“My jaw joint is clicking … is it a problem?”
This is a common question in a dental practice. Patients will present with different types of clicking and popping jaw joints and wonder if the clicking joint is a problem. Patients also will ask if any treatment is necessary as well as how to make the jaw joint stop clicking.
While these all are legitimate questions, there may not be a simple answer for each patient. The first step in discussing these clicking TM joints is to have a clearer understanding of what happens when a jaw joint clicks or pops.
There are two different types of clicking jaw joints. The first, which happens in probably less than two percent of cases, involves the condyle-disc assembly hyper-translating and moving anterior to the crest of the articular eminence. This is a rare occurrence, and the problem can be resolved by pushing down on the mandible while gently helping the condyle move back in to the glenoid fossa.
Explaining the anatomic arrangement and helping the patient avoid opening to the point where the condyle moves forward of the eminence is usually enough to take care of most patients.
The far more common click relates to a structural change in the TM joint. The TM joint is comprised of the soft tissue component (the disk) and the hard tissue component (the condyle). The disk is attached to the condyle by a ligament on the medial and lateral aspect of the condyle. If the ligamentous attachment of the disk to the bone is compromised (typically by an injury to the ligament), the disk will displace and not cover the head of the condyle.
The opening click occurs when the disk is anterior to the condyle and the patient moves forward to position the condyle under the disk. The closing click occurs when the patient closes and the condyle pops off the disk returning to the joint socket.
It is possible to have ligament damage of the lateral pole of the condyle, at the medial pole of the condyle or at both poles of the condyle. The soft tissue at the medial pole of the condyle helps distribute the load when compressive forces are placed on the condyle during rotational movements. The soft tissue at the lateral pole is compressed during translational movements. Additionally, the soft tissue at the medial pole of the condyle supports and maintains the vertical dimension of occlusion at the TM joint level.
If ligament damage is confined to the lateral pole of the condyle, there is a good chance for adaptation to the structural alteration in the TM joint. The lateral pole click is a common click and many patients can live for years without any pain from bite changes, since the structural alteration is confined to the lateral pole. This type of disk is referred to as a partially-herniated disk.
If the ligament damage includes the medial pole, there is an increased risk for the development of pain or changes in the occlusion. This is referred to as a completely herniated disk. While it is possible for patients to adapt to this type of joint clicking, there is a higher risk of pain or bite changes developing in this type of TM joint. From the soft tissue perspective, an anteriorly-displaced disk typically results in a loss of vertical dimension of the TM joint level.
In many patients, this presents clinically as a Class II bite shift. From a hard tissue perspective, the lack of soft tissue disk protection can result in eroded condylar bone, small condylar bone or edematous eroded bone. The changes in both soft and hard tissues can result in either pain, bite changes or both in some unfortunate patients.
It is also important to consider the age of the patient when determining if a clicking or popping TM joint warrants additional investigation. Risk factors increase when clicking or popping begins in growing patients.
When the TM joint soft tissue is damaged before growth is completed, there is an increased risk of incomplete growth. The greater the growth deficit, the greater the increase for retrognathia, facial asymmetry and compromised airway anatomy. It is better to err on the side of caution and assess clicking jaw joints in growing patients to evaluate the anatomy in the developing masticatory system.