Evaluation of the efficiency of removing root canal filling material of different rotary file systems by micro computed tomography

The purpose of this thesis is; to examine the retreatment efficiency of four NiTi rotary file systems with micro computer tomography and compare the time spent to remove root canal filling during retreatment. In the study, 40 human mandibular premolar teeth were used and their root lengths were standardized to be 15 mm. Samples were shaped up to F2 using the ProTaper Universal rotary file system, filled with MTA Fillapex root canal sealer with the single cone method. Root canals were closed with temporary filling material and kept in 37ºC and 100% humid environment for a month. The root canals were scanned with micro CT to evaluate the volume of root canal filling before retreatment. The samples were randomly divided into 4 groups according to the file system that was used to remove root canal filling (n = 10): Protaper Universal Retreatment NiTi system, ProTaper NEXT NiTi system, EdgeFile XR NiTi system and EdgeFile® X3 NiTi system. All samples were scanned with a micro CT device for the second time to evaluate the residual filling amount in the root canals. The percentages of filling removed from root canals were calculated based on the images obtained using the μCT Evaluation Program. Additionally, the time spent to reach the apex during the removal of the root canal filling and to remove the entire filling were recorded. Data were analyzed using the Shapiro Wilk test for suitability to normal distribution and Kruskal Wallis test for comparison between groups. There was no significant difference between the groups in the percentage of root canal filling removal values. However, the percentage of root canal filling removed in the EdgeFile® X3 group was determined to be less. The time taken to reach the apex according to the groups and the removal of the entire filling was obtained higher in EdgeFile® X3 system than other systems. Consequently, the study, determined that none of the NiTi file systems used can completely remove the root canal filling, EdgeFile XR system root canal filling removal is effective and the root canal filling removal efficiency of EdgeFile® X3 system is less than other file systems.