Trismus – Part Two

trismus 3

Trismus – Part Two


In the previous blog we introduced Trismus. We found that:
– Trismus is the limitation of movement and opening of the jaw.
– It can be caused by problems (derangements) either within (intra- articular) the Temporomandibular Joint (TMJ) or outside (extra-articular) of it I.e., muscles and nerves of the head and neck.

In this blog we will look at the intra-articular causes:

1) Internal derangement of the TMJ

This is a disruption within the internal aspect of the joint itself…..a displacement of the disc from its normal functional position with the mandibular condyle and the articular portion of the temporal bone. Let me explain: As can be seen in the image above, the TMJ like other joints in the body is moveable. The lower jaw is connected to the skull at its upper most point…it’s like a ‘boney’ ball in a socket type of joint. Between the convex boney ball of the lower jaw and the concave socket in the skull there is a disc, known as an Articular Disc. Imagine it as a cushiony pillow that separates the upper and lower jaw and allows ease of movement. If this disc becomes damaged (which is known as an internal derangement) in any way, then the movement of the joint may be thrown off.

2) Fracture or dislocation of the mandibular condyle

As mentioned above, the condyle is the upper most round boney portion of the lower jaw that fits into the concavity within the base of the skull. A fracture/dislocation of the condyle or the area below it (called the neck of the condyle) can result from any type of accident which causes trauma to the face. If the condyle fractures then the normal fluid motion of the joint is thrown off.

3) Arthritis of the TMJ

If there is trauma to the TMJ, then the actual healing process may lead to inflammation. This type of inflammation may cause tissue destruction and possibly arthritis of the joint. Some of the actual types of arthritis that may result are septic, ‘osteo’ and inflammatory (or Rheumatoid).

4) Ankylosis within the joint

This is a stiffness of the TMJ due to an abnormal adhesion and rigidity of the bones that are within it. It usually occurs as the result of an injury or disease.

5) Osteophyte Formation

This is a boney outgrowth I.e., bone spur associated with the degeneration of cartilage within the joint.

The above are a general overview of problems that may arise within the TMJ and result in trismus or a limitation of movement.

In the next blog we will discuss the extra-articular causes of trismus.

Yours in good dental health,

Dr. F. Keshavarz Dentistry, Dentist in Brampton

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