Comparative evaluation of canal transportation of DenFlex and ProTaper Gold rotary instruments in simulated S-shaped root canals: an in vitro study

Maintaining canal centering during preparation of severely curved root canals is still a major concern in endodontics. This study aimed to compare canal transportation in simulated S-shaped resin blocks instrumented with DenFlex (DenFlex, Seoul, South Korea) and ProTaper Gold (Dentsply Maillefer, Ballaigues, Switzerland) rotary file systems. Thirty S-shaped resin blocks (16 mm length) were randomly assigned to two groups: DenFlex (prepared up to size 25/0.06) and ProTaper Gold (prepared up to F2). Before and after preparation, canals were filled with fuchsin red and methylene blue dyes, respectively. Canal transportation at the coronal, middle, and apical thirds was measured via superimposition of pre- and post-preparation images, which were captured under a stereomicroscope at ×40 magnification. Data were analyzed by repeated-measures ANOVA and independent t-tests (α = 0.05). A significant interaction was found between the file system and canal region ( p < 0.001). DenFlex caused significantly greater transportation than ProTaper Gold at all regions ( p < 0.001). For both systems, the highest transportation occurred in the middle third and the lowest in the apical third ( p < 0.001). Four DenFlex files fractured during the procedure. Both systems were able to prepare simulated S-shaped canals, but DenFlex induced greater canal transportation compared to ProTaper Gold.