A nightguard is a device placed in the mouth on top of the teeth to help with grinding and clenching. Grinding implies the moving of the jaw back and forth, while clenching is biting down with pressure for an extended period of time. The guard acts as a protective layer between your top and bottom teeth.
These devices are also called occlusal guards, occlusal splints, or bite splints. Usually, the guard is made of plastic and is placed over some or all of the upper or lower teeth. In most cas-es, guards cover only your upper teeth. But sometimes, if you wear braces or have another den-tal appliance, a dentist can make a guard for your lower teeth, as well.