Effect of retreatment instruments on microcrack formation: a microcomputed tomography study.
The purpose of this study was to compare the occurrence of microcracks in teeth prepared with different retreatment systems using microcomputed tomography (micro-CT).METHODS
Forty-two freshly extracted mandibular premolar teeth were used. The root canals were instrumented with stainless steel K-files to an apical size of 35/.02 using the balanced-force technique and were obturated using the passive compaction technique. The specimens were divided into 3 experimental groups according to retreatment system used (n = 14): ProTaper Universal retreatment (PTUR), Mtwo retreatment (MTR), or D-RaCe retreatment (D-RC) systems. Each specimen was scanned using a high-resolution micro-CT system before instrumentation, after obturation, and after the removal of the filling material. The images were evaluated, and the presence of microcracks was recorded.RESULTS
The PTUR system demonstrated the highest percentage, while MTR and D-RC retreatment systems resulted in similar numbers of microcracks.CONCLUSIONS
Clinicians should be aware that all retreatment systems may cause microcracks.