Comparison of root canal preparation using RaCe and ProTaper rotary Ni-Ti instruments

Aim To compare various parameters of root canal preparation using RaCe (FKG Dentaire, La‐Chaux‐de‐Fonds, Switzerland) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) nickel‐titanium (Ni‐Ti) instruments. Methodology Fifty extracted mandibular molars with mesial root canal curvatures between 20° and 40° were embedded in a muffle system. All root canals were prepared to size 30 using RaCe or ProTaper rotary instruments in low‐torque motors with torque control and constant speed of 300 r.p.m. (ProTaper with ATR Tecnika, Advanced Technology Research, Pistoia, Italy; RaCe with EndoStepper, S.E.T., Olching, Germany). In both groups irrigation was performed with 2 mL NaOCl (3%) after each instrument size. Calcinase‐Slide (lege artis, Dettenhausen, Germany) was used as a chelating agent with each instrument. The following parameters were evaluated: straightening of curved root canals, postoperative root canal cross‐sections, safety issues and working time. Cleanliness of the root canal walls was investigated under the SEM using 5‐score indices for debris and smear layer. Statistical analysis was performed using the following tests: Wilcoxon's test for straightening and working time was used (P