A method and system for preventing head injury by providing parallel alignment of a jaw are disclosed. A method of preventing a head injury comprises providing a dental appliance having a left body, a right body and a lingual bar engaging the left body and the right body; placing the dental appliance over a plurality of teeth of a lower jaw so the lower jaw and a upper jaw are approximately parallel; and absorbing a force applied to the lower jaw, wherein the dental appliance absorbs the force applied to the lower jaw while preventing a condyle of a mandible from transferring the force to a temporal bone.