|
||||||||||||||||||
To define the term.
The joint itself is located directly in front of the ears. Place your finger tips about 1/4 inch in front of the ear opening and open your mouth.............you’ll feel the TMJ move under your finger tips. This joint moves in a very unusual manner.........first it simply hinges open (like most all the other joints in your body), then it glides forward and down (unlike any other joint) to complete its full cycle. The way our muscles, teeth and joint work together is extremely complicated. In fact the TMJ is the most complicated joint in your body. No other joint you have moves in the intricate ways that they do. Think about one simple aspect.................what other joint in your body has the right and left side connected?
|
![]() |
MUSCLES there are numerous muscles that “power” the TMJ.
The two illustrated here are the two most frequently involved in soreness / pain.
![]() |
![]() |
| Temporalis Muscle | Masseter Muscle |
|---|
Intra-articular disease - this is the damaging changes that occur directly to the jaw joint, such as degenerative joint disease (DJD), unusual growth and development, and other rarer changes. These are changes to the bony and soft tissue components of the joint - changes that for the most part are irreversible. These are the developments that most often are considered for surgery. For a discussion on TMJ surgery - click here.
Myofascial pain disease (MPD) - in a very simple explanation - the muscular and ligamental pains that occur due to overuse and tearing. This is quite often reversible.
These are often both referred to as "TMJ" but are actually VERY different. In the remainder of this section you will read about causes, symptoms, therapies and other topics.......they may be either intra-articular, MPD or a combination of both.
Most often when people have TMJ problems it results from the simple fact that when they put their teeth together, their TMJs are not in socket (remember this not a correct orthopedic position). In fact, this is another major difference between the TMJ and all your other joints - something outside of the joint itself (your teeth) can prevent the TMJs from staying in socket.
When people exhibit a problem with their TMJs, it is most often exhibited as;
| Quite often, the disc is displaced to a position in front of the condyle. This results in first a “clicking” or “popping” sound. The disc at this stage is still able to slip or pop back onto the top position on the condyle during the open / close cycle. | ![]() |
|
|
|
![]() |
Some people may then experience “locking” of the jaw joint. This occurs because the disc is no longer able to slip or pop back on top of the condyle during the opening or closing cycle. (It is perpetually trapped forward). Because this occurs, the mandible opens only in the first part of its motion and is not able to complete a full cycle - the person often exhibits a limited opening of their mouth. |
2. Pain emanating from the jaw joint itself
- usually either an inflammatory response within the joint and /or
- highly innervated tissue being compressed.
3. Problems associated with the muscles.
- Sore muscles (usually in the temple or cheek areas). Headaches that can be actually muscle soreness.
- Limited opening.
4. Problems with the teeth.
- Loose teeth.
- Sore teeth.
- Excessively worn teeth.
- Loss of bone support.
5. Ear problems.
- Hissing or ringing.
- Ear pain, ear ache (in the absence of infection).
- Vertigo, dizziness.
So what determines which symptoms or problems a person may acquire?
The answer is a combination of several factors -
- How far their teeth are misdirecting their TMJs.
- How much they brux (grinding of the teeth at night while sleeping).
- How much stress they're under - stress increases bruxing DRAMATICALLY.
- How much clenching they do during the day.
- How genetically susceptible they are. Many people have a bite that is "off", yet they do not show any TMJ symptoms.
In most cases, when there is a true TMD problem, there exists what is referred to as a "molar fulcrum". The following images and narratives will attempt to explain and demonstrate this condition.
| In this image a correct position for the jaw joint and teeth is demonstrated. Here the teeth make simultaneous and equal contact at the exact moment that the jaw joint is seated in its most stable position. The black arrows show that the force being applied to the joint is directly across the disc. Also, in this stable position, the muscles are in "neutral" (not firing) and there exists no damaging forces to either the disc, the bony components of the joint nor the teeth. | ![]() |
![]() |
This is where most TMD patients find themselves, the teeth are in a position where they make simultaneous and equal contact, BUT the jaw joint is pulled out of socket to make this happen. This position for the jaw joint leads to increased bruxing (night grinding), increased muscular activity and damage to some or all of the following - the disc, bony components of the joint, teeth or bone supporting the teeth.. |
| In this image the jaw joint pivots into a correct joint position with the forces now directed correctly across the disc and bony components of the joint, BUT the teeth do not strike together correctly. NOTE that the point of contact (green area) is at the last molar and therefore the term - "molar fulcrum". | ![]() |
People do not notice that they have this discrepancy present. The reason for this is that the muscles that control the joint position shift the jaw down (out of socket) just before the teeth make contact. This is known as an "avoidance pattern" - the muscles move the joint so that the teeth won't crash into each other.
Molar fulcrums are revealed through splint therapy (see section below). During splint therapy, the muscles will relax and the "avoidance pattern" will diminish over time until the "true" occlusion (bite) is revealed.
So what is the solution? What will make TMJ problems go away??
A very important aspect of this type of therapy is to understand that TMJ therapy is not a CURE ! It is much more a MANAGEMENT of the problem. The jaw joint is easily damaged and NO ONE is going to ever make it perfect again. So, successful treatment means that the damaged joint is put into the least traumatic position so that future damage and pain will be minimal.
If someone is truly having a problem that is associated with their TMJs..........then ..........providing a correct bite would be a big step in the right direction. A bite such that the "molar fulcrum" is eliminated and the TMJs remain in socket. This is where splint therapy comes into the picture. A splint (when made correctly) is a physiologically correct bite. In other words..........when the splint is placed over the upper teeth it instantly provides a bite where the muscles, joint and teeth do not antagonize each other, rather they work in harmony with each other as nature intended. So.........IF symptoms diminish while wearing a splint, then it can be assumed that the problem truly was TMJ in nature, and definitive treatment can be performed to minimize future problems.


Splint Therapy Discussions.....
(for a detailed narrative of splint fabrication click here)
(for a more in depth discussion of splint therapy click here)
As pointed out previously, the relationship of the jaw joint (TMJ) to a persons' bite is the "cornerstone" of correct diagnosis. Making models of the upper and lower teeth and then holding them with your hands where most teeth mesh together tells us nothing about this most important relationship. This is where articulators come in to play. With a simple manipulation of the lower jaw and warmed wax, a set of models can be related to show how they TRULY come together when the joint is in its most correct position.
An articulator is an instrument that relates models of teeth to the jaw joint.
In the case shown below, the patient came in for an orthodontic evaluation. Her needs seemed very straight forward initially. Then when a simple manipulation of the lower jaw was performed, it became obvious that there was a serious problem with the way her jaw joint and teeth were working against each other. Upon further questioning, it was discovered that this 13 year old girl had premature wearing of her teeth (from bruxing), a history of head/jaw pain and other related symptoms. Jaw joint x-rays revealed that her left joint had sustained damage. All this from the result of her bite not lining up with her jaw joints.
It was determined that splint therapy would assist in diagnosing her TMJ problems, orthodontic needs and bite therapies required.
In the photos below, the left side is shown with the models on the articulator demonstrating her actual bite after splint therapy. The right photos are those of her models being held with all teeth in contact representing the bite before splint therapy.
In photo #1 are the articulated models (the arrows are pointing to the jaw joint elements of the articulator). Photo #2 demonstrates very simply where the patient closes her teeth together all the time - thus in her case, forcing the jaw joint into a very harmful position.
The red lines above show how the upper and lower front teeth line up. In Photo #4, the patient is practically perfect when she closes. When her models are correctly related with the articulator (#3), the lower jaw is shifted to the left about 1/4 of an inch. Notice also how her right back teeth do not line up at all. So, this young girl is putting very harsh pressures on her jaw joint when she closes - this is not something that is noticeable to the patient, but none-the-less is causing considerable harm.
These right side views (#5 and 6) show the difference between the articulated and non-articulated models.
In these left side photos, the overbite difference is significant. NOTE the first contact on the last molar - a "molar fulcrum".
In summary, this patient wore a splint full time (24 hours a day) for approximately 5 months. During this time, the splint was being adjusted at regular intervals and the jaw joints (TMJs) slowly assumed a correct position in socket. Her symptoms diminished and eventually passed completely. Now with this accomplished, it was time to proceed with the treatment as described in the next section.
PHOTOS COURTESY - David R. Nelson, D.D.S.
TREATMENT
Definitive treatment is performing the steps necessary to take someone from the splint they are wearing, back to their teeth touching - while VERY carefully keeping their “system” in balance by maintaining the correct relationships between joint, muscles and teeth.
Since each case is different, this can consist of one of the following or a combination of more than one of the following:
- Adjusting the tops of the teeth so that mesh properly.
- Crowns, bridges and/or partials made to give a proper bite.
- Orthodontic therapy (braces)
- Jaw surgery (not within the joint itself) so as to correct an upper or lower jaw that doesn’t allow a proper bite.
OTHER POSSIBILITIES OF THERAPY
As previously stated, there are times where splint therapy alone will not accomplish all that we would like, in those cases it may be necessary to perform other adjunctive therapy such as
- Physical therapy
- Biofeedback therapy
- Jaw joint surgery (only in very limited circumstances)
- Muscle relaxers and /or anti-inflammatory drug therapy.