Three-dimensional nonlinear finite element stress analysis of prognathic mandible

Mandibular prognathism is the most familiar cranialfacial malformation. The mechanical environment in prognathic mandibles is different from that in normal human beings. In this paper, a 3D finitl element (FE) model based on CT slices of a female with mandibular prognathism was established. Contact surfaces were defined to represent the interaction between the articular disks and the cartilages of the condyles, the fossa - eminence complexe. The stress and deformation distributions in the model were analyzed under the load corresponding to centric clenching. The results showed that the stresses in sigmoid notch and gonial were 13.337MPa and 13.850MPa, respectively, which were the highest in the mandible; and the maximum deformation located at the temporomandibular joint (TMJ). Although the stress distributions in most regions of the model were consistent with normal mandibles, the stress distributions within the TMJ had signifucant differences. It indicates that mandibular prognathism may induce TMJ internal derangement, condylar resorption and disk perforation. Therefore as well as orthodontic or orthopedic therapies, the TMJ of prognathic mandible should be treated in time.