Effect of coronal flaring on apical extrusion of debris during root canal instrumentation using single-file systems

Aim To evaluate the effect of coronal flaring on the amount of debris extruded apically during root canal preparation using the Reciproc, WaveOne (WO) and OneShape (OS) single-file systems. Methodology Ninety extracted single-rooted mandibular incisor teeth were randomly assigned to six groups (n = 15 for each group) for canal instrumentation. Endodontic access cavities were prepared in each tooth. In three of the six groups, coronal flaring was not performed; coronal flaring was performed with Gates-Glidden drills on all teeth in the remaining three groups. The canals were then instrumented with one or other of the following single-file instrument systems: Reciproc, WO and OS. Debris extruded apically during instrumentation was collected into pre-weighed Eppendorf tubes. The tubes were then stored in an incubator at 70 degrees C for 5 days. The weight of the dry extruded debris was established by subtracting the pre-instrumentation and post-instrumentation weight of the Eppendorf tubes for each group. Data were analysed using one-way analysis of variance (ANOVA) and Tukey's post hoc tests (P = 0.05). Results Reciproc and WO files without coronal flaring produced significantly more debris compared with the other groups (P < 0.05). There was no significant difference in apical extrusion of debris amongst the other groups (P > 0.05). Conclusions All single-file systems caused apical extrusion of debris. Performing coronal flaring prior to canal preparation reduced the amount of apically extruded debris when using Reciproc or WO systems.