A post foaming oral care mousse is provided by the invention. The mousse includes at least a dentifrice composition and a compressed liquid propellant having a boiling point less than −10° C. The liquid propellant is blended into the mousse as an emulsion, and the emulsion is adapted to be dispensed from a container as a gel that foams after a time delay. The mousse has a viscosity of less than 30,000 centipoise when measured prior to the addition of the propellant. Preferably, the mousse expands at least 100 vol % in less than 5 seconds upon exposure to atmospheric pressure.