Patent Application
20240216235
Consumer products providing for teeth whitening are numerous and take many forms, but one of the more popular forms are as dentifrices, such as toothpastes. Toothpastes must typically have a semisolid form, able to hold shape well enough to be dispensed from a tube and rest on toothbrush bristles, but also fluid enough to be easily squeezed from the tube. Toothpastes must also be sticky enough to adhere to some degree to the teeth, but also soluble enough to disperse in the oral cavity. These different aims are commonly satisfied by formulating toothpastes in a high-water base (e.g., 10-40% water) with a mixture of liquid polar humectants, such as glycerin, polypropylene glycol, and sorbitol. Often various polymers are used to provide the gel-like consistency that is necessary for a toothpaste.
Unfortunately, many whitening agents have stability problems in the presence of water, humectants, and some polymers. Other inorganic species, such as fluoride sources and surfactants, can also interact negatively, resulting in instability and loss of activity of the active whitening agent. It thus becomes necessary to formulate a whitening toothpaste with various ingredients intended to improve stability and activity of the whitening agent active.
Abrasives can be particularly difficult to formulate into whitening toothpastes, because of the high surface area, hygroscopicity, and acidity of many abrasives. Yet abrasives can be a critical component of a whitening composition because many stains adhere strongly but superficially to the tooth surface and an abrasive helps remove such stains both by its intrinsic abrasive action and by providing better access of the whitening agent to the stain.
Products that are presently available to whiten teeth include a variety of different ingredients, and the primary active ingredient is most commonly a peroxide source such as hydrogen peroxide. The use of peroxide agents often presents numerous difficulties in both formulation and long-term stability of the resulting compositions. In addition, in high concentrations, or in prolonged contact with the oral mucosa, hydrogen peroxide can be highly irritating to the teeth and gums. Thus, alternative oxidizing agents with improved stability are needed, especially for whitening products which provide long-term contact with oral tissues.
Peroxysulfuric acid (H2SO5, also known as peroxymonosulfuric acid), and its salts, the peroxymonosulfates, are powerful oxidizing and stain removing agents. They are currently used for a variety of industrial and consumer purposes, including swimming pool treatment and denture cleaning. Peroxymonosulfate salts generally have the anion [HSO5]−, in contrast to the related peroxydisulfate salts which have the anion [HS2O8]−. Peroxymonosulfate whitening products have been explored for some oral care applications, including whitening strips, mouthwashes and toothpastes. One common peroxymonosulfate oxidizing agent is potassium peroxymonosulfate (KHSO5), also referred to as potassium monoperoxysulfate and abbreviated as KMPS or MIPS, and sold as part of the compositions Oxone® and Caroat® (each of which is potassium peroxymonosulfate triple salt, having about 45-50 wt. % potassium peroxymonosulfate).
The use of potassium peroxymonosulfate in oral care applications has been very limited by its instability in aqueous solution, especially in aqueous solution near or above neutral pH. Potassium peroxymonosulfate has been known to degrade even in the presence of small quantities of water and heat. Thus, potassium peroxymonosulfate whitening compositions face particular difficulties in formulation.
Potassium peroxymonosulfate can also react and decompose when combined with other common oral care excipients, especially polar compounds, such as humectants, and anionic or neutral hydroxylic polymers and surfactants. These excipients can destabilize the potassium peroxymonosulfate, resulting in a loss of whitening efficacy. It therefore becomes necessary to adjust the formulations having potassium peroxymonosulfate to avoid or reduce the amount of such ingredients, which makes it challenging to still formulate a composition having desirable mouth feel (e.g., foaming), appearance, viscosity, and other important properties. Furthermore, potassium peroxymonosulfate can also interact negatively with any common flavoring agents, which tend to have labile or oxidizable functional groups. This can make it challenging to formulate flavors into such compositions.
As noted above, in order to address the above issues of peroxymonosulfate stability, non-aqueous formulations have been pursued. However, such formulations may face their own formulation difficulties, such as maintaining proper viscosity during aging, ensuring adequate foaming in the absence of water, and interactions between ingredients introduced to replace the water. For example, formulation scientists have resorted to replacing the water in a toothpaste or gel with combinations of polyol humectants, polar and nonpolar polymers, and adding different surfactants, in order to ensure adequate stability, viscosity, and foaming. It has been found by the inventors, and others, that in general the polyol class of humectants, which are commonly used as water substitutes, promote peroxymonosulfate degradation. Propylene glycol, sorbitol, glycerol, and xylitol, for example, are very common oral care humectants, but their high polarity and hygroscopicity (due to their hydroxy functional groups) both directly and indirectly (by retaining water) promotes MPS degradation. In addition, the present inventors have unexpectedly discovered that some anhydrous toothpaste compositions in which potassium peroxymonosulfate is stabilized by calcium pyrophosphate in a poloxamer/polyethylene glycol/PEG-PPG random copolymer vehicle suffer from unusually low freezing points. Such compositions may either freeze, or if not frozen per se, can have unacceptably low viscosity, and consequently insufficient squeezability (extrudability), at temperatures of 20° C. and below (68° F. and below).
There remains a need for tooth whitening dentifrice products based on peroxymonosulfate whitening agents with improved stability, mouthfeel, appearance, viscosity, flavor, and consumer acceptability, without adverse effects on freezing point (e.g., improved squeezability or extrudability).
The present disclosure provides a tooth whitening oral care composition comprising potassium peroxymonosulfate by weight of the composition, stabilized with a combination of calcium pyrophosphate (Ca2P2O7) by weight of the composition, 5-25% propylene glycol, and 5-50% poloxamer (polyoxyethylene/polyoxypropylene triblock copolymer), by weight of the composition. In further embodiments, the compositions may further comprise one or more of polyvinylpyrrolidone, polyethylene glycol/polypropylene glycol random copolymer, polyethylene glycol, alkali metal polyphosphates, anionic surfactants, zwitterionic surfactants, cationic surfactants, and amphoteric surfactants. In at least one aspect, the tooth whitening oral care compositions of the present disclosure are low water or anhydrous. The compositions of the present disclosure provide a higher freezing point, and thus, improved squeezability (extrudability), compared to prior art compositions.
Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by referenced in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls.
Unless otherwise specified, all percentages and amounts expressed herein and elsewhere in the specification should be understood to refer to percentages by weight. The amounts given are based on the active weight of the material.
Open terms such as “include,” “including,” “contain,” “containing” and the like mean “comprising.” In this description, unless otherwise stated, the use of the singular also includes the plural. For example, “a lubricant” also comprehends the case where more than one lubricant is used.
“About” means plus or minus 20% of the stated value. Thus, for example, “about 5%” means from 80% to 120% of 5%, or 4.0% to 6.0%, inclusive of the end values of the range.
It has previously been found that the combination of calcium pyrophosphate (Ca2P2O7) and a poloxamer (polyoxyethylene/polyoxypropylene triblock copolymer) is highly effective in stabilizing potassium peroxymonosulfate against degradation, while also providing favorable rheological characteristics. Preferably, such compositions also comprise an anionic surfactant and a zwitterionic surfactant to optimize the foaming properties of the composition, such as sodium lauryl sulfate and cocamidopropyl betaine. However, the inventors have unexpectedly discovered that such compositions—which are stable in aging studies, and have good whitening and foaming characteristics—have a freezing point that is too high. The compositions can freeze or become too viscous at temperatures that may be encountered by a consumer or during shipping of the product. As a result, the compositions have insufficient squeezability (extrudability), which strongly impacts consumer acceptability. Without out being bound by theory, it is believed that the higher content of the poloxamer may cause the low freezing point of the composition. Thus, there is a need to find a different component to replace all or part of the poloxamer to provide a composition with a freezing point below 15° C., preferably above 10° C.
It has previously been reported that propylene glycol, and similar hydroxylic humectants, destabilize potassium peroxymonosulfate and causing rapid degradation and loss of active oxygen content. Thus, it was thought that propylene glycol cannot be used in a tooth whitening oral care composition comprising potassium peroxymonosulfate. However, the present disclosure unexpectedly demonstrates that while a composition having about 30% or more of propylene glycol is not stable, a composition having about 5-25% propylene glycol and 5-50% poloxamer has good stability and acceptable freezing point, resulting in improved squeezability (extrudability).
In a first aspect, the present disclosure provides a tooth whitening oral care composition (Composition 1) comprising potassium peroxymonosulfate, calcium pyrophosphate (Ca2P2O7) 5-25% propylene glycol, and 5-50% polyoxyethylene/polyoxypropylene triblock copolymer (poloxamer), by weight of the composition. In further embodiments, the present disclosure provides:
Potassium peroxymonosulfate (also known as MIPS, KMPS, potassium monopersulfate, or potassium monoperoxysulfate) is commercially available as Caroat® or Oxone®, both of which are a triple salt of potassium peroxymonosulfate, potassium hydrogen sulfate and potassium sulfate (2KHSO5·KHSO4·K2SO4).
Potassium peroxymonosulfate has limited stability in aqueous solutions and can be destabilized by other common toothpaste ingredients, even small amounts of water. Therefore, contact with water during processing and storage should be avoided or minimized. The compositions are preferably packaged in a moisture free environment.
The compositions of the present disclosure contain no water or have a low water content. As used herein, the term “low water content” means the total concentration of water, including any free water and all water contained in any ingredients. In various embodiments of the composition, the amount of water is in an amount of less than 4% by weight, or less than 3% by weight, or less than 2% by weight, or less than 1% by weight, or less than 0.5% by weight, or less than 0.1%, or about 0.0001% to about 4% by weight, or about 0.0001% to about 0.5% by weight or about 0.0001% to about 0.1% by weight. Preferably, the compositions have no added water.
The amount of potassium peroxymonosulfate in the compositions of the invention is effective to result in improved tooth whitening when used once or twice daily for about three months as compared to a control composition without the peroxymonosulfate salt. The amount of peroxymonosulfate salt typically is about 0.1% to about 10%, by weight of the composition, preferably about 1 wt. % or 2 wt. %.
In some embodiments, the compositions of the present disclosure contain a buffering agent. Examples of buffering agents include anhydrous carbonates such as sodium carbonate, sesquicarbonates, bicarbonates such as sodium bicarbonate, silicates, bisulfates, phosphates such as monopotassium phosphate and dipotassium phosphate, citrates, pyrophosphates (sodium and potassium salts) and combinations thereof. The amount of buffering agent is sufficient to provide a pH of about 5 to about 9, preferable about 6 to about 8, and more preferable about 7, when the strip is hydrated. Typical amounts of buffering agent are about 0.1% to about 5%, in one embodiment about 1% to about 3%, in another embodiment about 0.5% to about 1%, by weight of the total composition.
The compositions of the present disclosure comprise a polyoxyethylene-polyoxypropylene triblock copolymer, also known as a poloxamer. The term “poloxamer” or “poloxamer copolymer” refers to a nonionic triblock copolymer composed of a central hydrophobic chain of polyoxypropylene units (a.k.a. poly(propylene oxide) units) flanked by two hydrophilic chains of polyoxyethylene units (e.g., poly(ethylene oxide) units), Poloxamers have the following chemical structure:
wherein a and b are integers, each typically between 10 and 200. Poloxamers are named according to common conventions based on their molecular weight and ethoxy content, and include poloxamer 407, poloxamer 338, poloxamer 237, poloxamer 188 and poloxamer 124. Pluronic is the name of a line of poloxamer polymers manufactured by BASF. For example, Pluronic F-127 is poloxamer 407. Poloxamers are distinguished from other polyethylene glycol/polypropylene glycol copolymers (PEG/PPG copolymers or EO/PO copolymers) which have a structure other than as a triblock structure, such as a random copolymer structure. Such copolymers that are distinct from poloxamers include the PEG/PPG copolymers sold by BASF as the Pluracare® and Pluraflo® series polymers, which are random PEG/PPG copolymers.
For example, suitable poloxamers may include one or more of Pluronic® L35, Pluronic® L43, Pluronic® L64, Pluronic® L 10, Pluronic® L44, Pluronic® L62, Pluronic® 10R5, Pluronic® 17R4, Pluronic® L25R4, Pluronic® P84, Pluronic® P65, Pluronic® PI 04, and Pluronic® PI 05. Pluronic® brand dispersants are commercially available from BASF, Florham Park, NJ.
In some embodiments, the compositions of the present disclosure may comprise polyvinylpyrrolidone (optionally cross-linked), also known as poly-N-vinyl-poly-2-pyrrolidone, and commonly abbreviated to “PVP” (optionally cross-linked PVP). PVP generally refers to a polymer containing vinylpyrrolidone (also referred to as N-vinylpyrrolidone, N-vinyl-2-pyrrolidone and N-vinyl-2-pyrrolidinone) as a monomeric unit. The monomeric unit may include a polar imide group, four non-polar methylene groups, and a non-polar methane group. Cross-linked PVP includes those commercially available as KOLLIDON® and LUVICROSS®, marketed by BASF, Mount Olive, N.J., USA; and POLYPLASDO E® INF-10, marketed by, Ashland, Covington, Kentucky, USA.
The compositions of the present disclosure can optionally contain whitening (oxidizing) agents in addition to the potassium peroxymonosulfate, but preferably no other whitening agents are included. Whitening agents are generally materials which are effective to provide whitening of a tooth surface to which it is applied via oxidative action, and include agents such as hydrogen peroxide and urea peroxide. In various embodiments, the compositions of the present disclosure may optionally comprise a peroxide whitening agent, comprising a peroxide compound, but preferably no peroxide whitening agents or no peroxide compounds are included. A peroxide compound is an oxidizing compound comprising a bivalent oxygen-oxygen group. Peroxide compounds include peroxides and hydroperoxides, such as hydrogen peroxide, peroxides of alkali and alkaline earth metals, organic peroxy compounds, peroxy acids, pharmaceutically-acceptable salts thereof, and mixtures thereof. Peroxides of alkali and alkaline earth metals include lithium peroxide, potassium peroxide, sodium peroxide, magnesium peroxide, calcium peroxide, barium peroxide, and mixtures thereof. Organic peroxy compounds include carbamide peroxide (also known as urea hydrogen peroxide), glyceryl hydrogen peroxide, alkyl hydrogen peroxides, dialkyl peroxides, alkyl peroxy acids, peroxy esters, diacyl peroxides, benzoyl peroxide, and monoperoxyphthalate, and mixtures thereof. Peroxy acids and their salts include organic peroxy acids such as alkyl peroxy acids, and monoperoxyphthalate and mixtures thereof, as well as inorganic peroxy acid salts such as persulfate, dipersulfate, percarbonate, perphosphate, perborate and persilicate salts of alkali and alkaline earth metals such as lithium, potassium, sodium, magnesium, calcium and barium, and mixtures thereof. In various embodiments, the peroxide compound comprises hydrogen peroxide, urea peroxide, sodium percarbonate and mixtures thereof. In some embodiments, the peroxide compound comprises hydrogen peroxide. In some embodiments, the peroxide compound consists essentially of hydrogen peroxide. In some embodiments, the compositions may comprise a non-peroxide whitening agent. Whitening agents among those useful herein include non-peroxy compounds, such as chlorine dioxide, chlorites and hypochlorites. Chlorites and hypochlorites include those of alkali and alkaline earth metals such as lithium, potassium, sodium, magnesium, calcium and barium. One or more additional whitening agents are optionally present in a tooth-whitening effective total amount. In some embodiments the compositions additionally comprise an activator, e.g., tetraacetylethylenediamine. In some embodiments, the compositions of the present invention are free of all of the above enumerated additional whitening agents.
In some embodiments, the compositions may comprise a non-oxidative whitening agent. Non-oxidative whitening agents include colorants, such as titanium dioxide and blue pigment or dye, and hydroxyapatite. These agents cause a whiter appearance of the teeth through masking or covering stains, but not chemically removing or destroying the stains.
The compositions of the present disclosure optionally can also include other ingredients, e.g., flavor agents; fillers; surfactants; preservatives, e.g., sodium benzoate and potassium sorbate; color agents including, e.g., dyes and pigments; and sweeteners. In some embodiments, the compositions of the present disclosure comprise one or more surfactants, such as anionic, cationic, zwitterionic or non-ionic surfactants.
As used herein, “anionic surfactant” means those surface-active or detergent compounds that contain an organic hydrophobic group containing generally 8 to 26 carbon atoms or generally 10 to 18 carbon atoms in their molecular structure and at least one water-solubilizing group selected from sulfonate, sulfate, and carboxylate so as to form a water-soluble detergent. Usually, the hydrophobic group will comprise a C8-C22 alkyl, or acyl group. Such surfactants are employed in the form of water-soluble salts and the salt-forming cation usually is selected from sodium, potassium, ammonium, magnesium and mono-, di- or tri-C2-C3 alkanolammonium, with the sodium, magnesium and ammonium cations again being the usual ones chosen. Some examples of suitable anionic surfactants include, but are not limited to, the sodium, potassium, ammonium, and ethanolammonium salts of linear C8-C18 alkyl ether sulfates, ether sulfates, and salts thereof. Suitable anionic ether sulfates have the formula R(OC2H4)nOSO3M wherein n is 1 to 12, or 1 to 5, and R is an alkyl, alkylaryl, acyl, or alkenyl group having 8 to 18 carbon atoms, for example, an alkyl group of C12-C14 or C12-C16, and M is a solubilizing cation selected from sodium, potassium, ammonium, magnesium and mono-, di- and triethanol ammonium ions. Exemplary alkyl ether sulfates contain 12 to 15 carbon atoms in the alkyl groups thereof, e.g., sodium laureth (2 EO) sulfate. Some preferred exemplary anionic surfactants that may be used in the compositions of the present disclosure include sodium laurel ether sulfate (SLES), sodium lauryl sulfate, and ammonium lauryl sulfate. In certain embodiments, the anionic surfactant is present in an amount of 0.01 to 5.0%, 0.1 to 2.0%, 0.2 to 0.4%, or about 0.33%.
As used herein, “nonionic surfactant” generally refers to compounds produced by the condensation of alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound which may be aliphatic or alkyl-aromatic in nature. Examples of suitable nonionic surfactants include poloxamers (sold under trade name PLURONIC®), polyoxyethylene, polyoxyethylene sorbitan esters (sold under trade name TWEENS®), Polyoxyl 40 hydrogenated castor oil, fatty alcohol ethoxylates, polyethylene oxide condensates of alkyl phenols, products derived from the condensation of ethylene oxide with the reaction product of propylene oxide and ethylene diamine, ethylene oxide condensates of aliphatic alcohols, alkyl polyglycosides (for example, fatty alcohol ethers of polyglycosides, such as fatty alcohol ethers of polyglucosides, e.g., decyl, lauryl, capryl, caprylyl, myristyl, stearyl and other ethers of glucose and polyglucoside polymers, including mixed ethers such as capryl/caprylyl (C8-10) glucoside, coco (C8-16) glucoside, and lauryl (C12-16) glucoside), long chain tertiary amine oxides, long chain tertiary phosphine oxides, long chain dialkyl sulfoxides, and mixtures of such materials.
In some embodiments, the nonionic surfactant comprises amine oxides, fatty acid amides, ethoxylated fatty alcohols, block copolymers of polyethylene glycol and polypropylene glycol, glycerol alkyl esters, polyoxyethylene glycol octylphenol ethers, sorbitan alkyl esters, polyoxyethylene glycol sorbitan alkyl esters, and mixtures thereof. Examples of amine oxides include, but are not limited to, laurylamidopropyl dimethylamine oxide, myristylamidopropyl dimethylamine oxide, and mixtures thereof. Examples of fatty acid amides include, but are not limited to, cocomonoethanolamide, lauramide monoethanolamide, cocodiethanolamide, and mixtures thereof. In certain embodiments, the nonionic surfactant is a combination of an amine oxide and a fatty acid amide. In certain embodiments, the amine oxide is a mixture of laurylamidopropyl dimethylamine oxide and myristylamidopropyl dimethylamine oxide. In certain embodiments, the nonionic surfactant is a combination of lauryl/myristylamidopropyl dimethylamine oxide and cocomonoethanolamide. In certain embodiments, the nonionic surfactant is present in an amount of 0.01 to 5.0%, 0.1 to 2.0%, 0.1 to 0.6%, 0.2 to 0.4%, about 0.2%, or about 0.5%.
As used herein, the term “cationic surfactant” includes the cationic surfactants disclosed in WO 2007/011552A2, the contents of which are incorporated herein by reference in its entirety.
Examples of the surfactant that can be used are sodium lauryl sulfate, sorbitan fatty acid ester, polyoxyethylene (20) sorbitan monooleate (Polysorbate 80 or Tween 80), polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene alkyl phenyl ether, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene sorbitol fatty acid ester and polyoxyethylene glycerol fatty acid ester. In the present invention, each of them may be used solely or two or more thereof may be used jointly. Typical amounts of surfactant are about 0.1% to about 3%, in one embodiment about 0.1% to about 2%, in another embodiment about 0.1% to about 1%, by weight of the total composition.
Examples of the filler are crystalline cellulose, ethylcellulose, dextrin, various kinds of cyclodextrin (α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin), sodium sulfate, as well as derivatives thereof and pullulan.
Useful flavor agents include natural and synthetic flavoring sources including, e.g., volatile oils, synthetic flavor oils, flavoring aromatics, oils, liquids, oleoresins and extracts derived from plants, leaves, flowers, fruits, stems and combinations thereof. Suitable flavor agents include, e.g., citric oils, e.g., lemon, orange, grape, lime and grapefruit, fruit essences including, e.g., apple, pear, peach, grape, strawberry, raspberry, cherry, plum, pineapple, apricot, and other fruit flavors. Other useful flavor agents include, e.g., aldehydes and esters (e.g., benzaldehyde (cherry, almond)), citral, i.e., alpha-citral (lemon, lime), neral, i.e., beta-citral (lemon, lime), decanal (orange, lemon), aldehyde C-8 (citrus fruits), aldehyde C-9 (citrus fruits), aldehyde C-12 (citrus fruits), tolyl aldehyde (cherry, almond), 2,6-dimethyloctanal (green fruit), 2-dodedenal (citrus, mandarin) and mixtures thereof.
Suitable coloring agents include, e.g., food, drug and cosmetic (FD&C) colors including, e.g., dyes, lakes, and certain natural and derived colorants. Useful lakes include dyes absorbed on aluminum hydroxide and other suitable carriers.
Suitable sweetening agents include stevia, sugars such as sucrose, glucose, invert sugar, fructose, ribose, tagalose, sucralose, maltitol, erythritol, xylitol, and mixtures thereof, saccharin and its various salts (e.g., sodium and calcium salt of saccharin), cyclamic acid and its various salts, dipeptide sweeteners (e.g., aspartame), acesulfame potassium, dihydrochalcone, glycyrrhizin, and sugar alcohols including, e.g., sorbitol, sorbitol syrup, mannitol and xylitol, and combinations thereof.
It is understood that while general attributes of each of the above categories of materials may differ, there may be some common attributes and any given material may serve multiple purposes within two or more of such categories of materials. All of the ingredients in the compositions may have functions in addition to their primary function, and may contribute to the overall properties of the composition, including its stability, efficacy, consistency, mouthfeel, taste, odor and so forth. For example, a binder may also function as a disintegrating agent and vice versa.
In a second aspect, the present disclosure provides a method for whitening teeth comprising the steps of (a) applying Composition 1, or any of 1.1 et seq., to the teeth, and (b) maintaining contact of the composition with the teeth for a sufficient period of time (e.g., 0.1 to 60 minutes, or 0.1 to 30 minutes, or 0.1 to 10 minutes, or 0.1 to 5 minutes, or 0.1 to 2 minutes, or 0.1 to 1 minute) to effect whitening of the teeth contacted by the composition. In some embodiments, the composition may be applied using a toothbrush, and the composition maintained in contact with the teeth by using a brushing action. In some embodiments, the composition may be applied to the teeth using a dental tray, and the composition maintained in contact with the teeth by placement of the dental tray in the mouth until whitening is complete.
In other embodiments, the present disclosure provides for the use Composition 1, or any of 1.1 et seq., or any other embodiments thereof, for the whitening of the teeth.
Exemplary embodiments of the present disclosure will be illustrated by reference to the following examples, which are included to exemplify, but not to limit the scope of the present invention.
In the examples and elsewhere in the description of the invention, chemical symbols and terminology have their usual and customary meanings. Temperatures are in degrees Celsius unless otherwise indicated. The amounts of the components are in weight percent based on the standard described; if no other standard is described then the total weight of the composition is to be inferred. Various names of chemical components include those listed in the CTFA International Cosmetic Ingredient Dictionary (Cosmetics, Toiletry and Fragrance Association, Inc., 7th ed. 1997).
Potassium peroxymonosulfate is combined with calcium pyrophosphate, and other excipients and mixed to provide a homogenous product.
The compositions may have a formula as follows:
Testing of the formulas within the scope of the disclosure demonstrates that they provide improved stability and retained active oxygen activity compared to comparative formulas not within the scope of the present disclosure.
To evaluate the effect of replacing calcium pyrophosphate abrasive with high cleaning silica abrasive four compositions are prepared according to the following Table:
The Compositions A, B, C, and D, are compared in an accelerated aging study. Samples are placed in tubes and stored at 60° C./75% RH (relative humidity) for 2 weeks. Active oxygen (AO) levels are determined initially, and at 1 week and 2 weeks, by iodometric titration. The results are shown in the table below (expressed as percent of initial theoretical AO):
The results demonstrate that Compositions A and B, which are stabilized by calcium pyrophosphate abrasive and PEG/PPG triblock copolymer, retain nearly full active oxygen through the 2 week study. In contrast, using high cleaning silica abrasive (Compositions F, G), there is a rapid loss in active oxygen, due to decomposition of the potassium monoperoxysulfate. Without being bound by theory, it is believed that trace heavy metals in precipitated silica (such as high-cleaning silica) promotes catalytic decomposition of MPS (unlike fumed silica, which lacks such impurities). It is also noted that high cleaning silicas are more effective abrasives than calcium pyrophosphate (e.g., the RDA (relative dentin abrasivity) of high cleaning silica is about 160, but for calcium pyrophosphate it is about 90). Thus, this loss in abrasivity is a consequence of improving MPS stability.
Compositions A and B are compared using a Brookfield programmable viscometer during an aging study. All tests are performed with toothpastes in solid containers, 120 ml sample cups. The samples are stored for 2 or 3 months at 40° C./65% RH (relative humidity). A fresh spot is selected at least 1 cm from the wall of the jar and from spots of previous tests. The viscometer spindle is slowly lowered into the sample jar with as little disturbance of the sample as possible. Then the vane v74 spindle on the shaft of the viscometer is slowly lowered into the sample. A thixotropy loop test is performed according to the programmed software. Squeeze pressure (bar) is a measured to estimate the ability of a toothpaste or gel to be squeezed out of a tube. Acceptable squeeze pressures range from 0.03 to 0.1 bar, with about 0.05 bar being ideal. If the squeeze pressure is too low, the toothpaste will ooze out of the tube or be expelled from the tube too violently with gentle pressure. If the squeeze pressure is too high, the toothpaste will be too difficult to squeeze from the tube. Viscosity is measured at 1 rpm (in centipoise, cP). Viscosity for a toothpaste is preferably maintained during aging at 70,000 to 300,000 cP, most preferably at about 200,000 cP.
The results are shown in the table below (N.M.=not measurable, because the toothpaste could not be squeezed from the tube):
The results demonstrate that the compositions of the present invention retain stable rheological characteristics compared to similar compositions outside the scope of the present disclosure.
Composition A is tested against Composition E for whitening efficiency. Composition E is a commercial whitening toothpaste composition with high-cleaning silica. Composition E comprises (in descending order of concentration): Glycerin, hydrated silica, sodium hexametaphosphate, aqua, PEG-6, aroma, silica, sodium lauryl sulfate, cocamidopropyl betaine, trisodium phosphate, mica, Chondrus crispus powder, PEG-20M, sodium fluoride, xanthan gum, and sodium chloride, plus minor flavors, colors, and preservatives.
The heads of soft toothbrushes are cut from the handles and mounted for use on a brushing machine. Bovine teeth are mounted and stained with coffee and tea. Each toothpaste slurry is poured over each tray and brushing is immediately started on the teeth. The teeth are brushed for 2 minutes with 250 grams of pressure applied. The brushing machine is set to 120 strokes per minute. After 2 minutes, the brushing is stopped, the slurry is removed, and the teeth are rinsed with deionized water then dried. The brushing treatment is repeated a total of 14 times to model twice daily use of each product for 7 days.
Software from Medical High Technology (MHT) is used to measure the L*, a*, and b* values for each tooth before and after treatment. The L*, a*, and b* values are used to calculate the change in the whiteness index for each tooth after 14 treatments as compared to baseline. The Whiteness index is reported as ΔW*, wherein:
The absolute value of ΔW* is reported. It should be noted that the more positive the value of ΔW*, the closer the tooth color is to white.
The Analysis of Variance test is used to compare the mean ΔW* values for each product after 14 treatments. A subsequent Tukey multiple comparison test is performed in order to assess pair-wise comparisons of the products. A p-value less than 0.05 indicates statistically significant differences among the products.
The results are shown in the following table:
At treatment 14, the whitening results for Composition A are a statistically significant improvement over the whitening results for Composition E (p-value 0.0023). The results demonstrate that a whitening composition according to the present disclosure is highly effective, significantly more so than a current commercial whitening composition.
Teeth whitening is commonly performed using either abrasives (such as high-cleaning silica) to remove stain molecules from the surface of teeth, or using oxidizing agents to bleach out the color of stain molecules on the teeth, or both. The inventors have further discovered that using a blue pigment can mask the presence of stains by making the teeth appear whiter. This is important as both abrasive and oxidizing agents take some time (typically 1-2 weeks) to begin to show a substantial whitening effect, whereas the masking effect of blue pigment is much more immediate.
There compositions are compared in a whitening study. Composition A from Example 1, Composition A with 0.05% Blue 15 pigment (CI 74160) added, and a commercial whitening composition (Composition F) comprising 0.1% hydrogen peroxide and 0.05% Blue 15 pigment.
Extracted whole human molars are obtained from Therametric Technologies, Inc. The crowns and roots are separated and the isolated crowns are bisected longitudinally using a Buehler IsoMet low speed saw. The bisected crown pieces are mounted in a methacrylate resin so that only the enamel is exposed. 27 teeth are selected and three teeth are mounted per tray using a thermal setting impression compound. All nine trays are used to evaluate each product in a randomized order.
All measurements are taken with a Spectroshade Micro instrument manufactured by Medical High Technology (MHT). Before measuring the baseline optical properties of the teeth, the instrument is calibrated per the manufacturer's instructions. To take a measurement, the instrument is positioned so that one tooth is in the instrument's field of vision and then the image is captured. This is repeated for each measurement in the study.
A 1:2 (w/w) slurry of toothpaste to artificial saliva is prepared for each sample (e.g., about 250 g of toothpaste and 500 g of artificial saliva). The slurry is mixed by hand to completely homogenize the solution before addition to the tray.
The heads of soft toothbrushes are cut from the handles and mounted for use on a brushing machine. 9 mL of a standard toothpaste slurry is poured over each tray and brushing is immediately started. The teeth are brushed for 10 minutes with 250 grams of pressure applied. The brushing machine is set to 120 strokes per minute. After 10 minutes, the brushing is stopped, the slurry is removed, and the teeth are rinsed with deionized water then dried. Baseline spectrophotometer measurements are then taken. The teeth are then submerged in artificial saliva (9 mL/tray), and aged at 37° C. with agitation for 15 minutes. Then, the test toothpaste slurry is added to the tray, and the teeth are brushed for 2 minutes with 250 grams of pressure applied. The brushing machine is set to 120 strokes per minute. After 2 minutes, the brushing is stopped, the slurry is removed, and the teeth are rinsed with deionized water then dried. After-treatment spectrophotometer measurements are then taken. Data analysis is as described in Example 4.
The results are shown in the following table.
The results demonstrate that adding Blue 15 pigment enhances the immediate whitening effect (1 brushing cycle) of an MPS toothpaste according to the present disclosure. Furthermore, the whitening effect of the MPS combined with Blue 15 is greater than the same amount of Blue 15 added to a comparable hydrogen peroxide-based toothpaste composition (0.1% HP has an active oxygen content equivalent to 1% MPS).
Foaming properties are measured by using a Dynamic Foam Analyzer (DFA) from Kruss. The DFA is equipped with a cylinder with a prism attached on one side, which allows for measuring bubble size and bubble counts on the cylinder surface. 50 mL of each toothpaste slurry is made by mixing a toothpaste sample and water at a 1:3 weight ratio immediately before the test. The slurries are delivered to the DFA cylinder. To measure foaming speed, the flash foam test is run. In this test, as the foam height cannot be measured during stirring, stirring occasionally stops to measure foam height in the middle of foam growth. In detail, the slurries are stirred at 4000 rpm for 10 seconds, and stirring stopped for 15 seconds during which foam height is measured. This stir-stop sequence is repeated 12 times. After this flash foam test, the slurries remain unagitated for another 20 seconds, and the final foam height, bubble size and bubble count are measured. Bubble count is determined as both areal count (bubbles per square millimeter on a flat surface and volume count (bubbles per cubic millimeter). The test is repeated in triplicate for each composition tested. The analysis is performed using the Advance software by Kruss.
Composition A the MPS-whitening toothpaste described above, and for comparison, Compositions G and H are prepared, which correspond to Composition A except without CAPB (Comp. G) or without SLS (Comp. H). Composition J is commercial fluoride dental cream for comparison. The formulations of the compositions are shown in the Table below (all values are percent by weight of the composition)
The results of the testing are shown in the following Tables:
These results demonstrate that using the combination of an anionic surfactant (SLS) and a zwitterionic surfactant (CAPB) in an MIPS-based anhydrous toothpaste provides significantly improved foaming properties compared to using anionic surfactant (SLS) or zwitterionic surfactant (CAPB) alone. For the synergistic combination, total foam volume is increased at all time points, and there is a much faster and substantial increase in foam volume. For example, between 10 seconds and 110 seconds, foam volume only increased by 25% for Composition G and by 14% for Composition H, but increased by 45% for Composition A. Moreover, most of that increase was achieved rapidly, the foam volume for Composition A increasing by 35% from 10 seconds to 40 seconds. In contrast, Compositions G and H gained only 11% and 6% in foam volume, respectively in that period, The results for Composition A are similarly much improved over the commercial toothpaste Composition J.
In addition, it is found that the individual bubble size is substantially smaller for the SLS/CAPB surfactant combination, resulting in a greater number of bubbles forming per unit area and per unit volume. These results lead to an improved mouthfeel when brushing the teeth with the composition.
It was desired to evaluate whether a small amount of propylene glycol could replace a portion of the poloxamer in the above formulations while retaining stability, and improving the freezing point of the composition. Without being bound by theory, it is believed that the high freezing point of poloxamer polymers contributes significantly to the high freezing point of the final toothpaste compositions. Thus, replacing a portion of the poloxamer with propylene glycol should reduce the freezing point of the compositions. However, propylene glycol was previously reported to promote the degradation of potassium MPS. So, it was first necessary to evaluate whether a small amount of propylene glycol could be incorporated into the composition without adversely affecting the composition's stability.
To study this, accelerated aging studies evaluating the active oxygen (AO) content of various compositions are performed, as described in Example 2. Three compositions are compared: Composition A (as above, having about 31% poloxamer L35, but no propylene glycol), Composition K (having about 32% propylene glycol, but no poloxamer), and Composition L (having about 7.5% propylene glycol and 24% poloxamer L35). The Compositions K and L are otherwise the same as Composition A as shown in the preceding composition tables. Studies are conducted for 2 weeks at 60° C. and 75% relative humidity (RH), for 3 months at 40° C. and 60% RH, and for 3 months at 30° C. and 75% RH The results are shown in the following tables:
The results demonstrate that using 32% propylene glycol instead of the poloxamer results in a destabilization of the MPS and loss of active oxygen. However, using a combination of 7.5% propylene glycol and about 24% poloxamer (Comp. L) provides nearly identical AO stability results as compared to using about 31% poloxamer (Comp. A). Thus, it is unexpectedly shown that with a sufficiently low concentration of propylene glycol, MPS stability can be maintained.
In addition, it is found that the use of a lower amount of poloxamer results in an improvement in the taste of the composition, as judged by a panel of consumers or expert tasters. Moreover, propylene glycol is significantly less expensive than poloxamer L35, making the substitution highly cost favorable for manufacture of the product.
Squeezability Measurement with Texture Analyzer
A Texture Analyzer (TA) measures the response of a material when it is subjected to a force (e.g. compression or tension). Because of its adaptability, texture analysis has become commonplace in many industries to measure a specific range of characteristics or properties relating to the way a material behaves, breaks, flows, sticks, or bends. There are many fixtures available that allow a Texture Analyzer to be used for various tests which emulate specific processes. One of them is the tube extrusion fixture (TA-TR), which can be used to test extrusion of a material out of a package, such as a toothpaste tube. See, e.g., Ahuja et al., “Rheological measurements for prediction of pumping and squeezing pressures of toothpaste,” Journal of Non-Newtonian Fluid Mechanics, 258: 1-9 (2018).
In a typical experiment, the TA probe travels downwards with a speed of 20 mm/s and applies a constant force of 1.5 kg on a toothpaste tube for 5 seconds. During the experiment, the discharged amount of paste is collected and weighed. All pastes tested have similar densities (around 1.3 g/mL), and the mass was converted into volume and reported as a flow rate in mL/sec (“squeezability”). A force of 1.5 kg is selected because it closely represents the typical force that a human hand applies to a toothpaste tube based on recent studies on toothpaste tubes. See, e.g., J. Cepriá-Bernal et al., “Grip force and force sharing in two different manipulation tasks with bottles,” Ergonomics, 60:957-966 (2017); J. Cepriá-Bernal & A. Pérez-González, “Dataset of Tactile Signatures of the Human Right Hand in Twenty-One Activities of Daily Living Using a High Spatial Resolution Pressure Sensor,” Sensors (Basel), 21: 2594 (2021).
It is found that results for squeezability determined using this TA-TR method correlates well with data from a human tester panel. Preferred compositions are found to have a squeezability of greater than 0.1 mL/sec, typically in the range of 0.1 to 2 mL/sec, although compositions with higher squeezability are achievable.
Rheological measurements are conducted using a DHR rheometer. A standard 15 mm diameter, 4-paddled vane is used in the standard rheometer cup with the shear rate swept from 0.1 to 30/sec and back with 10 points per decade in logarithmic mode, at 10 seconds per point. This approximately corresponds to an RPM range of 0.5 to 200.
Two parameters are extracted from these rheological measurements: “squeezing pressure” as calculated by FitFlow; and viscosity “from rest” at the specific shear rate, 1 sec−1. Squeezing pressure is calculated by integrating the flow curve, and represents the pressure needed to push the paste through a reducer pipe roughly modeling a toothpaste tube. This measurement and the data analysis can be performed either on the rheometer or on a Brookfield viscometer using the FitFlow method, although using the rheometer is preferred. For the viscosity measurement, the test is performed from rest using low shear rates (e.g., 1 sec−1) because this best represents normal toothpaste tube squeezing conditions. This measurement is quite distinct from the usual Brookfield “viscosity” measurement, typically taken at 1 RPM after subjecting the sample to a high shear at 200 RPM.
It is found that squeezability both the “squeezing pressure” and the viscosity “from rest” measures correlate well with the TA-TR results. Preferred compositions are found to have a squeezing pressure of less than 0.1 bar, typically in the range of 0.001 0.07 bar (more preferably 0.001 to 0.04 bar), and a viscosity “at rest” of less than 400 Pa*s (Pascal*seconds), typically in the range of 10 to 200 Pa*s (more preferably 10 to 150 Pa*s).
Squeezability Inferred from Hardening Point
Another way of estimating squeezability is by determining the “hardening point” of the composition, which is the temperature at which the composition's viscosity derivative curve (i.e., the slope of the viscosity curve) reaches a minimum value. The viscosity curve (viscosity in Pa*s versus temperature, e.g., over 0 to 20° C.) can be quickly and easily determined using a rheometer, by cooling down the composition at a constant shear rate of 1 sec−1. From this plot, the first derivative can be taken, which provides a plot of viscosity slope (Pa*s/° C.) versus temperature (° C.), and the hardening point is the minimum of this plot. In general, the lower the hardening point (the temperature around which the viscosity increases abruptly), the higher will be the squeezability of the paste at cold temperatures.
The above methods are applied to the following toothpaste compositions:
The results demonstrate that the formula with propylene glycol provides a substantial improvement in squeezability, especially at low temperature. For example, the hardening point measurements are as follows:
For the MPS with PG formula, the viscosity slope versus temperature plot shows a decline beginning around 5° C., but the minimum is not reached by the lowest temperature measured (0° C.). The results obtained the Texture Analyzer and Rheological Characterization are comparable.
Hardening point values of less than 13° C. are preferred, especially less than 10° C., in order to ensure adequate squeezability at lower temperature.
Further data shows that the addition of PEG-400, or the use of PEG-400 instead of PEG-600, also imparts a significant improvement in hardening point, freezing point, and squeezability.
Further data shows that inclusion of salt additives such as potassium nitrate, zinc nitrate, potassium sulfate, potassium chloride, calcium chloride, sodium chloride, aluminum nitrate, also provide a significant reduction in hardening temperature, freezing point, and improved squeezability.
The invention has been described above with reference to illustrative Examples, but it is to be understood that the invention is not limited to the disclosed embodiments. Alterations and modifications that would occur to one of skill in the art upon reading the specification are also within the scope of the invention, which is defined in the appended claims.
This application is a nonprovisional application which claims priority to, and the benefit of, U.S. Provisional Application Ser. No. 63/436,352, filed on Dec. 30, 2022, the contents of which are hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63436352 | Dec 2022 | US |
