Effect of rotational speed on nickel-titanium file distortion.

Separation of instruments while performing root canals is something that has plagued all practitioners. The purpose of this study was to evaluate the effect of rotational speed on nickel-titanium file distortion and separation. Forty extracted human molars were instrumented with Profile (Dentsply Tulsa Dental Products, Tulsa, OK) ISO .04 rotary nickel-titanium instruments at 166.67 or 333.33 rpm. The instruments were evaluated after instrumentation for separation and/or distortion. The results of this study were statistically significant and indicate that file distortion and/or separation is four times as likely to occur at 333.33 rpm vs. 166.67 rpm.