A formulation starts as a gel and transforms into a foam under influence of light and heat to expand out into the oral cavity of a user for advantageous health benefits. A closed system mouthpiece includes light and heat generation to activate the formulation to increase its volume. Application of heat above a threshold temperature causes the gel to transform into foam and expand out of the mouthpiece and into the oral cavity. With the foam so dispersed within the oral cavity, activation of a light source embedded within the mouthpiece enhances the bacteria killing properties of the now foam material. The foam spreads onto the tongue of the user as well and acts to kill any damaging bacteria found there. As a result, the pH balance of the mouth is restored to a neutral level in the range of 6.75 to 7.25 or maintained at that pH level.