The Link Between TMJ Disorder and Nighttime Clenching

Stacy’s Note: This is a guest post written by Lee Weinstein, inventor of the SleepGuard biofeedback headband. Lee has designed hospital medical equipment for Hewlett Packard, and has taught electrical engineering at MIT.

For many people,  TMJ symptoms stem from habitual teeth clenching during sleep.

You may have heard of the term “sleep bruxism”, which includes both clenching and grinding. Everyone who grinds his or her teeth clenches as part of the grinding, but not everyone who clenches grinds. The grinding part causes tooth wear, but most of the problems of TMJ Disorder come directly from the clenching.

In this article we’ll take a look at three main things:
1. Why clenching causes so much more damage than chewing.
2. How diverse symptoms such as migraines, jaw pain, neck pain, TMJ joint problems, loose teeth, receding gums, and root canals can all come from clenching.
3. How nighttime clenching becomes a habit (and why the clenching habit remains even when you remove the original cause).

1. Why does clenching cause more damage than chewing?

All the joints of our bodies are designed to withstand much larger forces briefly than they can sustain over a longer period of time. When a runner runs on pavement, it is not unusual for his or her ankles and knee joints to sustain brief shock forces of 400 pounds for a few hundredths of a second each time a foot hits the pavement. When you chew a piece of meat, it is not unusual for your teeth to sustain a brief pulse of force of over 100 pounds for a tenth of a second on each chew. But…the protective tissue in our joints that cushions these blows can only do so briefly.

The protective tissue in our joints has many of the same qualities as Silly Putty. If you ever played with Silly Putty as a kid, you know that if you make it into a ball, you can bounce it. During the brief shock force of the bounce, it behaves like rubber, but if you squeeze it for even half a second, it mashes like dough. When something is resilient when you squeeze it briefly but mashes when you squeeze it longer, that property is called “thixotropic”. The thixotropic protective tissue in our temporomandibular joint and around the roots of our teeth gets mashed and accumulates damage when we clench for more than a couple of seconds at a time. That’s why clenching can cause so much more damage than grinding.

2. The many and varied consequences of clenching

Now lets look at the different consequences of that protective tissue being damaged.

Consequences of clenching:
Bacteria gets between teeth and the jaw (which leads to loose teeth, receding gums, an abcess, or some combination of these problems)
Jaw pain, clicking and popping
Nerve damage
Headaches, migraines, tinnitus

When the protective tissue that bonds teeth into the jaw is damaged, one bad consequence is that bacteria can get between the teeth and the jaw, and this can lead to loose teeth, receding gums, an abscess that requires a root canal procedure, or some combination of these problems.

When the protective tissue in the temporomandibular joint is damaged, many things can go wrong. The joint can become painful. The geometry of the joint can change so that clicking and popping can occur. But because the trigeminal nerve runs through that joint, as protective tissue in the nerve becomes damaged, many more things can go wrong.

When the trigeminal nerve gets mashed from clenching, direct pain may result, and in addition sympathetic and parasympathetic nerve fibers can carry signals to the brain that can bring on headaches or migraines. Facial pain, muscle pain, and ringing in the ear are also common effects.

3. How nighttime clenching becomes a habit

The way we build a habit is that over time we build a neural association (connection) in our brain between something we see or hear or feel and an action we take in response. We build good habits this way (like stepping on the brake when tail lights light up in front of us), and we sometimes build bad habits this way (like fingernail biting in response to stress).

Building a nighttime clenching habit looks like this:

Once the habit is in place, the original disturbance or intention that put the habit there can go away, and the habit remains.

An established habit looks like this:

Each time we use a neural pathway, it gets strengthened. This happens physically at the synapses between neurons. So as the habit gets more entrenched, this neural “path through the forest” may begin to look more like a road or a highway.

Do you grind or clench? Have you had any success trying to stop it? Share your experiences with us in the comments below.