Hyaluronate shows promise for TMJ osteoarthritis

Aug 2, 2009

Choosing the right treatment plan for temporomandibular joint (TMJ) osteoarthritis can, like the disorder itself, be a real pain. There's just no single approach that seems to work for everyone.

That's why some researchers are excited about hyaluronic acid injections. A naturally occurring polysaccharide in synovial fluid and cartilage, hyaluronic acid is critical to joint lubrication. In addition, the depolymerization of natural hyaluronic acid plays a role in the cartilage injury involved in osteoarthritis.

So theoretically injecting an osteoarthritic joint with hyaluronic acid should help increase lubrication, reduce joint friction, and improve pain and mobility symptoms. And externally introducing hyaluronic acid stimulates the synthesis of cells leading to endogenous hyaluronic acid formation, as described in a study in Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology (June 2007, Vol. 103:6, pp. e14-e22).

Hyaluronic has proved effective in the knee, and investigators have tried it for treating osteoarthritis in the TMJ since the late 1980s. More recently, in an August 2007 study in the Journal of Oral Rehabilitation (Vol. 34:8, pp. 583-589), researchers from the University of Oslo found it more effective than corticosteroids.

And in an open-label trial recently published in the International Journal of Oral and Maxillofacial Surgery (August 2009, Vol. 38:8, pp. 827-834), researchers investigated the effectiveness of treating TMJ osteoarthritis with a cycle of five weekly arthrocenteses plus hyaluronic acid injections. Patients experienced pain reduction and improvement in jaw function.

However, both these studies were relatively small, and neither had a placebo control group, noted Jeff Okeson, D.M.D., director of the Orofacial Pain Center at the University of Kentucky. "The question we still have to deal with is, are hyaluronic acid injections any better than [arthrocentesis or] nothing at all? We don't know that right now," he said.

Conservative treatment options

Tips for treating TMJ osteoarthritis

For a first-time patient, opt for the most conservative, noninvasive treatments first, such as rest and applying heat or ice to the jaw.
Don't assume that the patient is following your advice. Be creative in ensuring that your patient truly is resting his or her jaw, since many often use their jaw without realizing it. Discuss the diet your patient is following, and make sure it consists of liquids and soft foods that do not exert the jaw.
To help determine that the symptoms are not arising from another health complication, ask the patient when exactly pain is felt. If it is while chewing, the cause is probably jaw-related. But if their pain arises when they're climbing the stairs, you could be dealing with referred pain from a heart problem.
Teach your patient how to keep his or her lips together and teeth apart, to better minimize jaw stress.
If in 10 days the patient does not feel better with rest, consider prescribing nonsteroidal anti-inflammatory drugs (NSAIDs) and/or the use of a mouthpiece.
Dr. Cohen advises using a diclofenac, either in a patch (such as the Flector patch) or topical gel (such as Voltaren), instead of oral NSAIDs to help reduce the drug amount that enters the bloodstream, thus minimizing damage to the stomach and kidneys.
Remember that symptoms can arise from psychological reasons that could lead to repetitive habits such as crunching or grinding. Patients suffering from stress should be advised to consider behavioral management, physical therapy, and/or relaxation training.
Identify and refer: Having employed these conservative options, follow the patient's progress for two to four weeks. If symptoms persist or temporarily improve and return, do not delay in referring the patient out before complications arise.

What then is the best way for dentists to help patients with TMJ osteoarthritis? Dr. Okeson stresses the importance of conservative treatment.

"Nature has been treating this joint for way longer than dentists have been treating this joint," he said. "If you follow long-term studies, most people get well over time."

Joseph R. Cohen, D.D.S., an assistant professor at the University of California, Los Angeles School of Dentistry and president of the American Board of Orofacial Pain, agrees. "Each case is individual, but the majority of patients don't need invasive treatments like surgery," he said.

Unlike other joints in the body that are made of hyaline cartilage, the temporomandibular joint has fibrocartilage, which heals better. "Therefore, your jaw will do a lot better with long-term osteoarthritis than your knees," Dr. Cohen added.

"Most patients will get along with behavioral management, physical therapy, relaxation training, some medications, and the use of a mouthpiece for the more chronic cases. Acute cases don't often need mouthpieces unless it's shown they have grinding or crunching problems," he said.

For a patient experiencing jaw problems for the first time, dentists should recommend resting the jaw and applying heat or ice, consider anti-inflammatory medication, and teach the patient how to keep his or her lips together and teeth apart, Dr. Cohen advised.

These recommendations might be simple but still difficult for the patient to follow. "The biggest challenge is getting a patient to actually rest their jaw because the jaw is used for so many things," he said. "You have to be very creative and persistent, and remind and motivate them at every visit."

If symptoms do not improve in two to four weeks, Dr. Cohen recommends a mouth appliance. At this point, if the dentist has had additional training on orofacial pain, he or she should perform a complete diagnosis. It's important to determine whether the patient is experiencing nerve or muscle pain, or if the pain is referring to the jaw due to another problem, such as a heart attack or cancer in the abdomen, Dr. Cohen said. If you haven't had special training, refer the patient out, he noted.

"It's a scary thing, but if you're treating pain that's lasting for more than a month or two, then you have to be aware of these things," Dr. Cohen warned. "The biggest mistake that I see is that after a month or two, if the patient hasn't significantly gotten better or is continuing to get better, then the dentist continues to try various things that they are not really trained to do."