Adjunctive Steps for the Removal of Hard Tissue Debris from the Anatomic Complexities of the Mesial Root Canal System of Mandibular Molars: A Micro-Computed Tomographic Study

Abstract

Introduction: This in vitro study sought to compare the efficacy of a sonic irrigant activation device with ultrasonic activation and needle irrigation in removing hard tissue debris (HTD) from anatomic complexities of the root canal system.

Methods: Twenty-seven mesial roots of extracted human mandibular molars with 2 canals connected by an isthmus were selected based on micro-computed tomography scans (12-μm voxel size). The mesial canals were mechanically prepared to ProTaper Next X3 (Dentsply Maillefer, Ballaigues, Switzerland) and anatomically distributed into 3 groups (n = 9) according to the final irrigation protocol: sonically activated irrigation (SAI) using the EDDY system (VDW GbmH, Munich, Germany) for 3 × 20 seconds, ultrasonically activated irrigation (UAI) using a size 20 Irrisafe tip (Satelec Acteon, Mérignac, France) for 3 × 20 seconds, and conventional irrigation using a 30-G needle adapted to a syringe. Micro-computed tomographic scans were taken after instrumentation and after supplementary activation of the irrigant. After reconstruction and coregistration, the volume filled with HTD before and after irrigant activation was calculated, and the mean percentage of HTD reduction after final irrigation was compared within and among groups using the paired sample t test and 1-way analysis of variance post hoc Tukey test, respectively (α = 5%).

Results: A significant reduction in the volume filled with HTD after irrigant activation was observed in all groups (P < .05). The percentage reduction of HTD in the UAI group (66.8%) was significantly higher than that in the SAI group (36.4%) (P < .05), whereas the conventional irrigation group result (43.7%) did not differ statistically from the UAI or SAI groups (P > .05).

Conclusions: All tested supplementary irrigation steps significantly reduced the amount of debris created during root canal preparation. Ultrasonic activation resulted in the highest mean debris reduction.

Keywords: Hard tissue debris; irrigant activation; mandibular molars; micro–computed tomography; sonically activated irrigation; ultrasonically activated irrigation.