Effect of rotational speed on nickel-titanium file distortion

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