Cross reference to related applications

This application claims priority from Australian provisional application no. 2017900892, the entire contents of which are herein incorporated by reference in their entirety.

Field of the invention

The present invention relates to improved phosphopeptide stabilised amorphous calcium phosphate and/or amorphous calcium fluoride phosphate complexes and compositions containing those complexes. Methods of making the complexes of the invention and of treating or preventing dental sensitivity are also provided.

Background of the invention

The three mineralized components of teeth are enamel, cementum and dentine. In human teeth, enamel covers the crown dentine whereas cementum covers the root dentine. The dentine encloses the pulp of the tooth which provides the dentine with vascular and neural support. Unlike enamel and cementum, the dentine is transversed by a network of tubular structures, termed dentinal tubules. These tubules are shielded by the enamel (crown) and the cementum (root), which form a protective layer of the pulp against external physical and chemical influences, like temperature changes and acids, and prevent affection of the nerve protrusions and dentin hypersensitivity. The diameter of the dentinal tubules which protrude into the dentin layer and are open to the dental surface varies between 1 and 2.5 μιη.

The tubule walls in dentine are comprised of the calcified matrix of the dentine and the tubule space is filled with fluid (dentinal fluid) derived from pulp tissue fluid and serum. Because of their rigid walls, the fluid that fills the narrow dentinal tubules enables cold, tactile, evaporative and osmotic stimuli to be transmitted through the dentine to the pulp in the form of fluid movement. This movement of dentinal fluid is sensed as sharp pain of short duration. This pain is elicited when the odontoblasts that protrude into the pulpal ends of the tubules are disturbed and as a result, the mechano- receptors of the pulpal nerve fibers attached thereto are stimulated. The neural response is usually referred to as dentinal pain and the involved dentine as hypersensitive dentine.

Dentinal hypersensitivity results when protective enamel or cementum covering dentine is lost. Cementum is typically easier to breach than enamel, because cementum is thinner and more easily eroded by acids. However, breach of cementum cannot happen until there is gingival recession and exposure of the root surface to the oral environment. Individuals with breached cementum and suffering with dentinal hypersensitivity often experience pain when the exposed area of the tooth comes into contact with cold air, hot and cold liquids, foods that are sweet or acidic, or is touched with a metal object. Patients suffering from tooth hypersensitivity have larger number of open dentinal tubules and/or tubules with a larger in diameter than normal.

WO2015/095932 describes complexes that have certain beneficial properties. The present invention exhibits significant advantages over those complexes.

There is a need for compositions and methods for minimising exposure of dentinal tubules to treat and/or prevent dentinal sensitivity.

Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art.

Summary of the invention

In one aspect, the invention provides a stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex having a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP.

Preferably, the stannous ion content of the complex is between about 1 mole of stannous per mole of PP and about 2 moles of stannous per mole of PP. The stannous ion content of the complex may be about 1 mole of stannous per mole of PP or about 2 moles of stannous per mole of PP. Most preferably, the stannous ion content of the complex is about 1 .6 moles of stannous per mole of PP.

In other aspect, the present invention provides a composition comprising a stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex of the invention.

In another aspect, the present invention provides a composition comprising a phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex, and a stannous compound, wherein the composition has a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP.

Preferably, the stannous ion content of the composition is between about 1 mole of stannous per mole of PP and about 2 moles of stannous per mole of PP. The stannous ion content of the composition may be about 1 mole of stannous per mole of PP or about 2 moles of stannous per mole of PP. Most preferably, the stannous ion content of the composition is about 1 .6 moles of stannous per mole of PP.

Preferably, the composition further includes a pharmaceutically acceptable carrier, diluent or excipient.

In another aspect, the present invention also provides a method for treating or preventing dentinal sensitivity in an individual in need thereof comprising administering a stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex having a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP, thereby treating or preventing dentinal hypersensitivity in the individual. In another aspect, the present invention also provides a method for treating or preventing dentinal sensitivity in an individual in need thereof comprising administering a composition comprising a phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex, and a stannous compound, wherein the composition has a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP, thereby treating or preventing dentinal hypersensitivity in an individual.

Preferably, the dentinal sensitivity is dentinal hypersensitivity.

Preferably, the method further comprises the step of identifying an individual in need of treatment. For example, the invention includes, in addition to the steps of any method described herein, a step of identifying a subject suffering dentinal sensitivity, specifically hypersensitivity.

In another aspect, the present invention provides a method for occluding exposed dentinal tubules in an individual, the method comprising administering: a stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex having a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP; or a composition comprising a phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex, and a stannous compound, wherein the composition has a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP, thereby occluding exposed dentinal tubules in an individual. In another aspect, the present invention provides a method for forming a layer over exposed dentinal tubules in an individual, the method comprising administering: a stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex having a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP; or a composition comprising a phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex, and a stannous compound, wherein the composition has a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP, thereby forming a layer over exposed dentinal tubules in an individual.

Preferably, the method of occluding exposed dentinal tubules or forming a layer over exposed dentinal tubules further comprises the step of identifying exposed dentinal tubules in an individual.

In another aspect, the present invention provides the use of: a stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex having a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP; or a composition comprising a phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex, and a stannous compound, wherein the composition has a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP, in the manufacture of a medicament for the treatment or prevention of dentinal sensitivity. Preferably, the dentinal sensitivity is dentinal hypersensitivity.

In another aspect, the present invention provides, a stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex having a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP; or a composition comprising a phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex, and a stannous compound, wherein the composition has a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP, but less than 4 moles of stannous per mole of PP, for use in the treatment or prevention of dentinal sensitivity. Preferably, the dentinal sensitivity is dentinal hypersensitivity.

In any aspect of the invention described herein, the stannous ion content is between about 1 mole of stannous per mole of PP and about 2 moles of stannous per mole of PP. The stannous ion content may be about 1 mole of stannous per mole of PP or about 2 moles of stannous per mole of PP. Most preferably, the stannous ion content is about 1 .6 moles of stannous per mole of PP.

In any aspect of the invention, a complex of the invention, or composition of the invention, is administered to the oral cavity. Alternatively, administration may be directly to an oral site in need of treatment, for example a site that has exposed dentine. In either case, administration results in contact of the complex or composition to an oral site in need of treatment, such as exposed dentine.

In any aspect of the invention, the phosphopeptide is a casein phosphopeptide.

In one embodiment, the stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) complex consists essentially of, or consists of, phosphopeptides, stannous, calcium, phosphate and hydroxide ions and water.

In one embodiment, the stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACFP) complex consists essentially of, or consists of, phosphopeptides, stannous, calcium, phosphate, fluoride and hydroxide ions and water. In any aspect or embodiments as described herein, the stannous-associated phosphopeptide (PP) stabilized ACP or ACFP complex may be in a formulation with additional calcium phosphate. Typically, the formulation includes a stannous-associated phosphopeptide (PP) stabilized ACP or ACFP complex together with at least an equal amount by weight of calcium phosphate. In any aspect or embodiment of the invention described herein, a composition of the invention, or a stannous-associated PP stabilized ACP or ACFP complex of the invention, may be applied to the mouth, tooth or exposed dentine by the subject in need of treatment or by a dental health care professional. A stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex of the invention, or composition of the invention, may be contacted with the dental surface for a period of about 1 to 60 minutes, for about 1 to 30 minutes, for about 10 to 60 minutes, for about 10 to 30 minutes, for about 20 to 60 minutes, or for about 20 to 30 minutes. Preferably, the complex or composition is contacted with the dental surface for about 20 minutes.

In another aspect, the present invention provides a method of mineralizing a dental surface or sub-surface comprising contacting the dental surface or subsurface with a stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex of the invention, or composition of the invention, thereby mineralizing the dental surface or subsurface.

In a preferred embodiment of the invention, the stannous-associated phosphopeptide stabilised amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex in the composition has tightly bound and loosely bound calcium, wherein the bound calcium in the complex is less than the tightly bound calcium in an ACP or ACFP complex formed at a pH of 7.0. Optionally, the ACP or ACFP is predominantly in a basic form. In another preferred embodiment of the invention, the calcium ion content of the stabilised ACP or ACFP complex, or complex in a composition, is greater than 30 moles of calcium per mole of PP. Preferably, the calcium ion content of the stabilised ACP or ACFP complex is in the range of about 30 to 100 moles of calcium per mole of PP. More preferably, the calcium ion content is in the range of about 30 to about 50 moles of calcium per mole of PP.

The invention also relates to a kit for the treatment or prevention of dentinal hypersensitivity comprising:

(a) a composition of the invention, or

(b) a stannous-associated phosphopeptide stabilized ACP or ACFP complex of the invention. Preferably, the stannous-associated phosphopeptide stabilized ACP or ACFP complex is in a pharmaceutically acceptable carrier. Desirably, the kit further includes instructions for their use for treating or preventing dentinal hypersensitivity in an individual in need of such treatment. In one embodiment, the composition and the complex are present in suitable amounts for treatment of an individual.

The composition or kit of the invention may further include a source of fluoride ions. The fluoride ions may be from any suitable source. A source of fluoride ions may include free fluoride ions or fluoride salts. Examples of sources of fluoride ions include, but are not limited to the following: sodium fluoride, sodium monofluorophosphate, stannous fluoride, sodium silicofluoride and amine fluoride. These may be provided in solution (typically an aqueous solution), or a suspension.

As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings Figure 1. Scanning electron microscopy (SEM) of patients' dentine tubules treated with distilled, deionised water (DDW). Magnification 15,000x and 10μΜ scale shown. Exposed dentine tubules are clearly visible with no occlusion.

Figure 2. SEM of patient's dentine tubules treated with Sn/CPP molar ratio 1 .6:1 showing self-assembled nanofilaments on the surface of dentine occluding the tubules. Magnification 15,000x and 10μΜ scale shown.

Figure 3. SEM of patient's dentine tubules treated with Sn/CPP molar ratio 1 .6:1 showing self-assembled nanofilaments on the surface of dentine occluding the tubules. A single dentine tubule is shown. Magnification 60,000x and 2.0μΜ scale shown. Figure 4. SEM of patient's dentine tubules treated with Sn/CPP molar ratio 1 .6:1 showing self-assembled nanofilaments on the surface of dentine occluding the tubule. A single dentine tubule is shown (a different tubule to that shown in Figure 3). Magnification 60,000x and 2.0μΜ scale shown. Figure 5. SEM of patient's dentine tubules treated with Sn/CPP molar ratio 4:1 showing partial formation of self-assembled nanofilaments on the surface of dentine and partial occlusion of tubules. Magnification 15,000x and and 10μΜ scale shown.

Figure 6. SEM of patient's dentine tubules treated with Sn/CPP molar ratio 8.6:1 showing partial self-assembled nanofilaments on the surface of dentine and partial occlusion of any tubules. Magnification 15,000x and and 10μΜ scale shown.

Detailed description of the embodiments

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Reference will now be made in detail to certain embodiments of the invention. While the invention will be described in conjunction with the embodiments, it will be understood that the intention is not to limit the invention to those embodiments. On the contrary, the invention is intended to cover all alternatives, modifications, and equivalents, which may be included within the scope of the present invention as defined by the claims. One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. The present invention is in no way limited to the methods and materials described. All of the patents and publications referred to herein are incorporated by reference in their entirety.

For purposes of interpreting this specification, terms used in the singular will also include the plural and vice versa. As used herein, except where the context requires otherwise, the term

"comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps. As used herein, except where the context requires otherwise, "comprise" and "include" can be used interchangeably. The present invention is based on the surprising finding that stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex having a stannous ion content of equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP can form self-assembled nanofilaments which can occlude dentinal tubules. Specifically, the self-assembled nanofilaments form to such an extent that they span the entirely opening of dentinal tubules while forming network of nanofilaments across the dentine surface. This does not occur with a stannous ion content of greater than 4 moles per mole of phosphopeptide.

Without being bound by any theory or mode of action, it is believed that the stannous ions and phosphopeptides interact with the dentine surface to result in a unique pattern of surface coverage that displays a self-assembled network of nanofilaments across the dentine surface occluding the tubules. These nanofilaments are thought to be stannous cross-linked phosphopeptide which have released their cargo of calcium, phosphate and fluoride ions at the surface upon nanofilament formation. The results shown herein indicate that the molar ratio of equal to, or greater than, 1 mole but less than 4 moles of stannous to phosphopeptide is critical for the formation of cross-linked nanofilaments and therefore enhanced reduction in dentinal hypersensitivity.

The stannous containing compound, or stannous compound, can be any soluble stannous containing compound suitable for oral use. Preferably, stannous containing compound is a stannous salt. The stannous salt may contain fluoride. A stannous salt includes, but not limited to, stannous fluoride, stannous chloride, potassium stannous fluoride, sodium stannous fluorozirconate, stannous chloride fluoride, stannous acetate, sodium stannous fluoride, stannous hexafluorozirconate, stannous sulfate, stannous tartrate, stannous gluconate, disodium monostannous citrate. Preferred stannous salts include stannous fluoride and stannous chloride.

The stannous may be bound to the phosphopeptide stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) as determined using the experimental protocol in Example 2. In one embodiment, stannous-associated PP stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex are produced by the method as described herein, including but not limited to the method described in Example 1 .

In any aspect of the invention, the stannous ion content of a complex of the invention may be equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP. For example, the stannous ion content may be equal to, or greater than about 1 .0, 1 .2, 1 .4, 1 .6, 1 .8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8 or 4.0 moles of stannous per mole of PP. Also contemplated is a range of stannous ion content between any 2 values of 1 .0, 1 .2, 1 .4, 1 .6, 1 .8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8 or 4.0. In any aspect of the invention, the stannous ion content of a complex of the invention may be between about 1 mole of stannous per mole of PP and about 3 moles of stannous per mole of PP.

In any aspect, the stannous ion content of the complex is between about 1 mole of stannous per mole of PP and about 2 moles of stannous per mole of PP. This range includes 1 .0, 1 .1 , 1 .2, 1 .3, 1 .4, 1 .5, 1 .6, 1 .7, 1 .8, 1 .9 or 2.0 moles of stannous per mole of PP. The stannous ion content of the complex may be about 1 mole of stannous per mole of PP or about 2 moles of stannous per mole of PP.

In any aspect of the invention, the stannous ion content of a complex of the invention may be between about 1 .2 moles of stannous per mole of PP and about 1 .8 moles of stannous per mole of PP. Preferably, the stannous ion content is between about 1 .4 moles of stannous per mole of PP and about 1 .8 moles of stannous per mole of PP; or between about 1 .3 moles of stannous per mole of PP and about 1 .5 moles of stannous per mole of PP. Most preferably, the stannous ion content of the complex is about 1 .6 moles of stannous per mole of PP. A composition of the invention may also have a stannous ion content that is equivalent to a complex of the invention. For example, a composition of the invention may have a stannous ion content of 1 .6 moles of stannous per mole of PP. Accordingly, reference to a stannous ion content of a complex as used herein may also refer to the stannous ion content of a composition. The amount of stannous in a complex or composition may be determined by any method as described herein, or known in the art.

In any aspect, the present invention is applied to a dental surface of an oral site which may be dental enamel or dentine. Typically, the surface is exposed dentine which may be exposed as a result of loss of enamel or cementum. The exposed dentine is preferably causing dentinal hypersensitivity. The exposed dentine as a result of a breach of cementum may be identified by gingival recession and exposure of the root surface to the oral environment. Typically, the oral site is on a molar.

Typically, the exposed dentine contains dentinal tubules with openings greater than 1 .0, 1 .2, 1 .4, 1 .6, 1 .8, 2.0, 2.2, 2.4, or 2.5μηπ in diameter. An individual suffering from dentinal sensitivity, preferably hypersensitivity, may be one that experiences pain when an area of a tooth is exposed to thermal or tactile stimuli. Specifically, the individual may experience pain when an area of a tooth comes into contact with cold air, hot and cold liquids, foods that are sweet or acidic, or is touched with a metal object. In any aspect, an individual may be identified for treatment by exposure to any one of these stimuli prior to treatment to determine whether they experience a pain sensation. An individual with tooth hypersensitivity may be identified as having a larger number of open dentinal tubules and/or tubules with a larger in diameter than normal, for example the individual may have, or have a greater number of, dentinal tubules with openings greater than 1 .0, 1 .2, 1 .4, 1 .6, 1 .8, 2.0, 2.2, 2.4, or 2.5μιη in diameter. The words 'treat' or 'treatment' refer to therapeutic treatment wherein the object is to slow down (lessen) an undesired physiological change or disorder. For purposes of this invention, beneficial or desired clinical results include, but are not limited to, alleviation of symptoms, diminishment of extent of the condition, stabilized (i.e., not worsening) state of the condition, delay or slowing of condition progression, amelioration or palliation of the disease/condition state, and remission (whether partial or total), whether detectable or undetectable. Treatment may not necessarily result in the complete absence of detectable symptoms of the condition but may reduce or minimise complications and side effects of the condition. The success or otherwise of treatment may be monitored by physical examination of the individual or response to any thermal, tactile or chemical treatment as described herein. Preferably, the individual experiences a reduction in the severity of the pain or a reduction in the incidence of pain over time. Methods for identifying individuals having different degrees of dentinal sensitivity, and for measuring success of treatment or prevention, are described herein and also include those outlined in Med Oral Patol Oral Cir Bucal. 2008 Mar 1 ;13(3):E201 -6. Treatment of an individual may be determined by comparing the level of pain experienced when exposed to any stimuli described herein before and after treatment, whereby a reduction in pain after treatment indicates a reduction in sensitivity. The words 'prevent' and 'prevention' generally refer to prophylactic or preventative measures for protecting or precluding an individual not having sensitivity from progressing to sensitivity. Individuals in whom prevention may be required are those undergoing a dental procedure, particularly a dental procedure that exposes dentine. In any aspect of the present invention, the stannous ion content above may be the stannous ion content tightly-bound to the complex (as described herein). In assessing the stannous ion content, the tightly-bound stannous ion content is measured by the methods described herein, in particular, in Example 2.

The invention also provides a stannous-associated phosphopeptide stabilized ACP and/or ACFP complex comprising stannous ions that remain associated with the complex after centrifugation in a 1000 molecular weight cut off filter at about 3000g for 1 hour at room temperature, wherein the stannous ion content that remains associated with the complex is equal to, or greater than, 1 mole of stannous per mole of PP but less than 4 moles of stannous per mole of PP.

The invention also provides a stannous-associated phosphopeptide stabilized ACP or ACFP having at least 50, 60, 65, 70, 75, 80, 85, 90, 91 , 92, 93, 94, 95, 96, 97, 98, 99 or 100% of the stannous associated with the complex as tightly bound as determined by the method in Example 2.

In any composition of the invention, the amount of phosphopeptide stabilized ACP or ACFP, preferably CPP-ACP or ACFP, may be between about 2% to 5% and the amount of stannous compound, preferably SnF ₂ , may be 500ppm F. The phosphopeptide stabilized ACP or ACFP may be 2% or 5%.

In any composition of the invention, the amount of phosphopeptide stabilized ACP or ACFP, preferably CPP-ACP or ACFP, may be equal to, or greater than, about 0.1 , 0.5, 1 , 1 .5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10% by weight. Typically, the amount of stannous compound, preferably SnF ₂ , may be equal to, or greater than, about 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420, 440, 460, 480, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1 100, 2000, 3000, 4000 or 5000 ppm F.

In one aspect, the present invention provides a method of mineralizing a dental surface or sub-surface comprising contacting the dental surface or subsurface with a stannous-associated phosphopeptide (PP) stabilized amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex of the invention, or composition of the invention, thereby mineralizing the dental surface or subsurface.

In a preferred embodiment, the stannous-associated phosphopeptide stabilised amorphous calcium phosphate (ACP) or amorphous calcium fluoride phosphate (ACFP) complex has tightly bound and loosely bound calcium, wherein the bound calcium in the complex is less than the tightly bound calcium in an ACP or ACFP complex formed at a pH of 7.0. Optionally, the ACP or ACFP is predominantly in a basic form.

In another aspect the invention also provides a composition including stannous- associated phosphopeptide stabilized ACP or ACFP, further comprising fluoride, wherein fluoride is provided as stannous fluoride and/or sodium fluoride. Preferably, there are 2 moles of fluoride for every mole of stannous. Preferably, the composition is toothpaste or any other oral care composition as described herein.

In a preferred embodiment, the calcium ion content of the stannous-associated phosphopeptide stabilised ACP or ACFP complex is in the range of about 30 to 100 moles of calcium per mole of PP. More preferably, the calcium ion content is in the range of about 30 to about 50 moles of calcium per mole of PP.

In a preferred embodiment the stannous-associated phosphopeptide ACP and/or ACFP complex is in the form of a casein phosphopeptide stabilized ACP and/or ACFP complex.

In any aspect of the invention, the phosphopeptide or phosphoprotein is a casein phosphopeptide or phosphoprotein or a tryptic digest thereof.

Preferably, the phase of the ACP is primarily (i.e. >50%) a basic phase, wherein the ACP comprises predominantly the species Ca ²⁺ , PO ₄ ^3" and OH ^" . The basic phase of ACP may have the general formula [Ca ₃ (PO ₄ ) ₂ ]x[Ca ₂ (PO ₄ )(OH)] where x > 1 . Preferably x = 1 -5. More preferably, x = 1 , i.e. the two components of the formula are present in equal proportions. Accordingly, in one embodiment, the basic phase of ACP has the formula Ca ₃ (PO ₄ ) ₂ Ca ₂ (PO ₄ )(OH).

Preferably, the phase of the ACFP is a primarily (i.e. >50%) basic phase, wherein the ACFP comprises predominantly the species Ca ²⁺ , PO ₄ ^3" and F ^" . The basic phase of ACFP may have the general formula [Ca ₃ (PO ₄ ) ₂ ] _x [Ca ₂ (PO ₄ )F] _y where x > 1 when y = 1 or where y > 1 when x = 1 . Preferably, y = 1 and x = 1 -3. More preferably, y = 1 and x = 1 , i.e. the two components of the formula are present in equal proportions. Accordingly, in one embodiment, the basic phase of ACFP has the formula Ca ₃ (PO ₄ ) ₂ Ca ₂ (PO ₄ )F.

A stannous-associated PP stabilized ACP or ACFP complex as referred to herein includes a stannous-associated PP stabilized-ACP or ACFP complex formed at a pH of at, or below, 7.3. Preferably the complex is formed at a pH in the range of about 5.0 up to but below 7.3. More preferably the complex is formed at a pH range of about 4.0 to 7.3, or 5.0 to about 6.0. In one embodiment, the pH during formation is maintained at pH 7.3 or below. In a preferred embodiment, the complex is formed at a pH of about 5.5. Preferably, the ACP or ACFP in the complex is predominantly in a basic form. The stannous-associated stabilized ACP or ACFP complex when produced on an industrial scale may be produced in a bulk solution that may have a pH greater than about 7.3, preferably about 9.0, however the local pH at formation of the complexes is below about 7.3, preferably about 4.0 to 6.5, preferably about 5.5.

When stannous-associated PP stabilized ACP or ACFP, or stabilized ACP or ACFP, is produced in the laboratory, in smaller quantities than commercial production the pH of the entire solution may be maintained at a given pH, i.e. if the CPP-ACP was prepared at pH 5.5, then the entire solution during CPP-ACP formation was maintained at pH 5.5. However, it may be neither necessary nor desirable to reduce the pH of the entire bulk solution in commercial manufacture to 5.5 as the only part of the bulk solution required to have the acidic pH is where the complexes are forming and the bulk solution can have, and does have, localised fluctuations in pH. The pH fluctuations arise particularly from protons provided by the phosphate compound, for example dihydrogen phosphate, as it is added and the protons liberated from acidic phosphate ions when they convert into the basic form, PO ₄ ^3" . Therefore, while the overall pH of the bulk solution may be at above 7.3, for example about pH 9, the localised pH at which the CPP-ACP is formed is lower, typically below 7.3 or 6.5, preferably about 4.0 to 7.3, more preferably about 5.5. These fluctuations are localised due to the size of the bulk solution.

The present invention also provides a method or process for forming a stannous- associated PP stabilized ACP of the invention is a method comprising the steps of:

(i) obtaining a solution comprising at least one phosphopeptide and; (ii) admixing solutions comprising calcium ions, phosphate ions and hydroxide ions, while maintaining the pH at about 7.3 or below; and

(iii) admixing a stannous compound; or

(i) providing a solution of phosphopeptide stabilized ACP; and (ii) admixing a stannous compound.

The present invention also provides a method or process for forming a stannous- associated PP stabilised ACFP is a method comprising the steps of:

(i) obtaining a solution comprising at least one phosphopeptide and; (ii) admixing solutions comprising calcium ions, phosphate ions, hydroxide ions and fluoride ions, while maintaining the pH at about 7.3 or below; and

(iii) admixing a stannous compound; or

(i) providing a solution of phosphopeptide stabilized ACFP; and (ii) admixing a stannous compound.

The hydroxide ions may be titrated into the solution to maintain the phosphopeptide solution at an essentially constant pH. The calcium and phosphate ions may be titrated into the phosphopeptide solution with constant mixing and at a rate that avoids the formation of a calcium phosphate precipitate in the phosphopeptide solution.

The present invention also provides a method or process for forming a stannous- associated PP stabilized ACP of the invention is a method comprising the steps of:

(i) obtaining a solution comprising at least one phosphopeptide and;

(ii) admixing solutions comprising calcium ions and phosphate ions, while maintaining the pH at about 7.3 or below; and

(iii) admixing a stannous compound; or

(iv) providing a solution of phosphopeptide stabilized ACP; and

(v) admixing a stannous compound. Preferably, the method or process does not involve the addition of any base or acid. For example, no hydroxide ions are added separately to the solution comprising calcium ions, phosphate ions or stannous compound.

The present invention also provides a method or process for forming a stannous- associated PP stabilised ACFP of the invention is a method comprising the steps of:

(i) obtaining a solution comprising at least one phosphopeptide and;

(ii) admixing solutions comprising calcium ions, phosphate ions and fluoride ions, while maintaining the pH at about 7.3 or below; and

(vi) admixing a stannous compound; or

(iii) providing a solution of phosphopeptide stabilized ACFP; and admixing a stannous compound.

Preferably, the method or process does not involve the addition of any base or acid. For example, no hydroxide ions are added separately to the solution comprising calcium ions, phosphate ions, fluoride ions or stannous compound.

A stannous-associated PP stabilized ACP of the invention may be produced by a method comprising the step of admixing CPP-ACP and a stannous compound in an aqueous solution, while maintaining the pH at about 7.3 or below.

A stannous-associated PP stabilized ACFP of the invention may be produced by a method comprising the step of admixing CPP-ACFP and a stannous compound in an aqueous solution, while maintaining the pH at about 7.3 or below.

A stannous-associated PP stabilized ACP of the invention may be produced by a method comprising the steps of:

(i) obtaining a solution comprising CPP-ACP; and; (ii) admixing a stannous compound, while maintaining the pH at about 7.3 or below. A stannous stabilised ACFP of the invention may be produced by a method comprising the steps of:

(i) obtaining a solution comprising CPP-ACFP; and;

(ii) admixing a stannous compound, while maintaining the pH at about 7.3 or below. Preferably, the stannous compound is stannous fluoride. Optionally, the methods of producing stannous-associated PP stabilized ACP or stannous-associated PP stabilized ACFP further comprise admixing sodium fluoride in step (ii).

If necessary, the pH can be maintained with an acid, such as HCI.

Preferably the solution comprising CPP-ACP or CPP-ACFP is prepared by adding CPP-ACP or CPP-ACFP to distilled or deionised water. When a solution comprising 2% or greater, preferably 5%, CPP-ACP or CPP-ACFP is used there is no requirement for the addition of any base or acid during the method or process.

A stannous-associated PP stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex of the invention may be formed by mixing stabilized PP amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex with stannous fluoride.

In any method described herein for producing a stannous-associated PP stabilized amorphous calcium phosphate (ACP) and/or amorphous calcium fluoride phosphate (ACFP) complex, the amount of phosphopeptide stabilized ACP or ACFP, preferably CPP-ACP or ACFP, may be greater than, or equal to, 2% or 5% and the amount of stannous compound, preferably SnF ₂ , may be greater than or equal to 500ppm F.

A stannous-associated PP stabilized-ACP or ACFP complex as described in the current specification may have the form of a "closed" complex are shown in Figure 2 of Cross et al., 2007. Current Pharmaceutical Design, 13, 793-800.

A composition comprising a stannous-associated PP stabilized ACP and/or ACFP complex may further include at least an equal amount by weight of calcium phosphate. Preferably the calcium phosphate is CaHPO _4. Preferably, the calcium phosphate (e.g. CaHPO ₄ ) is dry blended with the PP stabilized ACP and/or ACFP complex. In a preferred embodiment, the PP-ACP and/or PP-ACFP complex: calcium phosphate ratio is about 1 :1 -50. more preferably about 1 : 1 -25, more preferably about 1 :5-15. In one embodiment, the PP-ACP and/or PP-ACFP complex: calcium phosphate ratio is about 1 :10.

Preferably, the form of calcium phosphate for dry blending is any soluble calcium phosphate including, but not limited to, CaHPO ₄ , Ca ₂ HPO ₄ and calcium lactate.

A composition as described herein may further include free fluoride ions. The fluoride ions may be from any suitable source. A source of fluoride ions may include free fluoride ions or fluoride salts. Examples of sources of fluoride ions include, but are not limited to the following: sodium fluoride, sodium monofluorophosphate, stannous fluoride, sodium silicofluoride and amine fluoride. These may be provided in solution (typically an aqueous solution), or a suspension.

The fluoride ions are preferably present in the composition in an amount greater than 1 ppm. More preferably, the amount is more than 3 ppm. In another embodiment, it is preferably more than 10 ppm. In typical embodiments described below, the amount may be 100ppm to 5,000 ppm, preferably 400ppm to 3000ppm, preferably l OOOppm to 300ppm. The fluoride content is typically measured as a ppm in oral compositions in the manner commonly used in the art. Where the fluoride is provided from a source with the stabilized ACP, the ppm refers to the concentration of the fluoride in that source, typically a solution or suspension of bioavailable fluoride.

"Phosphopeptide" in the context of the description of this invention means an amino acid sequence in which at least one amino acid is phosphorylated. Preferably, the phosphopeptide includes one or more of the amino acid sequence -A-B-C-, where A is a phosphoamino residue, B is any amino acyl residue including a phosphoamino residue and C is selected from a glutamyl, aspartyl or phosphoamino residue. Any of the phosphoamino residues may independently be a phosphoseryl residue. B is desirably a residue the side-chain of which is neither relatively large nor hydrophobic. It may be Gly, Ala, Val, Met, Leu, lie, Ser, Thr, Cys, Asp, Glu, Asn, Gin or Lys. In another embodiment, at least two of the phosphoamino acids in the sequence are preferably contiguous. Preferably the phosphopeptide includes the sequence A-B- C-D-E, where A, B, C, D and E are independently phosphoserine, phosphothreonine, phosphotyrosine, phosphohistidine, glutamic acid or aspartic acid, and at least two, preferably three, of the A, B, C, D and E are a phosphoamino acid. In a preferred embodiment, the phosphoamino acid residues are phosphoserine, most preferably three contiguous phosphoserine residues. It is also preferred that D and E are independently glutamic or aspartic acid.

In one embodiment, the ACP or ACFP is stabilized by a casein phosphopeptide (CPP), which is in the form of intact casein or fragment of the casein, and the complex formed preferably has the formula [CPP(ACP) ₈ ] _n or [(CPP)(ACFP) ₈ ] _n where n is equal to or greater than 1 , for example 6. The complex formed may be a colloidal complex, where the core particles aggregate to form large (eg 100 nm) colloidal particles suspended in water. Thus, the PP can be a casein protein or a phosphopeptide. The PP may be from any source; it may be present in the context of a larger polypeptide, including a full length casein polypeptide, or it may be isolated by tryptic or other enzymatic or chemical digestion of casein, or other phosphoamino acid rich proteins such as phosphitin, or by chemical or recombinant synthesis, provided that it comprises the sequence -A-B-C- or A-B-C-D-E as described above. The sequence flanking this core sequence may be any sequence. However, those flanking sequences in ocsi (59-79), β(1 -25), a _S2 (46-70) and oc _S2 (1 -21 ) are preferred. The flanking sequences may optionally be modified by deletion, addition or conservative substitution of one or more residues. The amino acid composition and sequence of the flanking region are not critical. Examples of conservative substitutions are shown in Table 1 below. TABLE 1

The flanking sequences may also include non-naturally occurring amino acid residues. Commonly encountered amino acids which are not encoded by the genetic code, include:

2-amino adipic acid (Aad) for Glu and Asp;

2-aminopimelic acid (Apm) for Glu and Asp;

2-aminobutyric (Abu) acid for Met, Leu, and other aliphatic amino acids; 2-aminoheptanoic acid (Ahe) for Met, Leu and other aliphatic amino acids; 2- aminoisobutyric acid (Aib) for Gly; cyclohexylalanine (Cha) for Val, and Leu and lie; homoarginine (Har) for Arg and Lys;

2, 3-diaminopropionic acid (Dpr) for Lys, Arg and His; N-ethylglycine (EtGly) for Gly, Pro, and Ala; N-ethylasparigine (EtAsn) for Asn, and Gin; Hydroxyllysine (Hyl) for Lys; allohydroxyllysine (AHyl) for Lys;

3- (and 4) hydroxyproline (3Hyp, 4Hyp) for Pro, Ser, and Thr; alloisoleucine (Alle) for lie, Leu, and Val; p-amidinophenylalanine for Ala; N-methylglycine (MeGly, sarcosine) for Gly, Pro, Ala. N-methylisoleucine (Melle) for lie; Norvaline (Nva) for Met and other aliphatic amino acids; Norleucine (Nle) for Met and other aliphatic amino acids; Ornithine (Orn) for Lys, Arg and His;

Citrulline (Cit) and methionine sulfoxide (MSO) for Thr, Asn and Gin;

N-methylphenylalanine (MePhe), trimethylphenylalanine, halo (F, CI, Br and I) phenylalanine, triflourylphenylalanine, for Phe. In one embodiment, the PP is one or more phosphopeptides selected from the group consisting of a _s i(59-79) [1 ], β(1 -25) [2], a _s2 (46-70) [3] and a _s2 (1 -21 ) [4]: [1 ] Gln ^b9 -Met-Glu-Ala-Glu-Ser(P)-lle-Ser(P)-Ser(P)-Ser(P)-Glu-G lu-lle-Val-Pro-Asn- Ser(P)-Val-Glu-Gln-Lys ⁷⁹ a _s i (59-79)

[2] Arg ¹ -Glu-Leu-Glu-Glu-Leu-Asn-Val-Pro-Gly-Glu-lle-Val-Glu-S er(P)-Leu-Ser(P)- Ser(P)-Ser(P)-Glu-Glu-Ser-lle-Thr-Arg ²⁵ β(1 -25) [3] Asn ⁴⁶ -Ala-Asn-Glu-Glu-Glu-Tyr-Ser-lle-Gly-Ser(P)-Ser(P)-Ser (P)-Glu-Glu-Ser(P)- Ala-Glu-Val-Ala-Thr-Glu-Glu-Val-Lys ⁷⁰ a _s2 (46-70)

[4] Lys ¹ -Asn-Thr-Met-Glu-His-Val-Ser(P)-Ser(P)-Ser(P)-Glu-Glu- Ser-lle-lle-Ser(P)- Gln-Glu-Thr-Tyr-Lys ²¹ a _s2 (1 -21 ).

In another embodiment of the invention, the stannous-associated PP stabilized ACP and/or stannous-associated PP stabilized ACFP complex is incorporated into oral compositions such as toothpaste, mouth washes or formulations for the mouth to aid in the prevention and/or treatment dentinal hypersensitivity. The oral compositions comprising an amount of stannous-associated PP stabilized ACP and/or ACFP sufficient to occlude exposed dentinal tubules or to form a layer over exposed dentinal tubules. The stannous-associated PP stabilized ACP and/or ACFP complexes may comprise 0.01 to 50% by weight of the composition, preferably 1 .0 to 50%, preferably 1 .0 to 30%, preferably 1 .0 to 20%, preferably 1 .0 to 10%, preferably 2 to 10% by weight of the composition. In a particularly preferred embodiment, the oral composition of the present invention contains about 2% stabilized ACP or ACFP complexes or a mixture of both.

The oral composition of this invention which contains a complex of the invention may be prepared and used in various forms applicable to the mouth such as dentifrice including toothpastes, toothpowders and liquid dentifrices, mouthwashes, mouthrinses, mouth sprays, varnish, dental cement, troches, chewing gums, dental pastes, gingival massage creams, gargle tablets, dairy products and other foodstuffs including yoghurt. The oral composition according to this invention may further include additional well known ingredients depending on the type and form of a particular oral composition. Certain compositions of the invention such as toothpastes, toothpowders and liquid dentifrices, mouthwashes, mouthrinses and mouth sprays have relatively low viscosity. A dentifrice or paste for localized application to a sensitive tooth site such as breached cementum of an orally exposed root surface may be one that is applied with a soft applicator. Such a dentifrice or paste may or may not contain conventional abrasive, foaming agent, and flavoring agents. In certain preferred forms of the invention an oral composition may be substantially liquid in character, such as a mouthwash, rinse or spray. In such a preparation the vehicle is typically a water-alcohol mixture desirably including a humectant as described below. Generally, the weight ratio of water to alcohol is in the range of from about 1 :1 to about 20:1 . The total amount of water-alcohol mixture in this type of preparation is typically in the range of from about 70 to about 99.9% by weight of the preparation. The alcohol is typically ethanol or isopropanol. Ethanol is preferred.

In other desirable forms of this invention, the composition may be substantially solid or pasty in character, such as toothpowder, a dental tablet or a toothpaste (dental cream) or gel dentifrice. The vehicle of such solid or pasty oral preparations generally contains dentally acceptable polishing material. Examples of polishing materials are water-insoluble sodium metaphosphate, potassium metaphosphate, tricalcium phosphate, dihydrated calcium phosphate, anhydrous dicalcium phosphate, calcium pyrophosphate, magnesium orthophosphate, trimagnesium phosphate, calcium carbonate, hydrated alumina, calcined alumina, aluminium silicate, zirconium silicate, silica, bentonite, and mixtures thereof. Other suitable polishing material include the particulate thermosetting resins such as melamine-, phenolic, and urea-formaldehydes, and cross-linked polyepoxides and polyesters. Preferred polishing materials include crystalline silica having particle sizes of up to about 5 microns, a mean particle size of up to about 1 .1 microns, and a surface area of up to about 50,000 cm ² /g., silica gel or colloidal silica, and complex amorphous alkali metal aluminosilicate.

When visually clear gels are employed, a polishing agent of colloidal silica, such as those sold under the trademark SYLOID as Syloid 72 and Syloid 74 or under the trademark SANTOCEL as Santocel 100, alkali metal aluminosilicate complexes are particularly useful since they have refractive indices close to the refractive indices of gelling agent-liquid (including water and/or humectant) systems commonly used in dentifrices. Many of the so-called "water insoluble" polishing materials are anionic in character and also include small amounts of soluble material. Thus, insoluble sodium metaphosphate may be formed in any suitable manner, for example as illustrated by Thorpe's Dictionary of Applied Chemistry, Volume 9, 4th Edition, pp. 510-51 1 . The forms of insoluble sodium metaphosphate known as Madrell's salt and Kurrol's salt are further examples of suitable materials. These metaphosphate salts exhibit only a minute solubility in water, and therefore are commonly referred to as insoluble metaphosphates (IMP). There is present therein a minor amount of soluble phosphate material as impurities, usually a few percent such as up to 4% by weight. The amount of soluble phosphate material, which is believed to include a soluble sodium trimetaphosphate in the case of insoluble metaphosphate, may be reduced or eliminated by washing with water if desired. The insoluble alkali metal metaphosphate is typically employed in powder form of a particle size such that no more than 1 % of the material is larger than 37 microns. The polishing material is generally present in the solid or pasty compositions in weight concentrations of about 10% to about 99%. Preferably, it is present in amounts from about 10% to about 75% in toothpaste, and from about 70% to about 99% in toothpowder. In toothpastes, when the polishing material is silicious in nature, it is generally present in an amount of about 10-30% by weight. Other polishing materials are typically present in amount of about 30-75% by weight.

In a toothpaste, the liquid vehicle may comprise water and humectant typically in an amount ranging from about 10% to about 80% by weight of the preparation. Glycerine, propylene glycol, sorbitol and polypropylene glycol exemplify suitable humectants/carriers. Also advantageous are liquid mixtures of water, glycerine and sorbitol. In clear gels where the refractive index is an important consideration, about 2.5 - 30% w/w of water, 0 to about 70% w/w of glycerine and about 20-80% w/w of sorbitol are preferably employed.

Toothpaste, creams and gels typically contain a natural or synthetic thickener or gelling agent in proportions of about 0.1 to about 10, preferably about 0.5 to about 5% w/w. A suitable thickener is synthetic hectorite, a synthetic colloidal magnesium alkali metal silicate complex clay available for example as Laponite (e.g. CP, SP 2002, D) marketed by Laporte Industries Limited. Laponite D is, approximately by weight 58.00% SiO ₂ , 25.40% MgO, 3.05% Na ₂ O, 0.98% Li ₂ O, and some water and trace metals. Its true specific gravity is 2.53 and it has an apparent bulk density of 1 .0 g/ml at 8% moisture. Other suitable thickeners include Irish moss, iota carrageenan, gum tragacanth, starch, polyvinylpyrrolidone, hydroxyethylpropylcellulose, hydroxybutyl methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose (e.g. available as Natrosol), sodium carboxymethyl cellulose, and colloidal silica such as finely ground Syloid (e.g. 244). Solubilizing agents may also be included such as humectant polyols such propylene glycol, dipropylene glycol and hexylene glycol, cellosolves such as methyl cellosolve and ethyl cellosolve, vegetable oils and waxes containing at least about 12 carbons in a straight chain such as olive oil, castor oil and petrolatum and esters such as amyl acetate, ethyl acetate and benzyl benzoate.

It will be understood that, as is conventional, the oral preparations will usually be sold or otherwise distributed in suitable labelled packages. Thus, a jar of mouth rinse will have a label describing it, in substance, as a mouth rinse or mouthwash and having directions for its use; and a toothpaste, cream or gel will usually be in a collapsible tube, typically aluminium, lined lead or plastic, or other squeeze, pump or pressurized dispenser for metering out the contents, having a label describing it, in substance, as a toothpaste, gel or dental cream.

Organic surface-active agents may be used in the compositions of the present invention to achieve increased prophylactic action, assist in achieving thorough and complete dispersion of the active agent throughout the oral cavity, and render the instant compositions more cosmetically acceptable. The organic surface-active material is preferably anionic, non-ionic or ampholytic in nature and preferably does not interact with the active agent. It is preferred to employ as the surface-active agent a detersive material which imparts to the composition detersive and foaming properties. Suitable examples of anionic surfactants are water-soluble salts of higher fatty acid monoglyceride monosulfates, such as the sodium salt of the monosulfated monoglyceride of hydrogenated coconut oil fatty acids, higher alkyl sulfates such as sodium lauryl sulfate, alkyl aryl sulfonates such as sodium dodecyl benzene sulfonate, higher alkylsulfo-acetates, higher fatty acid esters of 1 ,2-dihydroxy propane sulfonate, and the substantially saturated higher aliphatic acyl amides of lower aliphatic amino carboxylic acid compounds, such as those having 12 to 16 carbons in the fatty acid, alkyl or acyl radicals, and the like. Examples of the last mentioned amides are N-lauroyl sarcosine, and the sodium, potassium, and ethanolamine salts of N-lauroyl, N-myristoyl, or N-palmitoyl sarcosine which should be substantially free from soap or similar higher fatty acid material. The use of these sarconite compounds in the oral compositions of the present invention is particularly advantageous since these materials exhibit a prolonged marked effect in the inhibition of acid formation in the oral cavity due to carbohydrates breakdown in addition to exerting some reduction in the solubility of tooth enamel in acid solutions. Examples of water-soluble non-ionic surfactants suitable for use are condensation products of ethylene oxide with various reactive hydrogen- containing compounds reactive therewith having long hydrophobic chains (e.g. aliphatic chains of about 12 to 20 carbon atoms), which condensation products ("ethoxamers") contain hydrophilic polyoxyethylene moieties, such as condensation products of poly (ethylene oxide) with fatty acids, fatty alcohols, fatty amides, polyhydric alcohols (e.g. sorbitan monostearate) and polypropyleneoxide (e.g. Pluronic materials).

The surface active agent is typically present in amount of about 0.1 -5% by weight. It is noteworthy, that the surface active agent may assist in the dissolving of the active agent of the invention and thereby diminish the amount of solubilizing humectant needed.

Various other materials may be incorporated in the oral preparations of this invention such as whitening agents, preservatives, silicones, chlorophyll compounds and/or ammoniated material such as urea, diammonium phosphate, and mixtures thereof. These adjuvants, where present, are incorporated in the preparations in amounts which do not substantially adversely affect the properties and characteristics desired.

Any suitable flavouring or sweetening material may also be employed. Examples of suitable flavouring constituents are flavouring oils, e.g. oil of spearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus, marjoram, cinnamon, lemon, and orange, and methyl salicylate. Suitable sweetening agents include sucrose, lactose, maltose, sorbitol, xylitol, sodium cyclamate, perillartine, AMP (aspartyl phenyl alanine, methyl ester), saccharine, and the like. Suitably, flavour and sweetening agents may each or together comprise from about 0.1 % to 5% more of the preparation.

The compositions of this invention can also be incorporated in lozenges, or in chewing gum or other products, e.g. by stirring into a warm gum base or coating the outer surface of a gum base, illustrative of which are jelutong, rubber latex, vinylite resins, etc., desirably with conventional plasticizers or softeners, sugar or other sweeteners or such as glucose, sorbitol and the like. The composition of the invention may be a dual phase composition wherein each phase permits release of components over different time periods. For example, in use a dual phase composition may release stannous-associated stabilized ACP and/or stannous-associated stabilized ACFP, preferably CPP-ACP/SnF ₂ and/or CPP-ACFP/SnF ₂ , from a first phase at a faster rate than a compound that is capable of increasing or maintaining the pH of a solution from a second phase. Preferably, the dual phase composition is a dual phase chewing gum. An alternative composition may be one that provides phosphopeptide stabilized

ACP or ACFP and a stannous compound that then in situ, such as the oral cavity, forms stannous-associated phosphopeptide stabilized ACP or ACFP complexes of the invention. An exemplary composition may be a chewing gum that contains stabilized ACP or ACFP in the pellet and a stannous compound in the centre chew. Compositions of the invention may be in the form of a gel, liquid, solid, powder, cream or lozenge. Therapeutic compositions may also be in the form of tablets or capsules. In one embodiment, the stannous-associated PP stabilized ACP or ACFP complexes of the invention are substantially the only active components of such a composition. For example, a creme formulation may be employed containing: water; glycerol; complex of the invention; D-sorbitol; silicon dioxide; sodium carboxymethylcellulose (CMC-Na); propylene glycol; titanium dioxide; xylitol; phosphoric acid; guar gum; zinc oxide; sodium saccharin; ethyl p-hydroxybenzoate; magnesium oxide; butyl p-hydroxybenzoate and propyl p-hydroxybenzoate.

The invention further includes a formulation described above provided together with instructions for its use to treat or prevent dentinal hypersensitivity. In another embodiment, the compositions of the invention as described herein do not include a phosphate buffer and/or a calcium chelator. For example, any dentifrice described herein may not include a phosphate buffer and/or a calcium chelator.

In an embodiment of the present invention there is provided a composition for treating or preventing dentinal hypersensitivity comprising a stannous-associated PP stabilized ACP and/or ACFP complex of the invention, wherein the composition does not include a phosphate buffer and/or calcium chelator.

In another embodiment, the compositions of the invention as described herein do not include a viscosity regulator, or a viscosity regulator at 0.5 to 50%. In another embodiment, the compositions of the invention as described herein do not include sodium carboxymethylcellulose, or 0.01 to 10% sodium carboxymethylcellulose having the esterification degree of 0.7 to 1 .0.

In one embodiment, the active components of the composition consist essentially of the stannous-associated PP stabilized ACP or ACFP complexes of the invention. In a further aspect, there is provided a method of treating or preventing dentinal hypersensitivity comprising the steps of administering a composition a stannous- associated PP stabilized ACP and/or ACFP complex, to the teeth of a subject. Topical administration of the complex is preferred. The method preferably includes the administration of the complex in a formulation as described above. In a further aspect there is provided the use of a stannous-associated PP stabilized ACP or ACFP complex of the invention in a manufacture of a composition for the treatment and/or prevention of dental hypersensitivity.

In a further aspect there is provided the use of a stannous-associated PP stabilized ACP or ACFP complex of the invention in a manufacture of a composition for mineralizing a dental surface of subsurface.

According to a further aspect of the invention there is provided a composition for dental restoration, including a dental restorative material to which has been added a stannous-associated PP stabilized ACP or ACFP complex of the invention. The base of the dental restorative material can be a glass ionomer cement, a composite material or any other restorative material which is compatible. A glass ionomer cement is preferred. It is preferred that the amount of stannous-associated PP stabilized ACP or ACFP complexes included in the dental restorative material is 0.01 -80% by weight, preferably 0.5-10% and more preferably 1 -5% by weight. The dental restorative material of this invention which contains the above mentioned agents may be prepared and used in various forms applicable to dental practice. The dental restorative material according to this embodiment may further include other ions, eg. antibacterial ions Zn ²⁺ , Ag ⁺ , etc or other additional ingredients depending on the type and form of a particular dental restorative material. It is preferable that the pH of dental restorative material according to this embodiment be between 2-10, more preferably 5-9 and even more preferably 5- 7. It is preferable that the pH of the dental restorative material containing a stannous- associated stabilized ACP or ACFP complex be in the range of about 2 to 10, more preferably in the range of about 5 to 9 and even more preferably in the range of about 5 to 7. It will be clearly understood that, although this specification refers specifically to applications in humans, the invention is also useful for veterinary purposes. Thus in all aspects the invention is useful for domestic animals such as cattle, sheep, horses and poultry; for companion animals such as cats and dogs; and for zoo animals.

One example of a mineralizing composition comprises the following (in decreasing order of proportion): water glycerol

CPP-ACP/SnF ₂ D-sorbitol silicon dioxide sodium carboxymethylcellulose (CMC-Na) propylene glycol titanium dioxide xylitol phosphoric acid guar gum zinc oxide sodium saccharin ethyl p-hydroxybenzoate magnesium oxide butyl p-hydroxybenzoate propyl p-hydroxybenzoate

The invention will now be further described with reference to the following non- limiting examples.

Example 1

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) was acquired from Cadbury Enterprises Pte Ltd under the trademark name Recaldent™. Solutions was prepared using CPP-ACP and SnF ₂ to produce each of the following stannous associated PP stabilized ACP complexes:

- 0.4% CPP-ACP + 220 ppm F as SnF2 (Sn:CPP molar ratio 8.6:1 );

- 2% CPP-ACP + 500 ppm F as SnF2 (Sn:CPP molar ratio 4:1 ); and - 5% CPP-ACP + 500 ppm F as SnF2 (Sn:CPP molar ratio 1 .6:1 ).

Specifically, the CPP-ACP/SnF ₂ complexes were prepared by first adding CPP- ACP to distilled/deionised water and then SnF ₂ (solid or cone solution) added slowly. If the pH needed adjustment it would be adjusted by the addition of 1 M HCI or 1 M NaOH to maintain the pH between 4.0 - 7.3. The pH was not allowed to go above 7.3. There was no pH adjustment needed for when 5% CPP-ACP was used. The total volume of acid/base added was less than 1 % of the CPP-ACP/SnF ₂ solution volume. The final solution contained stannous associated PP stabilized ACP complexes.

Example 2 The following is a protocol for CPP stabilized ACP/SnF ₂ solution ion analysis.

Total (tightly & loosely-bound) and loosely-bound samples were prepared as follows:

Total (tightly and loosely-bound): One ml of any treatment solution 2) to 4) as shown in Example 3 solution can be taken and placed into 19 ml of 1 M HNO3 and incubated at room temperature with constant slow end over end mixing for 24 hrs (20 rpm). The mixture is centrifuged at 1000g for 15 minutes at room temperature. The supernatant is analyzed for calcium, stannous, phosphate and fluoride.

Loosely-bound: A sample of the same solution as for the 'total' analysis immediately above is taken and placed in a centricon with a 1000 MWCO filter and centrifuged at 3000g for 1 hour at room temperature to produce enough filtrate ( <10% of total sample to not affect equilibrium) for analysis by atomic absorption spectrophotometry (AAS) and ion chromatography (IC). The filtrates are then measured to give loosely-bound ions.

The total and loosely bound calcium, stannous, phosphate and fluoride in the solution are determined by ion chromatography (for fluoride and phosphate) and Atomic Absorption Spectrometry (for calcium and stannous).

CPP tightly-bound (colloidal retentate) ions are calculated from the difference between Total and loosely-bound (as explained above).

Example 3

Self-assembly of a nanofilament network on dentine by SnF ₂ /CPP-ACP at a molar ratio of Sn/CPP of 1 .6 is superior at occlusion of patent dentine tubules and therefore would be superior at reducing dentinal hypersensitivity.

The hydrodynamic theory of dental hypersensitivity indicates restriction of fluid movement through dentine tubules can result in a clinical reduction of hypersensitivity. Here the inventor shows the synergistic effect of combining CPP-ACP and SnF ₂ at a Sn(ll)/CPP molar ratio of 1 .6 on occlusion of tubules of surface dentine using scanning electron microscopy (SEM).

Extracted human third molars were sectioned to create coronal discs approximately 1 mm thick. The discs were covered with acid resistant nail varnish to expose a window of central dentine and were then submerged in 15% EDTA for 2 minutes to remove the smear layer. Discs were randomly allocated to one of four groups and were exposed to the following treatments for 20 min:

1 ) Double distilled water (DDW) treatment; 2) 0.4% CPP-ACP + 220 ppm F as SnF ₂ (Sn:CPP molar ratio 8.6:1 );

3) 2% CPP-ACP + 500 ppm F as SnF ₂ (Sn:CPP molar ratio 4:1 ); and

4) 5% CPP-ACP + 500 ppm F as SnF ₂ (Sn:CPP molar ratio 1 .6:1 ).

The discs were then dehydrated and sputtered with gold for examination under

SEM. The SEM images in Figures 2 to 6 show that dentine exposed to treatments 2 to

4 all exhibited surface precipitation and dentine tubule occlusion to varying degrees. The negative control, DDW treatment, showed smooth dentine surfaces with patent (open) tubules (Figure 1 ). The combined 500 ppm F SnF ₂ and 5% CPP-ACP solution (Sn/CPP molar ratio 1 .6) interacted with the dentine surface to result in a unique pattern of surface coverage that displayed a self-assembled network of nanofilaments across the dentine surface occluding the tubules (Figures 2 to 4). These nanofilaments are thought to be Sn-cross-linked CPP which have released their cargo of calcium, phosphate and fluoride ions at the surface upon nanofilament formation. Only the Sn/CPP molar ration 1 .6 solution resulted in the cross-linked nanofilaments indicating that the molar ratio of equal to, or greater than 1 mole but less than 4 moles of Sn(ll) to CPP is critical for the formation of cross-linked nanofilaments and enhanced reduction in dentinal hypersensitivity. Treatment of exposed dentine with a solution having a Sn:CPP molar ratio of 8.6:1 only resulted in partial occlusion of the dentinal tubules (Figure 6). Likewise, treatment of exposed dentine with a solution having a Sn:CPP molar ratio of 4:1 provided partial occlusion (Figure 5).

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.