Distribuição de tensões em próteses parciais fixas posteriores livres de metal com retentores intracoronários: análise em elementos finitos

• Ano de defesa: 2011
• Autor(a) principal: Silva, Marcelo Gomes da
• Orientador(a): Dias, Katia Regina Hostilio Cervantes
• Banca de defesa: Sampaio Filho, Hélio Rodrigues , Monnerat, Antonio Fernando , Mori, Matsuyoshi , Poiate, Isis Andréa Venturini Pola , Mello, Elson Braga de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Odontologia
• Departamento: Centro Biomédico::Faculdade de Odontologia
• País: BR
• Palavras-chave em Português: Prótese parcial fixa; Retentores intracoronários; Cerâmica; Compósito fibrorreforçado; Distribuição de tensões; Análise em elementos finitos; Pontes (Odontologia); Restaurações intracoronárias; Cerâmica odontológica; Compósitos poliméricos; Tensão Concentração; Método dos elementos finitos
• Palavras-chave em Inglês: Inlay-retained fixed partial denture; Ceramics; Fiber-reinforced composite; Stress distribution; Finite element analysis
• Área do conhecimento CNPq: CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA
• Link de acesso: http://www.bdtd.uerj.br/handle/1/13969

Inlay-retained fixed partial dentures (IRFPD) are an alternative to osseointegrated implants to replace a single missing posterior tooth. The aim of this study was to evaluate the stress distribution within these prostheses with three material combinations: yttria-tetragonal zirconia polycrystal (Y-TZP) ceramic veneered with fluorapatite ceramic (α), lithium-disilicate ceramic (β) or fiber-reinforced composite (γ). In composition α, an analysis was conducted on the presence or absence of the veneering ceramic on the cervical wall of the proximal boxes and three variations in the total area of the connectors cross-section (4 mm in width x 3.2, 4.2 or 5.2 mm in height). In 8 two-dimensional finite element models, a vertical load of 500 N was applied on the central fossa of the pontic. Maximum (tension) and minimum (compression) principal stresses were then shown in MPa. First, the 6 models with Y-TZP fixed partial dentures (FPD) and their variations were evaluated. The highest values of tensile stresses were found at the cervical third of the connectors. When present in these regions, the veneering ceramic received stresses beyond its flexural strength limit. In the comparison among models without veneering ceramic on the cervical wall of the proximal boxes, even the model with connectors of 3.2 x 4 mm, whose framework presented 2.5 x 3 mm, could be recommended for clinical use. High values of compressive stresses were recorded between the middle and occlusal thirds of the connectors, corresponding to the juncture of the ceramics. Owing to flexure, these stresses might lead to adhesive failures. Then, the Y-TZP model without fluorapatite ceramic on the cervical wall of the proximal boxes and total connector area of 4.2 x 4 mm was compared to the other two materials with connectors of the same area. For the lithium-disilicate FPD, the observed values would probably exceed its flexural strength limit. The fiber-reinforced composite FPD presented stresses far below the flexural strength limit of its framework, but, as observed in the Y-TZP model, high values of compressive stresses were concentrated between the middle and occlusal thirds of the connectors, where the juncture of the composite and the fiber framework is located. The results showed that the use of lithium-disilicate ceramics and the presence of fluorapatite ceramics on the cervical wall of the proximal boxes should be contraindicated for the condition proposed. A minimum of 2.5 x 3 mm for the connector area of the Y-TZP framework seems viable. The fiber-reinforced composite FPD presented structural resistance for the situation studied but, as was also the case of the Y-TZP fixed partial dentures, its weak points seem to be the adhesion between the framework and the veneering material, as well as the resistance of the veneering material itself.