Temporomandibular Joint Model for Asymptomatic and Dysfunctional Joints - Computational Biomechanics of the Musculoskeletal System - page 296

The stress level of the condylar cartilage with the perforated disc was lower than that in the base
model. On the other hand, disc perforation significantly increased the stress of the temporal carti-
lage, especially at the posterior articular eminence. The excessive stresses may cause some patho-
logical changes, such as flattening and perforation of the cartilage. Obviously, treatment should be
carried out prior to the perforation of the articular disc.
22.4.3 S ummary and S iGnificance
Relaxation of the anterior disc attachment could lead to increased stress in the lateral intermediate zone
of the disc, which is often susceptible to perforation. Relaxation of bilaminar zones could significantly
increase the stress of the posterior articular eminence and may cause some pathological changes.
Anterior disc displacement could produce stress concentrations in the intermediate zone of the
disc. Posterior and lateral displacements of the disc could induce significantly increased stresses
in the intermediate zones and the anterior bands of the discs. The maximum tensile stresses of
the displaced discs, located at the intermediate zones, were greater than the tensile failure stress.
Moreover, the maximum tensile stress of the anterior band of the posteriorly displaced disc was
close to the tensile failure stress. Medial disc displacement could lead to stress concentration in
each band of the disc. The maximum tensile stresses of the anterior and posterior bands of the disc
significantly exceeded the tensile failure stress. These significantly high stresses in the displaced
discs could cause thinning or perforation of the discs. On the other hand, disc displacements could
lead to stress concentration in the posterior articular eminence, especially with posterior and medial
disc displacements. The significantly increased stresses in the posterior articular eminence could
cause flattening and perforation of the cartilage and bone resorption.
Disc perforation could lead to stress concentration at the intermediate zone of the disc and the
posterior articular eminence. The excessive stresses may cause some pathological changes, such as
thinning of the disc and flattening and perforation of the temporal cartilage.
In summary, the increased stresses and the abnormal stress distribution in the discs and articular
cartilages could be induced by various TMDs, or could be the source of TMD development.
Therefore, effective methods to maintain and restore the normal structure and function of the TMJ
should aim to treat the disorder as soon as initial symptoms are noticed, such as clicking of the joint.
aCknowledgmentS
This work was supported by the National Natural Science Foundation of China (11202143).
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