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A teeth whitening composition

Abstract

A composition for a teeth whitening strip comprises sodium chlorite as the whitening agent, a vinyl pyrrolidone polymer thickener, alcohol and a chelating agent. Preferably the vinyl pyrrolidone polymer thickener is polyvinyl pyrrolidone (PVP) which is present in an amount of at least 10wt% of the composition. Preferably the chelating agent is EDTA (ethylenediaminetetraacetic acid). The composition is preferably in the form of a gel. The composition may further include a humectant, such as glycerine; hydroxypropyl methylcellulose thickener; a flavouring agent; and a tackifier. A teeth whitening composition comprising PVP (K30) 30wt%, hydroxypropyl methylcellulose 25wt%, glycerin 21wt%, PVP (K90) 15wt%, alcohol (50:50 v/v ethanol in water) 6.30wt%, sodium chlorite (25.2wt% solution in water) 1wt%; EDTA 1wt%, stevioside 0.5wt% and D,L-menthol 0.2wt% is exemplified.

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A61K8/41 Amines
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GB2525928A

United Kingdom

Inventor
Erik Thorild Lambert
Current Assignee
ROY ROGER GLOBAL Ltd

Worldwide applications
2014 GB

Application GB1408243.2A events
Withdrawn

Description

A teeth whitening composition
Field of the Invention
The present invention concerns compositions for oral care. More particularly, but not exclusively, this invention concerns compositions for teeth whitening strips.
The invention also concerns a teeth whitening system.
Background of the Invention
Tooth whitening has become popular in today's culture.
More and more consumers are searching for the best method to achieve LooLti wlilLenlng. Professional LooLli bleaching in a dental clinic by a dental practitioner is common. There are now non-professional methods available to persons interested in whitening their teeth using commercial products available over the counter at drug stores.
The most conunon apparatus for dental whitening outside of the clinic use formulations that include hydrogen peroxide as the active agent. The European Commission has recently issued a new Directive (Council Directive 2011/84/EU) regarding tooth whitening products, under which these are classified as cosmetic products. The new Directive also makes reference to restrictions and conditions of use of hydrogen peroxide in teeth bleaching products. According to the new Directive, only dental bleaching products with less than 0.1% hydrogen peroxide may be sold on the open market in the European Union. Furthermore, products having between 0.11-6% hydrogen peroxide content may only be sold to dentists, while all other tooth whitening products with more than 6% hydrogen peroxide are forbidden in the European Union, as an additional measure on product safety for the European consumers. This has meant that many existing types of products previously on the market, such as those described in EP1438928B1 and EP1100399E1, cannot be sold in the open market in the European Union as they contain at least 1% Hydrogen Peroxide.
A second generation of EU compliant formulations uses sodium chlorite as a teeth whitening active ingredient. An example cf such a second generation formulation is disclosed in US patent US5944528. In 2013, Stella White (Registered Trade mark) , a trade mark of The Roy Roger Global Company, Hong Kong, introduced a formulation that was compliant for home teeth whitening using sodium chlorite as a whitening agent. The formulation included the use of agua in the ingredients that would allow for easy application of the strip. Other ingredients of the formulation include glycerine, methylcellulose, erhylenediaminetetraacetic acid (EDTA), citric acid and D,L-menthol.
There remains a need for improved whitening strip formulations, in particular, there remains a need for a formulation which causes less irritation and which exhibits more effective whitening, whilst still using sodium chlorite as the active agent.
Summary of the Invention
According to a first aspect of the invention there is provided a composition for a teeth whitening strip comprising sodium chlorite as the whitening agent, polyvinylpyrrolidone (PVP) or other vinyl pyrrolidone polymer as a thickener, alcohol as a solvent and a chelating agent. The compositions of the invention comprising a vinyl pyrrolidone polymer and alcohol have been found to provide superior whitening properties to existing formulations that comprise sodium chlorite as the whitening agent. The compositions have been found to provide less irritation to the user than existing formulations. It has also been found that when the composition of the invention is applied to a teeth whitening strip, which is then placed over teeth, the composition results in improved fit and comfort of the strip.
The composition of the invention has further been found to have superior handling properties when applied to a strip, including an enhanced dry strip effect.
The composition of the first aspect of the invention may be a cosmetic composition or may be used in therapeutic application. The composition of the first aspect of the invention may be for use in a therapeutic method of whitening teeth and/or may be used in the manufacture of a medicament for use in a therapeutic method of whitening teeth.
According to a second aspect of the invention there is also provided a teeth whitening system comprising the composition of any preceding claim and a carrier film.
In a third aspect of the invention, there is provided a method of whitening teeth comprising the step of applying the composition of the first aspect of the invention or the teeth whitening system of the second aspect of the invention.
The method of the third aspect of the invention is advantageously a cosmetic method. Advantageously, the method of the third aspect of the invention is a non-therapeutic method. Alternatively, the method of the third aspect of the invention may be, or encompass, a therapeutic method of whitening teeth.
It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the system of the invention may incorporate any of the features described with reference to the composition of the invention and vice versa.
Detailed Description
The composition of the invention comprises sodium chlorite as a whitening agent. Sodium chlorite is used as a whitening agent that provides bleaching or stain removal effect to the teeth and is safe to use in the oral cavity.
The sodium chlorite is generally present in the compositions of the invention in an amount of from 0.01 wt% to 10 wt%, preferably from 0.05 wt%. to 5 wti, and more preferably from 0.1 wt% to 2 wt%, typically from 0.1 wt% to 0.5 wt%, for example about 0.2 wtl.
The sodium chlorite in the composition of the invention may be added in the form of a solution, for example, an aqueous solution, Optionally, the aqueous solution has from wt% to 40 wt% active sodium chlorite, such as from 20 wt% to 30 wt% for example 25.2 wt%, active sodium chlorite.
Advantageously, the compositions of the invention comprise less than 0.1 wt% hydrogen peroxide, such as less than 0.05 wt% hydrogen peroxide, especially substantially no hydrogen peroxide.
The composition of the invention comprises a vinyl pyrrolidone polymer as a thickener. Vinyl pyrrolidone polymers are safe for oral use, do not readily dissolve in saliva and do not react with or inactivate the oral care compounds incorporated in the composition. The vinyl pyrrolidone polymer may be a copolymer comprising vinyl pyrrolidone monomer units together with other monomer units, such as acetic acid ethenyl ester monomer units. Polyvinyl pyrrolidone (PVP)as a homopolymer has been found to be particularly suitable. PVP homopolymer is designated as Povidone in the USP. A vinyl pyrrolidone and acetic acid ethenyl ester copolymer is designated as Copovidone in the USP. Preferably, the vinyl pyrrolidone polymer is Povidone.
It has been found that the use of vinyl pyrrolidone polymer as a thickener provides sufficient adhesive attachment to the teeth. The vinyl pyrrolidone polymer may be in a form of a solution, for example an aqueous solution, or powder.
Preferably, the composition according to the present invention comprises at least 10 wti vinyl pyrrolidone polymer thickener, such as at least 15 wt%, especially at least 20 wtl, preferably at least 25 wtl for example from about 10 wtl to about 50 wtl, such as from about 20 wt% to wti± vinyl pyrrolidone polymer thickener. In one embodiment of the present invention, the composition comprises about 30 wt% vinyl pyrrolidone polymer thickener.
when a teeth whitening strip containing the composition of the present invention is applied to the teeth, the thickener in the composition helps the strip to conform better to the shape of the teeth whilst allowing for a balanced spread of the whitening agent across the teeth enamel.
Commercially, vinyl pyrrolidone polymer is supplied in different grades, designated by K-values, which are derived from viscosity measurements and calculated using Fikentscher's formula. PVP grades with a K-value of up to about 30 (M 50,000) are typically spheres e.g. formed by spray-drying processes. PVP grades with a K-value over about 90 (M 1,000,000) are typically plates, e.g. formed by drum drying. The K value of vinyl pyrrolidone polaner represents a function of the average molecular weight, the degree of polymerization and the intrinsic viscosity. Typically, the composition according to the present invention comprises vinyl pyrrolidone polymer, especially PVP, having a K-value in the range of from 12 to 90 as a thickener, such as a K-value in the range of from 17 to 60, especially a K-value in the range of from 25 to 40 as a thickener, for example a K-value of 30. The thickener in the composition of the invention may, for example, have a weight average molecular weight (My) in the range of from 2,500 to 400,000, such as from 8,000 to 200,000, especially from 30,000 to 100,000.
Typically, the composition comprises a PVP thickener having a spherical structure.
Advantageously, the composition of the invention comprises at least 10 wt% PVP, for example from 20 to 40 wt% PvP having a K-value in the range from 17 to 60, for example from 25 to 40, as a thickener.
The composition of the invention comprises an alcohol as a solvent. It has been found that when the composition of the invention is applied to a teeth whitening strip, the alcohol (e.g. ethanol) in the composition acts as a drying agent for the strip and provides a dry strip effect. This means that when the user accidentally touches the side of the strip on which the composition is applied, the composition does not get stuck on the user's fingers.
The alcohol is typically a Ci-Cio alkyl alcohol, such as a C2C4 alcohol, especially ethanol. The alcohol in the composition of the invention may be added in the form of an aqueous solution, for example, an aqueous solution of 50 wt% alcohol. Preferably, the alcohol is undenatured ethyl alcohol. Alcohol is generally present in the composition of the invention in an amount of from 0.5 wtl to 20 wt%., preferably from 1 wt% to 10 wti and more preferably from 2 wt% to 8 wt%, for example 2.5 to 6 wt%.
Advantageously, the composition of the invention comprises at least 10 wt% PVP, for example from 20 to 40 wt% PvP, having a K value in the range of from 17 to 60, for example from 25 to 40, as a thickener in combination with at least 1 wt% ethanol, for example from 2 to 10 wt% ethanol.
The composition of the invention comprises a chelating agent. The chelating agent advantageously chelates the sodium chlorite active ingredient. The chelating agent is generally present in an amount of from 0.1 wt% to 5 wt%, such as from 0.2 wt%: to 3 wt%, for example from 0.5 wt% to 2 wtl. Preferably, the chelating agent is ethylenediaminetetraacetic acid (EDTA) The composition of the present invention may be the form of a gel or a paste. Preferably, the composition of the invention is in the form of a gel. The gel is a high viscosity matrix which has been found to facilitate the application of the composition to a teeth whitening strip and helps the composition to stay on the surface of the teeth for a desirable period of time during teeth whitening treatment.
The composition of the present invention may optionally comprise water, for example, to obtain the desirable texture and/or viscosity of the composition. Preferably, any water present is deionized and free of organic impurities.
Typically, water is present in an amount of from 0.1 wt% to wt, preferably from 1 wtl to 30 wt% and more preferably from 2 wt I to 20 wt%. It has been found that replacing water with an alcohol solvent, improved properties can be obtained. In particular, it has been found that replacing water with alcohol leads to an enhanced dry strip effect.
Advantageously, the composition comprises less than 20 wt% water, such as less than 15 wt% water, especially less than 10 wt% water, for example less than 8 wt% water. Typically, the compositions of the invention contain less than 6 wt% water, such as less than 5 wt% water. The amounts of water described herein include the free water that is added and that amount that is introduced bound with other material (aqua) Preferably, the composition of the invention further comprises humeotants. Humectants have been found to keep the composition moisturized. Suitable humectants include glycerine, sorbitol, polyethylene glycol, propylene glycol, and other edible polyhydric alcohols. Humectants are generally present in the compositions of the invention in an amount of from 1 wt% to 80 wt%, such as from 5 wt% to 50 wt%, for example from 10 to 30 wtl. Preferably, the humectant is glycerine. It has been found that improved properties, such as improved adherence and dry strip effect are obtained when the formulation comprises less than 50 wti humectant, especially less than 40 wt% humectant, such as less than 30 wtl humectant.
Optionally, the composition of the invention further comprises a second thickener other than a vinyl pyrrolidone polymer. For example, the composition of the invention may further comprise hydroxypropyl methylcellulose as a thickener. It has been found that when a teeth whitening strip containing the composition of the invention is applied to the teeth, hydroxypropyl methylcelluiose works to improve the adhesiveness of the composition to the enamel surface of the teeth, especially when the composition is in contact with a moist tooth surface. A combination of a vinyl pyrrolidone polymer and hydroxypropyl methylcellulose has been found to provide greater adherence than other thickening agents or combinations of thickening agents, such as, for example, cellulose gum or PVP in combination with cellulose gum.
Optionally, the composition of the invention further comprises a tackifier. It has been found that the tackifier may help the composition or the whitening agent adhere to the tissues of the oral cavity. Typically, the tackifier is a polyvinyl pyrrolidone polymer, especially PVP, with a weight average molecular weight of from 500,000 to 3,000,000, for example, vinyl pyrrolidone polymer especially PVF with a weight average molecular weight of 600,000 to 2,000,000. The tackifier present in the composition of the invention advantageously has a K-value of greater than 60, such as a K-value of from 60 to 120, especially 90 to 120, for example, 90. The vinyl pyrrolidone polymer tackifier typically has a plate structure. Generally, the tackifier is present in an amount of from 1 wt%: to 30 wt%, such as from 5 wt% to 25 wt%, especially from 10 wti to 20 wti, for example about 15 wt%.
Advantageously, the tackifier is PVP with a weight average molecular weight of 500,000 or higher.
Typically, the composition of the present invention further comprises a flavouring agent. The flavouring agent improves taste of the composition and helps to improve the comfort of the teeth whitening process. The flavouring agent may be natural or artificial. Optionally, the flavouring agent may be a sweetener, for example, stevioside.
Optionally, the flavouring agent may impart a mint or refreshing flavor to the composition of the invention. The flavouring agent may be D,L-menthol. Flavouring agents are generally present in an amount of from 0.1 wt% to 5.0 wt%, such as from 0.2 wt% to 3 wt%, especially from 0.3 wti to 2.0 wt%.
Optionally, the composition of the present invention further comprises a p1-I adjusting agent or buffer agent. The pH adjusting or buffer agent is added to make the composition safe for oral tissues. The pH adjusting or buffer agent may be any material which is suitable to adjust the pH of the composition. Suitable pH adjusting and buffer agents include sodium bicarbonate, sodium phosphate, sodium hydroxide, ammonium hydroxide, sodium stannate, triethanolamine, citric acid, hydrochloric acid, sodium citrate, and combinations thereof. The pH adjusting or buffer agents are added to the composition in amounts sufficient to adjust the pH of the composition to 4.5 to 10, preferably from S to 8.5 and more preferably from S to 7. pH adjusting agents are generally present in the compositions of the invention in an amount of from 0.01 wt% to S wt%, such as from 0.05 wti to 2 wt%.
Optionally, the composition of the present invention further comprises other additives, for example, xylitol, opacifiers and/or coloring agents.
The teeth whitening system according to the second aspect of the invention may comprise one or more teeth whitening strips each comprising a film coated with the composition of the first aspect of the invention. The composition may be coated on at least one side of the film.
The amount of composition applied to the teeth will depend upon the size and capacity of the strip, concentration of the whitening agent, and/or the desired benefit. Generally, less than 1 g of composition is required per application, such as from 0.05 g to 0.5 g especially from 0.1 g to 0.4 g of the composition is used per application.
Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.
The formulation of an example of a composition of the present invention is shown in Table 1.
Table 1: The formulation of an example of a composition of the present invention INCI or Chemical % EINECS/ELI % by CAS No. Intended Function Name Active NCS Weight PVP (K30) 100 9003-39-8 N/A 30.00 Thickener Hydroxypropyl 9004-65-3 N/A 25.00 Thickener Methylcellu lose Glycerin 100 56-81-5 200-289-5 21.00 Moisturizer PVP (K90) 100 9003-39-8 N/A 15.00 Tackifier Alcohol# 50 64-17-5 200-578-6 6.30 Solvent Sodium Chlorae* 252 7758-19-2 231-836-6 1.00 Oxidizing/Oral Care EDTA 100 60-00-4 200-449-4 1.00 Chelating Flavoring Agent/ Stevioside 100 5781 7-89-7 260-975-5 0.50 Masking/Oral Care D,L-Menthol 100 89-78-I 201-939-0 0.20 Refreshing/Soothing #Alcohol is a 50:50 v/v mixture of ethanol in water.
*Sodium Chlorae is a 25.2 wt% solution in water, giving a total sodium chlorite level of 0.252 wt% in the composition of the invention.
In this example, the composition is a gel with a pH value of 5.5. The composition has been applied to teeth whitening strips and tested for safety and efficacy. It has been reported that the strips were comfortable on the teeth and easy to remove after a whitening session. It has also been reported that the composition exhibits a dry strip effect and does not adhere to the fingers of the user during application or removal of the strip. Clinical test results show that the composition provides significant improvements to the users' teeth shade when measured by the value-oriented VITA Classic Shade Guide compared to previously known compositions comprising sodium chlorite as a whitening agent. The strips of the invention, i.e. strips of the second aspect of the invention and/or strips comprising the composition of the first aspect of the invention have comparable whitening performance to that of first generation whitening strips that included substantial levels of hydrogen peroxide.
Where in the foregoing description, integers or
elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.

Claims (15)
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  1. Claims 1. A composition for a teeth whitening strip comprising sodium chlorite as the whitening agent, a vinyl pyrrolidone polymer thickener, alcohol and a chelating agent.
  2. 2. The composition of claim 1, comprising at least 10 wti vinyl pyrrolidone polymer thickener, such as at least 20 wtl vinyl pyrrolidone polymer thickener.
  3. 3. The composition of claim 1 or claim 2, wherein the vinyl pyrrolidone polymer thickener has a K-value in the range of from 17 to 60, especially a K-value in the range of from 25 to 30.
  4. 4. The composition of any preceding claim wherein the vinyl pyrrolidone polymer thickener is polyvinylpyrrolidone (PVP)
  5. 5. The composition of any preceding claim in the form of a gel.
  6. 6. The composition of any preceding claim having less than 8 wtl water.
  7. 7. The composition of any preceding claim further comprising a humectant.
  8. 8. The composition of claim 7 comprising 10 to 50 wt% humectant.
  9. 9. The composition of claim 7 or 8 wherein the humectant is glycerine.
  10. 10. The composition of any preceding olaim further comprising hydroxypropyl methylcellulose thickener.
  11. 11. The composition of any preceding claim further comprising a flavouring agent.
  12. 12. The composition of any preceding claim wherein the chelating agent is EPTA.
  13. 13. The composition of any preceding olaim further comprising a tackifler.
  14. 14. A teeth whitening system comprising the composition of any preceding claim and a carrier film.
  15. 15. A method of whitening teeth comprising the step of applying the teeth whitening system of claim 14 or the composition of any one of claims 1 to 13 to the teeth.