Research has found that about 50% of the population has excessive wear patterns on their teeth that may be seen even in the teenage patients. The biting force when chewing food is about 25 pounds per square inch. Clenching and grinding contacts may be ten times that much or more. Often these grinding contacts occur during sleep, two or three times an hour, and for perhaps ten to fifteen seconds each episode. Only 15% are heard to make grinding noises. Night grinding of teeth is called “bruxism” and can severely damage the teeth. A night guard appliance can be made to protect teeth from loss of length and protect crowns from breakage of porcelain.