Study of porcelain-zirconia composites for dental applications

• Ano de defesa: 2016
• Autor(a) principal: Santos, Rafaela Luiz Pereira
• Orientador(a): Nascimento, Rubens Maribondo do
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Rio Grande do Norte
• Programa de Pós-Graduação: PROGRAMA DE PÓS-GRADUAÇÃO EM CIÊNCIA E ENGENHARIA DE MATERIAIS
• País: Brasil
• Palavras-chave em Português: Porcelana feldspática; Zircônia; CPM; Prensagem à quente; Propriedades mecânicas; Compósitos
• Área do conhecimento CNPq: CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA
• Link de acesso: https://repositorio.ufrn.br/jspui/handle/123456789/21003

All-ceramic restorations have been widely used as aesthetic standard in nowadays dentistry, to replace the tooth structure (appearance and function). However, failures associated with chipping and delamination of the veneering porcelain from zirconia substructure still high when compared to metal-ceramic systems. This study aimed address these problems by improving the mechanical strength of veneering porcelain and by improving its adhesion to zirconia substrate. First, the addition of a stronger ceramic second phase (zirconia particles) to feldspathic porcelain was studied. This study began with the preliminary characterization of zirconia synthesized by Complex Polymerization Method (CPM) and commercial zirconia. It was found that the synthesized zirconia did not show improved properties when compared to commercial zirconia. Commercial zirconia powders were thus used thereafter. The influence of the type of powder (pre-sintered or agglomerated) in the mechanical properties and wear of porcelain composites (20vol.%) was evaluated. The pre-sintered powders increased the mechanical strength and wear of the composites compared to agglomerated powders. Then, it was determined the amount of second phase (0-50vol.%) that maximizes the mechanical properties of the porcelain-zirconia composites. It was concluded that the composites with 30vol.% of zirconia showed the best results for wear and flexural strength (198.5MPa). Finally, it was evaluated the influence of the type of surface treatment (sandblasting or holes) and the deposition of a composite interlayer (porcelain reinforced with 30vol.% of zirconia), on the zirconia surface, on the bond strength between the veneering porcelain and the zirconia substructure. The highest bond strength values were found for specimens having simultaneously holes on the surface of zirconia and the composite interlayer between the zirconia substructure and the veneering porcelain (138 ± 19MPa). It was demonstrated that the correct configuration of the interface between the zirconia substructure and the veneering porcelain can lead to all-ceramic restorations with enhanced mechanical strength and improved clinical performance.