Apical Extrusion of Debris During Root Canal Preparation Using Different Instrumentation Kinematics in Standardized 3D-Printed Tooth Models: An In Vitro Study

Abstract

Background: Apical extrusion of debris during root canal instrumentation is an unavoidable event that may contribute to postoperative pain and periapical inflammation. Instrumentation kinematics have been proposed as a key factor influencing debris extrusion; however, anatomical variability among extracted teeth limits the comparability of previous studies. Standardized 3D-printed tooth models may overcome this limitation. Objectives:
To evaluate and compare the amount of apically extruded debris during root canal preparation using continuous rotation, reciprocating, and adaptive motion kinematics in standardized 3D-printed tooth models. Methods: Sixty identical 3D-printed mandibular premolar models were randomly allocated into three groups (n = 20) according to the instrumentation kinematics used. Root canal preparation was performed to an equivalent apical size following manufacturers’ instructions. Apically extruded debris was collected using a modified Myers and Montgomery apparatus, dried, and weighed using a digital microbalance. Data were analyzed using one-way ANOVA and Tukey post hoc test (P ≤ 0.05). Results: All instrumentation systems produced measurable apical debris extrusion. The reciprocating group showed significantly higher debris extrusion compared with continuous rotation and adaptive motion groups (P < 0.05). Adaptive motion resulted in the lowest mean debris extrusion, although the difference compared with continuous rotation was not statistically significant (P > 0.05). Conclusion: Instrumentation kinematics significantly influence the amount of apically extruded debris.  Continuous rotation and adaptive motion systems resulted in less debris extrusion than reciprocating motion when standardized 3D-printed tooth models were used.