Temporomandibular joint (TMJ) disorders

The temporomandibular joint (TMJ) connects the lower jaw to the skull. Between the two articular surfaces lies a small cartilage disc that acts as a shock absorber during jaw movements.

In some people, this disc shifts slightly forward when the mouth is closed. On opening, the disc returns to its normal position, producing a clicking or “click” sound. This is known as reducible disc displacement. This situation is common and is not considered a serious disease.

In a rarer proportion of patients, this disc shifts slightly forward when the mouth is closed. On opening, the joint is unable to move back under this small cartilage disc, resulting in a mechanical blockage. This is known as irreducible disc displacement.