What is TMJ?

What is TMJ?

TMJ is an abbreviation for temporomandibular joint dysfunction.  It is also known as TMD (temporomandibular disorders).  The temporomandibular joint is the joint that connects your lower jaw to your skull.  It is located just in front of your ear.  When the jaw is misaligned it can cause a wide array of symptoms which is why TMJ dysfunction is referred to as a syndrome, meaning a collection of symptoms. Symptoms include jaw pain, headaches, tooth pain, neck pain, sinus pain, eye pain, visual disturbances, etc.

What Causes TMJ?

There is a disagreement in the dental community as to the cause of TMJ.  One group believes it is due primarily to stress leading to excess clenching.  The other group believes that it is due primarily to jaw misalignment causing excess work within the system.  Depending upon what you believe, your solution varies.  Often there is a little bit of both conditions present.

The dental profession as a whole is very poorly educated on TMJ.  Generally, most dental school curriculums give TMJ assessment and treatment options very little attention.

I believe this controversy continues in large part due to the fact that dentistry is based on structure, not function.  Dentistry does not have a functional model of ideal occlusion , only a structural model (class I occlusion).

I believe most cases of TMJ are caused by misaligned jaws, not stress.  When the jaw is misaligned one handles stress poorly.  There are a number of situations that can cause a person to develop a misaligned jaw: deviated septum, genetics, allergies, poor orthodontics, poor dental work, missing teeth, etc.

How do you diagnose TMJ?

Typically, upon examination of a TMJ patient I find that there is a substantial vertical height deficiency in back teeth. This necessitates that the lower jaw be pulled back in order to get the teeth together, thus causing compression in the TMJ and subsequent TMJ pain.  Clinically this is determined by 1)feeling the excess compression into the ear by the TMJ (stick your finger into your ear lightly and biting down; you should not be able to feel the condylar head through the ear).  On a normal person the condylar head is not palpable.  (2)Have the patient count from sixty to seventy.  Often with a misaligned jaw the lower jaw thrusts forward or sidewise with “s”  sounds (not ideal). (3) Have the patient open wide and close on a tongue blade (stick).  Most patients with TMJ bite significantly more forward with the tongue blade between their teeth that they bite in their normal bite.  The tongue blade keeps the front teeth from hitting ( hitting the front teeth would normally cause the jaw to bite back- compressing the TMJ).  (4) Take x-rays or MRI if necessary.

x-ray of TMJ

x-ray of TMJ

With this information you can very quickly determine if the TMJ is compressed.

TMJ Treatment:

Fixing the compression will typically get rid of symptoms and joint pain rapidly. This is done by inserting an appliance  in the mouth that builds the back teeth taller so that the jaw does not close up into the joint so far .  In picture overbite has been eleminated and the lower jaw is slighly forward of the upper. Eventually the case will be stabilized in the final determined therapeutic positon by orthodontic eruption of the back teeth.

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