TMJ refers to the temporomandibular joint which is the jaw joint. It is located just anterior to the ear and connects the lower jaw (mandible) to the skull. Problems with the joint, referred to as TMD or temporomandibular disorder, affect many people in the United States. TMD affects more women than men. TMD is most commonly caused by stress. Stress promotes the patient to unconsciously clench the teeth together usually at night. The pressure the clenching causes breaks down the cartilage surrounding the joint and over stimulates the facial muscles associated with opening and closing the mouth. Symptoms that this is occurring are pain followed by cracking sound when one opens his/her mouth, headaches, and receding gums.  TMD is treated with a device called a nightguard that prevents patients from putting an exorbitant amount of pressure on their TMJ. This device is worn at night when the patient sleeps.