Temporomandibular Joint Disorders

Biting Off More Than We Can Chew

By Ruth Werner
[Pathology Perspectives]

Do you have TMJ? I will answer that question: you do. In fact, you have two of them: a left one and a right one. TMJ, of course, refers to the temporomandibular joint. TMD is the label for temporomandibular joint disorders—and that is the focus of our discussion here. Before we begin, I want to offer my profound thanks to my friend Sherri F., who shared some of her experiences as I prepared this article, and also with the numerous teachers and practitioners who generously shared their insights.

Your Jaw-Dropping TMJs

Your temporomandibular joints are amazing! They allow movement in several planes, including up and down (elevation and depression), forward and back (protraction and retraction), side to side, and all directions together. Even more amazing, they do all those actions twice at the same time—it is impossible to move one TMJ without moving the other.

A fully functioning TMJ involves the temporal bone, the mandible, their articular cartilage, a flexible disc or meniscus that separates the bones, and a stretchy joint capsule that allows a generous range of motion. The muscles that cross the joint are short and powerful, and they have higher resting tension than most muscles. This means that the mouth is mostly closed when we’re relaxed. (It also means that those muscles get especially stressed when have our mouths open for long periods—for instance, when we undergo a dental procedure.)

Because the masseter, temporalis, and pterygoid muscles are located close to—even overlaying—the TMJ, their actions are extremely efficient. This gives us excellent bite force. (See the sidebar “How Strong is the Human Bite?” on page 42 for more information on this topic.)

When any combination of TMJ components has a problem, the repercussions ripple far beyond the jaw. The pain that ensues can affect virtually every aspect of our well-being. The pain initiated by TMJ irritation can quickly develop aspects of chronic pain and central sensitization. This means that the symptoms a person experiences are generated in the central nervous system, and not necessarily tied to the severity of specific biomechanical damage. It also means that repairing any damage may not lead to resolution of the pain. And the whole-body compensations that develop in response to jaw pain can exacerbate that pain, creating yet another self-sustaining pattern.

“I’ve had jaw problems for a while. I had some bad dental work in my 30s. I was in a couple of car wrecks, a dog bit my face, I had a fall. But I never had chronic pain until the last couple of years.”

Some TMD Statistics

It’s hard to say how many people have TMD, because consistent diagnostic criteria for this condition have not been established. Instead, statistics on TMD symptoms like orofacial pain and chewing difficulty are gathered as an indicator for how common TMD might be within a given population.

Estimates suggest that some 10 million people in the United States have symptoms of TMJ disorders—this works out to about 1 in every 8 adults. Women are diagnosed 2–9 times more frequently than men. This is such an extreme discrepancy that some researchers consider estrogen receptors in the jaw to be a possible contributing factor for TMD. 

People who live with mood disorders (especially anxiety, posttraumatic stress disorder, and depression) or addiction have TMD more often than the general population. People who have rheumatoid arthritis (RA) are very likely to also have TMD problems (53–93 percent of people with RA report pain at the jaw). 

Some TMD Contributors

It is clear that while problems at the jaw may trigger pain responses, the way that pain is manifested throughout the body goes far beyond biomechanical contributors. However, it is important to understand possible anatomical disruptions in the whole TMD picture. The table below lists the structures usually involved in jaw problems, and what can go wrong with them.

Here is a short list of possible contributors to jaw pain:

• Trauma, for instance, a car accident or blow to the jaw. Trauma can cause muscle strain or irritation, disc displacement, and chemical damage to structures related to inflammation.

• Jaw use, in the form of bruxism, teeth-clenching, and repetitive activities like gum chewing or playing the violin.

• Occlusion problems. A dysfunctional bite can distort the force that moves through the joint. Research suggests this can be one factor but is usually not alone.

• Hormones. As stated previously, a link exists between estrogen levels and TMD risk. Further, the higher a woman’s estrogen levels, the more pain with TMD she is likely to report.

• Psychological factors, especially about stress management, can be contributors and sustainers of TMJ dysfunction. And having a chronic pain syndrome that interferes with both eating and self-expression is especially challenging. It is easy to see how the stress of dealing with TMD can exacerbate symptoms to the point that jaw pain quickly becomes a whole-body problem.

“I know I’ve been kittywampus for years, but now I look in the mirror and I feel like I don’t recognize myself anymore. It’s incredibly upsetting.”

Symptoms of TMD

Pain is the number-one symptom of TMD. That pain can be sharp, dull, jabbing, or electrical. It can be at the jaw; in the teeth; and/or in the eyes, ears, and over the back of the head. It is often exacerbated by activity at the mouth—not just eating, but any kind of vocal expression can elicit pain.

“When I sing, or laugh, or even smile, I know I’ll pay for it later. It makes it hard at my daughter’s soccer games or dance recitals.”

In addition to mouth and facial pain, TMD can cause headaches. This can be a reflection of trigeminal nerve irritation, a trigger for migraines, or a referred pain pattern from trigger points in the jaw muscles. Trigger points can also form in overactive muscles that stabilize the neck and head; the sternocleidomastoid and splenius muscles are frequently involved here.

TMD can lead to vertigo, possibly because the proprioceptors in the jaw help to determine our orientation in space, and when they send messages that don’t match our eyes and inner ears, we get dizzy. Neck pain, arm and shoulder pain, back pain, and changes in gait can all be considered as ripples of TMJ dysfunction, as the body tries to compensate for problems at this keystone location.

TMD Treatment Options

Treatment for TMD begins with noninvasive, nonpharmacological interventions. These may include identifying and avoiding triggers, taking care with food and sleeping, using a splint to limit grinding, and addressing the psychological aspects of jaw pain with appropriate types of therapy.

If drugs are called for, they will typically include NSAIDs, tricyclic antidepressants, muscle relaxants, and antianxiety medications, including benzodiazepines.

More invasive interventions include trigger point injections, injections into the joint space (this might be with a steroidal anti-inflammatory and/or an anesthetic), and Botox injections into chronically tight muscles.

And if surgery is conducted, it is usually because specific structural damage has been identified and needs to be corrected. This might require a repair to the meniscus, or a whole joint replacement.

It is important once again to emphasize that when TMJ-related pain is a whole-body phenomenon, it is not realistic to expect that repairing the biomechanical structure will eradicate symptoms. This is a condition with deep and complex psychosocial factors that accompany the biomechanical ones.

“I’ve been to the dentist; the massage therapist; the chiropractor; the ear, nose, and throat doc; the naturopath. I know they won’t fix me. I have to do the work. I can’t expect any one treatment to be my miracle.”

How Strong is the Human Bite?

In 1861, Dr. G. E. Black, president of the Chicago Dental University, designed an instrument to measure bite force. He called it a gnathodynonometer. He found that the variable most likely to interfere with bite strength was the health of the teeth and gums. People stopped biting the testing device, he reported, because their teeth hurt. Of 1,000 test subjects, he found the average pressure at the molars at peak clench was 171 pounds on each side, and the very highest pressure he measured was about 275 pounds.

In 2010, a researcher named Stephen Wroe recreated a human skull in a way that could test bite force in three dimensions. He established that with this model, the human bite is stronger than what Dr. Black found. It turns out we exert about 1,300 Newtons (almost 300 pounds) at the molars. That is surprisingly strong; the only primates with stronger bite force than humans are gorillas and chimpanzees.

Interestingly, while jaw disorders cause pain and limited range of motion, they do not appear to affect bite force.

Implications for Massage Therapy

It seems like highly skilled massage therapy could play a useful role for clients with TMD, but the research on this topic is inconsistent. That said, many dental professionals enthusiastically recommend massage therapy as an early intervention for TMJ disorders.

As we stated before, the jaw appears to be a point of reflection for function and dysfunction throughout the body. If someone has chronic TMJ pain, the chances are good that they have pain elsewhere too, and a holistic approach that considers all the factors is probably more likely to have a positive outcome than a piecemeal approach. So, as we consider the jaw, let us also look at the shoulder girdle, the position of the pelvis, and how the feet hit the ground—they’re all connected, obviously.

And at the jaw itself, we have some choices. The masseter and temporalis muscles are obvious and easy to work with, and they have a lot of influence on the health of the joint. The pterygoid muscles require more specialized skill, but they are also palpable (at the back of the inside of the cheek) without the thick layers of skin, fat, and fascia that cover most muscles.

Work inside the mouth carries some serious responsibilities. Hygienically, of course, we use clean, hypoallergenic gloves to work in this location. But it is important to mention a few other points about intraoral massage:

• It’s not for beginners, and it’s not for dabbling. When things go wrong in this joint, problems can reverberate through the whole body. Let’s not accidentally contribute to dysfunction by being careless and undereducated. Are you interested in intraoral work? Get advanced training.

• Local laws about massage therapy and intraoral work vary. Some states don’t address it at all. Others require a doctor’s prescription. Others require signed client consent. And some don’t allow massage therapists to do intraoral work without documentation of a minimum standard of advanced training. Find out what your local laws allow, and be compliant.

• Intraoral massage may trigger unintended responses. A gag reflex is common and annoying, but emotional release in response to work in and around the mouth is also a strong possibility. It is critical that massage therapists be mindful of their scope of practice and respectful of their clients’ processes if this happens. Massage therapists must be prepared to be present, nonjudgmental, and appropriately supportive for this kind of event. Once again, it’s not for dabblers. If you want to do this work, get appropriate training.

• Intraoral work is the only place where we work inside the body. The rules here are different. The quality of the epithelium is different. The amount of tissue between our fingers and the targeted structures is different. And innervation is different: sensory supply inside the mouth is greater than in other parts of the body. A little touch here goes a long way, and a short session is likely to be more effective than a longer one.

This article barely scratches the surface of what we can understand about the TMJ, the way its status affects the whole body, and how massage therapy might be used in this context. You could say that in taking on this topic, I bit off more than I could chew (ha ha). Interested readers can find some more specific suggestions for bodywork in two fine Massage & Bodywork articles: “Working with the Masseter” by Til Luchau (September/October 2013, page 114) and “Clicking Jaw Syndrome” by Erik Dalton (January/February 2015, page 99).

We have important skills to offer our clients with TMJ disorders, if we are skillful, professional, well trained, and mindful of the power of our work. What are you waiting for?


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