Dental bleaching compositions containing sucralose

[0002] 1. The Field of the Invention

[0003] The present invention relates to dental bleaching compositions and methods for bleaching teeth surfaces. More particularly, the present invention is directed to dental bleaching compositions which incorporate a non-nutritive sweetener, sucralose.

[0004] 2. The Relevant Technology

[0005] Since its introduction in early 1989, there has been significant interest among the dental profession and the general public for home-use tooth bleaching products and methods. In its simplest form, home bleaching products typically include a dental bleaching composition having a form of hydrogen peroxide as the active bleaching agent. Some compositions are in the form of toothpastes that are simply brushed onto the teeth during a person's daily dental hygiene routine. Other, more specialized bleaching compositions are adapted for extended contact with the teeth to be bleached, such as by means of a dental tray.

[0006] As a general rule whitening toothpastes have largely been ineffective in whitening teeth due to their relatively low potency or concentration of active bleaching agent coupled with the short duration of contact of such formulations with a person's teeth. Because of the manner in which toothpastes are manufactured, shipped, stored and sold, toothpastes are largely incapable of incorporating higher concentrations of active bleaching agents that remain stable over the intended manufacturing and storage life of the toothpaste prior to use. Moreover, it is well-known that people typically brush for 60 seconds or less, thus further reducing the effectiveness of the already low concentration bleaching agent within over-the-counter toothpastes.

[0007] In view of the foregoing, bleaching compositions having increased bleaching activity coupled with methods that maintain such dental compositions in contact with the teeth for longer periods of time are necessary to effect a noticeable bleaching effect in most people. Typical dental bleaching compositions include from 5-20% by weight of carbamide peroxide (CO(NH₂)₂.H₂O₂), which is a complex of urea and hydrogen peroxide.

[0008] Such dental bleaching compositions are typically applied to a person's teeth using a dental tray configured so as to retain the dental composition against the person's teeth. A self-sealing dental “splint” that can be used with more fluid and less sticky dental bleaching compositions are disclosed in U.S. Pat. No. Re. 34,196 to Munro. Munro recommends the use of Proxigel®, manufactured according to U.S. Pat. No. 3,657,413 to Rosenthal, which at the time contained only 0.6% carboxypolymethylene as a thickening agent, or a mixture of Proxigel® and Peroxyl® gel, which is an even more fluid bleaching composition than Proxigel®. The Munro dental tray is especially suitable for use with such highly fluid dental compositions since it is made from a rigid plastic material and configured so as to form a fluid-tight seal against the person's gums. Such trays, however, are not always comfortable for the user, particularly when the dental tray is held in place over long periods of time within a person's mouth.

[0009] Flexible, more comfortable-fitting dental trays that are preferably used in combination with more sticky and viscous dental bleaching compositions are disclosed in U.S. Pat. Nos. 5,098,303 and 5,234,342, both to Fischer. Such dental trays, while being more flexible and generally thinner-walled compared to prior dental trays, are preferably trimmed in a preferred embodiment so as to terminate below the gingival margin and then scalloped up and around the interdental papilla. This provides maximum bleaching of the entire surface of the person's teeth while minimizing or eliminating actual contact with the person's gums, including the interdental papilla, thus providing minimum discomfort. Further enhancement of bleaching is provides by optionally building “reservoirs” into the dental trays so as to allow for increased loading of bleaching composition within the dental tray that can contact the teeth.

[0010] A problem with such dental bleaching composition, however, is that patients sometimes fail to use the compositions for adequate time periods due to the bitter taste of the dental bleaching agent. Attempts to camouflage the bitter taste have involved the use of a variety of sweeteners.

[0011] Nutritive sweeteners, which include sugars such as sucrose, fructose, mannose, sorbitol, mannitol, and xylitol, are unfortunately not sweet enough to disguise the bitter taste. Even when added in large quantities, such sugars simply still cannot render compositions containing bleaching agents such as peroxides and perborates to be sufficiently palatable. Additionally, tooth decay is enabled through the presence of nutritive sweeteners such as sucrose.

[0012] Non-nutritive sweeteners, which are sweeteners without caloric value, have also been utilized. An example of a non-nutritive sweetener is aspartame. Aspartame is unfortunately not stable in the presence of bleaching agents. One non-nutritive sweetener, sodium saccharine, is stable in the presence of bleaching agents. Sodium saccharine, however, has shown carcinogenic possibilities in some studies. As a result, sodium saccharine is only recommended for use by diabetics. Additionally, sodium saccharine causes an undesirable bitter after taste which compromises its usefulness in disguising the bitter taste of bleaching agents.

[0013] From the foregoing, it will be appreciated that what is needed in the art are improved compositions and methods for manufacturing suitable dental bleaching compositions that disguise the bitter taste of bleaching agents, remain stable in the presence of such bleaching agents and are not carcinogenic.

[0014] Additionally, it would be a significant advancement in the art to provide dental bleaching compositions having a stable sweetener that adequately disguises the bitter taste of bleaching agents which also had sufficient stickiness and viscosity so as to enable such compositions to adhere and retain a comfortable-fitting dental tray in place for the duration of a desired treatment regimen.

[0015] Such dental bleaching compositions and methods for their manufacture and use are disclosed and claimed herein.

[0016] The present invention is directed to dental bleaching compositions used to treat tooth surfaces containing sucralose. Sucralose and a bleaching agent are mixed with a carrier which enables the bleaching agent to contact and bleach teeth. The sucralose is much sweeter than sugar and is stable in the presence of bleaching agents so it disguises the bitter taste of such agents. This improved taste better enables patients to complete a bleaching regime and achieve the desired result.

[0017] The sucralose and bleaching agent are preferably dispersed within a sticky carrier. However, the sucralose and bleaching agent may also be dispersed within a carrier which is a liquid such as a liquid polyol or water. The sticky carrier may include other gelling agents such as finely divided gel-forming metal oxides and/or organic thickeners known in the art.

[0018] Because the dental bleaching compositions according to the present invention are preferably sticky and viscous, they are especially suitable for use in combination with a custom dental tray that is designed so as to not exert significant mechanical pressure onto a person's teeth. The elimination or substantial reduction of mechanical pressures that are exerted onto a person's teeth during bleaching greatly increases the comfort experienced by the user. The inventive dental bleaching compositions are preferably formulated so as to a have a stickiness and viscosity that causes the bleaching compositions to adhere and retain a flexible, thin-walled dental tray against a person's teeth for as long as needed to carry out the desired bleaching process, such as the type of dental tray disclosed in U.S. Pat. Nos. 5,098,303 and 5,234,342, both to Fischer. For purposes of disclosing flexible, thin-walled, comfortable-fitting dental trays suitable for bleaching a person's teeth, the foregoing patents are incorporated herein by specific reference.

[0019] In order to carry out a desired bleaching process, the bleaching compositions of the present invention can be placed against a person's teeth for as little as 10 minutes and as long as 8 hours or more, depending on the potency of the bleaching composition and the desired level of bleaching. Preferably, the bleaching compositions will be placed over a person's teeth for at least about 30 minutes, more preferably for at least about 1 hour, and most preferably for at least about 2 hours. Depending on the desired treatment regimen, the dental bleaching compositions according to the present invention can vary in potency and stickiness in order to optimize the performance of the bleaching composition for a given treatment regimen.

[0020] It is, therefore, an object of the present invention to provide improved compositions and methods for manufacturing suitable dental bleaching compositions that include sucralose.

[0021] Another important object of the present invention is to provide dental bleaching compositions containing sucralose which also have sufficient stickiness and viscosity so as to enable such compositions to adhere and retain a suitable dental tray in place for the duration of a desired treatment regimen.

[0022] Yet another significant object of the present invention is to provide sucralose containing dental bleaching compositions which are sufficiently stable so as to be stored and then used as desired to complete a bleaching regime such that the teeth are whitened as desired.

[0023] These and other objects and features of the present invention will become more fully apparent from the description which follows, or may be learned by the practice of the invention.

[0024] As summarized above, the present invention is generally related to dental bleaching compositions containing sucralose, a chlorinated sucrose derivative with enhanced sweetness. Other chemical names for sucralose include: 1,6-dichloro-1,6-dideoxy-β-D-fructo-furanosyl-4-chloro-4-deoxy-α-D-galactopyranoside; 4,1′,6′-trichloro-4,1′,6′-trideoxy-galacto-sucrose; 1′,4,6′-trichloro-galactosucrose; and TGS. Sucralose has the general formula C₁₂H₁₉Cl₃O₈and a molecular weight of 397.64. References which disclose methods for preparing sucralose include European Patent Application 30804 to Tate et al. and U.S. Pat. No. 4,343,934 filed on behalf of Jenner et al. U.S. Pat. No. 4,435,440 issued to Hough et al. describes the usefulness of sucralose as a sweetener. These references are hereby incorporated by reference.

[0025] Sucralose is non-nutritive so it has none of the disadvantages associated with nutritive sweeteners. However, it tastes very much like sugar while being approximately 600 times sweeter than sugar. Because sucralose is so sweet tasting, small amounts of sucralose are sufficient to disguise the bitter taste of bleaching agents. Additionally, dental bleaching compositions containing sucralose are stable for extended periods of time. Accordingly, dental bleaching compositions containing sucralose are the only stable dental bleaching compositions which disguise the bitter taste of bleaching agents and avoid the problems of prior art sweetened dental bleaching compositions.

[0026] Dental bleaching compositions containing sucralose within the scope of the present invention include any compositions suitable for bleaching teeth. The dental bleaching compositions essentially include a dental bleaching agent and sucralose dispersed in a carrier. The carrier may be any suitable fluid such as a liquid or a gel.

[0027] The dental bleaching compositions are preferably those which are useful use with flexible, thin-walled, comfortable fitting dental trays designed so as to not exert significant mechanical pressure onto a person's teeth. Dental bleaching compositions intended for use with such dental trays typically utilize a sticky carrier formed from a fluid and a thickener. The sticky carrier accordingly often comprises finely divided silica, such as silica fume, dispersed in a liquid, such as a polyol. Examples of suitable polyols include propylene glycol, glycerin, polypropylene glycols, sorbitol, polyethylene glycols and the like. The polyethylene glycols and the polypropylene glycols preferably have low molecular weights. While the carrier preferably includes thickeners, the carrier may also be only a liquid such as water or any of the liquid polyols without any thickeners.

[0028] Other thickening, gelling or tackifying agents may be used in addition to fumed silica, such as finely divided alumina, titanium dioxide, zinc oxide or other insoluble particulates that are capable of forming a gel when mixed with propylene glycol, glycerin and the like. In addition to finely divided inorganic particulate tackifying agents, organic tackifying agents known in the art can be added in order to adjust the viscosity and stickiness of the composition. Natural or synthetic polymers such as natural gums, proteins, cellulosic ethers, carboxypolymethylene, high molecular weight polyols, or other gel-forming admixtures, can be used. Carbopol NF 974 is the preferred carboxypolymethylene. Examples of natural polymers include xanthan gum, guar gum, gum arabic, gum tragacanth, gum karaya, starches, cellulosic ethers, proteins, and the like. Other examples of organic tackifying agents include high molecular weight polyethylene glycol, high molecular weight polypropylene glycols, high molecular weight polyacrylic acids and high molecular weight polyethylene oxide.

[0029] The dental bleaching agents may be any material capable of whitening teeth. Examples of suitable dental bleaching agents include aqueous hydrogen peroxide, carbamide peroxide, perborate-based bleaching agent such as sodium perborate monohydrate (NaBO₃.H₂O) and sodium percarbonate.

[0030] Colorants and other visual enhancing agents can be added as desired in order to yield a visually desirable dental bleaching composition. Other adjuvents and additives can also be added in minor amounts as needed to impart a desired property. For example, flavorants can be added as desired to yield bleaching compositions having a particular taste. Examples of such flavors include mint, spearmint, wintergreen, watermelon, banana, root beer, raspberry, peach, etc. Other sweeteners can also be added including xylitol, mannose, mannitol, sucrose, aspartame, sodium saccharin and fructose.

[0031] The dental bleaching agent may be included in an amount in a range from about 0.1% to about 85% by weight of the dental bleaching composition. The dental bleaching agent is preferably in a range from about 1% to about 50% by weight, more preferably in a range from about 10% to about 40% by weight of the dental bleaching composition and is most preferably in a range from about 20% to about 30% by weight of the composition. The content of the bleaching agent in the dental bleaching composition may be varied depending on factors such as the location of use and patient sensitivity. For example, bleaching kits used at home typically have lower concentrations of dental bleaching agents than do kits intended for use only in a dental office.

[0032] The amount of the carrier in the dental bleaching composition may range from about 1% to about 96% by weight of the dental bleaching composition. The carrier is preferably in a range from about 15% to about 90% by weight, more preferably in a range from about 30% to about 80% by weight of the dental bleaching composition and is most preferably in a range from about 45% to about 70% by weight. A presently preferred carrier is a polyol, propylene glycol. Note that these ranges are for the fluid component of the carrier only and exclude the content of a thickener as the thickener content is provided separately below.

[0033] The fumed silica or similar finely divided particle capable of forming a sticky and viscous carrier when mixed with glycerin, including fumed silica or other finely divided particles blended with optional organic thickeners, may be included in an amount in a range from about 0.5% to about 50% by weight of the dental bleaching composition. The thickener is preferably in a range from about 1% to about 40% by weight of the dental bleaching composition, more preferably in a range from about 5% to about 35% by weight, and most preferably in a range from about 10% to about 30% by weight of the dental bleaching composition. Fumed silica, precipitated silica and other appropriate finely divided particles that may be used to form a viscous and sticky carrier when mixed with one or more appropriate polyols will typically have a particle size from about 0.001 micron to about 1 micron. An example of a suitable silica fume that may be used to yield sticky and viscous dental bleaching compositions when mixed with a polyol is Aerosil 200, which is manufactured by Degussa of Germany.

[0034] The sucralose is added in any suitable amount to disguise the bitter taste of the bleaching agent. When larger concentrations of dental bleaching agents are included then the concentration of the sucralose is also increased. The sucralose is preferably present in a range from about 0.01% to about 15% by weight of the dental bleaching composition, more preferably 0.1% to 10% by weight and most preferably 0.2% to about 5% by weight. When other sweeteners are included in addition to sucralose, the total sweetener content may range from about 0.01% to about 70% by weight of the dental bleaching composition. Flavors may be present in an amount ranging from about 0.1% to about 6% by weight of the dental bleaching composition.

[0035] The stability of the dental bleaching composition containing sucralose is generally sufficient such that dental bleaching compositions can be stored for long periods and used with sufficient efficacy to whiten teeth. For example, a dental bleaching composition containing sucralose which is formed in accordance with the above discussed ranges is likely after 1 year to still have the same amount of sucralose as it contained when originally manufactured. In any event, the sucralose content would be expected after 1 year to be at least 85% of the amount contained in the composition after being formed. Similarly, such a dental bleaching composition would be expected after about 4 to 6 months to have at least 90% of the sucralose that it had when originally manufactured.

[0036] While the sucralose content remains stable, some compositions may maintain a greater bleaching efficacy for a longer period of time depending on several factors. One factor which influences the stability of the bleaching agent is the pH of the composition. High pH levels may decrease the stability of the bleaching agent in the composition. Accordingly, the composition is preferably constituted such that the pH is approximately neutral. Another factor which influences the stability of the bleaching agent in the dental bleaching compositions is the amount of the dental bleaching agent in the composition. Accordingly, compositions with high concentrations of dental bleaching agents may not have as long of a shelf life as those with lower concentrations. The type of bleaching agent utilized may also influence the shelf life stability. Carbamide peroxide is preferred for optimal shelf life stability as it is more stable than hydrogen peroxide. It is also generally necessary to refrigerate most dental bleaching compositions.

[0037] In any event, the particular shelf life of the compositions is not limited by the stability of the sucralose. The stability of the sucralose is such that the compositions of the present invention have adequate shelf life stability to enable a dentist to store a dental bleaching composition and to enable a patient to use the composition to complete a bleaching regime with the desired sweet taste. The only limitation on overall shelf stability is the degradation rate of the bleaching agent and this is controlled as discussed above.

[0038] Although the dental bleaching compositions are not limited to the particular method or apparatus by which they are applied to a person's teeth, a preferred method for applying the dental bleaching compositions involves the use of a dental tray. A dental tray shields the composition from being rubbed off or diluted by saliva so that it can remain against the person's teeth during the desired treatment regimen. Virtually any dental tray known in the art could be used in applying the inventive bleaching compositions disclosed herein.

[0039] In a preferred embodiment, flexible, comfortable-fitting, thin-walled dental trays that are designed so as to not exert significant mechanical pressure are used to apply the inventive dental bleaching compositions disclosed herein. The dental bleaching compositions are preferably sufficiently sticky and viscous so as to adhere and retain such dental trays in place for the duration of the desired treatment time. The dental trays may optionally be formed so as to include reservoirs in order to provide additional dental bleaching composition to one or more teeth of a dental arch needing more whitening than others, or to selected parts of a tooth needing more whitening than other parts. The dental trays are preferably trimmed to below the gingival margin and also scalloped up and around the interdental papilla. As stated above, preferred dental trays are manufactured according to U.S. Pat. Nos. 5,098,303 and 5,234,342 to Fischer, which have been previously incorporated by reference.

[0040] In order to carry out a desired bleaching process, the bleaching compositions of the present invention can be placed against a person's teeth for as little as 10 minutes and for as long as 8 hours or more, depending on the potency of the bleaching composition and the desired level of bleaching. Preferably, the bleaching compositions will be placed over a person's teeth for at least about 30 minutes, more preferably for at least about 1 hour, and most preferably for at least about 2 hours. Depending on the desired treatment regimen, the dental bleaching compositions according to the present invention can vary in potency and stickiness in order to optimize the performance of the bleaching composition for a given treatment regimen.

[0041] One currently preferred method of dispensing the bleaching agent uses a syringe. Squeezable tubes and other similar dispensing devices may also be used to dispense the bleaching agent. A syringe allows for the dispensing of a desired quantity of the dental bleaching composition, whether it be a unit dose or multiple doses. In the case of a syringe capable of providing for multiple doses of bleaching composition, graduations may be provided on the syringe to assist the user in dispensing a precise quantity of the bleaching composition each time.

[0042] The following examples set forth various exemplary dental bleaching compositions within the scope of the present invention. These examples are intended to be purely exemplary and should not be viewed as limiting the scope of the present invention.

[0043] A dental bleaching composition within the scope of the present invention was prepared by combining the following ingredients (in weight percent):

[0044] The ingredients were mixed together with the exception of sodium hydroxide. After the other ingredients were mixed, the sodium hydroxide was incrementally added in small amounts.

[0045] The foregoing procedure produced a dental bleaching composition wherein the bitter taste of the bleaching agent was fully disguised by the sucralose and was stable after 4 months. The composition contained the same amount of sucralose that was originally added. The composition also still had at least 85% of the bleaching capability that it had when originally formed. The bleaching composition was sticky and viscous and was able to adhere and retain a dental tray in place against a person's teeth. The dental bleaching composition was useful in bleaching the person's teeth.

[0046] A dental bleaching composition within the scope of the present invention was prepared by combining the following ingredients (in weight percent):

[0047] The resulting dental bleaching composition contained sufficient sucralose to fully disguise the bitter taste of the bleaching agent. The sucralose content remains essentially constant after 1 year. The bleaching capability remains stable for at least 1 year. The resulting dental bleaching composition is sticky and viscous like the composition of Example 1 but has higher bleaching power. The dental bleaching composition is able to adhere and retain a dental tray in place against a person's teeth. The dental bleaching composition is useful in bleaching the person's teeth.

[0048] A dental bleaching composition within the scope of the present invention is made according to the procedure of Example 1, except that the ingredients are combined in the following amounts (in weight percent):

[0049] The resulting dental bleaching composition contained sufficient sucralose to fully disguise the bitter taste of the bleaching agent. The sucralose content remains essentially constant after 1 year. The bleaching capability remains stable for at least 1 year. The resulting dental bleaching composition is sticky and viscous like the composition of Example 1 but has higher bleaching power. The dental bleaching composition is able to adhere and retain a dental tray in place against a person's teeth. The dental bleaching composition is useful in bleaching the person's teeth.

[0050] A dental bleaching composition within the scope of the present invention is made according to the procedure of Example 1, except that the ingredients are combined in the following amounts (in weight percent):

[0051] The resulting dental bleaching composition contained sufficient sucralose to fully disguise the bitter taste of the bleaching agent. The sucralose content remains essentially constant after 1 year. The bleaching capability remains stable for at least 1 year. The resulting dental bleaching composition is sticky and viscous like the composition of Example 1 and has the same bleaching power. The dental bleaching composition is able to adhere and retain a dental tray in place against a person's teeth. The dental bleaching composition is useful in bleaching the person's teeth.

[0052] A dental bleaching composition within the scope of the present invention is made according to the procedure of Example 1, except that the ingredients are combined in the following amounts (in weight percent):

[0053] The resulting dental bleaching composition contained sufficient sucralose to fully disguise the bitter taste of the bleaching agent and is much sweeter than in Example 1. The sucralose content remains essentially constant after 1 year. The bleaching capability remains stable for at least 1 year. The resulting dental bleaching composition is not sticky but is relatively viscous. The bleaching composition has a higher bleaching power than in Example 1. The dental bleaching composition is able to adhere and retain a dental tray in place against a person's teeth. The dental bleaching composition is useful in bleaching the person's teeth.

[0054] A dental bleaching composition within the scope of the present invention is made according to the procedure of Example 1, except that the ingredients are combined in the following amounts (in weight percent):

[0055] The resulting dental bleaching composition contained sufficient sucralose to fully disguise the bitter taste of the bleaching agent and is much sweeter than in Example 1. The sucralose content remains essentially constant after 1 year. The bleaching capability remains stable for at least 1 year. The resulting dental bleaching composition is sticky and viscous like the composition of Example 1 and has the same bleaching power. The dental bleaching composition is able to adhere and retain a dental tray in place against a person's teeth. The dental bleaching composition is useful in bleaching the person's teeth.

[0056] A dental bleaching composition within the scope of the present invention is made according to the procedure of Example 1, except that the ingredients are combined in the following amounts (in weight percent):

[0057] The resulting dental bleaching composition contained sufficient sucralose to fully disguise the bitter taste of the bleaching agent. The sucralose content remains essentially constant after 1 year. The bleaching capability remains stable for at least 1 year. The resulting dental bleaching composition is sticky and viscous like the composition of Example 1 and has the same bleaching power. The dental bleaching composition is able to adhere and retain a dental tray in place against a person's teeth. The dental bleaching composition is useful in bleaching the person's teeth.

[0058] From the foregoing, it will be appreciated the present invention provides improved compositions and methods for manufacturing suitable dental bleaching compositions that include sucralose.

[0059] Additionally, it will be appreciated that the present invention further provides dental bleaching compositions containing sucralose which also have sufficient stickiness and viscosity so as to enable such compositions to adhere and retain a suitable dental tray in place for the duration of a desired treatment regimen.

[0060] It will be further appreciated that the present invention provides sucralose containing dental bleaching compositions which are sufficiently stable so as to maintain the desired bleaching activity until bleaching of the teeth is desired.

[0061] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.