Apical transportation of nickel-titanium rotary Mtwo and RaCe instruments compared with conventional stainless steel hand instruments.

Introduction: Apical transportation is an important iatrogenic damage in endodontics. This study evaluates the transportation caused by two nickel-titanium (NiTi) rotary instruments compared with a stainless steel hand instrument. Materials and methods: This in vitro experimental study was performed on 51 simulated canals with a 40 degrees curvature angle, fabricated within transparent and hard polyester resin. The groups consisted of K-File stainless steel hand-instrument (n=15), RaCe NiTi rotary file (n=18), and Mtwo NiTi rotary file (n=18). Canals were instrumented according to the protocols recommended by manufacturers. Extents of apical transportation were measured on digital scanned and standardized images. Data were compared by ANOVA. Results: The groups had a significant difference (P<0.001). Tukey test showed that the difference between the rotary instruments was insignificant, while the difference between each of them and K-file was significant (P <0.05). Conclusion: Apical transportation caused by the stainless steel hand instruments is much greater than that of nickel titanium rotary instruments RaCe and Mtwo. Both rotary systems act alike.