Influence of Different Kinematics on Apical Extrusion of Irrigant and Debris during Canal Preparation Using K3XF Instruments.

Introduction: This in vitro study was designed to evaluate the amount of apically extruded irrigant and debris during root canal preparation using K3XF instruments (SybronEndo, Orange, CA) with different kinematics and using hand files with a step-back technique.

Methods: A total of 80 extracted mandibular premolars were selected and randomly assigned to 4 groups (n = 20). The root canals were instrumented with K-type stainless steel instruments using a step-back technique and with the K3XF system using the following kinematics: reciprocating motion, adaptive motion, and continuous rotation. Bidistilled water was used as an irrigant. Preweighed Eppendorf tubes were used to collect apically extruded debris during instrumentation. Extruded irrigant was collected from the drainage cannula using a plastic insulin syringe, and the volumes were recorded. After complete evaporation of the liquid inside the tube, the weight of extruded debris was determined for each specimen. Data were analyzed statistically using the Kruskal-Wallis and Mann-Whitney U tests at a significance level of P < .05.

Results: Hand file instrumentation was associated with a significantly greater extrusion of debris compared with the K3XF groups (P < .05). Among the different kinematics, the highest mean debris extrusion value was obtained with reciprocating motion and the least with continuous rotation, but this difference was not significant (P > .05). No significant differences were observed between groups in terms of irrigant extrusion (P > .05).

Conclusions: Hand instrumentation extruded more debris than K3XF instruments that were used with different kinematics. All instrumentation kinematics were associated with apical debris and irrigant extrusion.