DENTAL FORMULATION FOR THE TREATMENT OF TOOTH SENSITIVITY

Abstract

The present invention provides a dental formulation for the treatment of tooth sensitivity, wherein the formulation comprises specifically engineered apatite particles, having an ideal morphology, size and density for the occlusion of dentinal tubules.

Claims

1. A Dental formulation for the treatment of tooth sensitivity comprising: up to 50% by weight of one or more solid solutions, the one or more solid solutions comprising a solvent component and a solute component, wherein the solvent component is selected from hydroxyapatite, fluorapatite, oxyapatite, chlorapatite, substituted apatites, or mixtures thereof; wherein the solute component comprises potassium ions; wherein the one or more solid solutions are comprised of substantially spherical particles, wherein the particles comprise a single microcrystalline phase; and wherein at least 5% of the particles are below 3 microns in size.

2. The formulation of claim 1 wherein the solid solution has a molar ratio of potassium to calcium that is less than or equal to 0.15.

3. The formulation of claim 1, wherein the D50 value of the particles is not more than 10 microns.

4. The formulation of claim 1, wherein the dental formulation is a dentrifice, a gel or a dental strip.

5. The formulation of claim 1, wherein one or more Calcium ions in the apatite lattice are replaced by one or more different divalent cations.

6. The formulation of claim 5, wherein the divalent cation is selected from Zn, Ag, Sn.

7. The formulation of claim 1 wherein one or more phosphate anions are replaced by one or more different anions in the apatite lattice.

8. The formulation of claim 7, wherein the one or more different anions are selected from carbonate, hydrogen carbonate or silicate anions.

9. The formulation of claim 1, wherein the formulation also includes one or more additional components selected from bleaching agents, flavourings agents, stabilisers, viscosity modifiers, antimicrobials or fillers.

10. The formulation of claim 9 wherein the bleaching agent is chosen from one or more of arginine carbamide peroxide, hydrogen peroxide, sodium hydroxide, and other peroxide containing products.

11. The formulation of claim 9 wherein the flavouring or sweetening agent is chosen from one or more of mint, cinnamon, vanilla, xylitol, sucralose, sodium saccharin, and menthol.

12. The formulation of claim 9 wherein the stabiliser is chosen from one or more of carrageenan, soybean hemicellulose, dicalcium diphosphate, sodium triphosphate, and citric acid esters.

13. The formulation of claim 9 wherein the viscosity modifier is chosen from one or more of xanthan gum, cellulose gum, seaweed gum, glycerol, glycol and sorbitol.

14. The formulation of claim 9 wherein the antimicrobial is chosen from one or more of zinc citrate, triclosan, glucose oxidase, sodium fluoride, and sodium monofluorophosphate.

15. The formulation of claim 9 wherein the filler is chosen from one or more of calcium carbonate, hydrated silica, and sodium bicarbonate.

16. A method for the manufacture of a dental formulation according to claim 1, for the treatment of tooth sensitivity comprising combining: up to 50% by weight of one or more solid solutions, the one or more solid solutions comprising a solvent component and a solute component, wherein the solvent component is selected from hydroxyapatite, fluorapatite, oxyapatite, chlorapatite, substituted apatites, or mixtures thereof; wherein the solute component comprises potassium ions; wherein the one or more solid solutions are comprised of substantially spherical particles, wherein the particles comprise a single microcrystalline phase; and wherein at least 5% of the particles are below 3 microns in size.

17. (canceled)

Description

BRIEF DESCRIPTION OF THE FIGURES

[0034] The advantages and embodiments of the present application will be understood more clearly by reference to the accompanying drawings:

[0035] FIG. 1. Schematic representation of the potential desensitizing action of different particle types on open tubules at the tooth surface.

[0036] FIG. 2. Scanning electron Micrographs (SEM) and Focused Ion Beam (FIB) image detailing of FSS Hydroxyapatite microspheres.

[0037] FIG. 3. Scanning electron Micrographs (SEM) particulate Hydroxyapatite comprising aggregated primary nanocrystallites.

[0038] FIG. 4A pair of xrd patterns detailing the difference between FSS Hydroxyapatite microparticles and the aggregated nanocrystallites.

[0039] FIG. 5A pair of XRD patterns and an SEM micrograph detailing the distinction between Apatitic solid solutions containing potassium manufactured by FSS and typical synthesis techniques.

DETAILED DESCRIPTION

[0040] The similarity of Hydroxyapatite and its fluoride, chloride or carbonate substituted analogues to enamel and the mineral content of dentine makes it the material of choice for remineralisation and dentinal tubule occlusion for the treatment of DS. The ideal apatite particles for dentinal tubule occlusion are substantially spherical with a diameter approximately equal to or slightly smaller than the tubule diameters (1-3 micron). Additionally these particles are ideally dense and microcyrstalline providing the further advantage of being mechanically stable enough to withstand the mechanical stresses encountered during application and to penetrate any smear or pellicle layers encountered on the teeth. A further improvement in the desensitizing ability of the ideal apatite particles for desensitizing formulations is provided by the incorporation of K ions in the apatitic lattice as a solute without the formation of other Calcium Phosphate phases. The benefit of using such particles to occlude dentinal tubules relative to nanocrystallites is represented schematically in FIG. 1.

[0041] Apatitic particles with these characteristics have to date not been used to provide a desensitizing benefit in dental formulations for the treatment of tooth sensitivity. However by using such specifically engineered apatitic particles a significant benefit in the treatment of tooth sensitivity is achievable relative to the use of nanostructured apatitic materials and or soluble potassium salts.

[0042] The present invention provides a dental formulation for the treatment of DS that contains up to 50% by mass of an apatitic solid solution, the solid solution comprising particles with specific morphology, size and crystallinity.

[0043] Therefore, in accordance with the present invention, there is provided a dental formulation for the treatment of tooth sensitivity comprising:

[0044] up to 50% by weight of one or more solid solutions, the one or more solid solutions comprising a solvent component and a solute component, wherein

[0045] the solvent component is selected from hydroxyapatite, fluorapatite, oxyapatite, chlorapatite, substituted apatites, or mixtures thereof;

[0046] wherein the solute component comprises potassium ions;

[0047] wherein the one or more solid solutions are comprised of substantially spherical particles, wherein the particles comprise a single microcrystalline phase; and

[0048] wherein at least 5% of the particles are below 3 microns in size.

[0049] The dental formulation is selected from a dentrifice, a gel, a toothpaste, a mouth wash or mouth rinse, or a dental strip.

[0050] Typically, the solid solution has a molar ratio of potassium to calcium that is less than or equal to about 0.15.

[0051] According to one embodiment of the invention, the calcium ions in the apatite in the formulation may be substituted by one or more different divalent cations chosen from Mg, Ba, Sr, Zn, Ag or Sn.

[0052] In preferred embodiments of the invention the apatitic solid solution comprises an apatitic solvent with potassium.

[0053] In one embodiment the solid solution is an apatitic material with the general formula

Ca.sub.10 K.sub.x (PO.sub.4).sub.6 A.sub.2-x B.sub.x

Where A is OH (hydroxyl), F (fluoride), Cl (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) O (Oxy) and the solute potassium ions occupy the interstitials of the apatitic lattice. In preferred embodiments X is in the range 0.01 to 1.5 and the K/Ca molar ratio is in the range 0.001 to 0.15. The Ca/P molar ratio is close to that of a pure Calcium apatite 1.67. In a preferred embodiment X is in the range 0.5 to 1.0 and the K/Ca molar ratio is 0.05 to 0.1.

[0054] In one embodiment the solid solution is an apatitic material with a fraction of its Ca content substituted with other divalent ions, the solid solution has the general formula:

[Ca.sub.1-w M.sub.w].sub.10 K.sub.x (PO.sub.4).sub.6 A.sub.2-x B.sub.x

Where A is OH (hydroxyl), F (fluoride), CI (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) or O (Oxy) and the solute potassium ions occupy the interstitials of the apatitic lattice. M is a divalent cation chosen from Mg, Ba, Sr, Zn, Ag or Sn and the fraction of calcium substitution w is between 0 and 0.1. In preferred embodiments X is in the range 0.01 to 1.5 and the K/(Ca+M) molar ratio is in the range 0.001 to 0.15. The (Ca+M)/P molar ratio is close to that of a pure Calcium apatite 1.67. In a preferred embodiment X is in the range 0.5 to 1.0 and the K/(Ca+M) molar ratio is 0.05 to 0.1.

[0055] In a further embodiment of the present invention the solid solution is an apatitic material with one of the following general formulas:

[Ca.sub.1-w M.sub.w].sub.10 K.sub.x [(PO.sub.4).sub.1-Z (SiO.sub.4).sub.Z].sub.6 A.sub.2-X-6Z B.sub.X

[Ca.sub.1-w M.sub.w].sub.10 K.sub.x [(PO.sub.4).sub.1-Z (SiO.sub.4).sub.3Z/4].sub.6 A.sub.2-X B.sub.X

[Ca.sub.1-w M.sub.w].sub.10 K.sub.x (PO.sub.4).sub.6-X (SiO.sub.4).sub.X A.sub.2-Y B.sub.Y/2

Where A is OH (hydroxyl), F (fluoride), Cl (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) or O (Oxy) and the solute potassium ions occupy the interstitials of the apatitic lattice. M is a divalent cation chosen from Mg, Ba, Sr, Zn, Ag or Sn and the fraction of calcium. substitution w is between 0 and 0.1. Z is the fraction of Phosphate substitution by Tetravalent silicate and is in the range 0 to 0.1. In preferred embodiments X is in the range 0.01 to 1.5 and the K/(Ca+M) molar ratio is in the range 0.001 to 0.15. The (Ca+M)/P molar ratio is higher than that of a pure Calcium apatite and is in the range 1.67 to 1.89. In a preferred embodiment X is in the range 0.5 to 1.0 and the K/(Ca+M) molar ratio is 0.05 to 0.1. Y has a maximum possible value of 2.

[0056] In a further embodiment of the present invention the solid solution is an apatitic material with the general formula:

[Ca.sub.1-w M.sub.w].sub.10 K.sub.x [(PO.sub.4).sub.1-z D.sub.z].sub.6 A.sub.2-x-6z B.sub.x+6z

Where A is OH (hydroxyl), F (fluoride), Cl (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) or O (Oxy) and the solute potassium ions occupy the interstitials of the apatitic lattice. D is a divalent anion chosen from CO.sub.3 carbonate, or SO.sub.4 (sulphate) and z is between 0 and 0.2. M is a divalent cation chosen from Mg, Ba, Sr, Zn, Ag or Sn and w is between 0 and 0.1. In preferred embodiments X is in the range 0.01 to 1.5 and the K/Ca molar ratio is in the range 0.001 to 0.18. The (Ca+M)/(P) molar ratio is in the range 1.66 to 1.89. In a preferred embodiment X is in the range 0.5 to 1.2 and the K/(Ca+M) molar ratio is 0.05 to 0.14. Y has a maximum possible value of 2.

[0057] In a further embodiment of the present invention the solid solution is an apatitic material with the general formula:

[Ca.sub.1-w M.sub.w].sub.10 K.sub.x [(PO.sub.4).sub.1-z (HCO.sub.3).sub.z].sub.6 A.sub.2-x-12z B.sub.x+12z

Where A is OH (hydroxyl), F (fluoride), Cl (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) or O (Oxy) and the solute potassium ions occupy the interstitials of the apatitic lattice. Z is the degree of substitution of phosphate by the monovalent anion HCO.sub.3 (hydrogenearbonate), and z is between 0 and 0.2. N is a divalent cation chosen from Mg, Ba, Sr, Zn, Ag or Sn and w is between 0 and 0.1. In preferred embodiments X is in the range 0.01 to 1.5 and the K/Ca molar ratio is in the range 0.001 to 0.18. The (Ca+M)/(P) molar ratio is in the range 1.66 to 1.89. In a preferred embodiment X is in the range 0.5 to 1.2 and the KI(Ca+M) molar ratio is 0.05 to 0.14. Y has a maximum possible value of 2.

[0058] In a further embodiment of the present invention the solid solution is an apatitic material with the general formulas:

[Ca.sub.1-w M.sub.w].sub.10-x K.sub.x [(PO.sub.4).sub.1-z (SiO.sub.4).sub.z].sub.6A.sub.2-6z-x-y B.sub.y/2

[Ca.sub.1-w M.sub.w].sub.10-x K.sub.x (PO.sub.4).sub.6-x (SiO.sub.4).sub.x A.sub.2(1-x)-y B.sub.y/2

Where A is OH (hydroxyl), F (fluoride), Cl. (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) or O (Oxy) and the solute potassium ions occupy Ca positions in the apatitic lattice. Z is the degree of substitution of phosphate by the Tetravalent SiO4 (Silicate), and z is between 0 and 0.2. M is a divalent cation chosen from Mg, Ba, Sr, Zn, Ag or Sn and w is between 0 and 0.1. In preferred embodiments X is in the range 0.01 to 1.5 and the K/Ca molar ratio is in the range 0.001 to 0.18. The (Ca+M)/(P) molar ratio is in the range 1.66 to 1.89. In a preferred embodiment X is in the range 0.5 to 1.2 and the K/(Ca+M) molar ratio is 0.05 to 0.14. Y has a maximum possible value of 2.

[0059] In a further embodiment of the present invention the solid solution is an apatitic material with the general formulas:

[Ca.sub.1-w M.sub.w].sub.10-x K.sub.x [(PO.sub.4).sub.1-z (D).sub.z].sub.6 A.sub.2-6z-x B.sub.y/2+6z

[Ca.sub.1-w M.sub.w].sub.10-x K.sub.x (PO.sub.4).sub.6-x D.sub.x A.sub.2-y B.sub.y/2

Where A is OH (hydroxyl), F (fluoride), Cl (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) or O (Oxy) and the solute potassium ions occupy Ca positions in the apatitic lattice. D is a divalent anion chosen from CO.sub.3 carbonate, or SO.sub.4 (sulphate) and z is between 0 and 0.2. M is a divalent cation chosen from Mg, Ba, Sr, Zn, Ag or Sn and w is between 0 and 0.1. In preferred embodiments X is in the range 0.01 to 1,5 and the K/Ca molar ratio is in the range 0.001 to 0.18. The (Ca+M)/(P) molar ratio is in the range 1.66 to 1.89. In a preferred embodiment X is in the range 0.5 to 1.2 and the K/(Ca+M) molar ratio is 0.05 to 0.14. Y has a maximum possible value of 2.

[0060] In a further embodiment of the present invention the solid solution is an apatitic material with the general formulas:

[Ca.sub.1-w M.sub.w].sub.10-x K.sub.x [(PO.sub.4).sub.1-z (HCO.sub.3).sub.z].sub.6 A.sub.2-12z-x-y B.sub.y/2+12z

[Ca.sub.1-w M.sub.w].sub.10-x K.sub.x (PO.sub.4).sub.6-x/2 (HCO.sub.3).sub.x/2 A.sub.3-y B.sub.y/2

Where A is OH (hydroxyl), F (fluoride), Cl (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) or O (Oxy) and the solute potassium ions occupy Ca positions in the apatitic lattice. Z is the degree of substitution of phosphate by the monovalent anion HCO.sub.3 (hydrogencarbonate), and z is between 0 and 0.2. M is a divalent cation chosen from Mg, Ba, Sr, Zn, Ag or Sn and w is between 0 and 0.1. In preferred embodiments X is in the range 0.01 to 1.5 and the K/Ca molar ratio is in the range 0.001 to 0.18. The (Ca+M)/(P) molar ratio is in the range 1.66 to 1.89. In a preferred embodiment Xis in the range 0.5 to 1.2 and the K/(Ca+M) molar ratio is 0.05 to 0.14, Y has a maximum possible value of 2.

[0061] In a further embodiment of the present invention the solid solution is an apatitic material with the general formulas:

[Ca.sub.1-w M.sub.w].sub.10 K.sub.x [(PO.sub.4).sub.1-z-v D.sub.z (HCO.sub.3).sub.v].sub.6-x (SiO.sub.4).sub.x A.sub.2-6z-12v-y B.sub.x+6z+12v+y/2

[Ca.sub.1-wM.sub.w].sub.10 K.sub.x [(PO.sub.4).sub.1-z-u-v (SiO.sub.4).sub.u D.sub.z (HCO.sub.3).sub.v].sub.6 A.sub.2-x-6z-12v-6u-y B.sub.x+6z+12v+y/2

Where A is OH (hydroxyl), F (fluoride), Cl (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) or O (Oxy) and the solute potassium ions occupy the interstitials of the apatitic lattice. D is a divalent anion chosen from CO.sub.3 carbonate, or SO.sub.4 (sulphate) and z is between 0 and 0.2. U is the degree of substitution of phosphate by the Tetravalent SiO4 (Silicate), and u is between 0 and 0.2. V is the degree of substitution of phosphate by the monovalent anion HCO.sub.3 (hydrogencarbonate), and v is between 0 and 0.2. M is a divalent cation chosen from Mg, Ba, Sr, Zn, Ag or Sn and w is between 0 and 0.1. In preferred embodiments X is in the range 0.01 to 1.5 and the K/Ca molar ratio is in the range 0.001 to 0.18. The (Ca+M)/(P) molar ratio is in the range 1.66 to 1.89. In a preferred embodiment X is in the range 0.5 to 1.2 and the K/(Ca+M) molar ratio is 0.05 to 0.14. Y has a maximum possible value of 2.

[0062] In a further embodiment of the present invention the solid solution is an apatitic material with the general formula:

[Ca.sub.1-w M.sub.w].sub.10-x K.sub.x [(PO.sub.4).sub.1-z-u-v (SiO.sub.4).sub.u D.sub.z (HCO.sub.3).sub.v].sub.6 A.sub.2-x-6z-12v-6u-y B.sub.6z+12v+y/2

[Ca.sub.1-w M.sub.w].sub.10-x K.sub.x [(PO.sub.4).sub.1-u-v (SiO.sub.4).sub.u (HCO.sub.3).sub.v].sub.6-x D.sub.x A.sub.2-2v(6-x)-u(6-x)-y B.sub.2v(6-x)+y/2

[Ca.sub.1-w M.sub.w].sub.10-x K.sub.x [(PO.sub.4).sub.1-u-z (SiO.sub.4).sub.u D.sub.z].sub.6-x/2 (HCO.sub.3).sub.x/2 A.sub.2-6(z+u)+x(z+u)/2 B.sub.(12z-x)/2+y/2

Where A is OH (hydroxyl), F (fluoride), Cl (Chloride) or I (iodide), B is CO.sub.3 (Carbonate) or O (Oxy) and the solute potassium ions occupy Ca positions in the apatitic lattice. D is a divalent anion chosen from CO.sub.3 carbonate, or SO.sub.4 (sulphate) and z is between 0 and 0.2. U is the degree of substitution of phosphate by the Tetravalent SiO4 (Silicate), and u is between 0 and 0.2. V is the degree of substitution of phosphate by the monovalent anion HCO.sub.3 (hydrogencarbonate), and v is between 0 and 0.2. M is a divalent cation chosen from Mg, Ba, Sr, Zn, Ag or Sn and w is between 0 and 0.1. In preferred embodiments X is in the range 0.01 to 1.5 and the K/Ca molar ratio is in the range 0.001 to 0.18, The (Ca+M)/(P) molar ratio is in the range 1.66 to 1.89. In a preferred embodiment X is in the range 0.5 to 1.2 and the K/(Ca+M) molar ratio is 0.05 to 0.14. Y has a maximum possible value of 2.

[0063] In any of the formulations according to the invention, the one or more phosphate anions may be replaced by one or more different anions in the apatite lattice; the one or more different anions may be selected from, for example, carbonate, hydrogen carbonate or silicate anions.

[0064] In the embodiments of the present invention the solid solution is provided in powder form and the morphology of the particles are substantially spherical defined in that the average Roundness (RN) and Irregularity Parameter (IP) shape factors of the particles are both less than 1.10. In preferred embodiments the Roundness (RN) and Irregularity Parameter (IP) shape factors of the particles are both less than 1.05.

[0065] In preferred embodiments at least 60% of the particles comprising the apatitic solid solution are dense with no nanoporosity, defined in that the powder is microcrystalline as indicated by X-ray diffraction (XRD). More preferably at least 75% of the particles comprising the apatitic solid solution are dense with no nanoporosity and most preferably at least 90% of the particles comprising the apatitic solid solution are dense with no nanoporosity.

[0066] In preferred embodiments of the invention the powder comprising the apatitic solid solution has a D50 (median particle diameter) of not more than 10 micron and at least 5% of the powder particles are below 3 micron diameter. More preferably the powder comprising the apatitic solid solution has a D50 of not more than 7.5 micron and at least 10% of the particles are below 3 micron diameter. Most preferably the powder comprising the apatitic solid solution has a D50 of not more than 5 micron and at least 15% of the powder particles are below 3 micron diameter. The particle diameter refers herein to the distance across a particle at its widest point.

[0067] In preferred embodiments of the present invention the dental formulation contains between 0.1% and 50% by mass of the apatitic solid solution. More preferably the dental formulation contains between 10% and 40% by mass of the apatitic solid solution, and most preferably the dental formulation contains between 20% and 30% by mass of the apatitic solid solution.

[0068] The apatitic solid solutions of the present invention can be used to provide a desensitizing benefit in several different types of dental formulations. Preferred dental formulations include dentrifices, toothpastes creams and gels.

[0069] The dental formulation of the present invention will contain other conventional ingredients well known to those skilled in art depending on the form of the dental product. For instance, in the case of an oral product in the form of a dentifrice cream or paste, the product will comprise an humectant-containing liquid phase and optionally binders and or thickeners which act to maintain the particulate in suspension. A surfactant and a flavouring agent are also usual ingredients of commercially acceptable dentifrices.

[0070] Humectants commonly used are glycerol and sorbitol syrup (usually comprising an approximately 70% solution). However, other humectants are known to those in the art, including propylene glycol, lactitol and hydrogenated cornsyrup. The amount of humectant will generally range from about 10 to 85% by weight of the dentifrice. The remainder of the liquid phase will consist substantially of water.

[0071] Numerous binding or thickening agents have been indicated for use in dentifrices, preferred ones being sodium carboxymethylcellulose and xanthan gum. Others include natural gum binders such as gum tragacanth, gum karaya and gum arabic, Irish moss, alginates and carrageenans. Silica thickening agents include the silica aerogels and various precipitated silica's. Mixtures of binding and thickening agents may be used. The amount of binder and thickening agent included in a dentifrice is generally between 0.1 and 10% by weight.

[0072] It is usual to include a surfactant in a toothpaste and again the literature discloses a wide variety of suitable materials. Surfactants which have found wide use in practice are sodium lauryl sulphate, sodium dodecylbenzene sulphonate and sodium lauroylsarcosinate. Other anionic surfactants may be used as well as other types such as cationic, amphoteric and non-ionic surfactants. Surfactants are usually present in an amount of from 0.5 to 5% by weight of the dentifrice.

[0073] Flavours that are usually used in dentifrices are those based on oils of spearmint and peppermint. Examples of other flavouring materials used are menthol, clove, wintergreen, eucalyptus and aniseed. An amount of from 0.1% to 5% by weight is a suitable amount of flavour to incorporate in a dentifrice.

[0074] The oral compositions of the invention may also comprise a proportion of a supplementary abrasive agent such as silica, alumina, hydrated alumina or calcium carbonate.

[0075] The oral composition of the invention may include a wide variety of optional ingredients, These include an anti-plaque agent such as an antimicrobial compound, for example chlorhexidine or 2,4,4-min-trichloro-2-min-hydroxy-diphenyl ether, or a zinc compound; an anti-tartar ingredient such as a condensed phosphate, e.g. an alkali metal pyrophosphate, hexametaphosphate or polyphosphate or zinc citrate, a fluorine-containing compound such as sodium fluoride or sodium monofluorophosphate; sweetening agent such as saccharin; an opacifying agent, such as titanium dioxide, a preservative, such as formalin; a colouring agent; or pH-controlling agent such as an acid, base or buffer, such as benzoic acid.

[0076] According to another embodiment of the invention, the formulation may also include one or more additional components selected from bleaching agents, flavourings agents, stabilisers, viscosity modifiers, antimicrobials or fillers, or a combination thereof.

[0077] The bleaching agent may be selected from one or more of arginine carbamide peroxide, hydrogen peroxide, sodium hydroxide, and other peroxide containing products,

[0078] The flavouring or sweetening agent may be selected from one or more of mint, cinnamon, vanilla, xylitol, sucralose, sodium saccharin, and menthol.

[0079] The stabiliser may be selected from one or more of carrageenan, soybean hemicellulose, dicalcium diphosphate, sodium triphosphate, and citric acid esters.

[0080] The viscosity modifier may be selected from one or more of xanthan gum, cellulose gum, seaweed gum, glycerol, glycol and sorbitol.

[0081] The antimicrobial may be selected from one or more of zinc citrate, triclosan, glucose oxidase, sodium fluoride, and sodium monofluorophosphate.

[0082] The filler may be selected from one or more of calcium carbonate, hydrated silica, and sodium bicarbonate.

[0083] Also provided in conjunction with the present invention is a method for the manufacture of a dental formulation according to any preceding a claim, for the treatment of tooth sensitivity comprising combining:

[0084] up to 50% by weight of one or more solid solutions, the one or more solid solutions comprising a solvent component and a solute component, wherein the solvent component is selected from hydroxyapatite, fluorapatite, oxyapatite, chlorapatite, substituted apatites, or mixtures thereof;

[0085] wherein the solute component comprises potassium ions;

[0086] wherein the one or more solid solutions are comprised of substantially spherical particles, wherein the particles comprise a single microcrystalline phase; and

[0087] wherein at least 5% of the particles are below 3 microns in size.

[0088] The invention will now be illustrated further by the following Examples, which are intended to be illustrative only and in no way limiting upon the scope of the invention.

EXAMPLE 1

[0089] Premier Biomaterials were tasked with synthesizing spherical dense Hydroxyapatite suitable for use in the present invention by their FSS method. This material is compared with a typical Hydroxyapatite particle comprising an aggregation of primary nanocrystallites in FIGS. 2, 3 and 4. Panels 2a and 2b show the morphology of FSS Hydroxyapatite and 2c shows a FIB image respectively of one particle indicating the dense nature of same. Hydroxyapatite particles of this type are considered most suitable for the present application due to their mechanical stability as compared to microspheres comprised of aggregated primary nanocrystallites manufactured by typical wet precipitation and sintering techniques. FIG. 3 shows a series of micrographs of agglomerates comprising primary nanocrystallites with increasing magnification to reveal the primary structure of the micron particle. A distinction between the two types of particulate is clearly manifest in the XRD patterns of both materials wherein the Scherrer line broadening associated with the primary nanocrystallite size (FIG. 4h) is clearly evident in the XRD pattern of the nanostructured particles, while the microcrystalline dense nature of the FSS particles is manifest in the XRD of the FSS particles (FIG. 4a).

EXAMPLE 2

[0090] Premier Biomaterials were further tasked with incorporating potassium into the apatitic structure without inducing the precipitation of other calcium phosphate phases. FIG. 5 compares the XRD patterns of K-containing apatite manufactured by FSS and by standard mixing at ordinary temperatures and sintering. The same precursor mix was used in both cases. However the FSS method clearly formed only an apatitic structure without additional phases (5a) while the other process formed additional Ca.sub.2P.sub.2O.sub.7 phases. The insert micrograph (5c) indicates that the spherical structure and dense nature of the particles is maintained with the incorporated potassium.