Critical Reviews in Oral Biology & Medicine, Vol 11, 123-136, Copyright © 2000 by International & American Associations for Dental Research
Biomechanics of the mandible
T. M. van Eijden
Department of Functional Anatomy, Academic Center for Dentistry Amsterdam (ACTA), The Netherlands.
In this review the biomechanical behavior of the mandibular bone tissue,
and of the mandibular bone as a whole, in response to external loading is
discussed. A survey is given of the determinants of mandibular stiffness
and strength, including the mechanical properties and distribution of bone
tissue and the size and shape of the mandible. Mandibular deformations,
stresses, and strains that occur during static biting and chewing are
reviewed. During biting and the powerstroke of mastication, a combination
of sagittal bending, corpus rotation, and transverse bending occurs. The
result is a complex pattern of stresses and strains (compressive, tensile,
shear, torsional) in the mandible. To be able to resist forces and bending
and torsional moments, not only the material properties of the mandible but
also its geometrical design is of importance. This is reflected by
variables like polar and maximum and minimum moments of inertia and the
relative amount and distribution of bone tissue. In the longitudinal
direction, the mandible is stiffer than in transverse directions, and the
vertical cross-sectional dimension of the mandible is larger than its
transverse dimension. These features enhance the resistance of the mandible
to the relatively large vertical shear forces and bending moments that come
into play in the sagittal plane.
