Mechanical behaviour of dental ceramics based on lithium silicate

Reference	Presenter	Authors (Institution)	Abstract
02-050	Manuel Fellipe Rodrigues Pais Alves	Alves, M.F.(Universidade do Estado do Rio de Janeiro); SANTOS, C.(UERJ); Simba, B.G.(UNESP-FEG); Campos, L.Q.(UERJ-FAT); Ferreira, I.S.(UERJ-FAT);	In this work, three different commercial glass-ceramics based lithium silicate (VITA-Suprinity, DENTSPLY-Celtra-DUO, and IVOCLAR E-Max) were investigated for their mechanical properties for dental purposes. Following strictly the protocols of use recommended by the manufacturers, the glass-ceramics were heat-treated in different conditions. The glass-ceramics were characterized before and after the heat treatments, by X-ray diffraction, scanning electron microscopy, Young modulus, flexural strength and Weibull's statistics. The phase quantification indicated that the E-MAX glass ceramic presents Li2Si2O3 and amorphous phase as the main crystalline phases while VITA-Suprinity, DENTSPLY-Celtra DUO glass-ceramic still have amounts of Li2Si2O5 between 15 and 20%. After heat treatments, there is predominance of lithium disilicate, Li2Si2O5, and residual amorphous phase in all products. Young Modulus is sensible to the glass content. The results of flexural strength (?f) indicate that, as received, glass-ceramics have ?f lower than 180MPa in all products. After the heat treatments, the results point to ?f = 340MPa (E-MAX), ?f = 200MPa (CELTRA DUO), and ?f = 190MPa (SUPRINITY). Weibull modulus is near to 8-9 for all glass-ceramics. The higher flexural strength presented by E-MAX results from the microstructural aspects of this material, which presents larger amounts of elongated grains of Li2Si2O5. The results are discussed according to the requirements of ISO-6872, which governs ceramics for dental applications.
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