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Variables that Affect the Indentation Fracture Testing (IF) of a Dental Porcelain

2003; Trans Tech Publications; Volume: 416-418; Linguagem: Inglês

10.4028/www.scientific.net/msf.416-418.663

1662-9760

Paulo Francisco César, Carla Castiglia Gonzaga, Celso Y. Okada, André Luiz Molisani, William Santana, Hélio Goldenstein, Walter Gomes Miranda, Humberto Naoyuki Yoshimura,

Endodontics and Root Canal Treatments

The aim of this study was to investigate the influence of the indentation load, the period waste between indentation and measurement, and the gold coating on the fracture toughness (K Ic ) of a feldspatic porcelain (d.Sign, Ivoclar) measured by the Indentation Fracture Technique (IF). Porcelain beams (∼3x4x20mm 3 ) were fabricated by sintering green bodies at 870 C under vacuum with rapid heating and cooling rates. The samples presented microstructure composed of a glassy matrix, second phase particles and residual pores. Vickers hardness tester was used to produce indentation patterns on mirror polished surfaces. The diagonal of indentation (2a) and the length of crack (2c) were measured in an optical microscopy with better resolution than the hardness tester. The increase of indentation load from 0,2 to 5kg caused: i) increase of c/a ratio from 1,8 to 3,3; ii) almost no variation of Vickers hardness number; and iii) constancy of K Ic value from 0,3kg load. It was observed no influence of a gold coating on K Ic measurement. K Ic suffered significant reduction with time, mainly in the first hour.