Abstract: Tribological behaviors of submicron zirconia toughened alumina dental ceramic(Z2S) against Si_3N_4 were investigated on a UMT tribo-meter with a ball-on-disk configuration under lubrication of artificial saliva.As comparison,the triblogical performances of Vita and Dentsply,which are currently used in dental clinic,were used as the baseline.Z2S exhibited better triboligical performance than Vita and Dentsply did,as analyzed from friction coefficient and wear rate.The most promising aspect for Z2S is the wear rate,which is two order lower than that of the two commercial ceramics.The worn surface of Z2S is mainly characterized by mild abrasive wear with plastically deformed grooves,rather than severe plastic deformation and micro-fracture,which are commonly found on the worn surfaces of Vita and Dentsply.The wear mechanism of Z2S under the tested conditions is probably friction-induced phase transformation of ZrO_2.Additional experiments on the Z2S and Dentsply mated with human enamel were conducted.According to the friction and wear simulation,the Z2S/human enamel pair should be the good choice on the basis of the wear rates of the tribo-couple as well as the morphology of worn surface.The wear rate of Z2S is much lower than that of Dentsply,the initial microstructure of human enamel is well preserved as mated with Z2S while it is not as mated with Dentsply.Z2S shows potential application as dental all-ceramic.