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

Autor(es)

Gabriela Freitas RAMOS ^[1] ; Gabriel Kalil Rocha PEREIRA ^[2] ; Marina AMARAL ^[3] ; Luiz Felipe VALANDRO ^[4] ; Marco Antonio BOTTINO ^[5]

Afiliação do(s) autor(es)

^[1] Universidade Estadual Paulista. Science and Technology Institute. School of Dentistry - Brasil

^[2] Universidade Federal de Santa Maria. School of Dentistry - Brasil

^[3] Universidade Estadual Paulista. Science and Technology Institute. School of Dentistry - Brasil

^[4] Universidade Federal de Santa Maria. School of Dentistry - Brasil

^[5] Universidade Estadual Paulista. Science and Technology Institute. School of Dentistry - Brasil

• Tipo de documento: Artigo Científico
• Fonte: Brazilian Oral Research; v. 30, n. 1 2015-12-15.

Resumo

Abstract 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 µm (G80); 160 µm (G120), and 25 µm (G600), either untreated or heat-treated at 1200°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 (Ra and Rz) 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