Rheumatoid arthritis (R.A.) is common among all types and ages of people around the world, from young children to elderly citizens. In addition to achy joints, people suffering from R.A. can also experience jaw pain.

R.A., an autoimmune disease that affects joints and surrounding tissue, occurs when the body's immune system sends incorrect signals to joints.

The American College of Rheumatology has seven criteria for diagnosing R.A., including: simultaneous arthritis pain around three or more joints, including one hand; stiffness of joints in the morning that lasts more than one hour; X-ray proof of R.A. changes; and symmetric pain in joints.

Approximately 1 per cent of the world's population experiences R.A., and this statistical rate is consistent for individuals in the U.S., as well, with about two million people affected at any time.

Pain as a result of R.A. can occur in the upper or lower jaw, the jaw joint or the inner part of the mouth. Possible causes include weakening of the jaw, tiring of the jaw from excess use, or the effects of R.A.

R.A. can affect the temporomandibular joints that hold the jaw, and in young people who are suffering from a severe case of R.A., the top section of the jawbone can actually shorten as a result of degeneration. In extreme cases, the jawbone can fuse to the skull.