Introduction: Retrieval of separated instrument from a root canal may lead to increased dentin loss and prolonged treatment time.
Aim: The aim of this study was to evaluate the retrieval time and increase in root canal volume after instrument retrieval with two retrieval techniques under dental operating microscope.
Materials and methods: Forty extracted human mandibular molars with 30°-40° mesiobuccal root canal curvature were selected based on cone-beam computed tomography (CBCT) and divided into two groups (n = 20 each). Group 1: Terauchi group (Terauchi ultrasonic tips) and Group 2: Satelec group (Satelec ET25 ultrasonic tip) based on the retrieval technique. Groups 1 and 2 were further divided into two subgroups (n = 10 each) based on the size of the separated instrument; Groups 1a and 2a with ProTaper Gold (PTG) F1 and Groups 1b and 2b with PTG F2. The time taken for retrieval was calculated and increase in root canal volume was evaluated using CBCT. Results were statistically analysed with paired t-test and post hoc analysis by Tukey's HSD test.
Results: All separated instruments were successfully retrieved. The mean time for instrument retrieval was lower in Terauchi group than in the Satelec group (P > 0.05) but not significantly. The mean increase in total root canal volume post-retrieval as well as the mean volume corresponding to the coronal part of the separated instrument was significantly lower in Terauchi group than in Satelec group (P < 0.05).
Conclusion: Terauchi ultrasonic instruments resulted in reduced instrument retrieval time with lower loss of root dentin.
Keywords: CBCT; Canal curvature; dental operating microscope; mandibular molars; mesiobuccal canal; separated instrument retrieval.