WO2000009079A1

WO2000009079A1 - Methods and compositions for whitening teeth

Info

Publication number: WO2000009079A1
Application number: PCT/US1999/017949
Authority: WO
Inventors: Gerald G. Mclaughlin
Original assignee: Mclaughlin Gerald G
Priority date: 1998-08-11
Filing date: 1999-08-10
Publication date: 2000-02-24
Also published as: AU5394999A

Abstract

The invention provides a composition for whitening teeth, using a non-peroxide ionic bleaching compound. The compositions are made into various consistencies and forms such as pastes, gels, or solutions such that they can be placed in contact with teeth or a dentrifice to be treated. Ions and radicals in the materials penetrate into the tooth structure and cause a whitening effect both on the surface and below the surface. A method for whitening teeth by providing a bleaching agent or compositions to teeth or a dentrifice to be treated is also provided.

Description

METHODS AND COMPOSITIONS FOR WHITENING TEETH

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional Application Serial No. 60/096,047, filed August 11, 1998, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION The present invention relates to the field of dentistry, and specifically to the whitening of the teeth.

BACKGROUND OF THE INVENTION

Teeth generally become more darkly pigmented with age and exposure to such materials as tea and coffee, and it has long been a goal of dentistry to provide a means to safely and effectively reverse this darkening process. Historically there are two approaches to the problem. The first involves removing pigmentation that has adhered onto the surface of the teeth. This is commonly achieved through the use of abrasives, sometimes augmented with solvents. While rapidly effective, these techniques have the disadvantage of only being able to remove extrinsic stains, leaving all internal pigmentation unchanged. Thus, the whitening effect is extremely limited.

A more recent innovation involves a method of using either hydrogen peroxide or hydrogen peroxide mixed with urea (also known as urea peroxide or carbamide peroxide) to penetrate into the tooth structure and bleach out the undersired pigmentation.

At present, the preferred method of application of the whitening agent utilizes either custom or stock trays that are shaped to hold the bleaching agent against the teeth to be whitened. These trays are then filled with the peroxide, and worn for long periods of time - sometimes even overnight. After a series of lengthy treatments, the teeth will usually begin to show the desired whitening effect. Naturally the length of treatment can be discouraging and increase the cost. While effective on both extrinsic and intrinsic discolorations, one additional major problem encountered with this approach stems directly from the materials used. The two major pathways of action of the peroxides are through liberation of either hydroxyl free radicals or oxygen free radicals. In an environment with a pH lower than 8 the oxygen free radical is generally the most active, while the hydroxyl free radical becomes most important in an alkaline environment above a pH of 8. Unfortunately, some researchers feel that in some early studies these free radicals have been implicated as either carcinogens or co-carcinogens and the use of these peroxide products for the purpose of tooth bleaching has therefore been banned in many countries. In view of the foregoing, it will be appreciated that there is a decided need in the art for a method to simply and comfortably whiten teeth with materials that do not generate such high concentrations of what may be viewed as potentially damaging free radicals.

SUMMARY OF THE INVENTION

The present invention overcomes the problems noted above, and provides a greatly improved method for whitening discolored teeth. Through the use of this invention, the treatment time can be substantially shortened at the same time that the concentration of free radicals is diminished. Of course, other beneficial effects for the patient such as antisepsis and tissue debridement can be realized using the materials and methods described herein.

In one embodiment, the present invention provides a composition for whitening teeth including a therapeutically effective amount of a non-peroxide ionic bleaching compound in a mouthrinse, toothpaste, gel dentrifice, chewing gum, wax or lozenge vehicle. The bleaching compound is either an oxidizing or reducing agent, such as, for example persulfates. The concentration of the non-peroxide ionic bleaching compound can be from about 2 to 90% by weight, from about 20 to 85% by weight, or from about 50-80% by weight depending upon the formulation and application. Other agents may be included in the composition including, but not limited to, flavorants, abrasives, fluoride, peroxides, and palliative agents.

In another embodiment, the present invention provides a method for whitening teeth comprising contacting a tooth with a non-peroxide ionic bleaching compound. The bleaching compound can be included in a composition for appropriate delivery including, for example, gels, pastes, sprays, and mouthrinses. The bleaching compound can be contacted with the tooth either alone or in combination and either sequentially or contemporaneously with any number of additional agents well known in the art.

DETAILED DESCRIPTION OF THE INVENTION

The methods and compositions of the invention utilize an oxygenating agent that uses ions rather than free radicals for the oxidation process. In addition to increased safety, in sufficient concentration the agent can be placed on the stained tooth structure and achieve as much whitening effect in one hour as has previously only been possible in the tray system through several weeks of wearing time. This is achieved because the lifespan of the free radicals employed in peroxide-based bleaching has a lifespan measured in nanoseconds, whereas the active lifespan of the ions (i.e., oxidizing or reducing) of the present invention are substantially longer sometimes hours or longer. The whitening effect can be further accelerated through the application of energy, such as in the form of light, heat, electric potential, or electric current. For instance, the process can be accelerated through the simultaneous application of electromagnetic energy, such as heat or light. This can serve to excite the whitening agent, raise the activity level of the pigments to be whitened, and accelerate the chemical activity of the whole process. A laser source, as an example, can be made to strike the bleaching agent, causing it to more rapidly ionize or energize, and thus be more active in the bleaching process. Another example would be to use a plasma arc lamp as the source of light and/or heat.

The invention provides a composition for whitening teeth consisting of a therapeutically effective amount of a bleaching compound or agent which is not of the peroxide class. A "bleaching compound" or "bleaching agent" as used herein is any compound which has the ability of whitening teeth, but which is not of the peroxide class. "The peroxide class" refers to any compound whose main bleaching action is derived from the breakdown of peroxide ions such as hydrogen peroxide, carbamide peroxide, urea peroxide, sodium percarbonate, and perhydrol urea. Examples of bleaching compounds not of the peroxide class are potassium monopersulfate and ozone. By "non-peroxide ionic bleaching compound" is meant a bleaching compound that is not of the peroxide class and forms ions under the appropriate conditions. The bleaching agent is preferably water soluble, such as, for example, peroxymonosulfate, normally an alkali metal peroxymonosulfate, such as potassium or sodium peroxymonosulfate. Potassium peroxymonosulfate, KHSO₅, is available as the mixed salt 2KHSO₅.KHSO₄.K₂ SO₄, sold by E. I. DuPont DeNemours and Company, Inc. under the trademark Oxone. That product has an active oxygen content of about 4.5%. The active oxygen content of the mixed salt described is about 5.2% when the salt is pure and the corresponding active oxygen content of KHSO₅ is about 10.5%. Thus, the pure mixed salt has half as much active oxygen in it as has the pure peroxymonosulfate and the 86.5% pure mixed salt (Oxone) has 43% as much. In this specification when peroxymonosulfate is mentioned the single salt is intended, with its higher active oxygen content, but an equivalent proportion of the triple salt, such as that sold under the trademark Oxone, will normally be employed as the source of the active bleaching compound because of its ready availability, stability and desirable physical characteristics. Potassium peroxymonosulfate may also be named as potassium monopersulfate and its triple salt may also be considered to be a monopersulfate compound within this invention. Other oxidizing agents useful as bleaching agents include, for example, oxygen, persulfates, such as potassium peroxymonosulfate and potassium persulfate and sodium persulfate, peracids such as peracetic acid, peroxymonosulfuric acid (Caro's Acid), PXA (mixed peracids, such as a mixture of glacial acetic acid, concentrated sulfuric acid and hydrogen peroxide), and other peroxy compounds. Mixtures of oxidizing agents may be used. Where a reducing agent is desired formamidine sulfinic acid (FAS) (also known as thiourea dioxide) may be used as the reducing agent, other suitable reducing agents include, but are not limited to, sodium hydrosulfite and sodium borohydride. Mixtures of reducing agents may be used. By "therapeutically effective amount" is meant the quantity of bleaching agent, when placed in contact with the teeth of a subject according to the invention, necessary to whiten the teeth of the subject. A subject is any mammal, preferably a human.

Typically the bleaching agent employed is placed in the composition such that it will produce a strength in solution of at least 2% and can range up to a saturated solution. One particularly useful active agent utilized in such compositions is formed from the combination of water and a potassium monopersulfate compound. A useful potassium monopersulfate compound is produced by DuPont under the trade name "Oxone" and consists of a combination of materials as shown below:

Potassium peroxymonosulfate 43%

Potassium bisulfate 23%

Potassium sulfate 29% Potassium peroxidisulfate 3%

Magnesium carbonate 2%

For purposes of the present invention it has been found that the inclusion of magnesium carbonate is not essential although it is included in the mixture as an anti-caking agent. Another particularly active agent is that of ozone in solution with water.

This can be made by allowing ozone gas to dissolve into water by bubbling the gas through a container of water.

In one embodiment, the teeth needing whitening are first cleaned in the usual fashion. Some common methods include the use of a rotating brush and a mildly abrasive commercial tooth-cleaning material such as Oral-B Prophy Paste (Oral B, Inc.). A mixture of whitening materials is made up immediately before use consisting of sufficient water to create a slurry with, for example, potassium monopersulfate (Oxone, Dupont Chemicals). The teeth are then isolated from the soft tissues either with the use of a rubber dam or paint-on barrier material such as OpalDam (Ultradent). The slurry is then placed on the teeth in need of whitening and let stand for a period of time. The longer the time of exposure, the greater the whitening effect. It has been found that after approximately one hour a mixture as described can achieve as much whitening as is currently achievable through a normal two-week regimen of wearing bleaching trays with 10% carbamide peroxide. In another embodiment, other ingredients are added to the compound to enhance or modify its action. For example, one such mixture consists of 1 part potassium monopersulfate and a 1 part sodium fluoride. The sodium fluoride both raises the pH, and at the same time increases the resistance of the tooth to any etching of its surface from contact with acidic materials. In addition it serves to help prevent sensitization of the tooth and strengthens the tooth against future tooth decay. In addition, other compounds, for example, potassium nitrate can be added to the mixture to prevent sensitivity of the whitened tooth.

In another embodiment, a pigment or dye of the class called optical brighteners is added to the mixture. The optical brighteners are materials that absorb electromagnetic energy of one portion of the spectrum (often in the ultra-violet range) and re-emit the energy as visible light in the blue portion of the spectrum. The dye or pigment becomes incorporated into the structure of the tooth and the optical properties are thus enhanced. The additional blue light given off by the tooth is perceived by the eye as having a whitening effect. In addition, the pigment absorbs some of the ultra-violet energy and thereby protects the tissues form any untoward effects from exposure to that portion of the spectrum. An example of optical brighteners include Tinopal PT (Ciba-Geigy), Eastobright (Eastman Kodak), and Uvitex OB (Ciba-Geigy). In another embodiment other chemical enhancers such as ammonium persulfate, sodium persulfate, and potassium persulfate are added to the mixture to increase the oxidizing activity of the mixture.

Other chemicals of the class known as surfactants can be added to the mixture. It has been found that this allows greater uniformity in dispersion of materials in the mixture, while at the same time also increasing the wettability of the tooth surface and increasing the penetration of the mixture into the tooth. Examples of surfactants include sodium lauryl sulfate, Pluroni 127 (BASF Corp.), Tween 20, Surfynal 485w (Air Products & Pluronic Chemicals, Inc.), and sodium dodecylbenzenesulfanate.

The compositions of the invention can also contain materials added to give the mixture a consistency of paste or gel. For example, materials such as Carbopol (B.F. Goodrich), carboxymethyl cellulose, hydroxyethyl cellulose, gum arabic, sodium polyacrylate, potassium polyacrylate, and fused alumina silica can be used to give the compositions of the invention a consistency of a paste or gel. The mixture can also contain materials to give the mixture a smooth or creamy consistency. Examples of such material include, but are not limited to, Gantrez MS955 (ISP Technologies, Inc.).

In one embodiment, an abrasive material can be used with the composition of the invention. For example a dicalcium phosphate abrasive may be incorporated into the composition (e.g., see U.S. Patent 5, 171, 564). Examples of dicalcium phosphate abrasives include, but are not limited to dicalcium phosphate dihydrate, anhydrous dicalcium, or calcium pyrophosphate. Other abrasives for use with the subject invention include siliceous materials. Examples of such materials include, but are not limited to, silica abrasives, such as precipitated amorphous hydrated silica, and alumina abrasives, such as alumina trihydrate, aluminum silicate, calcined alumina, and bentonite.

When an abrasive material is included the vehicle may contain water, humectant, surfactant, and a thickener. Both mixtures of humectants and single humectants can be employed in the composition of the invention. Other materials from the class of humectants can be added to the compositions of the invention to serve as anti-drying agents. A "humectant" is any material that when added to the mixture serves to keep the material from drying during use. For example, humectants include, but are not limited to, sorbitol, and polyethylene glycol (molecular weight 200-1000). Thickeners may be incorporated in the abrasive component such as natural and synthetic gums such as carrageenan, xantham gum, sodium carboxymethyl cellulose, starch, polyvinylpyrrolidone, hydroxyethylpropylcellulose, hydroxybutyl methyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl cellulose. In another embodiment, an agent for administering fluoride, such as a fluorine providing salt, which has activity against cavities, may be incorporated into the composition of the subject invention. Such materials are characterized by their ability to release fluoride ions in water. Agents for administering fluoride include, but are not limited to, inorganic metal salts such as sodium fluoride, potassium fluoride, and tin fluoride such as stannous fluoride or stannous chlorofluoride, sodium fluorosilicate, ammonium fluorosilicate, and sodium monofluorophosphate.

The composition may also include palliative ingredients for periodontal tissues. Examples of such ingredients include, but are not limited to aloe, eugenol, and vitamin E. Pigments, sweeteners, colors, and flavors may also be incorporated into the composition. The flavorings or aromas, include, for example, mint or pineapple to make the mixture more pleasant to the senses. In another embodiment, the mixture can contain oxidizing agents from the class of peroxides although these would act in a supplemental manner to the non-peroxide agent(s) rather than providing the majority of the whitening action. The composition may further include an ingredient to decrease tooth sensitivity, such as potassium nitrate. The addition of these components to dental creams, such as toothpaste, are well known in the art.

In another embodiment, the mixture can contain materials to enhance the conversion of one form of energy to another. For instance the addition of certain materials will act to convert light energy to heat. Almost any colored material will produce this effect to one extent or another, and have been found to be useful in accelerating the whitening process. Others such as benzoil peroxoide do not necessarily display color when exposed to white light.

The compositions of the invention can also contain materials to either protect the soft tissues or to help them resist any ill effects of either the mixture or the external energy which is applied to the mixture. Examples of this group would be anti-oxidants such as melatonin, ascorbic acid, para amino benzoic acid, and aloe vera.

The compositions described herein can be applied to teeth or other tissues by any number of methods. For example, administration may be performed by using a toothbrush device, a syringe, held in a tray into which the teeth are immersed, sprayed on the surface, used as a mouth rinse, applied as a foam, as a toothpaste, gel dentifrice, chewing gum, wax or lozenge vehicle or other methods known to those of skill in the art. Techniques well known in the art of pharmaceutical compositions can be used to deliver the non-peroxide ionic bleaching agents of the invention in the form of a pharmaceutical carrier (see for example, Remington's Pharmaceutical

Sciences (Mack Pub. Co., Easton, PA, 1990). All that is necessary for effective use is for the composition (e.g., compositions comprising a non-peroxide ionic bleaching agent) of the invention to be in contact with the tissue or teeth to be treated. Normally the tissues or teeth which are not to be treated would be protected from contact, but with sufficiently dilute mixtures of the active agent such protection is not mandatory. In addition, the compositions of the present invention are useful in destaining or treating dentures, oral prosthetics, and retainers.

The chemicals and compositions of the invention can also be placed on the tooth prior to or contemporaneously with other composition or chemicals. For example, a slurry of potassium monopersulfate and water is first placed on the tooth and after several minutes it is followed by a solution of ozone and water. In another example, of this multi-stage approach the tooth is first washed with a mixture containing hydrogen peroxoide. This mixture is allowed to react with and penetrate the tooth before the application of an ozone solution. As described above, the effectiveness and stability of the bleaching materials is effectuated by the pH. Accordingly, the effectiveness and stability can be modulated by first wetting the tissue or teeth to be contacted with a solution of high pH. After allowing a period of time for this to penetrate the tooth structure the first solution is rinsed off and a second material is placed on the surface and allowed to penetrate into the tooth structure whose pH has just been effectively altered. By using a two stage approach in the application process it is possible to allow more effective penetration of the materials resulting in more effective bleaching.

As mentioned above, the oxidative ability of these mixtures, while most useful for tooth-whitening can also be employed for other purposes such as antisepsis of wounds and tissue debridement.

While specific chemicals in the mixture have herein been identified as belonging to one group or class (such as humectants, anti-oxidants, flavorants, etc.) It must be realized that some ingredients can perform more than one function and have not been repeated in the above list simply for reasons of brevity and clarity. Most typically the final composition will contain several chemicals taken from the above- listed groups in order to most exactly suit the requirements of the individual treatment situation.

The following examples are intended to illustrate but not to limit the invention in any manner, shape, or form, either explicitly or implicitly. While they are typical of those that might be used, other procedures, methodologies, or techniques known to those skilled in the art may alternatively be used.

EXAMPLES

EXAMPLE 1 A mixture of potassium monopersulfate compound such as that produced by Dupont under the trade name Oxone, was mixed with an equal amount of sodium fluoride into a slurry and placed on a human tooth for a period of one hour. During this time the adjacent soft tissues were protected from contact with the slurry by a rubber dam. As the slurry dried upon the teeth it was re-wetted using a small sable paintbrush that had been dipped in water. At the end of one hour the mixture was removed from the teeth and the teeth were rinsed with fresh water. The amount of whitening exhibited was approximately equal to that expected from a two-week regimen of wearing custom trays with peroxide gels.

EXAMPLE 2

A slurry was made as in Example 1 except that in place of plain water, a solution of water and ozone in a concentration of 3-4% was mixed and applied to the tooth. As the mixture began to dry it was stirred on the tooth with a small sable paintbrush that had been dipped into the ozone solution. The result of this treatment were even more dramatic than that of Example 1.

EXAMPLE 3 Various mixtures of agents listed above were placed on stained bovine teeth and the brightness of the teeth were measured both before and after a five minute exposure to the agents. The table below lists some of the combination tested and the results. A higher delta number indicates a greater amount of change in brightness of the substrate as a result of the exposure:

The table above shows the results while using a single representative from each of the various groups such as surfactants, optical brighteners and smoothing agents. Those skilled in the art will appreciate the number of variations and changes that can be made in the preferred methods hereof without departing form the spirit and scope of the invention. Such changes may include difference in specific steps and/or materials, so long as the essentials of the invention are satisfied. It is, of course, intended to cover all such variations and changes within the scope of the appended claims.

Claims

What is claimed is:

1. A composition for whitening of teeth, comprising a therapeutically effective amount of a non-peroxide ionic bleaching compound in a mouthrinse, toothpaste, gel dentifrice, chewing gum, wax or lozenge vehicle.

2. The composition of claim 1 , wherein the concentration of said bleaching compound is from about 2-90% by weight.

3. The composition of claim 1 , wherein the concentration of said bleaching compound is from about 20-85%) by weight.

4. The composition of claim 1 , wherein the concentration of said bleaching compound is from about 50-80%) by weight.

5. The composition of claim 1, wherein the non-peroxide ionic bleaching compound is an oxidizing agent.

6. The composition of claim 1 , wherein the non-peroxide ionic bleaching compound is a reducing agent.

7. The composition of claim 5, wherein said bleaching compound is selected from the group consisting of potassium peroxymonosulfate, potassium monopersulfate, oxygen, potassium persulfate, sodium persulfate, peracetic acid, peroxymonosulfuric acid (Caro's Acid), PXA and combinations thereof.

8. The composition of claim 6, wherein the bleaching compound is selected from the group consisting of thiourea dioxide, sodium hydrosulfite, sodium borohydride, and combinations thereof.

. The composition of claim 1 , wherein said bleaching compound comprises potassium monopersulfate.

10. The composition of claim 1, further comprising an abrasive agent.

11. The composition of claim 1 , further comprising an agent for administering fluoride.

12. The composition of claim 1 , further comprising a gel forming agent.

13. The composition of claim 1 , further comprising a palliative ingredient for periodontal tissues.

14. The composition of claim 13, wherein said palliative agent is selected from the group consisting of aloe, eugenol, and vitamin E.

15. The composition of claim 1 , further comprising an ingredient to decrease tooth sensitivity.

16. The composition of claim 15, wherein said ingredient to decrease tooth sensitivity is potassium nitrate.

17. A method for whitening teeth, comprising contacting a tooth with a non- peroxide ionic bleaching compound.

18. The method of claim 17, wherein the concentration of said bleaching compound is from about 2 -90%) by weight.

19. The method of claim 17, wherein the concentration of said bleaching compound is from about 20-85%) by weight.

20. The method of claim 17, wherein the concentration of said bleaching compound is from about 50-80%) by weight.

21. The method of claim 17, wherein the non-peroxide ionic bleaching compound is an oxidizing agent.

22. The method of claim 17, wherein the non-peroxide ionic bleaching compound is a reducing agent.

23. The method of claim 21 , wherein said bleaching compound is selected from the group consisting of potassium peroxymonosulfate, potassium monopersulfate, oxygen, potassium persulfate, sodium persulfate, peracetic acid, peroxymonosulfuric acid (Caro's Acid), PXA and combinations thereof.

24. The method of claim 22, wherein the bleaching compund is selected from the group consisting of thiourea dioxide, sodium hydrosulfite, sodium borohydride, and combinations thereof.

25. The method of claim 17, wherein said bleaching compound comprises potassium monopersulfate.

26. The method of claim 17, further comprising an abrasive agent.

27. The method of claim 17, further comprising an agent for administering fluoride.

28. The method of claim 17, further comprising a gel forming agent.

29. The method of claim 17, further comprising a palliative ingredient for periodontal tissues.

30. The method of claim 29, wherein said palliative agent is selected from the group consisting of aloe, eugenol, and vitamin E.

31. The method of claim 17, further comprising an ingredient to decrease tooth sensitivity.

32. The method of claim 31 , wherein said ingredient to decrease tooth sensitivity is potassium nitrate.