Relationship Between Occlusal Abnormalities and Temporomandibular Disorders
A direct relationship between an occlusal abnormality and a temporomandibular disorder does not always exist. However, in patients with mandibular abnormalities, we should always perform an occlusal analysis, as it has been demonstrated that this can be a primary etiological factor.
Class I:
Due to the increased overjet, disocclusion during protrusion movements does not occur immediately, which leads to posterior interferences that transmit forces to the joint and cause muscle dysfunction.
It is associated with stretching of muscles and ligaments and, at times, compression of the soft tissues adjacent to the articular disc.
Class II:
In this case, the range of motion is limited due to the overbite; furthermore, it forces the condyles to move distally, causing tissue inflammation. It is associated with retrodiscal temporomandibular pain.
Class III:
In many cases, there is an absence of anterior guidance and a lack of disocclusion during protrusive movements. There may also be an absence of canine guidance, leading to abnormalities in eccentric movements that can trigger occlusal trauma or temporomandibular dysfunction.
Increased vertical dimension:
This is usually due to iatrogenic causes resulting from prostheses with a very high occlusion that force the patient to maintain a semi-open position and a permanent separation of the articular surfaces. This leads to an increase in cartilage in the area to maintain the close relationship between the different surfaces.
Decreased vertical dimension:
This may be due to various causes, such as a reduction in the clinical crown, leading to condylar intrusion and compression in the retrodiscal space—which is highly innervated and vascularized—resulting in the characteristic pain associated with these situations.
This intra-articular pressure in the TMJ can be alleviated by increasing the vertical dimension, which would significantly reduce pain.
