Grinding intaglio surfaces of ceramic restorations with diamond burs is a common procedure to improve fit. This study evaluated the effects of simulated diamond bur grinding and subsequent veneer firing and glazing on a lithium disilicate glass-ceramic. The results revealed a significant reduction in the roughness and strength of the material after diamond bur grinding, whereas the strength was restored through crack healing and formation of a glass layer after heat treatment. The finding indicates that grinding of lithium disilicate ceramics with diamond burs may introduce flaws and cracks, and therefore subsequent heat treatments, veneer firing, or glazing, are suggested.