Deviations from the jaw joint - Oral diseases, dental and facial surgery

Deviations from the jaw joint often show a coherence. There may then be a cranio mandibular dysfunction, abbreviated CMD.

Deviations from the jaw joint - Oral diseases, dental and facial surgery
Deviations from the jaw joint often show a coherence. There may then be a cranio mandibular dysfunction, abbreviated CMD.

Deviations from the jaw joint


Deviations from the jaw joint often show a coherence. There may then be a cranio mandibular dysfunction, abbreviated CMD.


Wear and loss of dental tissue

In order to correctly diagnose a defect, the three different forms of wear to the teeth are first treated.

  1. The physiological (= normal) wear process of teeth due to the mutual contact during chewing and swallowing is called attrition. Although glaze is an exceptionally hard material, it can still wear off.
  2. The pathological wear of the dental material is called abrasion. This wear and tear occurs due to abnormal mechanical processes, such as abnormal mouth habits (grinding teeth, nail biting, pipe clamping between the teeth) and the abrasive action of (some) toothpastes (see image below).Abrasion a by grinding; b due to a wrong brushing habit.
  3. The pathological loss of tooth substance under the influence of chemical processes is called erosion. The caries process does not fall under the concept of erosion. Erosion occurs with factory workers who work with chemicals (acids), and with people who drink (many) acidic drinks or eat fruit.


These three deviations can also occur in combination.



A trismus is a restriction of the mouth opening. It is a relative term: the maximum mouth opening differs per person. The phenomenon can have more than one cause. The temporary trismus is known as a result of the surgical removal of a wisdom tooth in the lower jaw. The swelling and fluid retention in the muscles and the surrounding soft tissue impede the stretching of the chewing muscles, which means that the mouth cannot be opened as far. A trism after removal of a wisdom tooth will often last about a week. However, there are cases where the trismus persists for a long time. The cause of this can be:

  • A joint inflammation, arthritis;
  • A stiffening of the jaw joint, an ankylosis;
  • Neuromuscular disorders such as these occur with pain dysfunction syndrome to be treated below.


In general, a trismus will be treated by removing the cause. A heat lamp and exercise of the muscles help to increase mobility.


Pain Disorder Syndrome

The pain dysfunction syndrome manifests itself with the following symptoms:

  • Radiating pain in the jaw joint, often similar to ear pain;
  • Trismus and sometimes even 'locked' of the jaws. In the morning on waking the mouth is closed; only after some 'manipulation' can the lower jaw be moved again;
  • A tired feeling in the lower jaw, at the level of the jaw joint.


The cause of these symptoms is neuromuscular dysfunction due to:

  • Non-optimal occlusion and articulation of the teeth;
  • Mouth habits such as grinding teeth (bruxism) and nail biting;
  • Stress.


Treatment must be aimed at removing the causes or at least combating them. With non-optimal occlusion and articulation, this means trying to improve things. This is not easy, just as it is to prevent strange mouth habits. For the latter, the muscles must learn to relax.

  • Muscle relaxation can be achieved by applying a bite increase over the elements. Often this is an increase in (week-long) synthetic resin or rubber. The muscles must then learn a different neuromuscular pattern, the tension of the muscles must decrease. Often the therapy with the help of a bite increase is very successful.
  • Along with instructions to the patient to avoid strenuous jaw movements as much as possible, the treatment can even completely eliminate the symptoms. Because strange mouth habits or para-functions often go unnoticed, it can help when the partner or others in the patient's environment make him aware. By constantly reminding the patient, one can positively influence his mouth habits.
  • A new treatment method is to inject the chewing muscles with botulinum toxin, known under the brand name Botox. By injecting a small amount of bolulin toxin into the muscle masseter, this muscle becomes a lot less powerful. This prevents overloading of the jaw joint. Botulinum toxin has run out after twelve to sixteen weeks and the treatment must therefore be repeated regularly.


Luxation and subluxation

It often happens in practice that a patient cannot close the mouth after treatment. With some attempts it is possible to bring the lower jaw into place. In this case there is subluxation.


If the patient himself is unable to return the lower jaw to the normal position, we speak of a luxation. To remedy this condition, knowledge of the construction of the jaw joint is necessary: the jaw head (processus condylaris) has shot over the lowest point of the joint protrusion of the temporal bone, the tuberculum articulare. The lower jaw is 'shot out of the (joint) bowl'.


To place it back in the joint socket (to put it back), the jaw head must first be lowered, after which it can shoot back into the bowl over the tuberculum articulare.


The repositioning of the mandible is as follows. The dentist places both thumbs firmly on the chewing surfaces of the lower elements and grasps the lower edge of the jaw with his other fingers. Now the lower jaw can be moved downwards and he often shoots backwards, back into the bowl. The cause of (sub) luxations is usually too large a joint capsule or abnormal wear in the jaw joint. The patient must be told that he should not open the mouth too far and that he should prevent yawning with his mouth wide open.