[Study of biomechanical effects on the reconstruction of mandible defect with autogenous bone grafts]

The biomechanical effects of the reconstructed mandible with autogenous bone grafts were analyzed and evaluated, under simulated mechanical environment of occlusion. Based on anatomical feature of the human skeleton, muscle system and the clinical B, BS"S" and RB"S"defect patterns, the modularized model of mandible and the three finite element models of the fibula grafts and iliac crest grafts reconstruction mandible were made. The stress state calculations under bite force were also processed. The findings are as follows: Along the right connection area to left connection area (corresponding to far-end of the molar teeth alveolar ridge and the chin section respectively), the stress state on the various grafted bone all changes from compression stress to tensile stress. There is obvious change on the stress distribution between the fibula type reconstruction mandible and normal one. The stress on the grafted bone which is mainly made up of cortical bone is approximately 5 times higher than that of normal, which indicates the obvious stress shielding effect; the stress distribution of the iliac crest type reconstruction mandible is close to the normal mandible, the iliac crest used is mainly made up of cancellous. Therefore, the mechanical properties of the reconstructed mandible with iliac crest are more similar to normal mandible, which is beneficial to wound healing and further functional reconstruction.