Effervescent whitening dentifrice having oxygen-derived sensory signal

An effervescent two component whitening dentifrice composition is disclosed which comprises a first component containing a peroxide compound such as hydrogen peroxide and a second dentifrice component containing a mixture of iron and copper salts such as FeSO.sub.4 and CaSO.sub.4, which when the two components are combined and mixed upon application to the teeth provides an effervescent sensory signal concomitant with whitening of the teeth.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates generally to a two component effervescent dentifrice
 wherein, upon mixing of the separate components during brushing,
 significantly enhanced consumer perceived sensory sensations are provided
 which instill the consumer a perception of enhanced cleaning performance,
 and more particularly to a two component peroxide containing oral
 composition that provides enhanced sensory cues as well as providing a
 tooth whitening benefit.
 2. The Prior Art
 A tooth is comprised of an inner dentin layer and an outer hard enamel
 layer that is the protective layer of the tooth. The enamel layer of a
 tooth is naturally an opaque white or slightly off-white color. It is this
 enamel layer that can become stained or discolored. The enamel layer of a
 tooth is composed of hydroxyapatite mineral crystals that create a
 somewhat porous surface. It is believed that this porous nature of the
 enamel layer is what allows staining agents and discoloring substances to
 permeate the enamel and discolor the tooth.
 Many substances that a person confronts or comes in contact with on a daily
 basis can "stain" or reduce the "whiteness" of one's teeth. In particular,
 the foods, tobacco products and fluids such as tea and coffee that one
 consumes tend to stain one's teeth. These products or substances tend to
 accumulate in the protein pellicle enamel layer of the tooth. These
 staining and discoloring substances can then permeate the enamel layer.
 This problem occurs gradually over many years, but imparts a noticeable
 discoloration of the enamel of one's teeth.
 There are available in the marketplace oral compositions for home use which
 contain 1-3% by weight concentrations of a peroxide compounds such as
 hydrogen peroxide and when applied on the teeth effect whitening.
 Illustrative of oral compositions containing peroxygen compounds for
 whitening teeth include U.S. Pat. Nos. 5,766,574 and 5,648,064.
 U.S. Pat. No. 5,766,574 discloses dual component whitening dentifrice which
 comprises a first dentifrice component containing a peroxide compound such
 as urea peroxide and a second dentifrice component containing an abrasive
 such as alumina or silica which is incompatible with the peroxide, the
 first and second dentifrice components being maintained separate from the
 other until dispensed and combined for application to teeth requiring
 whitening.
 U.S. Pat. No. 5,648,064 discloses a two component whitening dentifrice
 composition which discloses a first component containing a peroxygen
 compound such as hydrogen peroxide and a second dentifrice component
 containing a manganese coordination complex compound such as manganese
 gluconate, which activates the peroxygen compound and accelerates the
 release of active oxygen for rapid whitening action, the first and second
 components being maintained separate from the other until dispensed for
 application to teeth.
 Further, it is known that bicarbonate-acid mixtures in toothpaste
 compositions will create an effervescent effect and that such effervescent
 effect can provide certain sensory and tooth cleaning benefits. For
 example, U.S. Pat. No. 5,885,871 discloses a two component effervescent
 dentifrice composition wherein the effervescent signal produced by the
 dentifrice derives form the evolution of carbon dioxide upon the mixing of
 a high alkaline pH paste (pH range 8-9) and a low acid pH (pH 2-4) gel.
 There is an ongoing need for new and novel sensory benefits to promote the
 use of dentifrices and particularly in dentifrices used in the tooth
 whitening.
 SUMMARY OF THE INVENTION
 In accordance with the present invention there is provided, an effervescent
 peroxide containing oral composition for whitening of teeth wherein there
 is provided a two component composition of separate unmixed phases
 comprised of (a) a first component containing a water soluble peroxide
 compound contained in an orally acceptable vehicle and unmixed (b) a
 second component containing a mixture of iron and copper salts in an
 orally acceptable vehicle in an amount effective to activate the peroxide
 compound and accelerate the release of active oxygen, the two phases being
 combined shortly before application to the teeth wherein the iron and
 copper salts interact with the peroxide constituent to accelerate the
 breakdown and rapid release of active oxygen from the peroxide compound,
 such rapid release being effective for whitening teeth and instilling in
 the consumer a perception of enhanced product performance.
 DETAILED DESCRIPTION OF THE INVENTION
 In the practice of the present invention the first peroxide containing
 dentifrice component is a gel containing the peroxide ingredient and is
 formulated using a vehicle containing water, humectant, a peroxide
 compound as the whitening agent and a thickener such as a
 polyoxyethylene/polyoxypropylene block copolymer.
 The amount of peroxide compound incorporated in the first gel component of
 the two component oral composition of the present invention will vary
 dependent upon its intended use. For use by trained professionals in
 office treatments, the concentration of peroxygen compound incorporated in
 the oral composition can vary from about 5 to about 30% by weight. For
 home use, such high concentrations of peroxide compounds cannot be used
 safely by the typical consumer and therefore the useful range of peroxide
 compound when the oral composition is a paste, gel or rinse is between 0.1
 to 6.0% by weight. The preferred range is between about 0.5 to about 2.0%
 by weight.
 Glycerin, and polyethylene glycol in combination with water are useful in
 formulating the vehicle for the whitening component of the dentifrice
 composition of the present invention. A combination of glycerine,
 polyethylene glycol and water is preferred as the vehicle in which the
 other ingredients of the peroxide component are contained.
 Illustrative of polyethylene glycols useful in the practice of the present
 invention include polyethylene glycols known by the trademark Carbowax
 which are nonionic polymers of ethylene oxide having the general formula:
EQU HOCH.sub.2 (CH.sub.2 OCH.sub.2).sub.n CH.sub.2 OH
 wherein n represents the average number of oxyethylene groups. The Carbowax
 polyethylene glycols are designated by a number such as 400, 600, 800,
 etc. which represents the average molecular weight. The average molecular
 weight of the polyethylene glycols used in the practice of the present
 invention is about 200-2000, preferably 400-800 and most preferably 600
 (PEG 600).
 Glycerin and polyethylene glycol is included in the peroxide dentifrice
 component of the present invention in an amount of from about 20 to about
 50% by weight and preferably about 30 to about 45% by weight. Water is
 incorporated in the peroxide whitening dentifrice compositions of the
 present invention at a concentration of about 20 to about 50 by weight of
 the composition and preferably about 25 to about 40% by weight.
 Thickening or gelling agents used in the formulation of the peroxide
 whitening dentifrice component include polyoxyethylene/polyoxypropylene
 block copolymers. Illustrative of polyoxyethylene/polyoxypropylene block
 copolymers useful in the practice of the present invention include block
 copolymers having the formula
EQU HO(C.sub.2 H.sub.4 O).sub.b (C.sub.3 H.sub.6 O).sub.a (C.sub.2 H.sub.4
 O).sub.b H
 wherein a is an integer such that the hydrophobic portion (moiety)
 represented by (C.sub.3 H.sub.6 O) has a molecular weight of about 2750 to
 4000, b is an integer such that the hydrophilic portion represented by
 (C.sub.2 H.sub.4 O) constitutes about 70-80% by weight of the copolymer.
 Block copolymers of this composition are available commercially under the
 trademark Pluronic F type. Pluronic F127, which has a molecular weight of
 4000 and contains 70% of the hydrophilic C.sub.2 H.sub.4 O moiety is
 preferred in the practice of the present invention.
 The thickening agent is preferably present in the peroxide dentifrice
 component in an amount within the range of about 10 to about 30% by weight
 and about 15 to 25% by weight is preferred.
 The peroxide containing component is normally applied to the teeth in the
 form of an aqueous gel. The peroxide gel may be prepared by suspending the
 peroxide ingredient in the vehicle heated to a temperature of 45 to
 140.degree. C. by mixing in any suitable mixer, such as a Lightening mixer
 for about 30 minutes until a homogeneous solution is formed. A
 substantially rigid, non-fluid gel product is obtained upon cooling.
 The dentifrice component in which an abrasive material is included is
 generally prepared using a vehicle which contains water, humectant,
 surfactant and thickener.
 The humectant is generally a mixture of humectants, such as glycerin and
 sorbitol but other mixtures of humectants and single humectants may also
 be employed.
 The humectant content is in the range of about 15% to about 30% by weight
 and preferably about 10 to about 20% by weight. The water content is in
 the range of about 10 to about 20% by weight.
 The iron and copper salts respectively are present in the second component
 of the two phase whitening oral composition of the present invention at a
 weight ratio of 0.5:2.0 to 2.0 to 0.5 and preferably 1:1, such ratio being
 dependent upon the amount of peroxide compound incorporated in the first
 component. When the whitening oral composition is to be used by trained
 professionals and the first component contains relatively high
 concentrations of a peroxide compound, e.g., 5 to 35% by weight, the
 amount of iron and copper salts incorporated in the second component will
 range between about 1.0 to about 3% by weight and preferably between 1.5
 to 2.0% by weight. For home use oral compositions in which the
 concentration range of peroxide compound in the first oral composition
 component is between about 0.1 to about 3.0% by weight, lower
 concentrations, e.g., between about 0.01 to about 1.0% by weight of iron
 and copper salt mixture is included in the second component and preferably
 about 0.03 to about 0.07% by weight.
 To prepare the paste dentifrice component, polishing agents or abrasives
 are incorporated in the component and preferred polishing agents are
 siliceous materials, such as silica, which have a mean particle size up to
 about 20 microns. A preferred silica is a precipitated amorphous hydrated
 silica, such as that marketed under the trade designation Sylodent 783
 XWA650 and Sylodent XWA 300 by W.R. Grace Company but other polishing
 agents may also be employed, including sodium metaphosphate, potassium
 metaphosphate, tricalcium phosphate, calcium phosphate dihydrate,
 anhydrous dicalcium phosphate, calcium pyrophosphate, magnesium
 orthophosphate, trimagnesium phosphate, alumina trihydrate, aluminum
 silicate, zirconium silicate, calcined alumina and bentonite.
 The polishing agent is present in the paste component of the present
 invention at a concentration of about 10 to about 30% by weight and
 preferably 15 to about 25% by weight.
 Inorganic thickeners may be included in the dentifrices of the present
 invention and include fumed silicas such as Cabosil available from Cabot
 Corporation, and thickening silicas including those available from J. M.
 Huber designated Zeodent 165.
 Organic thickeners such as natural and synthetic gums and colloids may also
 be incorporated in the dentifrice compositions of the present invention.
 Examples of such thickeners include carrageenan (Irish moss), xanthan gum
 and sodium carboxymethyl cellulose, starch, polyvinylpyrrolidone,
 hydroxyethyl propylcellulose, hydroxybutyl methyl cellulose, hydroxypropyl
 methyl cellulose and hydroxyethyl cellulose and carboxyvinyl polymers such
 as Carbopol 934, 940, 941 available from B.F. Goodrich consisting of a
 collodially water soluble polymer of polyacrylic acid and cross-linked
 with from about 0.75% to about 2.0% of polyallyl sucrose or polyallyl
 pentaerythritol.
 The inorganic or organic thickener may be incorporated in dentifrice
 components of the present invention at a concentration of about 0.05 to
 about 2% by weight and preferably about 0.1 to about 1.5% by weight.
 Surface active agents are incorporated in the abrasive dentifrice component
 to provide foaming properties. The surface-active material is preferably
 anionic, nonionic or ampholytic in nature, and most preferably is anionic.
 Suitable examples of useful anionic surfactants are higher alkyl sulfates
 such as potassium or sodium lauryl sulfate which is preferred, higher
 fatty acid monoglyceride monosulfates, such as the salt of the
 monosulfated monoglyceride or hydrogenated coconut oil fatty acids, alkyl
 aryl sulfonates such as sodium dodecyl benzene sulfonate, higher fatty
 sulfoacetates, higher fatty acid esters of 1,2 dihydroxy propane
 sulfonate, and the substantially saturated higher aliphatic acyl amides of
 lower aliphatic amino carboxylic acid compounds, such as those having 12
 to 16 carbons in the fatty acid, alkyl or acyl radicals, and the like.
 Examples of the last mentioned amides are N-lauroyl sarcosine, and the
 salts of N-lauroyl, N-myristoyl, or N-palmitoyl sarcosine.
 The surface active agent is generally present at a concentration of about
 0.5 to about 5.0% by weight of the present invention in the abrasive
 dentifrice component.
 Fluoride-providing salts having anti-caries efficacy may also be
 incorporated in the abrasive dentifrice component of the present invention
 and are characterized by their ability to release fluoride ions in water.
 Among these materials are inorganic metal salts, for example, sodium
 fluoride, potassium fluoride, a tin fluoride such as stannous fluoride or
 stannous chlorofluoride, sodium fluorosilicate, ammonium fluorosilicate
 and sodium monofluorophosphate. It is preferable to employ a fluoride salt
 to release about 10-1500 ppm of fluoride ion.
 Synthetic anionic polymeric polycarboxylates optionally may be included in
 the abrasive dentifrice component. Polymeric polycarboxylates are well
 known, being often employed in the form of their free acids or preferably
 partially or more preferably fully neutralized water-soluble alkali metal
 (e.g. potassium and preferably sodium) or ammonium salts. Preferred are
 1:4 to 4:1 copolymers of maleic anhydride or acid with another
 polymerizable ethylenically unsaturated monomer, preferably methyl vinyl
 ether (maleic anhydride) having a molecular weight (M.W.) of about 30,000
 to 1,000,000. These copolymers are available for example as Gantrez AN 139
 (M.W. 500,000), AN 119 (M.W. 250,000) and preferably S-97 Pharmaceutical
 Grade of ISP Corporation. Other operative polymeric polycarboxylates
 include those disclosed in U.S. Pat. No. 3,956,480, such as the 1:1
 copolymers of maleic anhydride with ethyl acrylate, hydroxyethyl
 methacrylate, N-vinyl-2-pyrrolidone, or ethylene, the latter being
 available for example as Monsanto EMA No. 1103, M.W. 10,000 and EMA Grade
 61, and 1:1 copolymers of acrylic acid with methyl or hydroxyethyl
 methacrylate, methyl or ethyl acrylate, isobutyl vinyl ether or
 N-vinyl-2-pyrrolidone.
 Additional operative polymeric polycarboxylates include those disclosed in
 U.S. Pat. Nos. 4,138,477, and 4,183,914, such as copolymers of maleic
 anhydride with styrene, isobutylene or ethyl vinyl ether, polyacrylic,
 polyitaconic and polymaleic acids, and sulfoacrylic oligomers of molecular
 weight as low as 1,000, available as Uniroyal ND-2.
 Other ingredients which may be incorporated in the abrasive dentifrice
 component of the present invention include pigment, sweetener, flavor and
 preservative. In white dental cream formulations, the pigment will be
 titanium dioxide, rutile, and the proportion thereof will normally be in
 the range of 0.5 to 1% by weight, preferably 0.75 to 1.25% by weight. The
 sweetener content will normally be that of an artificial or synthetic
 sweetener and the normal proportion thereof present will be in the range
 of 0.1 to 1% by weight, preferably 0.3 to 0.5% by weight. The flavor
 content, which is preferably of a mixed peppermint/menthol flavor, will
 usually be in the range of 0.5 to 2% by weight, preferably 0.5 to 1.5% by
 weight. F.D. & C grade dyes may be used in appropriate amounts to provide
 desired colors.
 Additional ingredients which may be incorporated in the abrasive dentifrice
 component of the present invention are antibacterial agents including
 noncationic antibacterial agents such as halogenated diphenyl ethers such
 as 2',4,4'-trichloro-2-hydroxy-diphenyl ether (Triclosan) and phenolic
 compounds including phenols, and their homologs, mono-and polyalkyl and
 aromatic halophenols, resorcinol and its derivatives, bisphenolic
 compounds and halogenated salicylanilides. Examples of other antibacterial
 agents which may be included in the abrasive dentifrice component include
 chlorhexidine, copper- and zinc-salts such as zinc citrate and sodium zinc
 citrate, sanguinarine extract, and metronidazole, quaternary ammonium
 compounds such as cetylpyridinium chloride, bis-guanides such as
 chlorhexidine digluconate, hexetidine, octenidine and alexidine.
 The antibacterial agent is present in the abrasive dentifrice component in
 an effective antiplaque amount, typically 0.01-5% by weight, preferably
 about 0.03 to about 1% by weight.
 Anti-inflammatory agents such as ibuprofen, flurbiprofen, aspirin,
 indomethacin etc. may also be included in the abrasive dentifrice
 component.
 An anticalculus agent which is effective against calculus such as
 pyrophosphate salts including the mono, di, tri and tetra alkali metal and
 ammonium pyrophosphate and tripolyphosphate salts is still another
 additional ingredient which may be present in the abrasive component of
 the present invention . Such agents are used in amounts sufficient to
 reduce calculus and are preferably in amounts which will release about 1%
 by weight P.sub.2 O.sub.7 ion and most preferably at least about 1.3% by
 weight P.sub.2 O.sub.7 ion.
 Salts having anti-tartar efficacy, including water soluble salts, such as
 dialkali or tetra-alkali metal pyrophosphate salts such as Na.sub.4
 P.sub.2 O.sub.7 (TSPP) K.sub.4 P.sub.2 O.sub.7, Na.sub.2 K.sub.2 P.sub.2
 O.sub.7, Na.sub.2 H.sub.2 P.sub.2 O.sub.7 and K.sub.2 H.sub.2 P.sub.2
 O.sub.7, long chain polyphosphate such as sodium hexametaphosphate and
 cyclic phosphates such as sodium trimetaphosphate as well as alkali metal
 tripolyphosphates such as sodium tripolyphosphate (STPP) and potassium
 tripolyphosphate may be incorporated in the dentifrice compositions of the
 present invention preferably at a concentration of about 0.5 to about 8.0%
 by weight.
 A striped dentifrice product is obtained in accordance with the practice of
 the present invention wherein colorants of contrasting colors are
 incorporated in each of the dentifrice components used in the practice of
 the present invention, the colorants being pharmacologically and
 physiologically non-toxic when used in the suggested amounts. Colorants
 used in the practice of the present invention include both pigments and
 dyes.
 Pigments used in the practice of the present invention include non-toxic,
 water insoluble inorganic pigments such as titanium dioxide and chromium
 oxide greens, ultramarine blues and pinks and ferric oxides as well as
 water insoluble dye lakes prepared by extending calcium or aluminum salts
 of FD&C dyes on alumina such as FD&C Green #1 lake, FD&C Blue #2 lake,
 FD&C R&D #30 lake and FD&C # Yellow 15 lake. The pigments have a particle
 size in the range of 5-1000 microns, preferably 250-500 microns, and are
 present at a concentration of 0.5 to 3% by weight.
 The dyes used in the practice of the present invention are distributed
 uniformly throughout the dentifrice component and are generally food color
 additives presently certified under the Food Drug & Cosmetic Act for use
 in food and ingested drugs, including dyes such as FD&C Red No. 3 (sodium
 salt of tetraiodofluorescein), FD&C Yellow No. 5 (sodium salt of
 4-p-sulfophenylazo-1-p-sulfophenyl-5-hydroxypyrazole-3 carboxylic acid),
 FD&C Yellow No. 6 (sodium salt of
 p-sulfophenylazo-B-naphtol-6-monosulfonate), FD&C Green No. 3 (disodium
 salt of
 4-{[4-(N-ethyl-p-sulfobenzylamino)-phenyl]-(4-hydroxy-2-sulfoniumphenyl)-m
 ethylene}-[1-N-ethyl-N-p-sulfobenzyl)-3,5-cyclohexadienimine], FD&C Blue
 No. 1 (disodium salt of dibenzyldiethyl-diaminotriphenylcarbinol
 trisulfonic acid anhydride), FD&C Blue No. 2 (sodium salt of disulfonic
 acid of indigotin) and mixtures thereof in various proportions. The
 concentration of the dye for the most effective result in the present
 invention is present in the dentifrice composition in an amount from about
 0.0005 percent to about 2 percent by weight.
 It is preferred that the colorant included in one of the dentifrice
 components be a pigment such as TiO.sub.2 and that the colorant
 distributed throughout the vehicle of the other dentifrice component be a
 dye and that the dye be of a different color than the pigment included in
 the first dentifrice component. To avoid bleaching of the dye by the
 peroxygen compound constituent it is critical that the peroxygen compound
 not be included in the dentifrice component in which a peroxygen sensitive
 dye ingredient is included.
 Any suitable flavoring or sweetening material may also be employed.
 Examples of suitable flavoring constituents are flavoring oils, e.g., oils
 of spearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus,
 marjoram, cinnamon, lemon, and orange, and methyl salicylate. Suitable
 sweetening agents include sucrose, lactose, maltose, sorbitol, sodium
 cyclamate, perillartine, and sodium saccharin. Suitably, flavor and
 sweetening agents may together comprise from 0.01% to 5% or more of the
 preparations.
 Various other materials may be incorporated into the oral composition
 components of this invention. Non-limiting examples thereof include
 preservatives, silicones and chlorophyll compounds, vitamins such as
 vitamins B6, B12, C, E and K, antibacterial agents such as chlorhexidene,
 halogenated diphenyl ethers such as triclosan, desensitizing agents such
 as potassium nitrate and potassium citrate and mixtures thereof. These
 adjuvants are incorporated in the oral composition components in amounts
 which do not substantially adversely affect the properties and
 characteristics desired, and are selected and used in proper amounts,
 depending upon the particular type of component involved.
 To prepare the second abrasive dentifrice component of the present
 invention, the humectant and thickener are dispersed in a conventional
 mixer until the mixture becomes a slurry which is smooth in appearance,
 after which water is added. This mixture is heated to 100-100.degree. F.
 and mixed for 10 to 30 minutes producing a homogeneous gel phase.
 Sweetener and color are added and mixed for 20 minutes. The mixture is
 transferred to a vacuum mixer and the abrasive is added and mixed for 10
 to 30 minutes at high speed under a vacuum in the range of 5 to 100
 millimeter of mercury pressure, preferably 5 to 50 mm Hg, providing a
 homogeneous mixture. The surfactant and flavor are then added to the paste
 which is followed by mixing another 10 to 20 minutes under vacuum of 5 to
 50 mm Hg. The resultant product is an abrasive dentifrice paste of a
 texture like that of normal toothpastes having a pH in the range of 5 to
 8, preferably 6.5 to 7.5, e.g., 7, and of satisfactory flavor.
 Any convenient means for effecting the separation of the peroxide
 dentifrice component from the abrasive dentifrice component containing the
 accelerator mixture of iron and copper salts before being combined for use
 can be utilized. For example, a single container can be compartmentalized
 so that the peroxide containing dentifrice component and the abrasive
 containing component are housed in separate compartments and are not
 combined and admixed until extrusion from the dual compartment container
 and application to the teeth. Alternatively, the peroxide containing
 component and the abrasive containing component can be housed in separate
 containers from which the respective components are dispensed together and
 combined just prior to use.

The following examples are further illustrative of the present invention,
 but it is understood that the invention is not limited thereto. All
 amounts and proportions referred to herein and the appended claims are by
 weight.
 EXAMPLE I
 A peroxide gel and abrasive paste compositions useful as components of an
 effervescent dual component whitening dentifrice of the present invention
 were prepared with the following ingredients.
 TABLE I
 Component A Component B
 Ingredients (Wt. %) (Wt. %)
 Dionized water 13.91 29.497
 Glycerin 12.00 30.00
 Sorbitol (70% solution) 27.0 0.0
 Polyethylene glycol 600 0.00 10.00
 Na saccharin 0.45 0.25
 Iota carrageenan 0.35 0.00
 Carboxymethyl cellulose 0.80 0.00
 NaF 0.243 0.243
 Tetrasodium pyrophosphate (TSPP) 1.00 0.00
 Sodium tripolyphosphate (STPP) 7.00 0.00
 TiO.sub.2 1.00 0.00
 FD&C - (1% solution) (Blue color) 0.00 0.00
 Zeodent 165 1.50 0.00
 Sylodent 183 11.00 0.00
 Sylodent XWA 300 10.00 0.00
 Sodium lauryl sulfate 1.50 0.00
 Hydrogen peroxide (35%) 0.00 5.71
 CaSO.sub.4 0.3285 0.00
 FeSO.sub.4 0.3285 0.00
 NaOH 2.00 0.00
 Flavor (Mint) 1.90 0.30
 Gantrez S97 7.69 0.00
 Pluronic Fl27 0 21.00
 Phosphoric acid 0 3.00
 Total 100.00 100.00
 Component A--Abrasive Paste Component
 The glycerin, sorbitol, polyethylene glycol, carboxymethyl cellulose were
 dispersed in a conventional mixer until the mixture became a slurry, which
 was smooth in appearance, water was added and mixed for 10 to 30 minutes
 producing a homogeneous gel phase in which the sodium monofluorophosphate
 and Gantrez w as dispersed. Sweetener was added mixed for 20 minutes and
 transferred to a vacuum mixer. The alumina, silica and TiO.sub.2 were then
 added and mixed for 10 to 30 minutes at high speed under a vacuum of about
 50 mm Hg, providing a homogenous mixture. The sodium lauryl sulfate and
 flavor were then added to the paste which was followed by mixing another
 20 minutes under vacuum of 50 mm Hg. The resultant product was a
 toothpaste with satisfactory flavor.
 The Peroxide Gel Component
 The peroxide dentifrice component was prepared in a Ross mixer. Water, NaF,
 saccharin, glycerin, phosphoric acid and PEG 600 were mixed for 10 minutes
 at low speed without vacuum. Pluronic F-127 was added and the mixture
 stirred for 30 minutes without vacuum and then an additional 30-45 minutes
 with vacuum of -15 mmHg. Then, peroxide was added with flavor and mixed
 for 10-15 minutes under vacuum. The resulting product was a gel.
 To determine the level of oxygen generation obtained by combining
 Components A and B, equal amounts of paste Compositions A and the gel
 Composition B were combined and mixed in a beaker, the open end of which
 was then sealed with stretched parafilm. The evolution of oxygen gas could
 be observed within less than one minute after through mixingly which
 stretched the parafilm which swelled, as if it were a balloon being,
 inflated. Gas evaluation was also evident from the fact that the volume of
 the contents of the beaker increased significantly. For example 21.6% of
 the combined dentifrice components, occupying an initial volume of less
 than 10 ml, rose to significantly overflow a beaker with a 40 ml real
 total volume (30 ml nominal volume), in what corresponds to, at least, a
 5-fold increase in volume.
 A second formula contained the same ingredients, but with the following
 variations in their amounts: sorbitol, 27.607%; ferrous sulfate, 0.025%;
 cupric sulfate, 0.025%. This second batch showed that even when the total
 amount of metal salts was 0.05%, there was gas evolution. In contrast, a
 similar product in which the Fe and Cu salts were replaced with 0.05%
 manganese gluconate did not produce oxygen gas, even within 45 minutes.
 EXAMPLE II
 To test the whitening efficacy of dentifrice Components A and B, naturally
 stained human teeth were stained with a staining broth consisting of
 coffee, tea, mucin, microbiological media and a chromogenic microorganism.
 Stained teeth selected for the test showed the same amount of
 discoloration. To test the whitening efficacy of the combined components,
 the teeth were immersed in 2 grams of a mixture of equal amounts of
 Components A and B at 37.degree. C. and then brushed 300 and 600 strokes.
 Before immersion, the color of the teeth was measured with a Minolta
 Chromameter in which L* is a measure of response to the eye to lightness
 and darkness, and b* is a measure of yellowness a* is a measure of
 blueness. The higher the L* value and lower b* value, the whiter teeth
 appear.
 The whitening index was calculated using the following equation:
EQU .DELTA.E=(.DELTA.L*).sup.2 +(.DELTA.a*).sup.2 +(.DELTA.b*).sup.2 ].sup.1/2
 The higher the AE the greater the whitening effect observed.
 The teeth remained immersed in the mixed components for 15 minutes. The
 whitening index (.DELTA.E) of the immersed teeth is summarized in Table II
 below. The mixed components are designated Composition X in Table II.
 For purposes of comparison, the procedure of Example II was repeated with
 exception that Component A did not contain the Fe/Cu salt mixture but was
 replaced with 0.05% manganese gluconate. This comparative composition was
 designated Composition "C". The whitening index of comparative Composition
 C.sub.1 is also summarized in Table II below.
 TABLE II
 .DELTA.E .DELTA.E
 Composition 300 Strokes 600 Strokes
 X 2.81 .+-. 0.45 3.30 .+-. 1.26
 C 2.23 .+-. 0.14 2.37 .+-. 0.13