A new way for TMJ: In jaw time
In the 1970s and ‘80s, many people were told that their jaw ached because of a problem with their temporomandibular joint (TMJ), the hinge-like connection on either side of the head that allows the lower jawbone to move up and down (see illustration). Physicians and dentists believed that the joint needed to be fixed to get rid of the pain — and, furthermore, that a bad bite (the medical term is malocclusion) was often the reason the joint didn’t work properly, in much the same way that an ill-fitting shoe might throw an ankle, knee or hip out of whack. As a result, jaws were operated on and all sorts of dental work — braces, crowns, the grinding down of teeth — were done to fix bad bites.
But in the last 10 years or so, the thinking about TMJ disorders has changed. Clinicians aren’t nearly so quick to point a finger at a malocclusion or a faulty temporomandibular joint. There’s now more attention paid to sorting out the myriad sources of jaw and facial pain, which can range from a dental problem to migraine headaches to clenching the teeth because of anxiety and stress.
Dr. Jeffrey Shaefer, a TMJ disorder expert at the Harvard School of Dental Medicine, says it’s often best to tackle several problems at once because the pain may have several interrelated sources. And, for the most part, the kind of dental work done in the past is now low on the list of interventions.
Clever Engineering
The temporo- in temporomandibular refers to the temporal bones that form the sides of the skull, and mandibular refers to the mandible, the medical term for the lower jawbone. Each temporal bone has a notch in it just in front of the ear. The two ends of the horseshoe-shaped mandible fit into those notches (see illustration) to form the TMJ joints. The ends of the mandible, or condyles, are wrapped in layers of tough but pliable fibrous cartilage that withstand shearing. Ligaments hold everything in place.
Despite the unwieldy name, the temporomandibular joint is another example of just how cleverly our bodies are put together. When you open your mouth a little, the condyles of the mandible rotate. In that limited range of motion, the joint works like a fixed hinge. But open wider, and the condyles rotate forward in the notches. This second, rolling kind of motion is called translation, and it allows the lower jaw to swing open without interfering with breathing or swallowing. You can get a firsthand feel for these movements by placing your fingertips on the sides of your head near the openings of your ears while opening and closing your mouth several times.
It takes a surprisingly large number of muscle groups, relaxing and contracting in a coordinated fashion, to operate the elegant joint. It’s pretty obvious from even a cursory look at the anatomy that the masseter muscles are instrumental: They form a thick band that connects the mandible to the cheekbone on both sides of the face (masseter comes from the Greek word maseter for chewer). It’s not so obvious, though, that many other muscle groups are involved, including some on the sides of the head (the temporalis muscles), in other parts of the face (the pterygoid muscles), and several in the neck. Part of the reason why TMJ problems are sometimes difficult to pin down is because the joint has connections to several muscle groups.
Noisy Is Not A Problem
The classic TMJ symptom is a dull ache on one side of the face that gets worse with chewing. The pain may radiate, spreading to the area around the ear, the side of the head, and the back of the neck. Some people also get headaches. The jaw sometimes clicks or produces a cracking, grinding sound (crepitus) because the cartilage in the joint is out of place. It may sound bad, but unless it’s painful, a noisy jaw by itself isn’t cause for concern or treatment.
Often, though, the main problem is muscle pain, which occasionally can be traced back to a faulty TMJ but more commonly comes from other sources. For example, many people with a TMJ disorder grind their teeth at night. One study found evidence of grinding (bruxism) in 78 percent of TMJ patients. Besides being bad for the teeth, all that extra motion can overwork the masseters and other jaw-related muscles.
TMJ symptoms frequently occur when people are under stress because they’re clenching their teeth all the time without being aware of it, and clenching also puts a strain on jaw and facial muscles. Taut head and face muscles can lead to headaches.
Detective Work
The diagnostic exam of someone with jaw or facial pain that could be TMJ-related will include a physical exam. As you might expect, the clinician will touch the area near the joint to see if it’s tender. Patients are also asked to move their jaw to see what kind of motion produces pain. If there’s discomfort with up-and-down movement but not when the jaw is wiggled side to side, it can be an indication that the primary problem is muscle pain, not in the joint itself, according to Dr. Shaefer. If both movements cause pain, that’s a sign that the joint itself may be the problem.
TMJ disorders can take some extra diagnostic detective work because jaw and facial pain have many causes. The patient’s history becomes paramount: a careful description of symptoms, when they started, what they are associated with, as well as a complete list of other medical problems.
Part of the reason TMJ disorders used to be overtreated with surgery and dental work is that doctors and dentists thought they had an objective means of diagnosis, in the form of imaging tests (x-rays, CT scans). The pictures showed what looked to be abnormalities in the joint and bite so doctors and dentists set about to fix them when they weren’t necessarily the source of the problem. Now, imaging tests are usually ordered only after initial treatment hasn’t worked.
Jaws-Ercise
Many people with TMJ pain from the joint or the surrounding muscles respond well to some combination of hot and cold packs, anti-inflammatory medications, and exercises — the isometric variety to strengthen jaw muscles, and others to stretch them out. We don’t normally think about exercising our jaws — aside from overzealous eating and talking — so a “jaw-ercise” routine might seem strange at first. One of the standard isometric exercises involves opening your mouth an inch and pressing your lower jaw against a fist held under the chin for a few seconds and then relaxing your jaw. Naturally, the exercises will help more if the main problem is muscle pain.
If these conservative measures don’t work, then the next step is often an occlusal splint, a fancy term for a device that resembles the mouth guards worn while playing sports. By propping open the bite slightly, occlusal splints take pressure off the temporomandibular joint and relax muscles. For people who grind, they have the added advantage of protecting their teeth.
Several years ago, University of Washington researchers conducted a study comparing conservative treatment against two types of splints — the hard, acrylic variety that requires special fitting and the inexpensive soft vinyl variety. After a year, the three treatments had about the same effect. This result argues for giving low-cost conservative treatment a try first. On the other hand, people with nighttime clenching or grinding habits and those with long-standing TMJ pain problems may benefit from a splint right from the start.
If a splint doesn’t help, other treatments include those used for chronic pain conditions, such as nerve blocks (injections of anesthetics that temporarily deaden nerves). Tricyclic antidepressants, which in low doses are used as pain killers, and muscle relaxants are sometimes prescribed. Surgery is an option if the pain is coming from the joint itself, although it’s now something of a last resort. The simplest procedure involves removing excess synovial fluid from the joint (arthrocentesis). There are operations that involve repair and removal of damaged cartilage, but these are seldom used.
Just Another Joint
TMJ problems are beginning to look more and more like those chronic pain syndromes — resistant to quick fixes and ready explanation but amenable to treatment. There’s also a psychological component — stress and anxiety are contributing factors — which may be as important as the biomechanics. Successful treatments require case-by-case judgment, careful diagnosis, and a well-defined treatment plan.
