Effect of instrument speed when used in reciprocating motion on root canal transportation and centering ability

Aim : This study aims to evaluate the root canal transportation, centering ability, and instrumentation times after root canal preparation using reciprocating motion at 300 rotations per minute (rpm) and 600 rpm. Materials and Methods : Twenty mesial root canals of mandibular first molars with curvature angles of 35°–70° and radii of 2–6 mm were included in the study. Root canal instrumentation was performed using R25 according to the manufacturer's instructions at 300 rpm or 600 rpm ( n = 10). Cone-beam computed tomography scanning was performed both pre- and post-instrumentation. Root canal transportation and the centering ratio were calculated for both the groups, and the data were analyzed using independent sample t -test for the instrumentation time, root canal transportation, and centering ratio at the 95% confidence level ( P = 0.05). Results : At the three levels (3 mm, 5 mm, and 7 mm), there were no significant differences in centering ratio between the groups ( P > 0.05). At 3 mm, 600 rpm resulted in more transportation than 300 rpm. However, there were no significant differences in the root canal transportation between the groups at 5 mm and 7 mm levels ( P > 0.05). Conclusion : At the 3 mm level, 600 rpm resulted in more transportation than 300 rpm. However, centering ratio was similar at both 600 rpm and 300 rpm.