WO2014136008A1

WO2014136008A1 - Tooth whitening with hydrogen peroxide and blue light

Info

Publication number: WO2014136008A1
Application number: PCT/IB2014/059104
Authority: WO
Inventors: Veena MOHAN; Nigel David Young
Original assignee: Koninklijke Philips N.V.
Priority date: 2013-03-06
Filing date: 2014-02-20
Publication date: 2014-09-12

Abstract

Compositions, systems, and methods for whitening teeth are disclosed. A tooth whitening composition includes a first component including up to 6% by weight of a bleaching agent and a second component including up to 4% by weight of an activator. A tooth whitening system includes the tooth whitening composition and a light source having a wavelength between about 402 nm to about 940 nm to activate the bleaching agent during a whitening treatment. A method of whitening teeth includes mixing the first component and the second component of the tooth whitening composition just prior to use, and applying the tooth whitening composition to a surface of at least one tooth. The at least one tooth may be exposed to the light source having a wavelength between about 402 nm to about 940 nm.

Description

TOOTH WHITENING WITH HYDROGEN PEROXIDE AND BLUE LIGHT

TECHNICAL FIELD

[0001] The present disclosure relates to compositions, systems, and methods for whitening teeth. More particularly, the present disclosure relates to light activated whitening treatments performed with a tooth whitening composition including up to 6% hydrogen peroxide and a light source which emits blue light.

BACKGROUND

[0002] Known processes for whitening teeth include "in-office" treatments in which a dental professional applies the necessary whitening gels, and "at-home" treatments which allow the consumer to perform the whitening process themselves. In either case, the tooth whitening process includes the application of bleaching compositions to the surface of the teeth. While surface stains on the enamel are bleached during the tooth whitening process, surface stains are readily removed by a visit to the hygienist, and thus, removal of surface stains is not the ultimate goal of the whitening process. Rather, tooth whitening demands the application of bleaching compositions to the tooth surface to bleach the dentin, since it is the dentin which principally contributes to tooth discoloration. The ultimate goal is therefore to bleach the outer surface of the dentin. The dentin, however, is inherently protected by the hard enamel layer of the tooth surface. Known techniques therefore require diffusion of reactive agents through the protective enamel layer to the enamel-dentin interface in order to effect bleaching.

[0003] A variety of peroxide compounds, including carbamide peroxide, hydrogen peroxide, sodium perborate and calcium peroxide, have been used as active ingredients for bleaching materials. The majority of contemporary tooth whitening products involve the use of gels containing varying concentration of hydrogen peroxide and carbamide peroxide. Lower concentrations of carbamide peroxide and hydrogen peroxide are used in "at-home" based whitening systems while higher concentrations are necessary for "in-office" treatments. Chair side techniques also make use of light sources (e.g., halogen, laser, and light-emitting diode) or chemicals to activate and accelerate the degradation of the bleaching gel. Additionally, evidence also suggest that light alone performs some decomposition of the chromaphore in the absence of whitening agent.

[0004] All peroxide gels work by forming hydrogen peroxide as their end product.

Hydrogen peroxide breaks down into water and numerous by products such as free radicals, hydrogen ions, oxygen ions, and molecular oxygen. The mechanism by which teeth is whitened by carbamide peroxide and hydrogen peroxide is by the diffusion of peroxide into and through the enamel to reach the enamel dentine junction and dentine regions.

[0005] Stains and proteins in the tooth are complex, long chain organic molecules, and it is the conjugation length of the molecule which gives rise to the color. Thus, stain removal is often attributed to the shortening of these molecules by the direct cleaving of conjugated bonds by -OH and -OOH radicals.

[0006] Two of the key factors in determining overall tooth whitening efficacy from peroxide containing products are the concentration of the peroxide and duration of application. Typically, products for "in-office" treatments use a 10% to 25% concentration of peroxide, but consequently demand the application of protective barriers to the soft oral tissues which would otherwise by attacked by the peroxide. By contrast, "at-home" treatments for tooth whitening typically use much lower concentrations of peroxide, in the order of 5% to 10%. "At-home" products are applied to the teeth in the form of gels or pastes that are held proximal to the teeth by either a dental tray or adhesive strips, and achieve their whitening effect over a much longer duration and in the absence of light. The lower concentration of peroxide in "at-home" treatments reduces the likelihood of damage to the soft oral tissues and reduces or obviates the need for their protection. However, in order to achieve a comparable effect, the use of lower concentrations of active agents requires longer treatment periods for whitening. Essentially, in the absence of optical accelerators, a longer duration is needed for the free radical concentration at the enamel-dentin interface to become sufficiently high to achieve a significant whitening effect. Typically, an "in-office" treatment lasts a total of 1 hour, and an "at-home" treatment requires a daily procedure for up to 8 hours per day for up to 14 days, a total of 112 hours. Thus, a drawback of tooth whitening products with a lower concentration of peroxide is the relatively long duration required for the whitening process as the production of radicals from peroxide occurs naturally at a very slow rate.

[0007] From the foregoing it may be seen that there remains a need for a method of whitening teeth with lower concentrations of peroxide in a shorter amount of time.

SUMMARY

[0008] According to an aspect of the present disclosure, a tooth whitening composition includes a first component including a solvent and up to 6% by weight of a bleaching agent, and a second component including up to 4% by weight of an activator. The second component may include up to 12% of a neutralizer. In embodiments, the solvent of the first component is water and the bleaching agent is hydrogen peroxide. In embodiments, the activator of the second component is ferrous gluconate and the neutralizer is potassium hydroxide.

[0009] In embodiments, the first and second components are free of thickeners, flavoring agents, fillers, gelling agents, stabilizing agents, desensitizers, and color enhancers. In such embodiments, the first component includes only the solvent and the bleaching agent, and the second component includes only the activator, a neutralizer, and a solvent. In other embodiments, the second component may include a thickener or gelling agent. In such embodiments, the second component includes only an activator, a neutralizer, a solvent, and a thickener.

[0010] According to another aspect of the present disclosure, a system of whitening teeth includes a two-component tooth whitening composition and a light source. The two-component tooth whitening composition include a first aqueous component including up to 6% by weight of a bleaching agent, and a second component including up to 4% by weight of an activator. The second component may include up to 12% of a neutralizer. The light source emits light at a wavelength between about 402 nm and about 940 nm, in embodiments, the wavelength is between about 450 nm and about 495 nm.

[0011] In embodiments, the bleaching agent of the first component is hydrogen peroxide and the activator is ferrous gluconate. In embodiments, the first aqueous component includes only a solvent and the bleaching agent, and the second component contains only the activator, a neutralizer, and a solvent. In such embodiments, the first and second components are free of thickeners, flavoring agents, fillers, gelling agents, stabilizing agents, desensitizers, and color enhancers. In other embodiments, the second component may include a thickener or gelling agent. In such embodiments, the second component includes only an activator, a neutralizer, a solvent, and a thickener or gelling agent.

[0012] According to another aspect of the present disclosure, a method of whitening teeth includes mixing a first component and a second component of a tooth whitening composition just prior to use, the first component including up to 6% by weight of a bleaching agent and the second component including up to 4% by weight of an activator, and applying the tooth whitening composition to a surface of at least one tooth. The method may further include exposing the at least one tooth to a light having a wavelength between about 402 nm to about 940 nm for a predetermined period of time, in embodiments, the wavelength is between about 450 nm to about 495 nm. In embodiments, the predetermined period of time is about 15 minutes to about 60 minutes. The application and exposure steps may be repeated for a predetermined number of successive cycles until the desired whitening effect is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The aspects of the present disclosure may be better understood with reference the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed on clearly illustrating the principles of the disclosure. In the figures:

[0014] FIG. 1 is a cross-sectional view of a dual barrel syringe containing the first and second components of a tooth whitening composition in accordance with an embodiment of the present disclosure; and

[0015] FIG. 2 is a perspective view of a light source which may be utilized with a tooth whitening composition in accordance with an embodiment of the present disclosure.

DETAILED DESCRD7TION

[0016] Described below are tooth whitening compositions of the present disclosure and methods of using the same, alone or in combination, with a visible light source. These compositions, systems, and methods may be applied in, and are expected to benefit consumers, in either an "in-office" or "at-home" environment. In accordance with the present disclosure, it has been found that teeth whitening can be achieved dramatically and quickly using light energy with whitening compositions containing only 6% hydrogen peroxide.

[0017] The whitening composition of the present disclosure is a two component composition including a first, peroxide component and second, activator component. In embodiments, the first and second components do not include thickeners, flavoring agents, fillers, gelling agents, stabilizing agents, desensitizers, and color enhancers, thereby avoiding complexity of the formulation. In other embodiments, the second component may include a thickener and/or gelling agent.

[0018] The first component is a solution including a solvent and a bleaching agent.

Suitable solvents which may be utilized in the tooth whitening composition of the present disclosure include, for example, water, glycerin, propylene glycol, and polyethylene glycol. Suitable bleaching agents include, for example, peroxide compounds such as hydrogen peroxide, carbamide peroxide, calcium carbonate peroxide, sodium carbonate peroxide, as well as other oxygen radical generating agents, and combinations thereof. The concentration of the bleaching agent in the solution of the first component is up to 6%, in embodiments, up to about 5%.

[0019] In embodiments, the solvent is water and the bleaching agent is hydrogen peroxide. The first component includes up to 6% by weight of hydrogen peroxide. In embodiments, the first component includes about 4% to about 6% hydrogen peroxide, in some embodiments, from about 4% to about 5% hydrogen peroxide, and in some embodiments, about 5% to about 6% hydrogen peroxide. In embodiments, the first component includes about 6% hydrogen peroxide.

[0020] The second component is a solution including a solvent, a neutralizer, and an activator. Suitable solvents may include those discussed above with respect to the solvent of the first component. Suitable neutralizers which may be utilized in the tooth whitening composition of the present disclosure include, for example, potassium hydroxide, sodium hydroxide, and the like. Suitable activators include, for example, metal salts such as ferrous gluconate, ferrous sulfate, ferrous nitrate, ferrous acetate and mixtures thereof, as well as chelating metal ions such as Manganese (II), Copper (Π), Cobalt (II) and mixtures thereof. The concentration of the neutralizer in the solution of the second component may be up to about 12%, in embodiments, up to 6%, although it should be understood that the concentration of the neutralizer may vary depending upon the desired pH of the tooth whitening composition. The concentration of the activator in the solution of the second component may be up to about 4%, in embodiments, up to about 1%, and in some embodiments, up to about 0.005%.

[0021] In some embodiments, the second component may also include a thickener and/or gelling agent. Suitable thickeners and gelling agents are within the purview of those skilled. It should be understood that the concentration of the thickener or gelling agent may vary depending on the desired coating properties of the tooth whitening composition.

[0022] In embodiments, the solvent is water, the neutralizer is potassium hydroxide, and the activator is ferrous gluconate. The second component includes up to 12% by weight of potassium hydroxide, in embodiments, from about 1% to about 12% potassium hydroxide. In embodiments, the second component may include up to about 6% potassium hydroxide, in some embodiments, about 5% to about 6% potassium hydroxide, and in some embodiments, about 0.3% to about 1.5% potassium hydroxide. The second component includes up to 4% by weight of ferrous gluconate. In embodiments, the second component includes from about 0.01% to about 4% ferrous gluconate, in some embodiments, from about 0.03% to about 2% ferrous gluconate, and in some embodiments, from about 0.04% to about 1% ferrous gluconate. In embodiments, the second component includes up to about 0.005% ferrous gluconate, and in embodiments, up to about 0.004% ferrous gluconate.

[0023] The first and second components of the tooth whitening composition are kept separate and isolated from each other, and are mixed at the point-of-use. In embodiments, as illustrated in FIG. 1, a dual barrel syringe 100 includes a first barrel 102 containing the first component "Ci" and a second barrel containing 104 the second component "C₂" thereby keeping the peroxide stable at an acidic pH. In embodiments, a closure cap (not shown) on the syringe 100 may be replaced with a mixing tip 106 including a static mixer 108 through which the first and second components "Ci" and "C₂" are mixed and dispensed upon actuation of a plunger 110 of the syringe 100.

[0024] Upon mixing, the potassium hydroxide makes the bleaching agent basic at a pH at or above 7.0. In embodiments, the pH of the tooth whitening composition upon mixture is about 7.0 to about 9.0, in some embodiments, about 7.5 to about 9.0, and in some embodiments, about 8.0. In embodiments, the pH of the tooth whitening composition upon mixture is about 9.0 to about 10.0, in embodiments, about 9.5. A basic pH helps reduce enamel erosion and increases the rate of reaction of the whitening process.

[0025] The whitening composition may be utilized with a light source to activate the bleaching agent. The wavelength of the light emitted from the light source may be between about 402 nm to about 940 nm. In embodiments, the light source emits visible light in the blue wavelength region of about 450 nm to about 495 nm, and in some embodiments, about 462 nm. The reaction rate of whitening is not only increased with light, but also visible light can penetrate into the depth of the tooth and promote radical production close to the site of the stain. The power density of the light may be from about 10 mw/cm² to about 1 ,000 mw/cm², in 2 2

embodiments, about 110 mw/cm to about 500 mw/cm , and in some embodiments, about 190 mw/cm .

[0026] The light source may be, for example, a halogen, laser, or light-emitting diode provided in a hand-held or portable device, or in a chair side lamp 200 as illustrated in FIG. 2. A suitable commercially available lamp is the PHILIPS^® Zoom WhiteSpeed lamp available through Koninklijke Philips Electronics N.V. The PHILIPS^® Zoom WhiteSpeed lamp includes adjustable lamp settings which provide additional benefits to a dental practitioner, as a variable range of light intensity settings allow the dental practitioner to make adjustments according to the patient's needs.

[0027] The mechanisms by which light can enhance whitening are varied and complex.

When photons are absorbed directly by the chromogen (as is the case with blue light and yellow- red stains) and have sufficient energy to break the chemical bonds, direct bleaching by bond- breaking and loss of conjugation in the chromogen occurs.

[0028] Other than direct bleaching of the chromagens, there is a more significant effect when both hydrogen peroxide and blue light are present together. The simplest mechanism for this would be one in which the hydrogen peroxide is directly cleaved into two radicals which subsequently react with the chromogen. However, although the blue light has sufficient photon energy for this cleavage, hydrogen peroxide does not absorb blue light significantly. Therefore, while not wishing to be bound by the present theory, it is believed that the chromogen absorbs the photon, and then transfers the energy to the hydrogen peroxide, resulting in the cleavage.

[0029] Alternatively, the absorption of the photon could raise the energy states of the

C=0, C=C, and C=C C=C conjugated bonds in the chromogen making them more reactive with the hydrogen peroxide molecules and its subspecies. Another group of processes through which the light can interact with the hydrogen peroxide are known as the photo-Fenton reactions. These are reactions which are associated with a metal salt activator, such as ferrous gluconate, which is used in the formulation as discussed above.

[0030] The whitening composition and light source may be utilized as a system for "in- office" treatment. In a method of use, the teeth are prepared for treatment. In embodiments, the gums may be masked thereby isolating the teeth so that only the teeth are exposed and the gums protected. The first and second components of the whitening composition may be mixed just prior to application to teeth. In embodiments, the first and second components may be provided in separate containers, or dual barrel syringes as described above, and the mixture applied to teeth. The teeth are then exposed to light from a light source at a predetermined wavelength and power density for a predetermined period of time (e.g., from about 15 minutes to about 60 minutes) to activate the bleaching agent and accelerate the bleaching process. In embodiments, the "in-office" treatment may be completed in one office visit, and may and includes a predetermined number of application cycles (e.g., four 15-minute chair side cycles).

[0031] The whitening composition may also be utilized in an "at-home" treatment. In a method of use, the first and second components of the tooth whitening composition are mixed and dispensed into a dental bleaching tray. In embodiments, the first and second components are provided in a dual barrel syringe. The dental bleaching trays are then positioned and maintained on the teeth for a predetermined period of time over a predetermined time interval (e.g., 2 times per day for 14 to 21 days). Alternatively, the "at-home" treatment may be provided on an as- needed basis.

[0032] In some embodiments, an "in-office" treatment is followed up with an "at-home" treatment by conducting the "in-office" treatment, as described above, and then allowing the patient to either wear the whitening composition out of the office with dental bleaching trays or providing the patient with the whitening composition and dental bleaching trays for "at-home" applications, as described above.

[0033] The Examples below include an illustrative tooth whitening composition of the present disclosure, and use of the tooth whitening composition alone as well as with illumination on stained filter papers to demonstrate the degree of whitening which may be achieved in a short period of time.

EXAMPLES

Example 1

Preparation of a Tooth Whitening Composition

[0034] A first aqueous peroxide solution containing about 24% hydrogen peroxide and a second aqueous activator solution containing about 6% potassium hydroxide and about 0.004% ferrous gluconate, were prepared as follows:

FIRST SOLUTION SECOND SOLUTION

Components Weight (g) Components Weight (g)

58% H₂0₂ 62 Water 94.116

Water 38 Ferrous Gluconate 0.003804

KOH 5.88

[0035] The first solution was diluted 1 : 1 in distilled water to get a half strength, i.e., 12%, hydrogen peroxide solution. The 12% hydrogen peroxide solution was diluted 1 : 1 with distilled water to get a quarter strength, i.e., 6%, hydrogen peroxide solution. Similarly, the second solution was diluted 1 : 1 in distilled water to get a half strength activator solution, and the half strength activator solution was diluted 1 :1 in distilled water to get a quarter strength activator solution. [0036] Four parts of the 6% peroxide solution were mixed with one part of the quarter strength activator solution to form a tooth whitening composition containing 4.8% hydrogen peroxide, 1.18% potassium hydroxide, and 0.001% ferrous gluconate.

Example 2

Kit for Demonstrating the Effect of the Tooth Whitening Composition

[0037] A demonstration kit contained artificially stained filter papers as substrates for demonstrating the whitening process of the tooth whitening composition of Example 1 in a short period of time. The filter papers were WHATMAN^® qualitative filter paper, Grade 1 , having a 1 cm diameter. The selection of filter papers avoided the complex physics and chemistry behind tooth whitening on in vitro samples, such as bovine or human teeth. The staining process was mimicked by artificially staining the filter paper in combined tea-coffee solutions at 37°C for four days. Tea-coffee solutions contain a complex mix of stain molecules (chromogens). Like other chromogens, they absorb visible light and appear yellow or red in color. [0038] The first and second solutions were mixed 4: 1, respectively, as provided above in

Example 1, immediately prior to application on the stained filter papers. One to two drops of the tooth whitening composition was applied to the top of the filter papers. The treated filtered papers were then separated into a light activated group and a non-light activated group to test the bleaching effect of the tooth whitening composition with and without illumination, respectively. The treated filter papers in the light activated group were illuminated under a PHILIPS^® Zoom WhiteSpeed lamp for about 2 minutes. The wavelength of the light was 462 nm and the setting was adjusted to high (power density of 190 mW/cm²).

[0039] After two minutes of illumination, the results were readily visible between the light activated and non-light activated whitening treatments. Color change of the filter filters was measured with a colorimeter (Konica Minolta Chromameter), where ΔΕ and Ab values represent the overall change in color (total color difference) and the change from yellow to blue color, respectively. The non-light activated treated filter papers presented ΔΕ of 0.3 and Ab of 1.1, while the light activated treated filter papers presented ΔΕ of 0.8 and Ab of 0.33.

[0040] The filter papers subjected to the non-light activated whitening treatment achieved a lesser, but still significant enhancement in coloration compared with the filter papers subjected to the light-activated whitening treatment. The demonstration shows that blue light accelerates the whitening process and reduces the treatment period compared to non-light activated whitening processes. Blue light was a key differentiator to providing better whitening results with a composition including a low concentration of peroxide (i.e., about 6% or less).

[0041] Many modifications and other embodiments of the compositions, systems, and methods of the present disclosure will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing description. Therefore, it is to be understood that the embodiments of the present disclosure are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

WHAT IS CLAIMED IS;

1. A tooth whitening composition comprising:

a first component consisting of a solvent and up to 6% by weight of a bleaching agent; and

a second component including up to 4% by weight of an activator.

2. The tooth whitening composition of claim 1 , wherein the second component further includes up to 12% of a neutralizer.

3. The tooth whitening composition of claim 1, wherein the solvent is water and the bleaching agent is hydrogen peroxide.

4. The tooth whitening composition of claim 2, wherein the activator is ferrous gluconate and the neutralizer is potassium hydroxide.

5. The tooth whitening composition of claim 4, wherein the second component consists of the ferrous gluconate, the potassium hydroxide, and water.

6. The tooth whitening composition of claim 1 , wherein the first and second components are free of thickeners, flavoring agents, fillers, gelling agents, stabilizing agents, desensitizers, and color enhancers.

7. The tooth whitening composition of claim 1 , wherein the second component consists of the activator, a neutralizer, a solvent, and a thickener.

8. A system of whitening teeth, the system comprising:

a two-component tooth whitening composition comprising: a first aqueous component including up to 6% by weight of a bleaching agent; and a second component including up to 4% by weight of an activator; and a light source having a wavelength between about 402 nm to about 940 nm.

9. The system of claim 8, wherein the second component further includes up to 12% of a neutralizer.

10. The system of claim 8, wherein the bleaching agent is hydrogen peroxide and the activator is ferrous gluconate.

11. The system of claim 8, wherein the first aqueous component consists of a solvent and the bleaching agent.

12. The system of claim 8, wherein the second component consists of the activator, a neutralizer, and a solvent.

13. The system of claim 8, wherein the second component consists of the activator, a neutralizer, a solvent, and a thickener.

14. The system of claim 8, wherein the first and second components are free of thickeners, flavoring agents, fillers, gelling agents, stabilizing agents, desensitizers, and color enhancers.

15. The system of claim 8, wherein the wavelength of the light source is between about 450 nm and about 495 nm.

16. A method of whitening teeth comprising:

mixing a first component and a second component of a tooth whitening composition just prior to use, the first component including up to 6% by weight of a bleaching agent and the second component including up to 4% by weight of an activator; and

applying the tooth whitening composition to a surface of at least one tooth.

17. The method of claim 16, further comprising:

exposing the at least one tooth to a light having a wavelength between about 402 nm to about 940 nm for a predetermined period of time.

18. The method of claim 17, wherein the step of exposing includes utilizing a light source that emits the light at a wavelength between about 450 nm to about 495 nm.

19. The method of claim 17, wherein the predetermined period of time is from about 15 minutes to about 60 minutes.

20. The method of claim 17, wherein the steps of applying and exposing are repeated for a predetermined number of successive cycles.