ABSTRACT
Objective To develop a 3D finite element model for the human craniomaxillofacial region in an attempt to offer basis to the research of simulation of craniomaxillofacial injury.Methods A healthy adult male was submitted to head CT scan, and the data was imported into the Mimics 15.0 software for threshold segmentation and 3D reconstruction according to the classifications of bone tissue, skin tissue and subcutaneous tissue.The reconstruction data was imported into 3D reverse software Geomagic Studio 2012, and the images were optimized and the 3D model was generated.The three parts of the model were fitted according to the actual proportion using the 3D control software Solidworks 14.0, and then the boundary conditions were derived.Hypermesh 12.0 finite element processing software was used to build the volume mesh, and the model was established.Each layer of the model was given to the material parameters, and the simulation conditions were provided to test the model.Results This model was completely composed of volume meshes, including 214,250 hexahedral meshes and 411,920 nodes.This model can clearly show the stress distribution, the trend of fracture line, the displacement of fracture block of soft and hard tissue during the simulation, and the results are consistent with clinical practice.Conclusion A three-dimentional finite element model with good performance is established, which can be used for biomechamics simulation analysis of multiple sites on the head or the whole structure, and has a certain significance in clinical and scientific research.
ABSTRACT
Objective:To investigate biomechanical changes of mandible in the impact injure simulated by finite element method (FEM).Methods:Mimics and Comsol software were used to build a FEM of human craniofacial bone based on CT scan data of a normal adult.LS-DYNA and Hypermesh software were used to simulate the impact with different quality,velocity and angulation pro-duced injures of human mandible,the biomechanical parameters of the mandible in the impact injury process were analysed.Results:A FEMof human maxillofacial bone was established,and the dynamic process of different impact force produced damage was simula-ted.Mandibular chin,angle and condylar neck was the stress concentrated area in the process of mandible injury.There was higher stress peak at the site which was closer to the impact position,the stress peak arrival time was also earlier.When the impactor with the same quality,the bigger the velocity,the greater the stress peak.When the impactor with the same velocity,the bigger the quali-ty,the greater the stress peak.When the impactor with the same velocity and quality,there was greater stress peak under the impact to mandible from angulation of 0 degree.Stress transfered to the surrounding bone from the impact position radially and gradually re-duced.The bone area with small cross-section was prone to high stress and more serious damage.Conclusion:The quality,the ve-locity,the impact angle and the impact site are the factors affecting the severity of impact injury.
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Objective To evaluate the effects of recombinant human bone morphogenetic-2-polylactide sustained release nanospheres (rhBMP-2-PLA-Ns) on cultured rabbit osteoblasts in vitro. Methods Rabbit osteoblasts were cultured in vitro, and rhBMP-2-PLA-Ns was added into the medium of the third generation of rabbit osteoblasts. The expression of the proliferating cell nuclear antigen (PCNA) was examined by immunofluoreacence staining, and the formation of tuberculums observed with alizarin red staining. Western blot was used to detect the effects of rhBMP-2-PLA-Ns on the expression of vascular endothelial growth factor (VEGF), which was compared with that in rhBMP-2 group and blank group. Results There was no significant difference in the number of osteoblasts with positive PCNA expression among three groups five days later. Ten days later, the number of osteoblasts with positive PCNA expression in rhBMP-2-PLA-Ns group was significantly higher than that in rhBMP-2 group and blank group, which indicated that rhBMP-2-PLA-Ns could enhance the expression of PCNA. Compared with rhBMP-2 group and blank group, rhBMP-2-PLA-Ns could significantly enhance the formation of tuberculums, with statistical difference (P<0.05). The expression of VEGF was detected in all three groups, and the level of the VEGF expression in rhBMP-2-PLA-Ns group was significantly higher than that in the other 2 groups (P<0.05). Conclusion The biological activity of rhBMP-2-PLA-Ns is superior than that of rhBMP2, and rhBMP-2-PLA-Ns can promote the proliferation, mineralization of osteoblasts and the secretion of VEGF, which has a better prospect in facilitating traumatic bone healing.
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Objective To compare the disinfectant effects of calcium hydroxide and traditional formaldehyde and cresol(FC) on the intracanal medicament in infected single rooted teeth. Methods A total of 84 single rooted teeth with chronic apical periodontits were randomly selected for the disinfection with calcium hydroxide or FC in root canal after the root canals were cleared routinely. Samples were taken before and after root canal disinfection a week later. The number and species of bacteria in the root canal and the change of clinic signs and symptoms were observed. All the patients were followed up for one year. Results The number and species of bacteria in the root canal decreased significantly and there was significant difference between the two groups ( P 0.05). Conclusion Calcium hydroxide is an effective disinfectant in root canal therapy.