Dentifrice comprising stannous fluoride plus zinc citrate and low levels of water

1. dentifrice composition comprising in a single phase: an orally acceptable carrier; a source of fluoride ions; source of stannous ions; a zinc ion source and, at least one polyphosphate salt selected from the group consisting of inorganic polyphosphates that are 3 or less of phosphorus atoms; wherein the total water content of the dentifrice composition is less than about 10% by weight of the composition. 2. The composition of claim 1, wherein the carrier includes a thickener comprising a polymer system comprising at least one resin and crosslinked polyvinylpyrrolidone. 3. The composition of claim 2 wherein the thickener comprises a combination of polyvinylpyrrolidone and crosslinked resin. 4. The composition of claim 1, wherein at least one polyphosphate selected from the group consisting of an alkali metal pyrophosphate, alkali metal tripolyphosphate, and mixtures thereof. 5. The composition of claim 4, wherein at least one polyphosphate selected from the group consisting of tetrasodium pyrophosphate, sodium tripolyphosphate and mixtures thereof. 6. The composition of claim 5, wherein at least one polyphosphate comprises tetrasodium pyrophosphate, and a mixture of sodium tripolyphosphate. 7. The composition of claim 6, wherein the mixture of tetrasodium pyrophosphate and sodium tripolyphosphate, tetrasodium pyrophosphate, and contains sodium tripolyphosphate in a weight ratio of about 2: 3. 8. The composition of claim 1, wherein at least one polyphosphate is from 1 to 10 wt%. composition. 9. The composition of claim 8, wherein at least one polyphosphate is from 3 to 7% by weight. composition. 10. The composition of claim 1 wherein the fluoride ion source and stannous ion source is stannous fluoride. 11. The composition of claim 1 wherein the zinc ion source is a zinc salt of an organic acid. 12. The composition of claim 11 wherein the source of zinc ion is zinc citrate. 13. The composition of claim 1, further comprising an aqueous buffer system for stannous ion source. 14. The composition of claim 13, wherein the buffer system is adapted for chelating stannous ions in the formulation. 15. The composition of claim 14, wherein the buffer system comprises at least one of an organic acid or its alkali metal salt. 16. The composition of claim 15, wherein the organic acid is citric acid. 17. The composition of claim 15, wherein the buffer system comprises a mixture of citric acid and trisodium citrate. 18. The composition of claim 15, wherein the buffer system is between 0.1 and 10% by weight. composition. 19. The composition of claim 15, wherein the buffer system is present in an amount by weight which is greater than the amount by weight of stannous ion source. 20. A dentifrice composition comprising in a single phase: an orally acceptable carrier, wherein the carrier comprises a polymeric thickener system, the combination comprising crosslinked polyvinylpyrrolidone and resin; wherein the total water content of the dentifrice composition is less than about 10% by weight of the composition. 21. The composition of claim 1 or 20, wherein the total water content of the dentifrice composition is less than about 6% by weight of the composition. 22. The composition of claim 2 or 20, wherein the resin comprises xanthan gum. 23. The composition of claim 22, wherein the resin is from 0.1 to 0.5% by weight. composition. 24. The composition of claim 23, wherein the resin is from 0.2 to 0.3% by weight. composition. 25. The composition of claim 2 or 20, wherein crosslinked polyvinylpyrrolidone homopolymer comprises N-vinyl-2-pyrrolidone. 26. The composition of claim 25, wherein crosslinked polyvinylpyrrolidone is from 0.05 to 15% by weight. composition. 27. The composition of claim 26, wherein crosslinked polyvinylpyrrolidone is from 0.75 to 1.25 wt%. composition. 28. The composition of claim 1 or 20, wherein the thickening agent additionally contains at least one of cellulose and synthetic block copolymer of ethylene oxide and propylene oxide. 29. The composition of claim 1 or 20, further comprising at least one wetting agent selected from the group consisting of glycerol, polyethylene glycol, propylene glycol and mixtures thereof. 30. A method for the treatment and prevention of bacterial plaque accumulation or preventing dental erosion comprising administering to the oral cavity of the dentifrice composition of claim 1. 31. A process for preparing a dentifrice composition comprising: providing a source of stannous ions; mixing a source of stannous ions with an aqueous buffer system, adapted to chelate stannous ion in the premix formed thereby; and premix association of at least one active ingredient and an orally acceptable carrier dentifrice composition. 32. The method of claim 31 wherein the stannous ion source comprises stannous fluoride. 33. The method of claim 31, wherein the buffer system comprises at least one of an organic acid or its alkali metal salt. 34. The method of claim 33, wherein the organic acid is citric acid. 35. The method of claim 31, wherein the buffer system comprises a mixture of citric acid and trisodium citrate. 36. The method of claim 31, wherein the buffer system is between 1 and 5% by weight. composition. 37. The method of claim 31, wherein the buffer system is present in an amount by weight which is greater than the amount by weight of stannous ion source. 38. The method of claim 31, wherein the at least one active ingredient comprises a source of zinc ions and at least one polyphosphate salt selected from the group consisting of inorganic polyphosphate salts that contain 3 or less of phosphorus atoms. 39. The method of claim 31, wherein the orally acceptable carrier comprises a thickening agent comprising a polymer system comprising a combination of polyvinylpyrrolidone and a crosslinked resin, the total water content of the dentifrice composition is less than about 10% by weight of the composition.