Patent Description:
Dental plaque (also known as dental biofilm) is a sticky, colorless deposit of bacteria that is constantly forming on the tooth surface. Dental plaque is generally made up of bacteria and extracellular polymer substances (so called "EPS"). EPS are biopolymers of microbial origin in which biofilm microorganisms are embedded. Saliva, food and fluids combine to produce these deposits that collect where the teeth and gums meet. Plaque buildup is the primary factor in poor oral health that can lead to caries and periodontal (gum) disease, including gingivitis. One-way dentifrice compositions help prevent and control plaque is by leveraging anti-bacterial agents; however, the disadvantage and formulation challenge is the unintended reactivity of anti-bacterial agents with formulation ingredients. This may include oxidative degradation, hydrolysis, adsorption or precipitation of oxy-hydroxide species, any of which can impact the bio-availability of the anti-bacterial agent. There is a continuing consumer need to provide such formulations that help prevent plaque formation on teeth and/or minimize the use of antimicrobial agents.

One solution to help inhibit biofilm formation or help disrupt biofilm is the use of baking soda (i.e., sodium bicarbonate). Baking soda mechanism of action against biofilm is likely at least two-fold. Baking soda can displace calcium ions so as to help disrupt or reduce the biofilm. Calcium ions act as a "glue" or "scaffold" of EPS components of dental biofilm. Baking soda may also act as an abrasive to aid in the physical removal of oral biofilm. Some levels of baking soda in dentifrice are reported at over <NUM> wt. %, and sometimes higher than <NUM> wt. However, some users report an unpleasant taste experience (attributable to the relatively high level of baking soda). The use of high-level baking soda compositions brings stability challenges around decomposition of the baking soda. An approach used to overcome such stability challenges has been to formulate baking soda composition in an anhydrous or low water compositions. However, this approach can lead to poor rheology properties and impairs the dispersion and delivery. Furthermore, dental plaque is particularly problematic in developing markets. And thus, dentifrice solutions are best cost effective (e.g., containing a relatively high level of water). Accordingly, there is a need for baking soda containing aqueous dentifrice compositions, maximizing the bicarbonate salt associated therapeutic benefits while minimizing the level of bicarbonate salt (e.g., < <NUM> wt. %) as to help with the flavor profile of the composition and improved dispersion and delivery. There is also a need for a composition that is cost effective for developing markets where arguably the need for such compositions are greatest.

<CIT> shows a toothpaste comprising <NUM>-<NUM>% sodium bicarbonate in an aqueous solution of sorbitol, and also comprising fluoride.

The present invention relates to a dentifrice composition comprising: (a) from <NUM>% to <NUM>%, by weight of the composition, of water; (b) from <NUM>% to <NUM>%, by weight of the composition, of bicarbonate salt; (c) from <NUM>% to <NUM>%, by weight of the composition, of neutral amino acid; and (d) from <NUM>% to <NUM>%, by weight of the composition, of a fluoride ion source.

One advantage of the present invention is the significant disruption and destabilization of the dental biofilm architecture achieved by a dentifrice composition comprising the combination of bicarbonate salt (e.g. sodium bicarbonate) and neutral amino acid (e.g. glycine). To this end, it is further surprising that the effect of the two components, in themselves, do not act as cidal or have an inhibitory impact on bacteria.

Further, there are commercial dentifrice compositions containing over <NUM>% sodium bicarbonate, which claim to provide a clinical benefit in treating gingivitis. However, users report an unpleasant sensory experience (e.g. taste, foaming, dispersion) associated at this higher a level of sodium bicarbonate. Another aspect of this invention is thus combining bicarbonate salt with neutral amino acid to provide a dentifrice composition that allows lowering the level of bicarbonate salt, while still destabilizing the biofilm and providing an improved sensorial experience.

Yet another aspect of this invention is the formulation of aqueous dentifrice containing relatively high content of both baking soda and water that has a good chemical and physical stability over the product shelf life, allowing for an improved dispersion and delivery that maximizes the bicarbonate salt associated therapeutic benefits.

Yet another aspect of the invention provides a method of treating dental biofilm comprising the step of brushing teeth with a composition of the present invention.

Yet still another aspect of the invention provides a method preventing or mitigating plaque formation on tooth enamel comprising the step of brushing teeth with a dentifrice composition of the present invention.

The term "comprising" as used herein means that steps and ingredients other than those specifically mentioned can be added. This term encompasses the terms "consisting of" and "consisting essentially of. " The compositions of the present invention can comprise, consist of, and consist essentially of the essential elements and limitations of the invention described herein, as well as any of the additional or optional ingredients, components, steps, or limitations described herein.

The term "dentifrice" as used herein means paste, gel, powder, tablets, or liquid formulations, unless otherwise specified, that are used to clean the surfaces of the oral cavity. Preferably the dentifrice compositions of the present invention are single phase compositions. One example of a dentifrice is toothpaste (for brushing teeth). The term "teeth" as used herein refers to natural teeth as well as artificial teeth or dental prosthesis.

All percentages, parts and ratios are based upon the total weight of the compositions of the present invention, unless otherwise specified. All such weights as they pertain to listed ingredients are based on the active level and, therefore do not include solvents or by-products that may be included in commercially available materials, unless otherwise specified. The term "weight percent" may be denoted as "wt. All molecular weights as used herein are weight average molecular weights expressed as grams/mole, unless otherwise specified.

As used herein, the articles including "a" and "an" when used in a claim, are understood to mean one or more of what is claimed or described.

As used herein, the words "preferred", "preferably" and variants refer to embodiments of the invention that afford certain benefits, under certain circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

The dentifrice compositions of the present invention comprise herein from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%. by weight of the composition, of water. The dentifrice composition can comprise from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, by weight of the composition, of water. The water may be added to the formulation and/or may come into the composition from the inclusion of other ingredients provided in aqueous solution. Preferably the water is USP water.

The compositions of the present invention comprise from <NUM>% to <NUM>% by weight of the composition, of bicarbonate salt. Preferably, the bicarbonate salt is selected from sodium bicarbonate, calcium bicarbonate, or mixtures thereof; more preferably sodium bicarbonate.

The dentifrice compositions of the present invention comprise a neutral amino acid.

The term "neutral amino acids" as used herein include not only naturally occurring neutral amino acids, such as alanine, asparagine, cysteine, glutamine, glycine, isoleucine, leucine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, but also biologically acceptable amino acid which has an isoelectric point in range of pH <NUM> to <NUM>. The biologically preferred acceptable neutral amino acid has a single amino group and carboxyl group in the molecule or a functional derivative hereof, such as functional derivatives having an altered side chain albeit similar or substantially similar physio chemical properties. In a further embodiment the amino acid would be at minimum partially water soluble and provide a pH of less than <NUM> in an aqueous solution of <NUM>/<NUM> at <NUM>.

Accordingly, neutral amino acids suitable for use in the invention include, but are not limited to, alanine, aminobutyrate, asparagine, cysteine, cystine, glutamine, glycine, hydroxyproline, isoleucine, leucine, methionine, phenylalanine, proline, serine, taurine, threonine, tryptophan, tyrosine, valine, salts thereof, or mixtures thereof. Preferably, neutral amino acids used in the composition of the present invention may include asparagine, glutamine, glycine, salts thereof, or mixtures thereof. The neutral amino acids may have an isoelectric point of <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, or <NUM>, in an aqueous solution at <NUM>. Preferably, the neutral amino acid is selected from asparagine, glutamine, or glycine, more preferably in its free form. If the neutral amino acid is in its salt form, suitable salts include salts known in the art to be pharmaceutically acceptable salts considered to be physiologically acceptable in the amounts and concentrations provided. The neutral amino acid is present in the amount of from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, by weight of the composition. In one aspect, the neutral amino acid is glutamine (or salt thereof). In another aspect, the neutral amino acid is asparagine (or salt thereof). In yet another aspect, the neutral amino acid is glycine (or salt thereof).

It has been surprisingly discovered that, the use of neutral amino acid provides biofilm prevention or reduction benefits in compositions containing bicarbonate salt (e.g. at reduced levels) while enabling improved taste due to relatively reduced levels of bicarbonate salt.

Furthermore, the introductions of amino acid provide gingival would healing benefit and thus be able to minimize the use of other anti-bleeding agents, for example tranexamic acid, epsilon aminocaproic acid, and p-aminomethylbenzoic acid. In one aspect, the dentifrice composition of the present invention is substantially free of, preferably essentially free of, and more preferably free of, tranexamic acid, epsilon aminocaproic acid, and p-aminomethylbenzoic acid.

In one aspect, the neutral amino acid is uncomplexed. The neutral amino acid is not complexed with zinc.

The compositions include an effective amount of an anti-caries agent. In one aspect, the anti-caries agent is a fluoride ion source. The fluoride ion may be present in an amount sufficient to give a fluoride ion concentration in the composition at <NUM>, and/or in one embodiment can be used at levels of from <NUM>% to <NUM>% by weight of the composition, preferably from <NUM>% to <NUM>%, by weight of the composition, to provide anti-caries effectiveness. Representative fluoride ion sources include: stannous fluoride, sodium fluoride, potassium fluoride, amine fluoride, sodium monofluorophosphate, zinc fluoride, or mixtures thereof. In one aspect, the dentifrice compositions of the present invention may have a dual fluoride ion source, specifically sodium monofluorophosphate and an alkaline metal fluoride. Without wishing to be bound by theory, such an approach may provide an improvement in mean fluoride uptake.

The compositions of the present invention can optionally, and in some aspects preferably, comprise from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, by weight of the composition, of a calcium-containing abrasive, wherein preferably the calcium-containing abrasive is selected from the group consisting of calcium carbonate, calcium glycerophosphate, dicalcium phosphate, tricalcium phosphate, calcium orthophosphate, calcium metaphosphate, calcium polyphosphate, calcium oxyapatite, sodium carbonate, and mixtures thereof; wherein more preferably the calcium-containing abrasive is calcium carbonate. Preferably, the composition comprises from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, by weight of the composition, of a calcium-containing abrasive.

Preferably, the calcium-containing abrasive is calcium carbonate. More preferably, the calcium-containing abrasive is selected from the group consisting of fine ground natural chalk, ground calcium carbonate, precipitated calcium carbonate, and combinations thereof. Non-limiting examples of the weight percentages of the calcium-containing abrasive include: <NUM>%, <NUM>%, <NUM>%, or <NUM>%, by weight of the composition, preferably wherein the calcium-containing abrasive is calcium carbonate.

The compositions of the present invention can optionally, and in some aspects preferably, comprise silica abrasive. Silica dental abrasives of various types, such as thickening silica, are preferred because of their unique benefits of exceptional dental cleaning and polishing performance without unduly abrading tooth enamel or dentine. The silica abrasive polishing materials herein, as well as other abrasives, generally have an average particle size ranging between about <NUM> to about <NUM> microns, and preferably from about <NUM> to about <NUM> microns. The abrasive can be precipitated silica or silica gels such as the silica xerogels describe in <CIT>, and <CIT>. Preferred are the silica xerogels marketed under the trade name "Syloid" by the W. R Grace & Company, Davison Chemical Division. Also preferred are the precipitated silica materials such as those marketed by the J. Huber Corporation under the trade name, Zeodent®, particularly the silicas carrying the designation Zeodent® <NUM>, Zeodent® <NUM>, Zeodent® <NUM> and Zeodent® <NUM>. The types of silica dental abrasives useful in the toothpastes of the present invention are described in more detail in <CIT>; and in commonly-assigned <CIT>; <CIT>; <CIT>; <CIT>, and <CIT>.

In one aspect, the composition comprises from <NUM>% to <NUM>%, preferably <NUM>% to <NUM>%, more preferably <NUM>% to <NUM>%, by weight of the composition, of a silica abrasive In one aspect, the composition is substantially free of silica abrasive.

In one aspect, the composition comprises calcium-containing abrasive and silica abrasive.

The pH of the dentifrice composition may be greater than about <NUM>, preferably greater than about <NUM>, preferably from about <NUM> to about <NUM>, preferably from about <NUM> to about <NUM>, preferably about <NUM> to about <NUM>, preferably from about <NUM> to about <NUM>. The relatively high pH of the present inventive composition is for fluoride stability. Without wishing to be bound theory, at below pH <NUM> calcium ion may bind with the fluoride. Thus, it is desirable to have the dentifrice composition have a greater than pH <NUM> to maximize the stability of the fluoride ion source. A method for assessing pH of dentifrice is described is below. For purposes of clarification, although the analytical method describes testing the dentifrice composition when freshly prepared, for purposes of claiming the present invention, the pH may be taken at anytime during the product's reasonable lifecycle (including but not limited to the time the product is purchased from a store and brought to the user's home).

The dentifrice compositions herein may include an effective amount of a pH modifying agent, preferably wherein the pH modifying agent is a pH buffering agent. The pH modifying agents, as used herein, refer to agents that can be used to adjust the pH of the dentifrice compositions to the above-identified pH range. The compositions can comprise from about <NUM>% to about <NUM>%, by weight of the composition, of pH modifying agent. The pH modifying agents may include alkali metal hydroxides, ammonium hydroxide, organic ammonium compounds, carbonates, sesquicarbonates, borates, silicates, phosphates, imidazole, and mixtures thereof. Specific pH agents include monosodium phosphate (monobasic sodium phosphate or "MSP"), trisodium phosphate (sodium phosphate tribasic dodecahydrate or "TSP"), sodium benzoate, benzoic acid, sodium hydroxide, potassium hydroxide, alkali metal carbonate salts, sodium carbonate, imidazole, pyrophosphate salts, tripolyphoshpate salts, sodium gluconate, lactic acid, sodium lactate, citric acid, sodium citrate, phosphoric acid. Without wishing to be bound by theory, phosphate may also have calcium ion chelating activity and therefore provide some monofluorophosphate stabilization (in those formulations containing monofluorophosphate).

A method for assessing pH of dentifrice is described. The pH is measured by a pH Meter with Automatic Temperature Compensating (ATC) probe. The pH Meter is capable of reading to <NUM> pH unit. The pH electrode may be selected from one of the following (i) Orion Ross Sure-Flow combination: Glass body - VWR #<NUM>-<NUM>/Orion #8172BN or VWR#<NUM>-<NUM>/Orion #8172BNWP; Epoxy body - VWR #<NUM>-<NUM>/Orion #8165BN or VWR#<NUM>-<NUM>/Orion #8165BNWP; Semi-micro, epoxy body - VWR #<NUM>-<NUM>/Orion #8175BN or VWR#<NUM>-<NUM>/Orion #3175BNWP; or (ii) Orion PerpHect combination:VWR #<NUM>-<NUM>/Orion #8203BN semi-micro, glass body; or (iii) suitable equivalent. The automatic temperature compensating probe is Fisher Scientific, Cat #<NUM>-<NUM>-<NUM>.

A <NUM>% by weight slurry of dentifrice is prepared with deionized water, and thereafter is centrifuged for <NUM> minutes at <NUM> rotations-per-minute using a SORVALL RC <NUM> centrifuge and SS-<NUM> rotor (or equivalent gravitational force, at <NUM> force). The pH is assessed in supernatant after one minute or the taking reading is stabilized. After each pH assessment, the electrode is washed with deionized water. Any excess water is wiped with a laboratory grade tissue. When not in issue, the electrode is kept immersed in a pH <NUM> buffer solution or an appropriate electrode storage solution.

The compositions herein contains relatively low amount, or even be substantially free or free, of humectants. Non-limiting examples of humectant levels, by weight of the dentifrice composition, include no more than about <NUM>%, no more than about <NUM>%, no more than about <NUM>%, no more than about <NUM>%, no more than about <NUM>%, or <NUM>%. Without wishing to be bound by theory, the presence of humectant (e.g., sorbitol/glyercol) may have a negative role in fluoride uptake in dental plaque in the high water and high carbonate containing dentifrice formulations of the present invention. Reduced levels of sorbitol/glycerol in these dentifrice compositions provide superior fluoride uptake results. Preferably the dentifrice compositions of the present invention comprise from <NUM>% to about <NUM>%, by weight of the composition, of a humectant, wherein the humectant is selected from sorbitol, glycerol, or mixtures thereof; more preferably the composition comprises from <NUM>% to about <NUM>%, preferably <NUM>% to about <NUM>%, by weight of the composition of said humectant. In one aspect, the composition is substantially free of humectant.

The term "humectant," for the purposes of present invention, include edible polyhydric alcohols such as glycerin, sorbitol, xylitol, butylene glycol, propylene glycol, or mixtures thereof. In one aspect, the humectant is a polyol, preferably wherein the polyol is selected from sorbitol, glycerin, or mixtures thereof. In yet another example, the humectant is sorbitol. A potential advantage of having a dentifrice composition that contains low levels of humectant (i.e., at or less than about <NUM> wt. %), without wishing to be bound by theory, is those dentifrice compositions that are free of humectants such as glyercol or sorbitol may provide better fluoride uptake as compared to those compositions having the high levels of such humectants. In one aspect, the dentifrice compositions of the present invention comprise from <NUM>% to about <NUM>%, preferably <NUM>% to about <NUM>%, more preferably <NUM>% to about <NUM>%, by weight of the composition, of glycerin and/or sorbitol. In one aspect, the composition is preferably substantially free of both glycerin and sorbitol.

The dentifrice compositions of the present invention may comprise a thickening system. Preferably the dentifrice composition comprises from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, more preferably from about <NUM>% to about <NUM>%, by weight of the composition, of the thickening system. More preferably the thickening system comprises a thickening polymer, a thickening silica, or mixtures thereof. Yet more preferably, when the thickening system comprises a thickening polymer, the thickening polymer is selected from a carboxymethyl cellulose, a linear sulfated polysaccharide, a natural gum, or mixtures thereof. Yet still more preferably, when the thickening system comprises a thickening polymer, the thickening polymer is selected from the group consisting of: (a) from about <NUM>% to about <NUM>% of a carboxymethyl cellulose ("CMC") by weight of the composition, preferably from about <NUM>% to about <NUM>%, more preferably from about <NUM>% to about <NUM>%, by weight of the composition, of CMC; (b) from about <NUM>% to about <NUM>%, preferably from about <NUM> % to about <NUM>%, more preferably from about <NUM>% to about <NUM>%, by weight of the composition, of a linear sulfated polysaccharide, preferably wherein the linear sulfated polysaccharide is a carrageenan; (c) from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, more preferably from about <NUM>% to about <NUM>%, by weight of the composition, of a natural gum; or (d) mixtures thereof.

Preferably, when the thickening system comprises a thickening silica, the thickening silica is from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, preferably about <NUM>% to about <NUM>%, by weight of the composition.

Preferably, the linear sulfated polysaccharide is a carrageenan (also known as carrageenan). Examples of carrageenan include Kappa-carrageenan, Iota-carrageenan, Lambda-carrageenan, or mixtures thereof.

In one aspect the thickening silica is obtained from sodium silicate solution by destabilizing with acid as to yield very fine particles. One commercially available example is ZEODENT® branded silicas from Huber Engineered Materials (e.g., ZEODENT® <NUM>, <NUM>, <NUM><NUM>, <NUM>, <NUM>, <NUM>).

In one aspect, the CMC is prepared from cellulose by treatment with alkali and monochloro-acetic acid or its sodium salt. Different varieties are commercially characterized by viscosity. One commercially available example is AqualonTM branded CMC from Ashland Special Ingredients (e.g., AqualonTM 7H3SF; AqualonTM 9M3SF AqualonTM TM9A; AqualonTM TM12A).

Preferably, a natural gum is selected from the group consisting of gum karaya, gum arabic (also known as acacia gum), gum tragacanth, xanthan gum, and mixtures thereof. More preferably the natural gum is xanthan gum. Xanthan gum is a polysaccharide secreted by the bacterium Xanthomonas camestris. Generally, xanthan gum is composed of a pentasaccharide repeat units, comprising glucose, mannose, and glucuronic acid in a molar ratio of <NUM>:<NUM>:<NUM>, respectively. The chemical formula (of the monomer) is C<NUM>H<NUM>O<NUM>. In one aspect, the xanthan gum is from CP Kelco Inc (Okmulgee, US).

Preferably the dentifrice compositions of the present invention have a viscosity range from about <NUM>,<NUM> centipoise to about <NUM>,<NUM> centipoise ("cP"). A method for assessing viscosity is described. The viscometer is Brookfield® viscometer, Model DV-I Prime with a Brookfield "Helipath" stand. The viscometer is placed on the Helipath stand and leveled via spirit levels. The E spindle is attached, and the viscometer is set to <NUM> RPM. Detach the spindle, zero the viscometer and install the E spindle. Then, lower the spindle until the crosspiece is partially submerged in the paste before starting the measurement. Simultaneously turn on the power switch on the viscometer and the helipath to start rotation of the spindle downward. Set a timer for <NUM> seconds and turn the timer on at the same time as the motor and helipath. Take a reading after the <NUM> seconds. The reading is in cP.

The compositions of the present invention may optionally comprise polyethylene glycol (PEG), of various weight percentages of the composition as well as various ranges of average molecular weights. In one aspect of the invention, the compositions have from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, more preferably from about <NUM>% to about <NUM>%, by weight of the composition, of PEG. In another aspect of the invention, the PEG is one having a range of average molecular weight from about <NUM> to about <NUM>, preferably from about <NUM> to about <NUM>, preferably from about <NUM> to about <NUM>, preferably from about <NUM> to about <NUM> Daltons. PEG is a water-soluble linear polymer formed by the addition reaction of ethylene oxide to an ethylene glycol equivalent having the general formula is: H-(OCH<NUM>CH<NUM>)n-OH. One supplier of PEG is Dow Chemical Company under the brandname of CARBOWAX™. Without wishing to be bound by theory, having some PEG in the dentifrice composition may help with physical stability.

The dentifrice compositions herein may include a sweetening agents. These sweetening agents may include saccharin, dextrose, sucrose, lactose, maltose, levulose, aspartame, stevia, sodium cyclamate, brazzein, pentadin, D-tryptophan, dihydrochalcones, acesulfame, sucralose, neotame, and mixtures thereof. Sweetening agents are generally used in oral compositions at levels of from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, by weight of the composition.

The dentifrice compositions herein may include a surfactant. The surfactant may be selected from anionic, nonionic, amphoteric, zwitterionic, cationic surfactants, or mixtures thereof. The composition may include a surfactant at a level of from about <NUM>% to about <NUM>%, from about <NUM>% to about <NUM>%, from about <NUM>% to about <NUM>%, from about <NUM>% to about <NUM>%, from about <NUM>% to about <NUM>%, or from about <NUM>% to about <NUM>%, by weight of the composition. Non-limiting examples of anionic surfactants may include those described at <CIT> at paragraphs <NUM>, <NUM>, <NUM>, and <NUM>. Non-limiting examples of zwitterionic or amphoteric surfactants may include those described at <CIT> at paragraph <NUM>; cationic surfactants may include those described at paragraphs <NUM> of the reference; and nonionic surfactants may include those described at paragraph <NUM> of the reference. Preferred surfactants include sodium lauryl sulfate, cocamidopropyl betaine, or mixtures thereof. In one aspect, the composition comprises from about <NUM>% to about <NUM>%, preferably about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, preferably from about <NUM> % to about <NUM>%, by weight of the composition, of an anionic surfactant, e.g. sodium lauryl sulfate (SLS).

The compositions herein may include a colorant. Titanium dioxide is one example of a colorant. Titanium dioxide is a white powder which adds opacity to the compositions. Colorant, e.g. titanium dioxide, generally can comprise from about <NUM>% to about <NUM>%, by weight of the composition.

The compositions herein may include from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, preferably from about <NUM>% to about <NUM>%, preferably about <NUM>% to about <NUM>%, preferably about <NUM>% to about <NUM>%, by weight of the composition, of a flavorant. The term flavorant is used in the broadest sense to include flavor ingredients, sensates, or combinations thereof. Flavor ingredients may include those described in <CIT> at paragraph <NUM>; sensates may include those described at paragraphs <NUM> - <NUM>, incorporated herein by reference. Excluded from the definition of flavorant is "sweetener" (as described above).

In one aspect, the composition of the present invention is free of an antimicrobial agent as described in <CIT>.

The following assay is used an in situ plaque biofilm for inventive oral care compositions of the present invention in order to assess the biofilm Extracellular Polymeric Substances (EPS) matrix destabilization and thickness of the dental biofilm by measuring fluorescent light emitted from the labeled calcium & EPS within the biofilm.

The term "biofilm" refers to the layer(s) of cells attached to a surface. A biofilm can be a bacterial biofilm that includes both alive and growing microbe cells as well as dead microbe cells. The biofilm can be composed of one cell type or it may be composed of two or more cell types, for example, a biofilm complex that is a multispecies bacterial community. A specific type of biofilm is "dental biofilm" (also known as "plaque biofilm," used herein interchangeably) which is biofilm that typically forms on tooth surfaces in the human mouth). Bacteria in a plaque biofilm have significantly different physiological characteristics, e.g. increased resistance to detergents and antibiotics, making biofilm research highly important. A non-limiting list of oral bacterial species is described at <CIT>, column <NUM>, lines <NUM>-<NUM>. These adherent microbe cells are frequently embedded within a self-produced matrix of extracellular polymeric substance ("EPS"). EPS are biopolymers of microbial origin in which biofilm microorganisms are embedded. Biofilm extracellular polymeric substance is a polymeric conglomeration generally composed of calcium, extracellular DNA, proteins, and polysaccharides.

Details of the assay are described below.

Hydroxyapatite ("HA") disks are used for in situ growth of biofilms. The HA disks are designed having three parallel grooves (i.e., <NUM> wide; <NUM> deep for two sides' grooves; while <NUM> wide and <NUM> deep for the middle groove) in each disk. When attaching disks to subject's mouth, keep these grooves vertical, to mimic interproximal gap between teeth, which is the hard-to-clean area where plaque generally tends to accumulate. This model allows the collection of undisturbed plaque from the grooves. HA disks are manufactured by Shanghai Bei'erkang biomedicine limited company (Shanghai, China).

Human subjects wear the splint. Each subject wears up to <NUM> HA disks on the splint to ensure that, at least, <NUM> HA disks are available after <NUM> hours. A non-limiting example of such a splint and HA disks are shown in <FIG>. With reference to <FIG>, the device (<NUM>) holds a plurality of HA disks (2a-2d). In a specific example, and with reference to <FIG>, the HA disk (<NUM>) has three parallel grooves (<NUM>) (the two sides' grooves (203a and 203c) are <NUM> wide and <NUM> deep; while the middle grove (203b) (in between the two side grooves) is <NUM> wide and <NUM> deep). The middle groove is designed wider and deeper than the two sides' grooves so that the HA disk can be more easily separated into two identical half-disks for head-to-head comparison purposes. <FIG> is a schematic of a cross-sectional view of the groove (<NUM>) with biofilm (<NUM>) therein. Further details of the HA disks are described in <CIT> (e.g. paragraphs [<NUM>] - [<NUM>]).

Although not shown in <FIG>, the disks can be positioned such that the recede is in the inter-dental space between the teeth (since this location is prone to plaque (given the difficulty in cleaning, etc.)). The subjects withdraw the splint only during meals (the splint stored in an opaque container in humid conditions) and to perform oral hygiene procedures. Immediately thereafter, the splint is worn again. Subjects are asked to use a straw when drinking.

All HA disks are removed from the splint at <NUM> hours by tweezers. Tweezers are used to hold the edge of HA chips and transfer the HA disk to a <NUM> centrifuge tube containing PBS (phosphate buffered saline) solution. Tweezers are washed thoroughly (water; <NUM>% alcohol; and then deionized water) before every disk transfer.

<NUM> grams of deionized water is added to <NUM> grams toothpaste (using any one of the Examples <NUM>- <NUM>). After stirring thoroughly, the mixture is centrifuge at <NUM>,<NUM> RPM for <NUM> minutes. The supernatant is prepared one day before usage and stored at <NUM>.

After the HA disks are removed from the splint. The HA disks are used for ex vivo treatment by the different inventive and comparative compositions. After being treated with the subject supernatant and labeled with microbial fluorescent probe and stannous fluorescent probe (such as described in <CIT>; Shi et al. ), the biofilms in the grooves are measured by confocal laser scanning microscopy ("CLSM") (as described below).

The HA disks are rinsed in PBS solution and each HA disk is divided into two halves by tweezers. Thereafter, each half-disk is placed into <NUM>-<NUM>µL of PBS solution statically for <NUM> minute. Each disk is treated for two minutes by either PBS solution or toothpaste supernatant. Each disk is washed by holding each disk with tweezers, shaken for ten rounds of back and forth in <NUM> of PBS solution, and then this washing cycle is repeated. Then each disk is immersed into <NUM>-<NUM>µL PBS solution statically for <NUM> minutes.

After being treated with PBS and/or the oral care composition (e.g., toothpaste) supernatant and labeled with specific fluorescent probes, the biofilm in the grooves is measured by confocal laser scanning microscopy (CLSM).

"Ion fluorescent probe" means a fluorescent probe that specifically binds to one kind of ions and emit fluorescence at a certain wavelength. In recent years, significant emphasis has been placed on the development of new, highly selective fluorescent probes of ions because of their potential applications in biochemistry and environmental research. Many kinds of signaling mechanisms have been proposed and utilized for optical detection of ions, including photo-induced electron/energy transfer (PET), intramolecular charge transfer (ICT), fluorescence resonance energy transfer (FRET), and so on. Some of these fluorescent probes can also be applied in fluorescence bioimaging, which causes little cell damage and is highly sensitive with high-speed spatial analysis of living cells. Specifically, FRET imaging that affords simultaneous recording of two emission intensities at different wavelengths in the presence and absence of analytes has provided a facile method for visualizing complex biological processes at the molecular level. This technique appears to be suited to the study of physiological functions or pathogenesis of ions in biofilm and human body.

Fluorescence labeled calcium probes are molecules that exhibit an increase in fluorescence upon binding Ca2+. The biofilm is labeled with a calcium fluorescent probe. Examples of a calcium fluorescent probe suitable for labeling the biofilm may be any one or more of the following compounds:.

One or more of these probes may be available from ThermoFisher Scientific Company, Waltham, MA.

Fluo-<NUM>™ is used to image the spatial dynamics of Ca2+ signaling. Biofilm may be treated with the AM™ ester forms of calcium probes by adding the dissolved probe directly to biofilm. Fluo-<NUM>™, AM™, cell permeant fluorescent probes are used for intracellular and extracellular calcium staining using confocal microscopy, flow cytometry, and microplate screening applications (absorption/emission maxima ~<NUM>/<NUM>). It is reported that the Concanavalin A™ (Con A), Alexa Fluor® <NUM> Conjugate is a reliable alternative to stain EPS of biofilm. Alexa Fluor® <NUM> conjugate of Con A exhibits the bright, red fluorescence of the Alexa Fluor® <NUM> dye (absorption/emission maxima ~<NUM>/<NUM>). Concanavalin A™, Alexa Fluor® <NUM> Conjugate selectively binds to α-mannopyranosyl and α-glucopyranosyl residues which are rich in EPS part of biofilm.

One specific example is Concanavalin A™, Fluorescein Conjugate™, wherein excitation is <NUM>, and maximum light emission is detected at <NUM>. These EPS fluorescent probes are widely available as well as the procedure details in how to use them to quantitatively determine the location and/or amount of EPS.

Examples of an EPS fluorescent probe suitable for labeling the biofilm may be any one of the following compounds:.

One or more of these probes may be available from ThermoFisher Scientific Company, Waltham, MA.

After treatment and immersing, each half-disk specimen is stained with a dye mixture solution of the Fluo-<NUM>™, AM™, cell permeant fluorescent probe together with Concanavalin A™, Alexa Fluor® <NUM> Conjugate probe (containing <NUM> Fluo-<NUM>™ + <NUM> Con-A™) for <NUM> minutes in the dark. After staining, each specimen is immersed into <NUM>-<NUM> ul PBS solution statically for <NUM> minutes. The Fluo-<NUM>™, AM™/ Concanavalin A™, Alexa Fluor® <NUM> Conjugate dye stained samples, the following parameters are used: λex = <NUM>/<NUM>, λem= <NUM>/<NUM>, 20X objective lens, and scanning from bottom of surface bacteria for <NUM> with step size= <NUM>.

The Leica™ TCS SP8 AOBS spectral confocal microscope is used. The confocal system consists of a Leica™ DM6000B upright microscope and a Leica™ DMIRE2 inverted microscope. An upright stand is used for applications involving slide-mounted specimens; whereas the inverted stand, having a <NUM> incubation chamber and CO<NUM> enrichment accessories, provides for live cell applications. The microscopes share an exchangeable laser scan head and, in addition to their own electromotor-driven stages, a galvanometer-driven high precision Z-stage which facilitates rapid imaging in the focal (Z) plane. In addition to epifluorescence, the microscopes support a variety of transmitted light contrast methods including bright field, polarizing light and differential interference contrast, and are equipped with 5x, 20x, 40x, 63x (oil and dry) and 100x (oil) Leica™ objective lenses.

The laser scanning and detection system is described. The TCS SP8 AOBS confocal system is supplied with four lasers (one diode, one argon, and two helium neon lasers) thus allowing excitation of a broad range of fluorochromes within the UV, visible and far red ranges of the electromagnetic spectrum. The design of the laser scan head, which incorporates acousto-optical tunable filters ("AOTF"), an acousto-optical beam splitter ("AOBS") and four prism spectrophotometer detectors, permits simultaneous excitation and detection of three fluorochromes. The upright microscope also has a transmission light detector making it possible to overlay a transmitted light image upon a fluorescence recording.

Leica™ Confocal software LAS AF3. <NUM> is used. The confocal is controlled via a standard Pentium PC equipped with dual monitors and running Leica™ Confocal Software. The Leica Confocal Software LAS AF3. <NUM> (available from Leica Lasertechnik GmbH, Heidelberg, Germany) provides an interface for multi-dimensional image series acquisition, processing and analysis, that includes 3D reconstruction and measurement, physiological recording and analysis, time-lapse, fluorochrome co-localization, photo-bleaching techniques such as FRAP and FRET, spectral immixing, and multicolour restoration.

Ca:EPS; The Fluo-<NUM>™/Con-A™ stained specimens, both fluorescence channels are chosen to quantify fluorescence intensity ratio of green pixels (Calcium) to red pixels (EPS) and Con-A™ fluorescence channel is chosen to measure the biofilm thickness. Whereby, six selected fields of Con-A™ fluorescence channel of each specimen are evaluated. These fields are considered as representative of the whole sample after the observer's general examination. The distance is measured from the surface of the biofilm to its base, measuring the thickness of the field, and subsequently the mean thickness of the biofilm of the corresponding specimen is calculated.

Provided below are non-limited examples of the dentifrice compositions of the present invention, as well as comparative examples and a control example, in the form of toothpastes.

Data regarding Fluorescence Ratio of Ca/EPS and Biofilm Thickness, according to the test method described above, is provided for specific compositions as referenced in Tables <NUM> & <NUM> below.

Specific compositions as referenced in the Tables <NUM> and <NUM> along with controls were evaluated for saltiness taste, foam amount and in use dispersion using a method is a paired comparison study with randomised brushing order using <NUM> trained sensory panelists. Each assigned dentifrice is dispensed upon an Oral B Navigator brush and brushed for a controlled <NUM> minutes, with each panelist recording the sensorial attributes on the standard questionnaire with using a <NUM> to <NUM> grading score, with score of <NUM> being least sensorial preferred and <NUM> being the most sensorial preferred.

TABLES <NUM>, <NUM> and <NUM> show the synergistic benefits of adding a suitable neutral amino acid, such as glycine, with sodium bicarbonate to reduce both Ca:EPS ratio and the biofilm thickness, whilst allowing for a more preferred sensorial experience.

Study #<NUM>, used calcium carbonate abrasive compositions, as shown in TABLE <NUM>. <NUM>, is a control composition that represents the salivary salts of a phosphate buffer solution. The use of Ex. <NUM> in Study # <NUM> TABLE <NUM>, led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>. <NUM> is a comparative dentifrice composition, as shown in TABLE <NUM>, with absence of both sodium bicarbonate and glycine. The use of Ex. <NUM> led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>. A<NUM> is a commercial dentifrice composition, with <NUM>% sodium bicarbonate and no neutral amino acid (such as glycine). The use of Ex. A led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>. The high sodium bicarbonate content of Ex. A led to a reduction in biofilm thickness and Ca:EPS ratio. However, this high sodium carbonate formulation of Ex. A, also led to poor sensorial grading for high saltiness taste (<NUM>) and poor/low foam (<NUM>) as shown in TABLE <NUM>. <NUM> is a comparative dentifrice composition, as shown in TABLE <NUM>, with a lower sodium bicarbonate level and the absence of glycine. The use of Ex. <NUM> led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>, similar to Ex. A<NUM>, though had an improved sensorial experience grading with an acceptable saltiness taste (<NUM>) and moderate foaming (<NUM>). <NUM> is a dentifrice composition, as shown in TABLE <NUM>, with the combination of both sodium bicarbonate and glycine. The use of Ex. <NUM> led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>, and acceptable sensorial experience. <NUM> is a dentifrice composition, as shown in TABLE <NUM>, with the combination of both mid-level of sodium bicarbonate and glycine. The use of Ex. <NUM> led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>, and an acceptable sensorial experience. <NUM> is a dentifrice composition, as shown in TABLE <NUM>, with the combination of both sodium bicarbonate and glycine and combination of mixed surfactants (sodium lauryl sulfate and cocamidopropyl betaine). The use of Ex. <NUM> led an improved sensorial experience, with acceptable saltiness (<NUM>) and good foaming (<NUM>).

Unexpectedly, the synergy in combining glycine with sodium bicarbonate, as in Ex. <NUM> with a calcium carbonate abrasive, led to a final biofilm thickness of <NUM>, and Ca:EPS of a <NUM>. In other words, the addition of <NUM> wt. % of glycine with <NUM> wt. % sodium bicarbonate led to a <NUM>% reduction in biofilm thickness and <NUM>% reduction in Ca:EPS biofilm ratio vs. <NUM> wt. % sodium bicarbonate only as in Ex. Additionally, Ex. <NUM> had improved sensorial experience vs. commercial high sodium bicarbonate dentifrices such as Ex. The addition of glycine at <NUM> wt. % with <NUM> wt. % sodium bicarbonate as in Ex. <NUM>, led to a final biofilm thickness of <NUM>, which was a <NUM>% reduction in biofilm thickness relative to the commercial high sodium bicarbonate dentifrice in Ex. A<NUM> (i.e. with no glycine), and had improved sensorial experience.

Further, Study #<NUM> using silica based abrasive compositions, as shown in TABLE <NUM>, also delivers similar unexpected synergy in combining glycine and sodium bicarbonate to reduce biofilm thickness, Ca:EPS ratio and have improved sensorial experience. The use of Ex. <NUM> in Study # <NUM> TABLE <NUM>, led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM> Ex. <NUM> is a comparative dentifrice composition, as shown in TABLE <NUM>, with absence of both sodium bicarbonate and glycine. The use of Ex. <NUM> led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>. A<NUM> is a commercial dentifrice composition, with <NUM>% sodium bicarbonate and no neutral amino acid (such as glycine). The use of Ex. A led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>. The high sodium bicarbonate content of Ex. A<NUM> led to a reduction in biofilm thickness and Ca:EPS ratio. However, this high sodium carbonate formulation of Ex. A<NUM>, also led to poor sensorial grading for high saltiness taste (<NUM>), poor/low foam (<NUM>) and poor dispersion (<NUM>) as shown in TABLE <NUM>. B<NUM> is a commercial dentifrice composition, with circa <NUM>% to <NUM>% sodium bicarbonate and no neutral amino acid (such as glycine) formulated as an anhydrous composition, led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>. However, this anhydrous composition of Ex. B<NUM>, also led to poor sensorial grading for saltiness taste (<NUM>), poor/low foam (<NUM>) and dispersion (<NUM>) as shown in TABLE <NUM>. <NUM> is a dentifrice composition, as shown in TABLE <NUM>, with the combination of both sodium bicarbonate and glycine. The use of Ex. <NUM> led to a final biofilm thickness of <NUM>, a Ca:EPS biofilm ratio of <NUM>, and acceptable sensorial experience, with acceptable saltiness (<NUM>), good foaming (<NUM>) and good dispersion (<NUM>).

Unexpectedly, the synergy in combining glycine with sodium bicarbonate with a silica abrasive , as in Ex. <NUM>, led to a final biofilm thickness of <NUM>, and Ca:EPS of a <NUM>. In other words, the addition of <NUM> wt. % of glycine with <NUM> wt. % sodium bicarbonate led to a <NUM>% reduction in biofilm thickness and <NUM>% reduction in Ca:EPS biofilm ratio vs. <NUM> wt. % sodium bicarbonate only as in Ex. Additionally, Ex. <NUM> had improved sensorial experience vs. commercial high sodium bicarbonate dentifrices such as Ex. A<NUM> and Ex B<NUM>. The addition of glycine at <NUM> wt. % with <NUM> wt. % sodium bicarbonate as in Ex. <NUM>, led to a final biofilm thickness reduction of <NUM>% and <NUM>% compared to the sodium bicarbonate dentifrices in Ex. A<NUM> & Ex. B<NUM> respectively (i.e. with no glycine), and had improved sensorial experience.

Claim 1:
A dentifrice composition comprising:
(a) from about <NUM>% to <NUM>%, by weight of the composition, of water:
(b) from <NUM>% to <NUM>%, by weight of the composition, of bicarbonate salt;
(c) from <NUM>% to <NUM>%, by weight of the composition, of neutral amino acid: and
(d) from <NUM>% to <NUM>%, by weight of the composition, of a fluoride ion source; and
wherein the neutral amino acid is not complexed with zinc.