Efficacy, cleaning ability and safety of different rotary NiTi instruments in root canal retreatment

Aim To evaluate the efficacy, cleaning ability and safety of three different rotary nickel‐titanium instruments with and without a solvent (eucalyptol) versus hand files in the removal of gutta‐percha root fillings. Methodology Eighty extracted single‐rooted anterior teeth were enlarged to size 35 and obturated with laterally condensed gutta‐percha using AHPlus as the sealer. Removal of gutta‐percha was performed with the following devices and techniques: FlexMaster, GT Rotary, ProTaper and Hedström files. All techniques were used with and without the solvent eucalyptol. The following data were recorded: time taken to reach the calculated working length and time required for the removal of gutta‐percha. The teeth were split longitudinally and photographed. Cleanliness of the root canal walls was scored using the projected slides with a total magnification of approximately 70×. Statistical analysis was performed using the two‐way anova (P