Sonic irrigation for removal of calcium hydroxide in the apical root canal: A micro-CT and light-coupled tracking analysis

This study aimed to evaluate the efficacy of three sonic irrigation systems for removal of calcium hydroxide dressing from the apical root canal. A total of 96 single-rooted teeth in three categories of root canal curvatures (straight: 0–5⁰, moderate: 6–20⁰, and severe: > 20⁰ were allocated to four groups: conventional needle irrigation, EndoActivator, EQ-S, and Vibringe. The root canals were instrumented using Protaper NEXT and filled with calcium hydroxide. After removal of calcium hydroxide, the remaining volume of calcium hydroxide was measured by micro-CT analysis. Data were compared among root canal curvatures and irrigation systems using the Kruskal-Wallis test and Mann-Whitney test ( p  < .05). The oscillating range of each irrigation system was measured using light-coupled motion tracking. The volumes of calcium hydroxide remained in the canals of severe curvature were significantly lower than in those of straight curvature ( p  < .05). In the canals of moderate or severe curvature, EQ-S showed the highest removal percentage, followed by EndoActivator, Vibringe, and needle irrigation ( p  < .05). Light-coupled tracking showed the largest oscillating range in EQ-S ( p  < .05). Sonically activated irrigation systems with a flexible tip can be beneficial for cleaning of intracanal medication in the curved apical canals.