(PO11) Changes in Working Length During Stages of Mechanical Preparation When Utilizing Protaper Gold and Protaper Ultimate File Systems

Abstract: This study investigated in vitro the variations in root canal length (RCL) during endodontic instrumentation when utilizing ProTaper Gold and ProTaper Ultimate files combined with two different functions of an endodontic motor. Thirty-six artificial mandibular molars were accessed, and the occlusal tables were flattened. Samples were randomly divided into four groups (n=9), to be instrumented using either the ProTaper Gold or Ultimate systems, with or without the "Twist-on" functionality of the Coltene Canalpro JENI motor. RCL was determined by placing a hand instrument to the apical foramen under magnification during three stages: initial, after pre-flaring, and after completion of preparation. The lengths of the files were measured using digital images (ImageJ software). Data were statistically analyzed (significance set at 5%). A significant reduction in the RCL after root canal preparation was observed regardless of the canal, stage, and file (p < .05), but not for Twist control (p > .05). The total reduction was significantly different among the canals (p < .05), being -0.43 mm (±0.24) for the distal canal, -0.64 mm (±0.21) for MB, and -0.83 mm (±0.24) for ML. When comparing the different stages, the reduction in the RCL after pre-flaring (0.4 mm ± 0.26) was statistically higher than after the completion of the root canal preparation (0.23 mm ± 0.18). ProTaper Gold resulted in more RCL reduction for distal and MB canals (p < .05). Overall, ProTaper Ultimate resulted in fewer changes compared to ProTaper Gold. The variation in root canal length across the different stages highlights the importance of constant monitoring of the apical extent of root canal preparation.