Machinability of a newly developed pre-sintered zirconia block for dental crown applications

This study aimed to investigate the machinability of zirconia blocks pre-sintered at four different temperatures (900 degrees C, 1000 degrees C, 1100 degrees C, and 1200 degrees C). Vickers hardness and fracture toughness were measured to obtain the brittleness index (BI) of the zirconia blocks. The shrinkage percentage of the blocks pre-sintered at different temperatures was also determined upon final sintering at 1500 degrees C. The blocks were then subjected to machining, and the machined surfaces were morphologically analyzed. Although the materials pre-sintered at 900 degrees C and 1000 degrees C could be machined, noticeable trace lines and grooves formed on the machined surface due to lack of strength prior to sintering. BI and surface morphology confirmed that the new zirconia block can be milled at a pre-sintering temperature of 1100 degrees C and can achieve an acceptable shrinkage value for machining upon final sintering. (C) 2019 Elsevier B.V. All rights reserved.