Objective To investigate the intensity changes of different thickness ratios of Empress Ⅱ glass ceramic and GI-Ⅱ glass-infiltrated alumina ceramic before and after Hertzian contact cyclic fatigue. Methods Disk-shaped specimens of different thickness ratios of EmpressⅡglass ceramic and GI-Ⅱglass-infiltrated alumina ceramic were respectively fabricated. Hertzian contact technique was imposed on the specimens. Critical loads of the specimens before and after 105 cycles loading were recorded. Results The average values of critical loads of all specimens reduced significantly after cycles loading（P
