The Stress Distribution With Forces At China: 3D Finite Element Analysis

Objective:To study the condition and character of stress distribution in the mandible by use of 3D finite element analysis, of which forces are applied on chin.Methods:The electronic CT images of mandible were scaned and then imported to the Mimics software. A 3D finite-element model of mandible was finally established. At the angle of 90°,0°, and 60°in the middle saggital plane to the Frankfort plane,1000N forces were applied on chin in Ansys software. Thereafter, the condition of stress distribution and Von Mises stress of the weak parts of the mandible were expressed.Results:When force is applied in inferior border of the 3D model of mandible at the angle of 90°, the Von Mises stress of mandibular angle reaches 101.680±10.235 MPa (which is much higher than 83.2 MPa,the yield limit of the bone cortex.) and the mandibular angle is subject to be fractured. Central symphysis and condyle neck may show fissure(s), while mental foramen is slightly damaged. When force is applied in the front edge of the mandibular 3D modle at the angle of 0°, the Von Mises stress of central symphysis is 386.516±7.498 MPa, and the mandibular central symphysis is prone to be fractured. The mandibular angle may show bone fissure(s), while mental foramen and condyle neck are slightly damaged. At the angle of 60°,force is applied in the front edge of mandible. The Von Mises stress received by the symphysis and mandibular angle are 327.194±17.802Mpa,109.938±11.363Mpa respectively and they are subject to be fractured. The condyle neck may show bone fissure(s), while mental foramen was only slightly damaged.Conclusion:The internal mandibular exists three stress trochoids that play a certain role in the distribution and conduction of the stress. while forces were applied in chin, Von Mises stress mainly concentrated on the weak parts of mandible.The parts which receive higher stress are closely related to the parts where fractures occur easily. This provides theoretical basis for clinical preliminary diagnosis for mandibular fractures and at the same time, provides a good deal of basis for making appropriate pre-operation design for mandibular osteotomy and osteogenesis.