MXPA01008249A - Method to enhance peroxide tooth whitening - Google Patents

Abstract

A method is disclosed for effecting heightened whitening of teeth wherein there is first applied to the teeth an aqueous rinse composition having an alkaline pH and thereafter brushing the teeth with a peroxide dentifrice.

Description

METHOD TO IMPROVE THE BLEACHING OF TEETH WITH PEROXIDE Background of the Invention Field of the Invention This invention relates generally to a method for whitening human teeth, and more particularly, to a method for whitening the teeth by first sequentially applying an alkaline rinse to the teeth followed by brushing with a peroxide-containing dentifrice.

Previous Art A tooth is composed of a layer of internal dentin and a layer of external hard enamel that is the protective cap of the tooth. The enamel layer of a tooth is naturally a slightly whitish or opaque white color. This enamel layer can become stained or discolored. The enamel layer of a tooth is composed of crystal hydroxyapatite minerals that create something of a porous surface. It is believed that this porous nature of the esmalt layer is what allows staining agents and bleaching agents to permeate the enamel and discolor the tooth.

Many substances that a person confronts or contacts daily can "stain" or reduce the "bleaching" of teeth. In particular, food, tobacco products and fluids such as tea and coffee that one consumes tend to stain teeth. These products or substances tend to accumulate in the enamel layer of the tooth and form a film on the teeth. These bleaching and staining substances can then permeate the enamel layer. This problem occurs gradually over a period of many years, but imparts a noticeable discoloration of the enamel of the teeth.

The means known in the art for effecting and bleaching of the teeth include the application, as by brushing, of the teeth of the peroxide containing dentifrice compositions of the type described in United States of America Nos. 5,256,402 and 5,814,309.

The aqueous dentifrice compositions disclosed in these patents contain a hydrogen or urea peroxide compound, an alkaline pyrophosphate salt and an abrasive material. Although such prior art peroxide dentifrice compositions are effective in whitening teeth, the art continuously seeks means to effect an even greater tooth whitening efficiency.

Synthesis of the invention In accordance with the present invention it has now been found that the tooth whitening efficiency of the peroxide-containing toothpaste compositions can be substantially improved by a method wherein first an aqueous rinse composition having a pH is applied to the teeth. alkaline around 8.0 and around 11.0 after brushing the teeth to which the rinse was previously applied with a peroxide-containing toothpaste.

It is believed that the application of alkaline rinse the teeth prior to brushing with the active peroxide dentifrice and promotes the rapid release of oxygen from the peroxide contained in the dentifrice, such rapid release that responds by the observed unexpected improved bleaching obtained by brushing.

Detailed description of the invention The rinse formulations used in the practice of this invention comprise an alkaline solution having a pH of at least about 8.0 or higher, preferably about 8.5 to 10.5. The solvent for the rinse ingredients may be water or a solution of ethanol and ethanol and such a solvent generally comprises about 70% to about 95% of the rinse, and preferably about 65% to 95% water and about 0%. % to 35% ethanol.

Polyoxyethylene and polyoxypropylene block polymers, such as those available from BASF-yandott Co., of yandotte, Michigan are useful as surfactants in the rinse preparation and serve to solubilize the flavor components as well as to provide foaming action while rinse. Additionally, other surfactants available for use in the preparation of the rinse composition include anionic surfactants such as sodium lauryl sulfate or sodium lauryl sulfonate. The surfactant is employed in the rinse composition in concentrations ranging from about 0.1% to about 10% by weight of the rinse, and more preferably from about 0.5% to about 2% by weight.

Humidifiers such as glycerin and sorbitol in amounts up to about 25% by weight, preferably about 15% to 20% by weight can also be used in the preparation of the rinse.

About 3 about 10% by weight preferably about 4 to about 8% by weight of alkali metal such as sodium bicarbonate, sodium carbonate, sodium hydroxide and mixtures thereof are included in the composition of the rinse to adjust the pH au alkaline range of about up to about 8.0 about 11.0 and preferably about 9.0 to about 10.5.

Condoms such as sodium benzoate, methylparaben, propylparaben and benzoic acid are included in the rinse compositions in concentrations of about 0.1 to about 1.0% by weight by weight, preferably 0.4 to 0.6% by weight. Sodium benzoate is the preferred preservative.

Flavoring oils are incorporated into the rinse composition at concentrations of about 0. to 1.0% by weight, examples of which are peppermint, peppermint, pyro, menthol, cineole, and limonene oils. menthone and menthyl acetate.

A sweetening material is also preferably used as a complement to the flavoring material. Suitable sweetening agents include sodium saccharin, sodium cyclamate, xylitol, and aspartame at concentrations of about 0.01 to 1.0% by weight. Sodium saccharin is preferred.

The rinse of such is prepared by mixing the ingredients together to form a homogeneous solution of the constituent ingredients. The rinsing is used mediant first to apply a small amount in the mouth, such as a full lid, and to rinse around the surfaces of the tooth. As may be shown here, an astonishing increase in bleaching is observed over a relatively short period of use. when the rinse of this invention is first employed in sequential steps with a peroxide dentifrice.

The composition ingredients of the peroxide dentifrice used in the practice of the present invention are dissolved or suspended in a vehicle comprised of water and a humectant such as glycerin or polyethylene glycol d sorbitol. The water constitutes about 10 to about 40 by weight of the peroxide dentifrice of the present invention preferably about 20 to about 30% by weight.

Illustrative polyethylene glycols useful in the practice of the present invention include the polyethylene glycols known by the brand name Carbowax which are nonionic polymers of ethylene oxide having in the general formula: H0CH2 (CH20CH2) nCH2OH wherein n represents the average number of oxyethylene groups. Carbowax polyethylene glycols are designated by a number such as 400, 600 800, 1000, 2000 which represent the average molecular weight. The molecular weight range of the polyethylene glycols used herein is about 200 about 200 and preferably about 600 hereinafter referred to as PEG 600.

The polyethylene glycol component included in the compositions of the present invention constitutes about 10 to about 35% by weight of the dentifrice composition and preferably about 15 to about 35 by weight.

Glycerin is included in the dentifrice composition of the present invention in the range of 10 to about 20% by weight and preferably 12 to about 15% by weight.

The peroxide compound used to prepare the dentifrice composition used in the practice of the present invention is included in an amount sufficient to allow the release of sufficient oxygen during the brushing of the teeth to effect the bleaching thereof. Typically the peroxide compound is employed in the dentifrice composition in amounts so that at least about 1.0 of the composition comprises a peroxide. PreferablyThe peroxide compound comprises from about 5 hast about 15% by weight of the composition. Examples of suitable peroxide compounds used to prepare the dentifrice compositions used in the practice of the present invention include calcium peroxide, hydrogen peroxide and peroxides including urea peroxide, and peroxide glycerin, peroxide of benzoyl and the like A preferred peroxide compound is urea peroxide.

Suitable abrasives for use in the preparation of the dentifrice composition include silica, calcium pyrophosphate, dicalcium diphosphate and calcined alumina. The abrasive is incorporated into the dentifrice composition in a concentration of about 0 to 30% by weight and preferably about 5 to 10% by weight, the preferred abrasive being a calcined alumina.

Thickening agents are included in the peroxide compositions of the present invention in amounts of from about 10% to about 25% by weight of the composition and preferably from about 12 to about 20 by weight. Examples of suitable thickeners include polyoxypropylene polyoxyethylene block copolymers having the formula HO (C2H40) b (C3H60) b (C2H40) bH e where a is an integral such that the hydrophobic base represented by (C3H60) It has a molecular weight of around 2750 4000, b is an integral such that the hydrophilic part represented by (C2H40) concept and about 70 to 80% by weight of copolymer. The block copolymers of this composition are commercially available under the brand name of Pluronic type F. Pluronic F127, which has a molecular weight range of about 9000 about 14000 and contains 70% d hydrophilic polyoxyethylene use in a gelling agent in the practice of the present invention.

Metal ion chelating agents when included in the peroxide dentifrice compositions used in the practice of the present invention contribute to the chemical stability of the peroxide composition when an abrasive such as calcined alumina or calcium pyrophosphate is also present. in the toothpaste. Examples of the metal ion chelating agents include the alkaline metal stannates such as sodium and potassium stannate, ethylenediaminetetraacetic acid (EDTA) and their salts. The metal ion chelating agents are incorporated into the composition of the dentifrice of the present invention at a concentration d around 0.01 to about 1% by weight.

In the preparation of the peroxide compositions of the present invention, the pH of the composition is adjusted to a range between about 3.0 and about 8 preferably about between about 5 and about with acid such as Sosphoric acid.

Pyrophosphate salts having an anticalculus efficiency such as tetraalkyl or dialkyl metal pyrophosphate salts such as Na4P207, K4P207, and Na2K_P207, Na2H2P207, and K2H2P207, can be included in the dentifrice composition of the present invention in a concentration of about 0.5 to about 8.0% by weight preferably about 1.5 to 5% by weight.

Fluoride salts having an anticaries efficiency can also be incorporated into the dentifrice composition of the present invention and are characterized by their ability to release fluoride ions in water, for example, sodium fluoride, potassium fluoride, sodium fluorosilicate, and sodium monofluorophosphate (NaMFP). It is preferable to use a fluoride salt to release about 10 about 1500 parts per million of fluoride ion.

The flavor ingredients are incorporated into the composition of the peroxide dentifrice at a concentration d around 0.5 to 5.0% by weight. Suitable flavoring constituents are the flavor oils, for example peppermint, peppermint, pyro, menthol, cineole, d limonone, menthone and menthyl acetate oils.

A surfactant is also included in the composition of the dentifrice of the present invention and serves as a solubilizing, dispersing, emulsifying and moisturizing agent and is specifically effective in solubilizing the flavor ingredient present. The surfactants which may be used in the practice of the present invention include cationic surfactants, anionic surfactants such as sodium lauryl sulfate and sodium lauryl sulfoacetate, amphoteric and ampholytic surfactants such as cocoaminopropyl betaine.

A sweetening material is also preferable used as a complement to the flavoring material. Suitable sweetening agents are water soluble and include sodium saccharin, sodium cyclamate, xylitol, and aspartame and the like, in concentrations of about 0.01 1.0% by weight. Sodium saccharin is preferred.

To prepare the peroxide dentifrice compositions of the present invention, the water soluble salts such as sodium saccharin and NaMFP are dissolved in an aqueous vehicle containing such a humectant, PEG 600 and glycerin followed by the addition of a polyoxyethylene-polyoxypropylene block copolymer gelling agent and the ingredients are mixed until a gel phase is formed. An abrasive compound such as calcium pyrophosphate is added to the mixed gel to form a paste. The paste when formed and delivered at about 90 to 130 ° F, preferably around d 100 ° F. A metal ion chelating agent, a buffered agent and the peroxide compound are then added to the paste. The ingredients are mixed to obtain a homogeneous mixture. The flavor and the surfactant are then added to the mixture to obtain a whitening tooth paste. finished with the present invention.

The following example further illustrated the present invention, but it is understood that the present invention is not limited thereto. All amounts and the amounts referred to herein and in the appended claims are by weight unless otherwise indicated.

Example 1 An alkaline rinse and a peroxide toothpaste used in the method of the present invention were prepared containing the ingredients listed in Tables I and I below.

TABLE I Rinse Ingredients by Weight Ethyl Alcohol (95%) 10.0 Pluronic FIO8 1.0 Pluronic F127 1.0 Mint Flavor 0.150 Purified Water 68.32980 Glycerin 15.0 Sodium Bicarbonate 4.0 Sodium Benzoate 0.50 Sodium Saccharin 0.020 Green Color No. 3 FD &C 0.0002 TOTAL 100.0 The rinse was prepared by dissolving in the mixture of the ethanol / water at room temperature the rest of the ingredients listed in table I. The pH of the rinse was 8.5.

TABLE II Whitening Toothpaste Ingredients% by Weight Glycerin 12.0 PEG 600 15.0 PEG 2000 6.0 Purified Water 21,070 Sodium Saccharin 0.50 NaMFP 0.760 Pluronic F127 18.0 Pyrophosphate Acid < Sodium 2.0 EDTA - Disodium Dihydrate (99%) 0.020 Sodium Lauryl Sulfate 0.80 Flavor 100.01.350 Urea Peroxide 10.0 Phosphoric Acid (85%) 0.50 Calcinated Alumin 12.0 TOTAL 100.00 The toothpaste composition was prepared by dispersing the PEG 2000 in a mixture of PEG 600 and glycerin. The water was added to the mixture and the ingredients mixed for about 5 minutes. The sodium saccharin and sodium monofluorophosphate (NaMFP) was added and the resulting mixture stirred for 10 minutes, followed by the addition of Pluronic F127 and stirring for 1 hour. The mixture was then ventilated for 5 minutes and the sodium pyrophosphate acid and calcined alumina were added and the paste was mixed for 15 minutes at high speed under vacuum. The urea peroxide was added to the pulp which was further mixed for 10 minutes under vacuum at high speed. The flavor oil was then added to the paste and mixed under vacuum for 5 minutes. Sodium lauryl sulfate was then added under vacuum for 5 minutes at low speed. The phosphoric acid was added to adjust the pH of the composition to 4.0 to 5.0.

Twenty subjects determined by a dental examiner to demonstrate the presence of dental stains were supplied with a pack containing the rinse and peroxide dentifrice compositions from Tables I and II and an adult toothbrush with soft bristles. Subjects were instructed to rinse with 5 milliliters of rinsing for 3 seconds immediately followed by brushing with toothpaste for one minute, twice a day (in the morning and in the evening) for four weeks, without rinsing with water between rinse regime and the dentifrice regime.

The level of stain on the teeth of the subject before the application of the rinse / dentifrice or base regimen and after two, three and four weeks of intervals evaluated using the Vita Tone Guide Method to Evaluate the Tooth Cabbage. This normal shade guide which used by dental profession includes sixteen shades. Previous tone change evaluations using the brush regimen only without the benefit of pre-rinse produced a change tone from 3.0 to 4.0, over a period of 4 weeks. The results of the present evaluation are recorded in table I below.

TABLE III Weeks of Treatment Change of Base Line Deviation Standard 2 5.9500 2.5438 3 7.1000 2.5935 4 8.4500 2.0641 The results recorded in table III show that using the alkaline rinse before brushing with a peroxide dentifrice improves the bleaching effect observed only by brushing which produces a change in shade of around 6 around 8.5.

Claims (6)

1. A method for effecting improved bleaching of the teeth which comprises the sequential steps of first applying to the teeth an aqueous rinse composition which has an alkaline pH of about 8.0 about 10.5 then brushing the teeth to which the rinse has given them. sid previously applied with a toothpaste peroxide to effect the bleaching of the teeth.

2. The method as claimed in clause 1, characterized in that the teeth are brushed with the toothpaste immediately followed by the rinsing application.

3. The method as claimed in clause 1, characterized in that the peroxide is urea peroxide.

4. The method as claimed in clause 1, characterized in that the peroxide compound is present in the dentifrice composition in a concentration d about 1.0 to about 10% by weight of the composition.

5. The method as claimed in clause 1, characterized in that an abrasive is present in the dentifrice composition in a concentration of about to about 30% by weight of the composition.

6. The method as claimed in clause 5, characterized in that the calcined alumina abrasive compound.