results were obtained: p < 0.0005 Example 2 The catalyst was further evaluated as follows Synthetic hydroxyapatite discs (an alternative mimic of the tooth surface) were polished and placed in sterile saliva overnight to form a pellicle. They were then stained by immersing in a tea/coffee mixture for four days before being immersed in experimental bleach solutions. The change in colour of the discs was measured using a Minolta chromameter and the percentage stain removal was calculated. Example 3 Double Pump Bicarbonate Paste Composition Peroxide Gel Composition PAP Composition Example 4 Encapsulated Formulation

Claims: Claims : 1. An oral care composition with an improved teeth whitening effect comprising particulate abrasive cleaning agents, a peroxy compound and a catalyst for the peroxy compound characterised in that the catalyst is an iron compound containing pentadentate nitrogen- containing ligands, in which the H-atom of the C-H group of the methylamine moiety, present in the ligands is substituted by other groups. 2. A composition according to claim 1, characterised in that the catalyst is FeMeN4Py. 3. An oral care composition according to claim 1 or 2 , characterised in that the peroxy compound is selected from the group consisting of hydrogen peroxide, hydrogen peroxide liberating agents, peroxyacids and mixtures thereof . 4. An oral care composition according to any preceding claim, characterised in that the FeMeN4Py is present in the formulation at from 0.0005 to 0.5% by weight. 5. An oral care composition according to any preceding claim, characterised in that the peroxy compound is hydrogen peroxide and comprises from 0.001 to 5% by weight of the composition. 6. An oral care composition according to any preceding claim, characterised in that the peroxy compound is urea peroxide and comprises from 0.001 to 15% by weight of the composition. 7. An oral care composition according to any preceding claim, characterised in that the peroxy compound is hydrogen peroxide liberating agent and comprises from 0.001 to 60% by weight of the composition. 8. Oral care composition comprising at least two independently stored formulations, characterised in that one formulation comprises the peroxy compound of any preceding claim and another formulation comprises a catalyst according to any preceding claim and wherein the independently stored formulations are dispensed simultaneously and come into contact with each other prior to brushing. 9. Use of a peroxy compound and a catalyst according to claim 1 as teeth whitening agent .

Inventors: JOINER ANDREW, THORNTWHAITE DAVID WILLIAM, JOINER, ANDREW, THORNTWHAITE, DAVID, WILLIAM
Applicants: JOINER ANDREW, LEVER HINDUSTAN LTD, THORNTWHAITE DAVID WILLIAM, UNILEVER NV, UNILEVER PLC, HINDUSTAN LEVER LTD, JOINER, ANDREW, THORNTWHAITE, DAVID, WILLIAM, UNILEVER N.V.
Application year: 2000
Main classification: A61K7
IPC codes: A61K8, A61Q11