Effect of Different Irrigation Needle Tips on Apical Extrusion of Irrigants in Over-instrumented Root Canals

This study evaluated the effect of various irrigation needle types on the amount of apically extruded irrigant in teeth with both intact and disrupted apical constrictions. A total of 40 mandibular teeth were examined under a dental operating microscope to determine the apical foramen, and the specimens were divided into two groups (n = 20). In one group, the teeth were instrumented 0.5 mm short of the apical foramen, while in the other, the instrumentations were were done 0.5 mm beyond the apical foramen. An open-tip needle and three different types of closed-tip (side-vented) needles were used for final irrigations. All specimens were irrigated with each needle type using a randomized crossover design. The extruded irrigants were collected in plastic containers with floral foam inserts, which were weighed before and after irrigation to determine the amount of extrusion by subtracting initial weights from final weights. Statistical analysis was conducted using repeated measures of two-way ANOVA and Tukey’s post hoc tests. In the over-instrumented group, all needle types resulted in significantly higher extrusion compared to the intact apical foramen group. Among the needles, the double-side-vented needle produced the least extrusion in the intact group, while the open-tip needle produced the most. In the over-instrumented group, the one-side-vented needle resulted in the least extrusion, with the open-tip needle again causing the most. Within the limitations of this study, the one-side-vented needle is recommended for irrigation procedures in over-instrumented teeth.