Question: What is the most-used joint in your body?

If you answered the knee or fingers, you were wrong.

It's actually the temporomandibular joint (TMJ) that attaches our lower jaw to the temporal bone in our skull in front of each ear. These flexible joints allow the jaw to move easily. Muscles attached to the temporomandibular joint control the position and movement of the jaw.

Think about it.

Every time we talk, chew, even swallow, we are using our temporomandibular joint. And if there are problems with the joint, we can sometimes even hear it.

Snap. Crackle. Pop.

Ouch.

A dysfunction in this very complex joint system can cause a variety of health problems-from headaches to ear pain (and ear ringing) to discomfort that occurs each time you swallow or talk.

Over the years, pain and dysfunction of the jaw area have been identified by many names. In the 1960s, health experts referred to it as TMJ pain and dysfunction syndrome (TMPD). In the '70s, the dental community added myofascial pain dysfunction syndrome (MPD) to the mix. In the '80s, the phrase temporomandibular disorders (TMD) became the way most health experts defined the set of particular syndromes. The condition is most commonly referred to as TMJ-a catchall term for a hodgepodge of symptoms.

According to The National Institute of Dental and Craniofacial Research of the National Institutes of Health, more than 10 million people in the United States suffer from TMJ problems at any given time. Many don't even know what's wrong with them. Indeed, the majority of TMJ sufferers end up at their dentist's office only after exhausting other options.

"The most common complaint in TMJ disorder is headache pain," says Dr. Thomas Doan, DMD, whose Sarasota office specializes in diagnosing and correcting TMJ. "Many of our patients don't associate their pain with a mouth or dental problem. Half of our referrals come from physicians who have seen the patient for neurological complaints."

Doan says that the first step to an accurate diagnosis is to gather a complete patient history. Next, they will also check the sound of the joint-and then X-ray it. With this information, a specialist can perform a muscle evaluation of the sound that joint makes. In severe cases, Doan says, MRI technology is used to determine if there is a deformity of the joint itself. The dentist will also check to see if the patient shows signs of grinding his teeth, known as bruxism, by observing patterns on the teeth.

But how does TMJ disorder come about and who gets it?

According to Doan and other experts in the field, findings show that more women are diagnosed with the disorder than men.

"A lot of our patients are middle-aged women," says Doan. "But that's probably just because statistically they are more prone to investigate causes of their pain. That said, we've had patients as young as 13 and up into their 90s."

Causes for TMJ problems vary. Injury to the jaw area can certainly affect the joint. Auto accidents are frequently the cause, especially when whiplash is concerned. Biting into a piece of food that's too big for your mouth can tear the ligament that holds the joint and knock the jaw out of position. Poor posture is also a factor; holding the head forward all day in front of a computer screen can strain the muscles of the neck. Even chewing gum too vigorously can lead to TMJ.

Doan says that stress is often the culprit.

"Stress, in general," he says, "overloads our system. Often it comes down to unhealthy lifestyle habits. We look at sleep patterns, eating habits and posture. Learning ways to relax our muscles, even the way we rest our mouth while we sleep, can help. Education is really key here-learning how to better care for ourselves, and what signs to watch for."

Teeth that do not fit together properly are also a leading cause of TMJ disorders. Doan says we can compensate for an improper bite by moving the jaw in certain ways, especially while we sleep. "The jaw wants to rest in a comfortable place so that the teeth can rest," he says. "If the bite is off, it may lead to clenching and grinding of the teeth, especially during REM sleep. The stressful force of clenching causes pressure on the muscles, tissues, and other structures around the jaw."

Arthritis and other conditions that occur in the joints can also precipitate or aggravate TMJ pain and dysfunction.

So, you have a TMJ disorder. What's next?

After the diagnosis is made, most experts recommend simple therapies to begin with. Doan says that some of the first steps include putting the patient on a softer diet to determine if the pain is connected to eating habits. He'll also often recommend lowering stress levels through a change in lifestyle. Treatment might include massage and learning better sleep habits.

If an improper bite is the culprit, he might recommend a bite appliance that will help realign the joint to its proper position and create "new muscle harmony" within the head and neck system. These curatives work, he says, in 90 percent of the cases his office sees.

Other remedies include the use of certain medications, including anti-inflammatories and muscle relaxants. If the cause is stress, the patient might even be referred to a psychotherapist who specializes in stress management.

Many dentists feel that patient management and awareness are key to controlling TMJ-associated problems. "It's a gray zone," says Dr. Mitchell Strumpf, DDS. "I find a good level of success with patients who are aggressive in their management and aware of their symptoms. For instance, if we recommend that moist heat be applied to the area, those patients who use the heat the next time they have an episode will find their problem taken care of. At this level, it's management of the symptoms."

If all conservative treatments have been exhausted and the pain still occurs, the patient might be referred to an oral surgeon or prosthodontist.

"If the problem stems from an adhesion formed between the disc and tissue, an oral surgeon could break up the adhesions and any inflammatory cells," says Doan. The next level might be open joint surgery in order to reposition the disc itself. But according to Doan, this latter treatment is not always successful. In severe cases, he says, a total joint replacement (replacing the joint with a titanium plate) is done. He stresses, however, that only 10 percent of the patient population will require a specialist for treatment; of these, only five percent will require surgery.

Dr. Howard Chasolen, DMD, is a Sarasota-based prosthodontist who regularly treats disorders of the temporomandibular joint. He agrees with his colleagues that the first step is always careful diagnosis to determine if the problem is a muscle or a joint disorder. Muscle disorders are treated with a combination of therapies, including massage therapy, mild medications, small adjustments to the bite, and behavioral or stress management.

If the problem is within the joint itself, these same conservative principles can be applied, he says. In addition, more invasive procedures may be necessary. Sometimes, bite reconstruction might be involved. "The treatment goal is to try to manage the force transmitted to the jaw joint. We might work on changing the relationships of how the teeth meet by either capping or crowning some or all of the teeth."

In certain circumstances, when the cartilage in the joint is badly damaged (from traumatic injury, degenerative arthritis, or years of a bad bite), surgery may be indicated. "The goal of surgery is either to repair the cartilage or to replace the joint itself, which is also a procedure that is reserved for very advanced situations," says Chasolen.

Chasolen stresses that the patient with severe TMD will need to work with a team of specialists experienced in joint mechanics and bite reconstruction. These will include a prosthodontist, orthodontist and an oral surgeon.

The good news for those who suffer from TMJ-related problems is that, in most cases, treatment is simple and effective. The key is proper diagnosis, so make sure to take a list of questions with you when you visit your health professional. For more information, you can contact the TMJ Association (www.tmj.org).

And next time you're about to bite into that Dagwood-style hoagie, be careful!

Talking TMJ

10 questions to ask your physician.

* What's the purpose of the proposed treatment and why is it necessary?

* Is the treatment reversible?

* Will it reduce my pain?

* What side effects may I experience and what can be done about them?

* Has this treatment been studied for safety and effectiveness?

* What other treatments are available?

* How does this treatment compare with others with respect to benefits and risks?

* What will happen if I leave this condition untreated?

* How much will it cost, and how do these costs compare with other treatments?

* How many follow-up treatments will be necessary?

* Will insurance cover the treatment costs?

JOINT VENTURES

Temporomandibular joint (TMJ) implants have existed for more than a quarter century for patients unable to find relief through any other method. But because they entered the market long before the Food and Drug Administration (FDA) began regulating new medical devices in 1976, it's only been a few years since FDA required them to demonstrate their safety and effectiveness.

From 1984 through 1998 (the last year for which numbers are available), FDA reported 434 "adverse events" for TMJ implants. Fifty-eight percent were associated with patient injuries, 28 percent with device malfunctions, and 14 percent with "other." None caused death, and more than 75 percent were caused by just two manufacturers, Dow Corning and Vitek, who no longer manufacture these implants.

Since 1995, the number of adverse events has dropped dramatically; only 15 percent were reported between 1996 and 1998, and most of those were attributed to surgery to remove faulty implants, pain, physical reaction to the implant, or loss of range of motion.

These problems were due mostly to design. Made mostly of plastic, Teflon, silicone and metals like cobalt and chrome, these older artificial devices often did not restore normal joint movement and were sometimes unable to relieve the pain associated with TMJ.

Dr. Craig Misch, a specialist in oral and maxillofacial surgery and prosthodontics, says that newer implants have a very high success rate, but adds, "The jaw joint is very difficult to replicate." Unlike other joints that operate in only one or two directions, he says, "[The jaw joint] has to allow the jaw to open and close, or go left or right."

A complete jaw joint replacement consists of two separate pieces that are attached with screws to the skull and lower jaw. The surgery requires a hospital stay and general anesthesia. That's why Misch prefers to try arthroscopic surgery to clean the joint or inject steroids first. "TMJ surgery is the last resort to managing this condition," he says.

Plus, all implants degenerate over time. "The problem we had in the past was, implants come in two pieces," says Misch. "When you have two pieces of material like metal rubbing together, they degrade and can cause irritation and inflammation." Misch says newer models made from titanium and polymer that mimic the composition of the actual jaw joint have only been available for about five years. "Hopefully, we'll get more use out of them, at least 10 years."

Newer implants can also be custom fitted to individual patients. "In the past, we used to pick out the implant that we thought would best fit the patient's anatomy," Misch explains. Today, by examining patient CT scans, "We can have a computer make a model that is anatomically identical."

At the same time, researchers are turning their focus to biological alternatives. Misch is currently involved in one plan to implant human cells that may grow new bone or cartilage over time, and another that involves stem cell research. Last August, researchers at Duke University announced they had produced a polymer liquid gel that can be injected into damaged joint cartilage tissue, then solidified with laser lights. Once in place, the body's own cells grow around it to help rebuild the damaged tissue, and eventually, the joint. The National Institutes of Health reported that in only two weeks, researchers grew new cartilage in a rabbit knee joint.

Misch looks forward to what this means for human joint replacement. "Certainly this will happen in my lifetime," he says. "In the next five or 10 years, we'll be doing these procedures in clinical studies. It'll change everything." -Pat Haire