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Objective: To observe the change of stromal cell-derived factor 1α/cysteine X cysteine receptor 4 (SDF-1α/CXCR4) signaling pathway during the process of axial stress stimulation promoting bone regeneration, and to further explore its mechanism. Methods: A total of 72 male New Zealand white rabbits were selected to prepare the single cortical bone defect in diameter of 8 mm at the proximal end of the right tibia that repaired with deproteinized cancellous bone. All models were randomly divided into 3 groups ( n=24). Group A was treated with intraperitoneally injection of PBS; Group B was treated with stress stimulation and intraperitoneally injection of PBS; Group C was treated with stress stimulation and intraperitoneally injection of AMD3100 solution. The X-ray films were taken and Lane-Sandhu scores of bone healing were scored at 2, 4, 8, and 12 weeks after operation, while specimens were harvested for HE staining, immunohistochemical staining of vascular endothelial growth factor (VEGF) and CXCR4, and Western blot (SDF-1α and CXCR4). The bone healing area was scanned by Micro-CT at 12 weeks after operation, and the volume and density of new bone were calculated. Results: X-ray film showed that the Lane-Sandhu scores of bone healing in group B were significantly higher than those in groups A and C at 4, 8, and 12 weeks after operation ( P<0.05). Micro-CT scan showed that the bone defect was repaired in group B and the pulp cavity was re-passed at 12 weeks after operation. The volume and density of new bone were higher in group B than in groups A and C ( P<0.05). HE staining showed that the new bone growth in bone defect area and the degradation of scaffolds were faster in group B than in groups A and C after 4 weeks. The immunohistochemical staining showed that the expressions of VEGF and CXCR4 in 3 groups reached the peak at 4 weeks, and group B was higher than groups A and C ( P<0.05). Western blot analysis showed that the expressions of SDF-1α and CXCR4 in group B were significantly higher than those in groups A and C at 4 and 8 weeks after operation ( P<0.05). Conclusion: Axial stress stimulation can promote the expression of SDF-1α in bone defect tissue, activate and regulate the CXCR4 signal collected by marrow mesenchymal stem cells, and accelerate bone regeneration in bone defect area.
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Objective: To investigate the effect of axial stress stimulation on tibial and fibular open fractures healing after Taylor space stent fixation.
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OBJETIVO: desenvolver e validar, através do Método dos Elementos Finitos (MEF), um modelo numérico tridimensional (3D) de um incisivo central superior para simular o movimento dentário. MÉTODOS: esse modelo contempla a unidade dentária, o osso alveolar e o ligamento periodontal. Permite a simulação dos diferentes movimentos dentários e a determinação dos centros de rotação e de resistência. Limita o movimento ao espaço periodontal, registrando a direção, quantificando o deslocamento dentário e as tensões iniciais no ligamento periodontal. RESULTADOS: a análise dos deslocamentos dentários e das áreas que recebem tensões iniciais possibilita determinar os tipos de movimentos dentários. Com base nas forças ortodônticas, é possível quantificar a intensidade das tensões em cada região do dente, do ligamento periodontal ou do osso alveolar. Com base nas tensões axiais ao longo do ligamento periodontal e da tensão capilar, é possível predizer, teoricamente, as regiões em que deve ocorrer a remodelação óssea. CONCLUSÃO: o modelo foi validado pela determinação do módulo de elasticidade do ligamento periodontal de forma compatível com dados experimentais existentes na literatura. Os métodos utilizados na construção do modelo permitiram a criação de um modelo completo para uma arcada dentária, o qual possibilita realizar variadas simulações que envolvem a mecânica ortodôntica.
OBJECTIVE: To develop and validate a three-dimensional (3D) numerical model of a maxillary central incisor to simulate tooth movement using the Finite Element Method (FEM). METHODS: This model encompasses the tooth, alveolar bone and periodontal ligament. It allows the simulation of different tooth movements and the establishment of centers of rotation and resistance. It limits the movement into the periodontal space, recording the direction, quantifying tooth displacement and initial stress in the periodontal ligament. RESULTS: By assessing tooth displacements and the areas that receive initial stress it is possible to determine the different types of tooth movement. Orthodontic forces make it possible to quantify stress magnitude in each tooth area, in the periodontal ligament and in the alveolar bone. Based on the axial stress along the periodontal ligament and the stress in the capillary blood vessel (capillary blood stress) it is theoretically possible to predict the areas where bone remodeling is likely to occur. CONCLUSIONS: The model was validated by determining the modulus of elasticity of the periodontal ligament in a manner consistent with experimental data in the literature. The methods used in building the model enabled the creation of a complete model for a dental arch, which allows a number of simulations involving orthodontic mechanics.
Subject(s)
Finite Element Analysis , Imaging, Three-Dimensional , Tooth Movement Techniques/classification , Periodontal Ligament , Surface Tension , Facial Bones , Incisor , Orthodontic Brackets , Orthodontics , Tooth SocketABSTRACT
[Objective]To explore the effects of axial stress regulation on healing of lengthened callus.[Method]Tibiaes of 40 rabbits divided into 2 groups were lengthened with circular external fixator.X-ray bone density and histology tests were performed.[Result]The X-ray showed lengthened callus was different after operation.In the control group,lengthened center had a serial callus and cortex had not formed,in the experimental group lengthened center had serial cortex and ttransfixial medullary cavity expects serial callus.[Conclusion]Axial stress regulation and periodicity continue to shortened micromovement stress may promote healing after bone lengthening.
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AIM: To explore the effects of axial stress regulation on healing of lengthened ca llus. METHODS: Tibiofibulars of 30 rabbits were lengthened 2 cm with t wice plane sreminobicular crib external fixator. Experimental group continues to lengthen 3 mm, and then were drawn and shortened 0.5mm once every 24 h separate ly for 10 days. Ten days later, tibiofibulars were axial short-stressed 1 mm wee kly with three times. Animals were killed 58 days after operation and X-ray, bon e density and histology tests were performed with lengthened bone. RESULTS: X-ray examination had no significant difference between two group animal when le ngthen ended, but X-ray showed lengthened callus was different on day 58. In con trol group, lengthened center had a serial callus and cortex had no formed, in experimental group, lengthened center had serial cortex and transfixial medullar y cavity expect serial callus. Bone density tests with two-energetic X-ray bone density measuring device showed bone density was higher in experimental group th an control group (P