A method of cleaning an oral appliance allows a dental patient or other oral appliance wearer to clean the appliance while the appliance is in place in the wearer's mouth. The appliance wearer dispenses a quantity of foamed, cleanser formulation into to his or her mouth, swishes the cleanser around in the mouth for a desired amount of time, and then expectorates any remaining cleanser. A cleaning kit for an oral appliance is also provided and includes a mixture of water, hydrogen peroxide, and at least one surfactant in a foam-dispensing bottle.