WATER OIL WATER EMULSION CONTAINING HIGH METAL SALT CONCENTRATION

1 . A high metal ion concentration emulsion, comprising:

an oil phase, the oil phase comprising:

at least two emulsifiers; and

an oil; and

a water phase, the water phase comprising:

stannous fluoride;

a chelating agent;

citric acid; and

water.

2 . The emulsion of claim 1 , wherein the oil phase further comprises:

10-40 wt. % of the at least two emulsifiers; and

60-90 wt. % of the oil, based on the total weight of the oil phase.

3 . The emulsion of either claim 1 , wherein the water phase further comprises:

5-15 wt. % of the stannous fluoride;

15-45 wt. of the chelating agent;

1-4 wt. % of the citric acid; and

36-79 wt. % of the water, based on the total weight of the water phase.

4 . The emulsion of claim 1 , further comprising:

2-10 wt. % of the at least two emulsifiers;

10-30 wt. % of the oil;

3-12 wt. % of the stannous fluoride;

10-30 wt. % of the chelating agent;

0.5-3 wt. % of the citric acid;

15-75 wt. % of the water, based on the total weight of the emulsion.

5 . The emulsion of claim 1 , wherein the at least two emulsifiers comprise a hydrophobic emulsifier and a hydrophilic emulsifier.

6 . The emulsion of claim 5 , wherein the oil phase comprises:

5-20 wt. % of the hydrophobic emulsifier; and

5-20 wt. % of the hydrophilic emulsifier, based on the total weight of the oil phase.

7 . The emulsion of claim 5 , further comprising

1-5 wt. % of the hydrophobic emulsifier; and

1-5 wt. % of the hydrophilic emulsifier, based on the total weight of the emulsion.

8 . The emulsion of claim 1 , wherein the conductivity of the emulsion is in the range of 0.1 to 1000 us/cm.

9 . The emulsion of claim 1 , wherein the average particle size (D50) of the emulsion is 1-30 μm.

10 . The emulsion of claim 1 , wherein the viscosity of the emulsion is 1-1000 Pa·s.

11 . The emulsion of claim 1 , wherein the retention of SnF 2 in the emulsion after being in an oven at 40° C. for 1 month is greater than 90%.

12 . The emulsion of claim 1 , further comprising 1-20 wt. % of metal ions, based on the total weight of the emulsion.

13 . A dental solution, comprising:

a water-oil-water (W/O/W) emulsion, the W/O/W emulsion comprising:

at least two emulsifiers;

an oil;

stannous fluoride;

a chelating agent;

citric acid; and

water.

14 . The dental solution of claim 13 , further comprising 0.05-10 wt. % of the W/O/W emulsion, based on the total weight of the dental solution.

15 . The dental solution of claim 13 , wherein the pH of the W/O/W emulsion is 5.5-10.

16 . The dental solution of claim 13 , wherein the percent retention of SnF 2 after aging for 1 month at 50° C. is greater than 80%.

17 . The dental solution of claim 13 , wherein the W/O/W emulsion further comprises:

2-10 wt. % of the at least two emulsifiers;

10-30 wt. % of the oil;

3-12 wt. % of the stannous fluoride;

10-30 wt. % of the chelating agent;

0.5-3 wt. % of the citric acid;

15-75 wt. % of the water, based on the total weight of the emulsion.

18 . The dental solution of claim 13 , wherein the at least two emulsifiers comprises a hydrophobic emulsifier and a hydrophilic emulsifier.

19 . A method of forming a water-oil-water (W/O/W) emulsion, comprising:

combining a water phase into an oil phase during constant stirring at 100-1000 rpm for 1-60 min to form the W/O/W emulsion;

wherein the oil phase comprises:

at least two emulsifiers; and

an oil; and

wherein the water phase comprises:

stannous fluoride;

a chelating agent;

citric acid; and

water.

20 . The method of claim 19 , further comprising:

heating the oil phase and the water phase to 55-80° C. before combining; and

comprising cooling the W/O/W emulsion at room temperature under stirring at 100-1000 rpm for 15 min to 2 hours.