People who grind their teeth can sometimes develop a serious problem with their jaw, which left untreated, can adversely affect the teeth, gums and bone structures of the mouth. One of the most common jaw disorders is related to a problem with the temporomandibular joint, the joint that connects your lower jaw to your skull, and allows your upper and lower jaw to open and close and facilitates chewing and speaking. People with temporomandibular joint disorders (TMD) often have a clicking or popping sound when opening and closing their mouths. Such disorders are often accompanied by frequent headaches, neck aches, and in some cases, tooth sensitivity. Some treatments for TMD include muscle relaxants, aspirin, biofeedback, or wearing a small plastic appliance in the mouth during sleep. Minor cases of TMD involve discomfort or pain in the jaw muscles. More serious conditions involve improperly aligned joints or dislocated jaws. The most extreme form of TMD involves an arthritic condition of the jaw joint.