[Scanning electron microscopy evaluation of wear of turbine rotary instruments].

A wear test was conducted to evaluate carbide and diamond dental burs, in air turbines at 400,000 r.p.m., by using a dentine-enamel substrate. There is less variability within each bur type. All of the burs showed a decreased ability to make a standard cut with succeeding trials. Generally, a linear dulling rate was observed with a progressive reduction of cutting effectiveness, except for middle grain burs, that showed better characteristics among tested burs.