Failure of ProFile instruments used with high and low torque motors

Aim The purpose of this study was to evaluate the failure incidence of ProF ile nickel-titanium rotary instruments when used in conjunction with differ ent motors and a specific instrumentation technique. Methodology ProFile Ni-Ti rotary instruments (PRI) with 0.06 taper were use d in a crown-down technique. In groups 1. 2 and 3, an airs a high torque an d a low torque motor were used, respectively. Each group included 30 canals in extracted human molars. One set of PRI sizes 40-15 was used for each ca nal: they were sterilized before each case. A 2.5% NaOCl solution was used as an irrigant. The number of deformed and separated instruments was record ed for the various experimental groups. Results Instrument separation did not occur in any of the three groups. One and two instruments were deformed when using the air and high torque motor s, respectively. Conclusions The results indicated no difference between the three motors wi th respect to the incidence of instrument failure. The results suggest that the use of PRI in a crown-down manner with air control motors was safe.