Methods: In this experimental study, 40 disto-buccal root canals of human maxillary first molars were selected and divided into two groups of 20 canals. One group was instrumented with Hero rotary system and the other with Race rotary system according to the manufacturer instructions. A standard amount of irrigant was used for each canal. Apically extruded debris and irrigant were collected in pre-weighted vials. Then the vials were located in the desiccator and after removing the irrigant, the weight of dry debris was estimated. The mean weight of the extruded debris for each group was analyzed using one sample Kolmogorov-Smirnov test and independent sample test.
Results: The weight of extruded debris showed that the Race rotary system resulted in less debris extrusion (0.0043485 gr) compared to Hero rotary system (0.0072135 gr). The difference was statistically significant (P=0.004).
Conclusions: Under the conditions of this study, the Race rotary system extruded less debris than the Hero rotary system.