Nonsurgical root canal retreatment is frequently successful. A vital factor for success depends on the complete elimination of the original root canal filling material beginning with various filing procedures. Yet endodontic tools initially designed for shaping fall short of total elimination of material debris within the canal. A new study conducted by Dr. Marc Krikor Kaloustian of the Department of Endodontics at Saint Joseph University in Beirut, analyzed a combination of TS2 file (2Shape manufactured by Micro-Mega) / R25 instrument (Reciproc R25 instrument manufactured by VDW-Dental) retreatment and subsequent passive ultrasonic irrigation to determine the effectiveness to produce fewer debris remnants in the retreated root canal.

Endodontic specialists shaped the mesial canals of 88 extracted mandibular teeth and then obturated them. Then the teeth were stored for 14 days to allow the sealer to set. Before retreatment, each tooth underwent micro-CT imaging for reference. The researchers then performed retreatment by removal of gutta-percha and sealer from the mandibular molars. Then passive ultrasonic irrigation was performed with different ultrasonic irrigation devices, each on half of the subject teeth. Following retreatment, the roots were scanned with micro-CT to determine the volume and percentage of filling material remnants in the coronal, middle, and apical thirds.

The combination of TS2 and passive ultrasonic irrigation appeared to be more effective than R25 retreatment also in conduction with passive ultrasonic irrigation. Differences in ultrasonic devices did not appear to change the result that TS2 use was more effective than R25 retreatment.

A limitation of this particular study was the in vitro design yet the authors concluded use of TS2 and passive ultrasonic irrigation improved filling material removal.