A mouth guard designed to minimize discomfort and speech interference associated with conventional mouthpieces is disclosed. The mouth guard has a substantially uniform thickness on the facial/buccal and biting surfaces of the anterior and posterior teeth, and along the lingual surface of the posterior teeth. The thickness of the mouth guard along the lingual surface of the anterior teeth is greater near the biting surface than near the gum line. This minimizes interference with the wearer's tongue, making it relatively easy to drink, speak, and breathe, while protecting the anterior and posterior teeth from impact from the front or underneath. The mouth guard can be a boil-and-bite or custom-made mouth guard, and can also include an impact shield, one or more power wedges or shock absorbers, a flavoring component, and/or an antibacterial component.