Abstract: A resilient composition including a thermoplastic material and gas pockets dispersed therein, where the pockets being formed by a blowing agent. A mouthpiece including a resilient thermoplastic material having a quantity of gas pockets dispersed therein. A method of making a mouthpiece achieved by first mixing a predetermined quantity of blowing agent with a resilient thermoplastic material. The mixture is then heated to a predetermined temperature forming gas pockets therein from the decomposition of the blowing agent. The mixture is then ejection molded in a mold to form the mouthpiece. A mouthpiece including a U-shaped base having a U-shaped cross-section. The base including a lower, horizontal floor with upwardly extending inner lingual and outer labial walls and having a posterior section proximate the user's molar teeth and an anterior section proximate the user's canine and incisor teeth.