Temporomandibular Joint Disorder, or TMJ, is a painful condition that can cause annoying symptoms such as popping, clicking and tenderness of the jaw. Perhaps most alarmingly, it can make it difficult to move the jaw. Some common causes of TMJ include stress, injury, and misaligned jaws. For example, stress can cause teeth grinding that can alter the way the teeth fit together, leading to jaw misalignment. Injuries and a dislocated jaw can also cause such misaligning changes to the jaw structure. As is the case with any joint in the body, the temporomandibular joint can also develop arthritis that makes it painful and difficult to move. Fortunately, TMJ-related pain often responds to non-invasive measures such as stress reduction exercises, heat packs and dietary changes. For persistent pain, your dentist can prescribe a night guard designed to reduce teeth grinding, jaw strengthening exercises and medications.