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Abstract(s)
Introdução: Os valores das forças exercidas nas áreas oclusais dos dentes apresentam elevadas variações. O método dos elementos finitos é uma técnica computadorizada que permite a determinação da tensão e deformação, resultante da ação de forças externas, como de outros fenómenos. As reabilitações cerâmicas produzidas pelo sistema CAD-CAM apresentam poucos estudos clínicos randomizados, comprovando o sucesso clínico destas restaurações.
Objetivos: Analisar os valores das forças incidentes em molares de humanos, através de pesquisa na literatura; Estudar a distribuição de tensões, deformações e a resistência de materiais de restauração indireta, na presença de cargas estáticas, através do método de elementos finitos.
Materiais e Métodos: Três coroas com uma variação entre a região cervical e o equador dentário de 0,3 mm, 1,5 mm e 2,4 mm foram digitalizadas pela tomografia computorizada de feixe cónico e posteriormente processadas pelo MeshLab® e Autodesk®Inventor 3D CAD. Seguidamente, as coroas foram analisadas pelo método de elementos finitos com o Autodesk® Simulation Mechanical, considerando distintos materiais de restauração indireta.
Resultados: Os valores médios das forças verificados na intercuspidação máxima e na mastigação de molares, foram de respetivamente 523,938 e 74,033 Newton. Relações inversas foram obtidas entre o valor da tensão e/ou deformação de von Mises e a distância ao local da aplicação da força e entre as deformações de von Mises e os módulos de elasticidade dos distintos materiais. A crista dentária, comparativamente à fossa dentária, apresentou tensões e deformações de von Mises superiores. As tensões/deformações não apresentaram um aumento linear, com o aumento da dimensão mesiodistal das coroas. As tensões apuradas no estudo apresentaram-se inferiores à resistência à flexão/limite de escoamento reportados pelos fabricantes.
Conclusão: Todos os materiais apresentaram tensões similares, contudo os mesmos detêm de resistências à flexão/limites de escoamento distintos. De acordo com as características do paciente, o médico dentista deve selecionar o material de restauração indireta que garanta o sucesso da reabilitação oral.
Introduction: The values of the forces exerted on occlusal areas of the teeth have high variations. The finite element analysis is a computerized technique that allows the determination of stress and/or deformation caused by the action of external forces, as well as other phenomena. Ceramic restorations produced by CAD-CAM system have just a few randomized clinical trials that demonstrated clinical success of these restorations. Objectives: To analyse the values of the forces present in human molars according to the literature; To study the stress distribution, deformation and the resistance of indirect restoration materials, in the presence of static loads by finite element method. Materials and Methods: Three crowns with a variation between the cervical region and the dental equator of 0,3 mm, 1,5 mm and 2,4 mm were scanned by cone beam computed tomography and subsequently processed by MeshLab and Autodesk® Inventor 3D CAD. Then the crowns were analysed using the finite element method by Autodesk Simulation Mechanical, considering distinct indirect restoration materials. Results: The forces mean values for maximum intercuspation were 523,938 Newton and 74,033 Newton for chewing. Inverse relationships were observed between the value of the stress / deformation of von Mises and the distance to the site of application of the force and between the von Mises deformations and the moduli of elasticity of different materials. Dental crest compared to the dental fossa presented higher von Mises stresses and deformations. The stresses/deformations did not show a linear increase with the increasing mesiodistal size of the crowns. Tensions showed in the study were lower than the flexural strength/yield strength reported by manufacturers. Conclusion: All materials have similar stresses, but they have distinct resistance to bending/yield point. According to the characteristics of the patient, the dentist should select the indirect restorative material to ensure the success of oral rehabilitation.
Introduction: The values of the forces exerted on occlusal areas of the teeth have high variations. The finite element analysis is a computerized technique that allows the determination of stress and/or deformation caused by the action of external forces, as well as other phenomena. Ceramic restorations produced by CAD-CAM system have just a few randomized clinical trials that demonstrated clinical success of these restorations. Objectives: To analyse the values of the forces present in human molars according to the literature; To study the stress distribution, deformation and the resistance of indirect restoration materials, in the presence of static loads by finite element method. Materials and Methods: Three crowns with a variation between the cervical region and the dental equator of 0,3 mm, 1,5 mm and 2,4 mm were scanned by cone beam computed tomography and subsequently processed by MeshLab and Autodesk® Inventor 3D CAD. Then the crowns were analysed using the finite element method by Autodesk Simulation Mechanical, considering distinct indirect restoration materials. Results: The forces mean values for maximum intercuspation were 523,938 Newton and 74,033 Newton for chewing. Inverse relationships were observed between the value of the stress / deformation of von Mises and the distance to the site of application of the force and between the von Mises deformations and the moduli of elasticity of different materials. Dental crest compared to the dental fossa presented higher von Mises stresses and deformations. The stresses/deformations did not show a linear increase with the increasing mesiodistal size of the crowns. Tensions showed in the study were lower than the flexural strength/yield strength reported by manufacturers. Conclusion: All materials have similar stresses, but they have distinct resistance to bending/yield point. According to the characteristics of the patient, the dentist should select the indirect restorative material to ensure the success of oral rehabilitation.
Description
Keywords
Tensões Deformações Restaurações indiretas Forças mastigatórias Método dos elementos finitos Stress Deformations Crowns Masticatory forces Finite element method