Abstract: By using a reciprocating sliding wear test machine, wear behaviors of natural teeth at different tetracycline stained extent opposite to the titanium alloy are studied. The results show that friction and wear behaviors of lightly tetracycline stained teeth are similar to those of normal permanent teeth, and the worn surface is characterized by scratch and slight plough. However, significant plough and delamination are dominant for heavily tetracycline stained teeth accompanying with strong discontinuities in the evolution of coefficient of friction and rather high stable friction coefficient, whose tribological property is inferior to normal permanent teeth. It is suggested that the resistance against wear of natural teeth decreases with the increasing of tetracycline stained extent.

Key words: Microstructure, Friction and wear, Tetracycline stained tooth