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Fri 1 Jun 2007 12:00 AM

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Caution in treating temporomandibular disorders

Female patients may be ready to try anything for relief from jaw pain. But unproven fixes can cause greater injury and disability.

For most of us, jaw pain is a fleeting experience - caused, perhaps, by a too-wide yawn, a big bite on a bagel, or an afternoon of dental work. But for women with temporomandibular disorders (TMD), jaw pain - sometimes radiating to the ear, eyes, face, neck, and shoulders - can be a source of unrelenting misery. In desperation, some women have undergone extensive orthodontia, used a variety of oral appliances, or had teeth ground down or selectively removed.

None of these approaches has any proven benefit in treating TMD. Other women have received artificial implants that were never tested for safety or effectiveness, sometimes with disastrous results.

A major effort is underway to understand TMD’s causes and identify who is at greatest risk.

About 10 million people in the United States have TMD. Two-thirds of them are women, and so are 80% to 90% of those treated for the disorder. Symptoms usually first appear after puberty and peak between the ages of 20 and 40. Apart from jaw pain, symptoms include limited jaw movement (or a feeling that the jaw is "locked"), aching while chewing, chronic headache, and clicking or popping sounds in the temporomandibular joint (TMJ).

TMD was generally considered a matter best left to dentists and oral surgeons. But experts have concluded that it's a more complex disorder, often encompassing other medical conditions (including various forms of arthritis), and influenced by genes, hormones, trauma, or environmental triggers. A major effort is underway to understand TMD's causes and identify who is at greatest risk - necessary first steps in developing safe and effective treatments. In the meantime, health experts strongly recommend using non-invasive, reversible measures in most cases.

What causes all the trouble?

TMD encompasses a range of conditions that cause pain and dysfunction. Most complaints fall into one or more of the following categories: myofacial pain (pain in the muscles controlling the jaw), damage or dislocation in the joint (for example, a displaced disc or injury to the condyle), and arthritis (joint degeneration). Especially when it is chronic, TMD pain can contribute to other problems, including depression, sleep disorders, and physical disability.

In some cases, direct injury to the jaw or joint precedes the development of TMD. Osteoarthritis, poor posture, and misuse or overuse of jaw joints may also be factors. Jaw clenching, which is common among TMD patients, can exacerbate the condition by causing collagen in the joint to break down and trigger the release of substances that encourage inflammation. But in most cases, scientists don't know what precipitates TMD. Research has shown that jaw noises, orthodontic work, and a bad bite are not direct causes. The role of stress, tooth grinding (bruxism), and hormones is controversial.

Because reproductive-age women suffer disproportionately from TMD, there's some thought that hormones are involved. The temporomandibular joint contains estrogen receptors, although their role remains unclear. Experiments in rats suggest that estrogen replacement enhances bone remodeling in the joint. But in human studies, use of estrogen has been associated with an increased likelihood of developing TMD. Ultimately, the influence of estrogen may depend on individual genetic makeup.

TMD's shifting landscape

According to the TMJ Association, TMD has long been considered the "turf" of dentists. The American Dental Association doesn't recognise the disorder as an official subspecialty, but that hasn't stopped some dentists from declaring expertise in TMJ disorders and providing treatments that are unproven, useless, and sometimes harmful, most of them paid for out of the patient's own pocket, since insurance rarely covers TMJ appointments and procedures.

TMD gained notoriety during the 1970s and '80s, when new imaging techniques led some dentists to advocate treatments that changed a patient's bite and oral surgeons to focus on correcting displaced disc cartilage. The surgery appeared to work 50% to 80% of the time, but when it didn't, jaw implants were next.

Many patients were victimized by this industry, which was unregulated at the time. Two jaw implants, Vitek and Silastic, caused some patients to develop severe chronic pain, bone and tissue degeneration, and even vision and hearing problems, but insurance companies refused to pay for removing them.

After a congressional hearing in the early 1990s, the outlook started to improve. The Dental Products Advisory Panel of the FDA has placed TMJ implants in the highest risk category, Class III, which requires pre-market approval contingent on a demonstration of safety and effectiveness. Also, the National Institute of Dental and Craniofacial Research, part of the National Institutes of Health, is conducting a seven-year study to identify risk factors for the disorder. Called Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA), the study will follow 3,200 healthy volunteers for three to five years to track the onset and natural course of TMD. It could help open the way to better, more precisely targeted therapies.

Selected resources

The Aging Eye: Preventing and Treating Eye Disease (Harvard Health Publications, 2006)

Cataracts: A Patient's Guide to Treatment, by David F. Chang, M.D., and Howard Gimbel, M.D. (Addicus Books, 2004)

Finding relief

Surgery should be considered only as a last resort.

The first step is proper diagnosis, says Dr. Jeffry Shaefer, clinical director of the Orofacial Pain Clinic at Boston's Massachusetts General Hospital. Many conditions can mimic TMD - nerve problems, cancer, sinus infections, and even heart disease can cause pain in the jaw. Your primary care provider can help rule out such causes while checking for muscle tenderness and joint function. It's also a good idea to consult your dentist, who may want to refer you to a specialist in orofacial pain.

Health experts generally agree that until we know more, TMD should be managed first with conservative treatments. A person with TMD may want to eat soft foods, apply ice packs or heat, avoid extreme jaw movements (such as wide yawning and gum chewing), and learn techniques for reducing jaw tension and emotional stress. Over-the-counter pain medications, such as ibuprofen, can help relieve symptoms. Physicians may also recommend muscle relaxants and tricyclic antidepressants, which are used to treat chronic nerve-related pain. The aim is to improve pain-free function of the jaw and increase its range of motion. Research has also shown that supplements such as omega-3 fatty acids, chondroitin, and glucosamine can help in controlling inflammation. Some clinicians suggest physical therapy to gently exercise the jaw and massage to relax the muscles.

Stabilization splints are widely used in treating TMD. These plastic bite guards, which fit over the upper or lower teeth, are designed to loosen the muscles and reduce pressure on the teeth and joints. The evidence for their effectiveness is mixed. If you don't get any symptom relief after two months, or if you observe changes in your bite, stop using the splint. It's important to avoid doing anything that causes permanent changes in the structure or position of the jaw and teeth.

Surgery should be considered only as a last resort, and only after you get several independent opinions from oral surgeons and other qualified professionals. More research is needed to evaluate irreversible treatments such as implants and joint replacement, orthodontics, and the grinding down of tooth surfaces.

At a glance: Anatomy of the temporomandibular joint

The temporomandibular joint, or TMJ, connects the lower jaw (mandible) to the temporal bone on either side of the head. To feel the joints move, place your fingertips just in front of your ears and open your mouth.

The condyle (bony prominence) on the upper end of the mandible glides forward within the joint socket of the temporal bone, and then moves back as the mouth closes. A disc between the condyle and the temporal bone facilitates smooth movement. When working properly, the TMJ can move up and down and side to side, glide forward and back, and rotate.

The joint and its associated muscles and ligaments allow us to chew, talk, and yawn. Nerves leading to the face, the sides of the head, and the chewing muscles run through the area. It's also a major pathway for nerves connecting the brain and spinal cord. The structure and function of the joint make this area especially vulnerable to injury.

This article is provided courtesy of Harvard Medical International. © 2007 President and Fellows of Harvard College.

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Ruthie 9 years ago

What happen to my comments and also Barb Drexler's? They were on here for years and now just disappear? Being part of the TMJ Implant Disaster and our government covering up this whole disaster and now you too? The implant disaster continues to this day. What do we all have to do to be heard...go put a gun to our mouths?