Dental Nightguards

Bruxism is the unconscious and involuntary clenching or grinding of the teeth. The excessive wear caused by bruxism can lead to worn down teeth, chipped teeth, and increased sensitivity and pain. In addition, constant grinding of the teeth can result in the development of prominent jaw muscles which interfere with normal jaw alignment. A dental nightguard is a custom appliance designed to prevent the grinding of the upper and lower teeth against one another. An impression is made of your teeth and sent to a dental laboratory which will fabricate a comfortable acrylic guard designed to keep the surfaces of the teeth from damaging one another.

http://www.ada.org/public/topics/grinding.asp
http://www.toothiq.com/dental-diagnoses/dental-diagnosis-bruxism-overview.html