Occlusal splints, also known as bite guards, oral orthotics, and oral appliances, are utilized frequently in dental practices. They are commonly used to relax jaw muscles, prevent temporomandibular jaw trauma, protect dentition, and control headaches. How well occlusal splints work is another matter. Numerous studies, when taken as a whole, suggest only a modest indication that they are useful. This review applies principles of neurophysiology to analyze the usefulness of several types of occlusal splint in relation to their design and function. A unique occlusal splint with a design based on neurophysiology is described.