Do the apical limit and diameter of the instrumentation influence the extrusion of sodium hypochlorite solution? A...

This study evaluated the influence of the apical limit and the diameter of the instrumentation on the extrusion of the irrigating solution. Sixty human lower premolars were distributed into 5 groups according to the apical limit and diameter of the root canal instrumentation (n = 12): (G-1₄₀) R40 instrument 1 mm above the tooth length (TL) (Control); (G-1₅₀) R50 instrument 1 mm above the TL; (GF₂₅) R25 instrument at the TL; (GF₄₀) R40 instrument at the root canal length and (GF₅₀) R50 instrument at the TL. A space of 33.5 ± 1 mm³ was created for storage of the extruded solution. Omnipaque contrast was added to the NaOCl solution in a 1:2 ratio, totaling 15 mL of solution to allow its visualization when extruded in microcomputed tomography. Final irrigation was performed with a syringe and needle and activated with a passive ultrasonic irrigation (PUI). Three activation cycles were performed. Data were tabulated and statistically analyzed (one-way ANOVA) with a significance level set at 5%. It was observed irrigating solution extrusion after final irrigation in all groups. However, there were no statistically significant differences among experimental groups, regardless of the diameter or apical limit of root canal instrumentation (p > 0.05). The different apical limits and diameters of root canal instrumentation did not influence the volume of extruded irrigating solution using passive ultrasonic irrigation.