Effect of grinding and heat treatment on the mechanical behavior of zirconia ceramic

Autor(es)

Ramos, Gabriela Freitas ; Rocha Pereira, Gabriel Kalil ; Amaral, Marina ; Valandro, Luiz Felipe ; Bottino, Marco Antonio

• Tipo de documento: Artigo Científico
• Fonte: BRAZILIAN ORAL RESEARCH; v. 30, n. 1, p. 8-pg., 2016-01-01.

Resumo

The present study investigated the effect of grinding on roughness, flexural strength, and reliability of a zirconia ceramic before and after heat treatment. Seven groups were tested (n = 15): a control group (labeled CG, untreated), and six groups of samples ground with diamond discs, simulating diamond burs, with grits of 200 mu m (G80); 160 mu m (G120), and 25 mu m (G600), either untreated or heat-treated at 1200 degrees C for 2 h (labeled A). Yttria tetragonal zirconia polycrystal discs were manufactured, ground, and submitted to roughness and crystalline phase analyses before the biaxial flexural strength test. There was no correlation between roughness (R-a and R-z) and flexural strength. The reliability of the materials was not affected by grinding or heat treatment, but the characteristic strength was higher after abrasion with diamond discs, irrespective of grit size. The X-ray diffraction data showed that grinding leads to a higher monoclinic (m) phase content, whereas heat treatment produces reverse transformation, leading to a fraction of m-phase in ground samples similar to that observed in the control group. However, after heat treatment, only the G80A samples presented strength similar to that of the control group, while the other groups showed higher strength values. When zirconia pieces must be adjusted for clinical use, a smoother surface can be obtained by employing finer-grit diamond burs. Moreover, when the amount of monoclinic phase is related to the degradation of zirconia, the laboratory heat treatment of ground pieces is indicated for the reverse transformation of zirconia crystals. (AU)

• Processo FAPESP: 11/16716-0 - Influência do desgaste e do tratamento térmico sobre a resistência à flexão biaxial de cerâmicas à base de zircônia estabilizada por ítrio
• Beneficiário: Gabriela Freitas Ramos
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica