Method of forming stable dental gel of stannous fluoride

Claim 1

A method for producing a commercial-scale size batch of a stable gel consisting essentially of from about 96% to about 98% of anhydrous glycerin, from about 1.8% to about 2.2% of hydroxyethyl cellulose and from about 0.38% to about 0.43% of stannous fluoride wherein the concentration of stannous fluoride in said gel is stable during storage against deterioration to levels below that enabling the use of said gel as a topical treating agent for the prevention of dental caries, the first stage of said method comprising the sequential steps: (a) dissolving 50% of the stannous fluoride present in said gel from about 15% to about 18% of the anhydrous glycerin present in said gel at a temperature in the range of from about 150° C. to about 180° C.; (b) adding a sufficient quantity of anhydrous glycerin to said mixture to reduce the temperature thereof of from about 130° C. to about 150° C.; (c) dissolving in said mixture 50% of the hydroxyethyl cellulose present in said gel; and (d) adding to said mixture sufficient anhydrous glycerin to bring the volume thereof up to about 50% of the volume of said gel; and the second stage of said method comprising repeating the said sequential steps of said first stage and combining the product of said second stage with the product of said first stage.

Claim 2

A method for producing a commercial-scale size batch of a stable gel consisting essentially of from about 96% to about 98% of anhydrous glycerin, from about 1.8% to about 2.2% of hydroxyethyl cellulose and from about 0.38% to about 0.43% of stannous fluoride wherein the concentration of stannous fluoride in said gel is stable during storage against deterioration to levels below that enabling the use of said gel as a topical treating agent for the prevention of dental caries, the first stage of said method comprising the sequential steps: (a) dissolving 50% of the stannous fluoride present in said gel from about 15% to about 18% of the anhydrous glycerin present in said gel at a temperature in the range of from about 150° C. to about 180° C.; (b) adding a sufficient quantity of anhydrous glycerin to said mixture to reduce the temperature thereof of from about 130° C. to about 150° C.; (c) dissolving in said mixture 50% of the hydroxyethyl cellulose present in said gel; and (d) adding to said mixture sufficient anhydrous glycerin to bring the volume thereof up to about 50% of the volume of said gel; and the second stage of said method comprising repeating the said sequential steps of said first stage and combining the product of said second stage with the product of said first stage.