• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Master's Dissertation
DOI
https://doi.org/10.11606/D.18.2020.tde-15012020-094206
Document
Author
Full name
Johnata Cavalcanti Fonseca
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2019
Supervisor
Committee
Ferreira, Eduardo Bellini (President)
Carrazedo, Rogério
Pinelli, Ligia Antunes Pereira
Title in Portuguese
Análise tridimensional por elementos finitos das tensões residuais em próteses cerâmicas bicamadas para aplicação dentária
Keywords in Portuguese
Cerâmicas dentárias
Método dos Elementos Finitos (MEF)
Restaurações cerâmicas bicamadas
Tensões térmicas residuais
Abstract in Portuguese
Restaurações cerâmicas bicamadas têm sido amplamente utilizadas em próteses dentárias devido à biocompatibilidade e estética atraente. Todavia, ainda se observam problemas com relação à durabilidade dos materiais que as compõem. No presente estudo, modelos tridimensionais de coroas dentárias bicamadas foram criados a partir da geometria de um primeiro pré-molar superior derivada de imagens de tomografia. Os modelos com espessuras de porcelana de cobertura variando de 0,3 a 3,0 mm foram analisados em computador pelo método dos elementos finitos (MEF) para o cálculo das tensões térmicas residuais geradas durante o resfriamento de 700 °C até a temperatura ambiente a 30 e 200 °C/min. As propriedades necessárias para os cálculos com elementos finitos foram obtidas da literatura e avaliadas experimentalmente. Os materiais IPS e.max Ceram (porcelana de cobertura), ICE Zirkon Translucent e ICE Zirkon Translucent Plus (infraestruturas) foram caracterizados por difração de raios X (DRX), dilatometria, picnometria de hélio e análise química. A porcelana de cobertura foi também analisada por microscopia eletrônica de varredura (MEV) e de transmissão (MET), calorimetria exploratória diferencial (DSC), termogravimetria, e a granulometria do pó por espalhamento a laser. Os resultados mostraram que as porcelanas com maiores espessuras apresentaram menores tensões residuais de superfície. Taxas maiores de resfriamento produziram tensões mais elevadas. Não foi possível identificar fluorapatita por DRX no material IPS e.max Ceram. No entanto, uma pequena e heterogênea cristalinidade foi detectada por MEV e MET em escalas micro e nanométricas, respectivamente. As temperaturas de transição vítrea medidas por DSC e dilatometria foram inferiores à indicada pelo fabricante. As infraestruturas foram identificadas como zircônias tetragonais policristalinas estabilizadas por Ítria (Y-TZP) por DRX e as propriedades medidas coincidiram com as da literatura.
Title in English
Three-dimensional finite-element analysis of residual stresses in bilayered ceramic prostheses for dental application
Keywords in English
Bilayered ceramic restorations
Dental ceramics
Finite Element Method (FEM)
Thermal residual stresses
Abstract in English
Bilayered ceramic restorations have been widely used in dental prostheses due to the biocompatibility and attractive esthetics. However, there are still problems with the durability of the materials that compose them. In the present study, three-dimensional models of bilayered dental crowns were created from the geometry of a first upper premolar derived from tomography images. The models with veneer thicknesses ranging from 0.3 to 3.0 mm were analyzed on computer by the finite element method (FEM) for the calculation of residual thermal stresses generated during the cooling from 700 °C to room temperature at 30 and 200 °C/min. The properties required for finite element calculations were obtained from the literature and evaluated experimentally. The materials IPS e.max Ceram (veneer), ICE Zirkon Translucent and ICE Zirkon Translucent Plus (cores) were characterized by X-ray diffraction (XRD), dilatometry, helium pycnometry and chemical analysis. The veneer was also analyzed by scanning (SEM) and transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetry, and powder particle size by laser scattering. Results showed that the veneers with greater thickness had lower residual surface tensions. Higher cooling rates produced higher stresses. It was not possible to identify fluorapatite by DRX in the IPS e.max Ceram material. However, a small and heterogeneous crystallinity was detected by SEM and TEM at micro and nanoscale, respectively. The glass transition temperatures measured by DSC and dilatometry were lower than the indicated by the manufacturer. The cores materials were identified as yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) by XRD and the measured properties coincided with literature.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
Publishing Date
2020-01-30
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
CeTI-SC/STI
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2020. All rights reserved.