Univ.-Prof. Dr. Dr. Gerhard Undt
Specialist for TMJ (temporomandibular joint) disorders, TMD, facial pain and salivary gland diseases

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Disc displacement

 
Pain and dysfunction in the temporomandibular joint are generally associated with displacement of the articular disc (which used to be called disc luxation). In a healthy temporomandibular joint, the disc sits on the condyle of the lower jaw when the mouth is closed.


Normal disc position

Magnetic resonance imaging (an MRI scan) clearly shows the position of the articular disc when the mouth is opened and closed. The following acrylic models of the temporomandibular joint show the position of the articular disc even more clearly. These models show the bony structures in white and the disc in red.

Modelle eines normalen Kiefergelenks

Acrylic models of a normal TMJ. When the mouth is closed, the articular disc is in its normal position; when opening, the disc follows the anterior movement of the condylar head

 

Disc displacement with reduction

If the disc slips forwards from its normal position this is referred to as disc displacement. The articular disc is initially only in front of the condyle of the lower jaw when the mouth is closed, but then as the mouth opens it slides back onto the condyle. This process is accompanied by a clearly audible click in the temporomandibular joint.

Kiefergelenkmodelle DVmR

Disc displacement with reduction. The disc is dislocated anteriorly when the mouth is closed and slides back onto the condyle as the mouth opens

 

Disc displacement without reduction

Sometimes the temporomandibular joint clicks for months or even years before it suddenly jams. One day, the disc just does not slide back onto the mandibular condyle. It is difficult and painful to open the mouth; it can also be very difficult to chew. This is called a "closed lock". The temporomandibular joint does not click when this happens. This lock can last a very short time - for a split second - or longer, for minutes or hours.

Kiefergelenkmodell DVoR

Disc displacement without reduction. The disc is totally displaced in the closed mouth position and does not slide back to the condyle when opening

   

Formation of adhesions

If it lasts longer, it is essential to seek advice from a temporomandibular joint specialist immediately. If this lock lasts for several days, it is very difficult, even for a specialist, to mobilise the disc again. The longer the disc displacement without reduction goes without being treatment, the greater the risk of adhesions forming in the joint, thereby permanently restricting mouth opening.

Adhäsion im Kiefergelenk

Broad adhesion within the upper joint compartment with signs of severe inflammation. The adhesion is cut with micro scissors under direct arthroscopic vision