Separated file removal.

Background The use of ultrasonic devices has been shown to be very successful for the removal of various canal obstructions.3-5 The use of ultrasonics is advantageous over conventional methods for removal of separated instruments as it is able to set separated instruments free from canals while making the sacrifice of dentin significantly less.6 However, there are several negative factors when using ultrasonics for the removal of separated files. First, ultrasonics sometimes causes secondary fracture of separated files, as shown in Figures 1a and 1b. Ward et al,7 in a study using ultrasonics to remove separated files from simulated canals and extracted teeth, observed that a portion of the separated instrument would occasionally break off from the original fragment, leaving a shorter fragment behind. Smaller fragments are more difficult to remove than larger fragments, and the removal rates are low for fragments that are located apical to the canal curvature.810 Secondly, ultrasonic vibration sometimes pushes the separated file out of the canal, as shown in Figures 2a and 2b. Thirdly, aggressive use of ultrasonics sometimes results