What is Crepitation?

February 21, 2021

What is Crepitation?
What is Crepitation?

Crepitation in general means a crackling or rattling sound. In dentistry, such a sound can be heard at the joint near the ears called the temporomandibular joint (TMJ). This joint is the reason why we are able to smoothly carry out functions of speech, chewing, etc. It is the joint that connects the lower jaw to the skull. The TMJ allows us in opening and closing the mouth, sideways movement of the jaw, forward and backward movement of the jaws, etc.


The range of motions that the TMJ carries out is because of a disc and fluid that is present between the condyle (part of the lower jaw) and the temporal bone (part of the skull). The disc is called the articular disc. The fluid is called the synovial fluid that is present in all major joints of the body for easy motion. Any dysfunction in the TMJ can directly result in restriction or limitation of the movements of the jaw. Moreover, an accompanying sound may also manifest. This can be a simple clicking sound or a louder sound like a crepitation. Let us see how this sound is produced.


When our mouth opens, the articular disc between the condyle and the fossa (depression in the temporal bone where the condyle moves) acts as a cushion between the two. In the entire cycle of mouth opening and closing, the condyle rotates freely as needed due to the support of the articular disc. However, when this articular disc displaces from its original position, an abnormality occurs. When the mouth opens and the condyle rotates, it loses its contact with the disc and thus a clicking sound can be heard. A similar sound can be heard when the person closes his mouth as the disc tries to get back to its actual position.


Sounds of clicking can be because of abnormal oral habits like bruxism (clenching), abnormal bite (malocclusion), postural habits, emotional stress or traumatic injuries. Clicking sounds however may or may not be serious. Pain and locking of the jaw may or may not occur. The person might not require any treatment for the same. The more serious issue occurs when the sound becomes enlarged and results in crepitation.


Crepitus or crepitation is a grinding like sound. It occurs in advanced stages where degenerative changes occur in the TMJ. The sound is produced when the condyle strikes the fossa. This leads to flattening and wearing of the condyle head. The movement of the lower jaw thus causes pain and limits the jaw movements. A better view of the TMJ and its structures can be obtained through MRI or CT scans.


Crepitus can occur due to all the reasons for the same reason as to why clicking occurs. However, it is more intense in terms of damage done to the articular disc. A tear in the ligament attached to the disc itself can also lead to crepitus. Chronic (long standing) conditions of the TMJ, rheumatoid arthritis, tumours, etc are some of the causes of crepitation. It is often heard during side-to-side movements of the jaw. An individual can perceive the sound of crepitus much louder since the joint is close to the ear. Crepitus is a definitive sign for the diagnosis of osteoarthritis.


In order to resolve crepitus, a surgical approach maybe needed in order to correct the position of the articular disc. However, the underlying cause may also be a tumour or a degenerative condition which needs to be targeted first. Bruxism can be countered with night guards whereas malocclusions are corrected through dental appliances that are designed accordingly. Anti-inflammatory drugs and physiotherapy are adjunctive treatments.


Occurrence of crepitus is rare in comparison with clicking or popping sounds. It is less common among older adolescents and young adults. The crackling of the TMJ can often be overlooked if it is not heard regularly. However, the sound should not be ignored by the patient as it is a direct result of bony frictions due to articular disc derangement. Crepitus is thus a sign of an underlying TMJ disorder that should be addressed at the earliest to retain the physiologic and functional integrity of the TMJ.


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