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BACKGROUND:Condylar fracture can occur under direct and indirect forces, and however, its risk and correlation with the impact site are rarely reported. OBJECTIVE:To quickly establish normal mandible three-dimensional finite element model and to analyze the strain conditions of the condyle under force at different parts of the mandible. METHODS: An adolescent volunteer was examined by multilayer spiral CT scans, whose mandible was normal and oral cavity was healthy. We used the reverse engineering software Mimics and large finite element software MSC.Patran to establish the three-dimensional finite element model of the mandible and to verify the feasibility of the model in the impact test at the body of the mandible, chin, mandibular angle and condyle. RESULTS AND CONCLUSION:A rapid establishment of mandible dimensional finite element biomechanical model could reproduce the morphology of the mandible, which was able to obtain the overal visual impression of the mandibular condyle. Geometric model included 80 044 nodes and 18 441 units. The mandibular chin, one side of the body, mandibular angle and condyle were given 100 N force respectively. The maximum equivalent stress of the bone cortex appeared in condylar region. So the mandibular condylar fractures were at the greatest risk. Experimental results contribute to mechanicaly analyze the condylar fracture type and to judge the severity of fractures.
RESUMO
<p><b>OBJECTIVE</b>This preliminary study aims to investigate the effects of titanium and titanium alloy micro-nano-dimensional topography on the biological behavior of osteoblasts in vitro.</p><p><b>METHODS</b>Electrolytic etching (EE) method was used to produce micro-nano dimensional titanium surfaces. The surfaces were observed to determine their effects on the adhesion, proliferation, cell morphology, and alkaline phosphatase (ALP) activity of osteoblasts.</p><p><b>RESULTS</b>The surfaces of the titanium and titanium alloy groups exhibited higher adhesion and proliferation of osteoblasts than those of the mechanical group. The titanium surface was covered with a group of cells, a large number of filopodia, and functional particles. The ALP activity of the titanium group was significantly higher than that of the titanium alloy and mechanical groups.</p><p><b>CONCLUSION</b>EE method in pure titanium and titanium alloy surfaces result in bowl-like nests and nanostructures of different diameters and depths. The diameters of the pure titanium and titanium alloy surfaces range from 30 to 50 μm and 5 to 8 μm, respectively. The former is more conducive to promote the proliferation and differentiation of cells.</p>