Sleep bruxism involves the involuntary, unconscious, excessive grinding or clenching of teeth during sleep. It may occur along with other sleep disorders. For example, it is often associated with sleep apnea. Sleep bruxism may lead to problems including abnormal wear of the teeth and jaw muscle discomfort. The severity of bruxism can range from mild cases to severe cases that involve evidence of dental injury. In some cases, bruxism can be prevented with the use of a mouth guard. The mouth guard, supplied by a dentist, can fit over the teeth to prevent teeth from grinding against each other.