Are TMD and TMJ the same thing?

TMD (temporomandibular joint disorders) is the name for a group of problems that cause pain and dysfunction in the jaw joint (temporomandibular joint -- TMJ) and the muscles that control jaw movement. TMJ is an abbreviation for the temporomandibular joint. However, the phrase TMJ disorder, or just TMJ, is widely used instead of TMD to mean a group of jaw-related conditions.

No. TMJ refers to temporomandibular joints, the joints and jaw muscles that make it possible to open and close your mouth. The TMJ joints work together when you chew, speak or swallow and include muscles and ligaments, as well as the jaw bone.

TMD stands for temporomandibular disorder or TM problems. Any problem that prevents this complex system of muscles, ligaments, discs and bones from working properly, including tenderness, clicking, popping or difficulty moving, is considered TMD. Some TM problems result from arthritis, dislocation or injury. All can cause pain and dysfunction. The muscles that move the joints are also subject to injury and disease. Other factors relating to the way the upper and lower teeth fit together (the bite) may cause some types of TM disorders. Stress and teeth grinding are also considered as possible factors. 

There are several treatments for TM problems which may include stress-reducing exercises, wearing a mouth protector to prevent teeth grinding, orthodontic treatment, medication or surgery. Your dentist may also request specialized x-rays for the TM joints. Depending on the diagnosis, the dentist may refer you to a physician or another dentist.