RESUMO
The aim of this study was to evaluate the biomechanical behavior of Bone Level dental implants with four different neck designs in contact with cortical bone. Numerical simulations were performed using a Finite Element Method (FEM) based-model. In order to verify the FEM model, the in silico results were compared with the results obtained from histological analysis performed in an in vivo study with New Zealand rabbits. FEM was performed using a computerized 3D model of Bone Level dental implants inserted in the lower jaw bone with an applied axial load of 100 N. The analysis was performed using four different implant neck designs: even surfaced, screwed, three-ring design and four-ring design. Interface are of bone growth was evaluated by analyzing the Bone-Implant-Contact (BIC) parameter obtained from in vivo histological process and analyzed by Scanning Electron Microscopy (SEM). Bone Level implants were inserted in the rabbit tibia, placing two implants per tibia. The BIC was evaluated after three and six weeks of implantation. FEM studies showed that the three-ring design presented lower values of stress distribution compared to the other studied designs. The lower levels of mechanical stress were then correlated with the in vivo studies, showing that the three-ring design presented the highest BIC value after 3 and 6 weeks of implantation. In silico and in vivo results both concluded that the implants with three-ring neck design presented the best biomechanical and histological behavior in terms of new bone formation, enhanced mechanical stability and optimum osseointegration.
Assuntos
Implantes Dentários , Planejamento de Prótese Dentária , Teste de Materiais/métodos , Animais , Parafusos Ósseos , Calibragem , Implantação Dentária Endóssea/instrumentação , Implantes Dentários/normas , Planejamento de Prótese Dentária/métodos , Planejamento de Prótese Dentária/normas , Análise de Elementos Finitos , Mandíbula/cirurgia , Osseointegração/fisiologia , Coelhos , Estresse Mecânico , Tíbia/cirurgiaRESUMO
BACKGROUND: Cell adhesion is a process that involves the interaction between the cell membrane and another surface, either a cell or a substrate. Unlike experimental tests, computer models can simulate processes and study the result of experiments in a shorter time and lower costs. One of the tools used to simulate biological processes is the cellular automata, which is a dynamic system that is discrete both in space and time. METHOD: This work describes a computer model based on cellular automata for the adhesion process and cell proliferation to predict the behavior of a cell population in suspension and adhered to a substrate. The values of the simulated system were obtained through experimental tests on fibroblast monolayer cultures. RESULTS: The results allow us to estimate the cells settling time in culture as well as the adhesion and proliferation time. The change in the cells morphology as the adhesion over the contact surface progress was also observed. The formation of the initial link between cell and the substrate of the adhesion was observed after 100 min where the cell on the substrate retains its spherical morphology during the simulation. The cellular automata model developed is, however, a simplified representation of the steps in the adhesion process and the subsequent proliferation. CONCLUSION: A combined framework of experimental and computational simulation based on cellular automata was proposed to represent the fibroblast adhesion on substrates and changes in a macro-scale observed in the cell during the adhesion process. The approach showed to be simple and efficient.
RESUMO
It is a well-known fact that computational biomechanics and mechanobiology have deserved great attention by the numerical-methods community. Many efforts and works can be found in technical literature. This work deals with the modeling of nutrients and their effects on the behavior of intervertebral discs. The numerical modeling was carried out using the Boundary ELement Method (BEM) and an axisymmetric model of the disc. Concentration and production of lactate and oxygen are modeled with the BEM. Results agree well enough with those obtained using finite elements. The numerical efforts in the domain and boundary discretizations are minimized using the BEM. Also, the effect of the calcification of the disc that causes the vascularization loss has been studied. The glucose, oxygen and lactate components behavior has been analyzed applying a mixed loading-unloading process, then allowing the study of the disc-height variations due to the degradation of the disc.
Assuntos
Glucose/fisiologia , Disco Intervertebral/fisiologia , Ácido Láctico/metabolismo , Mecanotransdução Celular/fisiologia , Modelos Biológicos , Oxigênio/fisiologia , Animais , Simulação por Computador , Módulo de Elasticidade/fisiologia , Humanos , Porosidade , Viscosidade , Suporte de Carga/fisiologiaRESUMO
The behaviour of the blood flow passing through artificial heart values in aortic position is numerically simulated by discretizing the Navier-Stokes equations for viscous incompressible flow through the finite element method. Three different artificial valves, Starr-Edwards, St Jude and disc valves, are modelled by using the finite element method as well as the Navier-Stokes equations for viscous incompressible flow. The blood flow behaviour is characterized by discretizing both planar and axisymmetric domains of the value devices. The streamlines as well as the velocity distributions are studied and compared. Likewise, the pressure patterns are analysed and compared. Some numerical examples of the three valves are presented and discussed herein.