Effectiveness of two different file systems to remove root canal filling material in oval sectioned canals: Micro-computer tomography study

Effectiveness of Two Different File Systems to Remove Root Canal Filling Material in Oval Sectioned Canals: Micro-computer Tomography Study Complete removal of root canal fillers is crucial for the success of renewed root canal treatments. Although Ni-Ti file systems are the fastest and most effective method used to remove canal filling, recent studies have focused on the use of additional cleaning tools, as no file system has been able to provide definite success. As part of this research, twenty extracted human mandibular premolars with single root, single and oval cross-section canals were used. A working length of 15 mm was determined so that the roots prepared in equal lengths were 1 mm short Roots prepared in the same size have been extended to F4 size by the ProTaper Universal(Dentsply Maillefer, Ballaigues, Switzerland) Ni-Ti file system. After the root canals were filled with AH Plus (Dentsply DeTrey, Konstanz,Germany)root canal sealer and gutta-perka cones by cold lateral candensation method, they were left for 1 month at 37 oC and in a 100% humid environment. Then the samples were divided into 2 groups and the micro-CT device (Skyscan 1272, Bruker. Kontich, Belgium) with the initial scans were reviewed. After the canal fillings of the samples were removed with the Protaper Retreatment file set (Dentsply Maillefer, Ballaigues, Switzerland) powered by an electric motor, the Gentlefile Brush (MedicNRG, Kibbutz Afikim, Israel) was attached to its special head and used with 6500 vibrations/min. The final micro-CT scan of the samples was then performed and the raw images obtained were calculated using the Nrecon software program and the volume values of the canal filler were calculated. In both PTUR+XP-EF and PTUR+GFB groups, initial fill volumes before processing were significantly higher than post-processing fill volumes (p<0.05). Changes in volume % of samples were compared with the Mann Whitney U test, and the change rate of samples in the PTUR+XP-EF Group was significantly higher than the change rate of samples in the PTUR+GFB group (p<0.05). Although there was a significant decrease in the removal of the canal filler in both groups used, the canal filler could not be completely removed in both groups. It was found that the XP-EF file was statistically significantly more effective in removing the canal filler than the GFB file. Key words: retreatment, oval section root canal, residuel canal filling material, micro-CT, Protaper, XP-endo Finisher, Gentlefile Brush