Headaches, TMJ and the Bite

While the general population talks about “the bite” when referring to how the teeth fit together, dentists, for some reason, talk about “occlusion.” We’ll stick with “the bite.”  When the public asks about “adjusting the bite,”  dentists are thinking “occlusal equilibration.”  I mention these terms in case you run across them while talking to insurance companies or wandering about the Internet. I’ll try never to mention them again. 🤐

The teeth of each jaw function in harmony with each other and with the jaw joints. The jaw joints are called the Temporo-MandibularJoints. Thankfully there is a short form for that – TMJ. Also performing as part of this harmonious “choir” are the muscles we call cheeks, lips and tongue (and many other muscles of the head and neck.) The choir director is the brain. When all is well, beautiful music results –  speaking, chewing, swallowing , smiling,  and even actual music – whistling and singing.

Let’s drop the choir analogy before it breaks down.

There are many reasons that this enormously complex system can break down, and many practitioners who might become involved in fixing it- dentists, chiropractors, speech therapists, neurosurgeons – depending on the cause of the problem.

Headaches

Recall the phrase I used above – many other muscles of the head and neck. When these muscles have been under stress over time – especially and most commonly overnight – one would expect these muscles to be sore or stiff. That often happens, but the most frequent symptom is a headache. The pain that seems to be originating deep inside the head is actually coming from the muscles just under the skin.

While seeking dental services for a toothache is intuitive, seeing a dentist for headaches is not. Nevertheless, the dentist is a great place to start when seeking the cause of frequent headaches. These are often referred to a “tension headaches” because of the awareness that that the headaches are stress-related. In contrast are migraine headaches which are frequently more sudden, more severe and, fortunately, less frequent than tension headaches.  Migraines are frequently preceded by visual changes called an “aura” and  do not seem to be related to jaw function.

Those complaining of tension headaches usually have no idea that the cause is a faulty bite. Over the years, many chronic headache problems have been eliminated by fixing the way the jaws function in making the teeth fit together.  Please don’t interpret that to mean that all chronic tension headaches respond to this treatment.

What is Going Wrong?

The back teeth – the molars and premolars – are the ones you grind or chew with. The six front teeth – the eye teeth and incisors – are used to bite things off. (The words “incisors” and “scissors” are derived from the same root.)  Try this experiment.

Place your index finger between your upper and lower back teeth. Slowly and gently squeeze your finger with your back teeth. For heaven’s sake be careful – don’t hurt yourself! Slowly increase the pressure until you begin to feel discomfort. Stop before you think it might begin to hurt.  Now repeat the process with your finger between your front teeth. You should notice with the front teeth that more effort is required to get to the point where it might begin to hurt. The point is that the back teeth are subject to much more force than are the front ones.

So Nature, clever as she is, designs  the back teeth  to withstand more force – within limits. The limitation is that the force must be vertical – parallel to the length of the tooth from top to bottom. That can be a problem because the biting surface of back teeth is made up of hills and valleys (“cusps” and “fossae.”)  When biting, if a lower cusp fails to fit precisely into an upper fossa (and vice versa) then the slopes of the hills and valleys will clash.  The slopes direct the forces the teeth put on each other sideways. This sideways force is detected by receptors (sensors) in the tissue that attaches the tooth to the bone. A message is sent to the brain – “Don’t make me bite in this position. I’m suffering damage.” The brain will respond by adjusting the jaw position slightly. Problems arise when several other teeth send the message, “Whoa.  Stop that. Up till now you were doing a great job. Now I’m suffering damage with this crazy new position you’ve put me in.”  When the brain receives conflicting demands, it does the best it can. Sometimes the result is chaos. The muscles operating the jaw never get to rest properly. They become stressed. The chronically stressed muscles are sometimes noticed as sore or stiff muscles of the face, head or neck. More often the result is a headache, and muscles are never even suspected.

Less often, the extra muscular activity which is intended to spare the teeth from encountering sideways pressure doesn’t seem to be very effective, and the result is that the teeth do get sore.  At other times, the extra muscle activity is so chaotic that people will notice that they will frequently bite their tongues or cheeks by accident.

While the front teeth don’t seem to play a role in grinding up food, if the teeth are arranged ideally, they play an important role in protecting the back teeth from sideways forces. If your teeth are arranged the way the textbooks say they ought to be, when you clench your back teeth together, you should feel lots of pressure on your back teeth and very little or none on your front teeth. But, if you then move your lower jaw even slightly forward or to one side or the other you ought to notice that the front teeth or eye teeth “get in the way” so that your back teeth are no longer in contact. The back teeth aren’t getting the enormous sideways force they otherwise would.

That force is now on the front teeth. But, we have already discovered that, because of their location towards the front of the jaw, that force is much reduced. To aid the front teeth in accepting their sideways forces, their roots are much longer. Clever design!

Bruxing

I suppose that if we were so designed that the position of each individual back tooth could be adjusted by the brain, then the brain could solve the problem.  However nature no doubt decided that such an incredibly complex design would be subject to many more kinds of failure and require too many resources to maintain it. So adjusting an individual tooth’s position is not an option for the brain. Sometimes the solution nature chooses is to grind all the teeth together presumably to wear the offending ones down to a better shape that fits. This grinding habit goes by the name “bruxism.” It can cause a lot of damage.

Bite Adjustment

To the rescue, comes the dental profession.  We do have the option to adjust an individual tooth’s position.  On rare occasions actually moving a tooth to improve its function is done as a preliminary step in bite adjustment. But even if that is done, the final step is fine tuning the way the back teeth mesh by slightly reshaping the teeth until the forces they put on each other are vertical.

Night Guards

Another way of accomplishing this is with a rigid removable plastic device that clips over either the lower or upper jaw that provides an instant perfect bite.  That means that when the device is in the mouth it is only possible for the back teeth to apply vertical forces on each other and then only when the jaws are in a position to provide a “power bite.”  When the teeth jaws move even slightly away from that clenching posture, all the forces are on one or more of the front teeth.

For most people, excessive forces on the teeth are delivered during sleep. That’s when we dream and try to resolve the stresses of life. People have being expressing stress by “gnashing their teeth” all through recorded history. So usually wearing such a device will go a long way towards resolving headaches by night wear only.  Some need to wear the device on and off throughout the day.

For some people, the device stops the grinding.  For others, the grinding habit persists, but even it it does, the physical wear occurs on a renewable resource – plastic – instead of a non-renewable one – tooth structure.  We dentists can repair or replace such tooth structure but its never quite as good as the original that nature provided.

Sports Store/Drug Store “Night Guards”

Devices sold in stores accomplish what most people think the night guard just described does – it cushions the teeth from excessive force because it is a soft, elastic, pliable material. It does nothing to restrict  forces to the directions they ought to go. Such devices are actually sports mouth guards. In some cases, a sports guard might work to reduce or eliminate headaches. They are unlikely to reduce bruxing, but if they can be worn throughout the night, they will reduce damage from bruxing. Store bought mouth guards are less effective than custom-made ones.

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