A rigid or flexible prefabricated appliance that overlays the occlusal surfaces of the teeth. It is used to maintain the position of displaced or moveable teeth, to treat clenching and bruxism and their sequelae, and to provide temporary relief from muscle or temporo-mandibular joint (TMJ) pain (e.g., from TMJ dysfunction). It is typically made of standard, preformed materials or items for adaptation/direct insertion into the patient's mouth. This is a reusable device.