Microcomputed tomographic investigation of the trepan bur/microtube technique for the removal of fractured instruments from root canals without a dental operating microscope

Objectives The aim of this study was to evaluate the removal of fractured instruments in mandibular incisor canals by using the trepan bur/microtube technique without a dental operating microscope (DOM). Materials and methods Thirty-four mandibular incisors were selected, and 5-mm apical segments of #25/.06 taper K3 NiTi instruments were fractured in the apical portion of each canal. Coronal enlargement was performed, and a staging platform was prepared at the coronal aspect of the fractured instrument. Then, a trepan bur was used to expose 1–1.5 mm of the fragmented instrument, and a microtube device was used to withdraw the fragment. Microcomputed tomographic (micro-CT) imaging was used to evaluate the geometric changes in the root canal and dentin. The time required for fractured instrument removal in each sample was recorded, and the results were statistically analyzed with a paired t test. Results The trepan bur/microtube technique exhibited a success rate of 76.47%, and the average fractured instrument removal time was 8.55 ± 5.81 min. The changes in canal volume and dentin volume from the coronal end of the fractured instrument to 1.5 mm apical to the end were significantly greater than those from the cementoenamel junction (CEJ) to the coronal end of the fractured instrument during fractured instrument removal ( P