Optimized Sintering and Mechanical Properties of Y-TZP Ceramics for Dental Restorations by Adding Lithium Disilicate Glass Ceramics

The novel dental ceramics can be fabricated at lower temperatures when sol–gel derived lithium disilicate glass ceramics (LDGC) was used as an additive for yttria stabilized tetragonal zirconia polycrystalline (Y–TZP) ceramics. The effect of LDGC on the sintering, mechanical, and translucent properties of Y–TZP ceramics was investigated in the present study. The results showed that the LDGC additive effectively improved the densification of Y–TZP at 1100 ℃, which was much lower than the sintering temperature for pure Y–TZP. When sintered at 1100 ℃ , the Y–TZP with 1 wt% LDGC reached a relative density of 95.45%, and prossessed a flexural strength of 482.4 MPa and a fracture toughness of 5.94 MPa·m^1/2. Moreover, its translucency was also improved. While, the addition of LDGC could result in an escape of yttrium atoms from the grain lattice of zirconia, which induced the tetragonal–monoclinic transformation of zirconia and abnormal growth of monoclinic grains. The escaped yttrium atoms diffused into the intergranular glass phase. The results indicated that the novel Y–TZP–LDGC ceramics has a great potential to be used for all-ceramic restorations.