Comparison of sodium hypochlorite extrusion by five irrigation systems using an artificial root socket model and a quantitative chemical method

This is to compare the volumes of irrigant apically extruded by five irrigation systems in an artificial socket model simulating clinical conditions. Twenty extracted human single-rooted teeth were enlarged to size 40/04 and then embedded in silicone impression material. The root canal space was irrigated with nominal 3% sodium hypochlorite (NaOCl) using standard needle irrigation (SNI) with a 30-gauge notched needle, EndoActivator (EA), XP Endo Finisher (XP Endo), EndoVac (EV), and photon-induced photoacoustic streaming (PIPS). Extruded NaOCl was collected, reacted with taurine to form taurine-monochloramine, and absorbance of taurine-monochloramine was measured at 252 nm using a spectrophotometer. The five irrigation systems were compared with repeated measures ANOVA and pairwise comparisons. The EV group had very low extrusion (mean +/- SD = 0.12 +/- 0.2 mu L) and differed significantly from the other four groups (P ae<currency> 0.001). Larger volumes of irrigant were extruded in the other irrigation groups. There were no significant differences in the extruded volumes among the SNI (7.4 +/- 3.4 mu L), EA (7.0 +/- 6.1 mu L), and XP Endo (7.8 +/- 4.1 mu L) groups (P = 1). The PIPS group had the highest mean extruded volume (12.9 +/- 6.8 mu L) and differed significantly from SNI (P = 0.030), EV (P < 0.0005), and EA (P = 0.02), but not XP Endo (P = 0.154). Under the in vitro conditions of this study, irrigant extrusion appears unavoidable unless negative pressure irrigation such as EV is used. PIPS extrudes more irrigant than other systems, while SNI, EA, and XP Endo extrude similar volumes of irrigant. The findings help clinicians select the optimal irrigation system to avoid irrigant extrusion.