Efficacy of Four Retreatment Techniques in the Removal of Root Filling Material: A Confocal Laser Scanning Microscopy Assessment

AIM AND OBJECTIVE: To compare the Efficiency of different retreatment instrumentation techniques to remove the filling material (GP and sealer) from the root canal walls, during retreatment procedure and to assess the remaining filling material using Confocal laser Scanning microscope (CLSM). 1. To compare the Efficiency of different retreatment instrumentation techniques in removal of the filling material (GP and sealer) from the root canal walls during retreatment, under Dental operating microscope.. 2. To compare the Effectiveness of solvent and time taken to remove the root filling material. 3. To assess the Percentage of remaining filling material on root canal walls at 2,4 and 6mm from the root apex, using Confocal laser scanning microscope. METHODOLOGY: 60 single rooted human mandibular premolars were prepared with Protaper Universal and 20 premolars were prepared with Mtwo instruments, filled with gutta-percha and Tubli-Seal EWT eugenol sealer manupilated with 0.1% rhodamine B dye. The roots were thermocycled to 3500 cycles and assigned into four groups, with two sub groups of 10 each. GR IA-Protaper-R, GRIB-Protaper-R with solvent; GRIIA-Mtwo-R, GRIIB-Mtwo-R with solvent; GRIIIA-Ultrasonic, GRIIIB-Ultrasonic with solvent: GRIVA-Extra Enlargement, GRIVB- Extra Enlargement with solvent. Following removal of the root filling material with different techniques, canals were refilled with gutta-percha and AH plus sealer manupilated with 0.1% fluorescein dye. The percentage of remaining filling material (GP and Tubli-seal sealer) were analysed at 2,4 and 6mm from the apex using Confocal laser scanning microscope.Additionally,10 teeth were prepared with Protaper Universal for Negative control group (n=5) filled with gutta-percha/Tubli-seal+rhodamine and positive control group (n=5) filled with gutta percha/AH plus+fluorescein . RESULTS: In this in vitro study, there was statistically significant difference in the remaining filling material (GP and Sealer) between different retreatment techniques (P < 0.001). Protaper-R was significantly faster compared to other instrumentation techniques. It was observed that solvent was not helpful in reducing remaining filling material in the root canal walls and the time taken. Apical segment revealed maximum residues. CONCLUSION: All Retreatment instrumentation techniques presented residual filling material in the root canal wall. However, extra enlargement group showed better results compared to other groups. Operating microscope with its enhanced vision facilitates better detection of residual filling material in order to maximize its removal