Bars were fired according to manufacturers’ instructions and polished before induction of cracks by a Vickers indenter (19.6 N, 20 s). Four specimens were stored in air/room
temperature, and three in saliva/37 ◦C. Five indentations were made per specimen and crack
lengths measured at the following times: ∼0; 1; 3; 10; 30; 100; 300; 1000 and 3000 h. The stress
corrosion coefficient n was calculated by linear regression analysis after plotting crack length
as a function of time, considering that the slope of the curve was [2/(3n + 2)]. Microstructural
analysis was performed to determine LC.