|Pain||Most common complaint among patients with TMD.|
Present in muscles of mastication and/or TMJ.
|TMJ sounds||Clicking or popping are discrete sounds.|
Crepitus (grating or grinding) is a more continuous sound.
|Limitation in range of motion||Less than 40 mm opening.|
Less than 7 mm lateral movement.
|TMJ catching or locking||Catching is typically brief and transient, multiple episodes can occur.|
Locking can last from a few seconds to weeks, may be continuous, and may occur as multiple episodes.
Pain is the most common complaint of TMD patients and it can occur in the masticatory and related muscles, the TMJs or both.3 Pain can be present at any time, even in the absence of any jaw activity. The pain intensity can be mild to severe and its duration can also vary considerably from momentary to constant. For some individuals there can be multiple episodes over weeks or months. For many patients the TMD pain eventually resolves, but for some patients the pain can persist for years.
Some patients have clicking, popping, and/or crepitus (a crunching sound similar to what is heard when one walks on wet sand at the beach) sounds when moving their condyle. These findings alone are not an indication that TMD treatment is necessary, in spite that most clicking or popping sounds are caused by the articular disc being displaced. Joint sounds generally occur from normal variations in the physical characteristics of the joint. There are many individuals without any TMD related pain, who have clicking jaw joints. For example, in a large epidemiological survey of individuals with and without any current TMD pain, 25% of those without any pain had clicking during a clinical examination.5 In the same study, among the individuals with TMD pain, 40% had clicking on clinical examination. Crepitus was much less common and only occurred in fewer than 10% of the individuals, whether or not they had TMD pain. Crepitus is usually the result of either current or past arthritic activity within the TMJ.
Limitation in Opening
The inability to open wide without pain is a common TMD patient complaint and clinical finding. Such limitation in opening may be the result of muscle hyperactivity or strain that prevents a patient from opening a normal distance. When measuring the opening distance, the incisal vertical overlap is added to the incisal edge-to-incisal edge measurement; 40 mm is considered minimum of normal for an adult of normal stature. In less frequent cases, limitation in opening can be caused by the articular disc being displaced and blocking the person from fully opening. In such cases, patients generally exhibit a deviation to one side upon opening and pain from the TMJ is generally present.
Deviation in Opening
A deviation in opening is generally due to muscle tension or a displaced disc. There are various degrees of deviations and patterns that can occur.
TMJ Catching or Locking
Catching or locking within the TMJ may occur upon opening or closing and there are several potential causes for these. This interference to smooth condylar movement may vary from a momentary catching to a continuous lock. About 15% of individuals with TMD pain report that they have had at least one locking episode.5