抄録
Mechanisms of disc displacement in temporomandibular
joint (TMJ) internal derangement (ID) in
mandibular asymmetry have not been clearly
defined. This study examines the degree and
direction of disc displacement and their relationship
with vertical asymmetry in terms of both clinical
and biomechanical aspects. A retrospective
study of disc displacement was performed in 31
mandibular asymmetry patients using MR imaging.
The degree and direction of disc displacements on
the shifted side and contralateral side TMJ were
investigated with the degree of vertical asymmetry.
Furthermore, three-dimensional finite element
models of entire mandible include TMJ and maxillary
teeth in occlusion were created to simulate displacement
of the articular disc during clenching
condition. The direction of displacement on the
shifted side and contralateral side were significantly
different. Articular disc has tendencies to
displace more on the shifted side even in mild
degree of vertical asymmetry. The degree of displacement
was correlated with the amount of
asymmetry. The MR results were consistent with
the tendencies of disc displacement predicted
from the finite element models. We suggest that
disturbance in the direction of stress distribution
through asymmetry of the mandible is one of the
mechanisms related to disc displacement.
