First, let’s review the anatomy of the joint and learn how this joint can cause pain.
The Temporo-Mandibular Joint (TMJ) is the joint between the lower jaw bone (Mandible) and part of the skull bone (Temporal). The TMJ is responsible for all jaw movements, and is the most used joint in the body.
The unique feature of the TMJ is an elastic cartilage between the two bones called Disc . Disc acts as a cushion between the two bones and allows the mouth to smoothly open and close.
For the mouth to open, the mandibular condyle (the top section of the mandible where it connects to the temporal bone) and the disc have to move forward ( as shown in Figure 1.)
When the mouth is closing, the mandibular condyle and disc move back together to their resting position.
What are TMJ Disorders or TMD?
Any of the following symptoms could be called TMD:
- Pain when the joint is at rest or during movement (talking, chewing or yawning)
- Painful clicking when closing the mouth
- Limited range of motion causing restriction when opening the mouth
- Jaw getting locked
The TMD can be associated with facial pain, headaches, earache and tinnitus (noise in ears).
If you feel clicking or popping in the joint but do not have any pain or dysfunction, you do not have TMJ Disorder or TMD.
What causes TMD?
The causes for TMD could be muscular or articular (joint related):
- Muscular Causes include guarding, spasming, tightening or inflammation of the mastication muscles (see figure 2)
- Articular Causes include arthritic changes in the joint or disc displacement
Even though bite problems, clenching and grinding have been blamed for TMD, the studies have not determined whether or not these issues have a direct relationship with TMD.
However, studies do indicate that most times TMD is associated with upper neck issues. Upper neck issues could result from poor posture, trauma such as whiplash, injury or arthritis.
Issues with joint structures frequently lead to TMD. Most often, the disc is the cause of the joint dysfunction. The disc can be displaced forward or backward relative to the mandibular condyle and joint space.
For example, if the disc is displaced forward relative to the mandibular condyle, it can limit the ability of the jaw to fully open. This condition is associated with pain and a clicking sound when closing the mouth. Also, the limitation in Range of Motion (ROM) over time can cause facial pain secondary to increased tension in the mastication (chewing) muscles. Fortunately, this problem improve
s over time as ligamentous tissues gratually conform and function just like the disc.
If the disc is displaced backward relative to the mandibular condyle, it causes the jaw to be locked in an open position (locking jaw). Most times this condition requires a manipulation to the jaw by a clinician.
Arthritic changes in the joint due to Infectious arthritis, Rheumatoid arthritis, or Osteoarthritis could also cause more serious issues associated with pain and inflammation. These patients might require surgery for the TMD in order to reduce pain and dysfunction.
What is the treatment for TMD?
Physical therapy is one of the most common and effective treatments for TMD issues. The treatment could include:
- Manual therapy to improve joint mobility and reduce muscle tension in the neck and mastication (chewing) muscles
- Postural exercises to enhance upright posture and restore normal alignment
- Educating patients in better ergonomics to prevent stress to the joint
- Dry needling to improve the health of the joint, reduce muscle tension and resolve the secondary symptoms such as headaches and tinnitus. The research shows that the use of dry needling for TMJ is quite effective in reducing pain, muscle tension and restoring joint function.
Sometimes, in addition to physical therapy treatment, patients are prescribed medications such as anti-inflammatories and muscle relaxants to reduce pain and muscle tension.