Research On Stress Distribution In Loaded Mandible With Age Change And Its Relationship With Fracture Incident

The mandible accounts for one third of skull, it is important to facial hairdressing and connects the nest of temporal bone to constitute temporomandibular joint , which is the exclusive joint of skull. The fracture rate of mandible is very high , if the fracture is fixed inappositely, the abnormality concrescence will lead to the change of teeth arrangement, temporomandibular joint derangement, and affect facial hairdressing. Thus, comparing to the fixation of other bone, the mandible should be fixed more suitably. In order to reconstruct mandible more cutely or fix it more effectively, it is of consequence to master biomechanics characteristic of mandible.Through CT scans, we get the mandible DICOM data of an elder , an adult , and a child. Then, we put the data into MIMICS soft and generate the three-dimension models which we put into HYPERMESH soft and mesh elements. Finally, we carry out the finite analysis with ANSYS soft.In the study, we simulate the condition of occluding of front teeth and midmost occluding of all the teeth midmost occluding when the teeth are exposed to vertical loads, and achieve stress distribution in the mandible. From the simulation , we know that in the two conditions, the stress distribution in each part of the mandible is approximately the same, the loads added to the two sides of the mandible are approximately symmetrical, the stress distributing at the mandible is mostly pull stress, the greatest Von Mises appears at the mandible angles, and the intense stress appears at the mandible necks, the back side of coronary prominency, and the mandible angles. Furthermore, aiming to obtain theforces that put on the mandible necks, we extract the reverse forces along X axis, Y axis, and Z axis, and draw the conclusion that the forces along three axises are all great, among which the forces along Z axis is the greatest.At the same time, we study the stress distribution in three groups of different age mandibles, including an elder, an adult, and a child, when the midmost of the mandibles are exposed to different forces. We find that the stress distribution in each part of three mandibles is almost the same, stress added to each part is different and added to different sides of mandibles is approximately symmetrical. The mandibles bear mostly pull stress, and the greatest Von Mises appears at the mandible angles. The greatest Von Mises appearing at the mandible angles of the adult is far greater than that of the elder and the child, and that of the child is little greater than that of the elder. Then, we also research the law of the forces added to the three mandible necks. We draw the conclusion that the stress of the adult distributes at the body, the branches and the necks of mandible, while that of the elder and child only distribute at the body of mandible. Furthermore, we analyze the relationship of the stress distribution and fracture incident of mandible, and put forward the viewpoint that the more intense of the stress is, the more frequently the mandible would be fractured.