Comparative Computed Tomographic Analysis of Efficacy of Hand Instrument and Different Rotary Instruments to Remove Gutta-Percha from Root Canals: An In Vitro Study

AIM : To determine the efficiency of rotary NiTi instrumentation with ProTaper retreatment file, Mtwo retreatment file, DRaCe retreatment file and, hand instrument with Hedstrom file without a solvent METHODOLOGY : Forty straight single rooted premolars were prepared with ProTaper Universal instruments up to F3 size and root canals were obturated with a F3 ProTaper gutta-Percha points and a epoxy resin based sealer by using the single cone technique. The samples with the obturation material were divided in to four groups each containing 10 samples for volume analysis using Spiral CT. Group 1 retreated with ProTaper retreatment file, Group II retreated with Mtwo retreatment file, Group III retreated with DRaCe retreatment file and group IV retreated with Hedstrom file without solvent. A second Spiral CT was done for all the specimens and the volume of remaining material in each root canal was estimated by three dimensional volume rendering software to calculate the removal efficiency. Data were analyzed statistically. RESULTS : D RaCe group had the highest mean removal efficiency followed by M two R, Pro Taper R. Least mean removal efficiency was observed among Hedstrom file. Group III ≥ Group II ≥ Group I > Group IV. However this difference was not found to be statistically significant (p=0.06). Lowest mean time taken for retreatment was by DRaCe Group followed by Mtwo and ProTaper while highest mean total time for retreatment was observed with Hedstrom file. CONCLUSIONS : All root canals had residual filling material after retreatment. Additional instrumentation is required to enhance cleaning efficiency during retreatment. Guttapercha with epoxy resin based sealer can be removed from canal without solvent by rotary NiTi file and removal with Hedstrom file is tedious and time consuming