Transportation of Severely Curved Canals: Comparison of One Shape and K3 Rotary Systems

Background and Objectives: This study sought to compare canal transportation and centering ability of One Shape and K3 rotary systems in preparation of severely curved mesiobuccal root canals of human mandibular first molars using cone beam computed tomography (CBCT). Materials and Methods: In this in vitro, experimental study, 40 mandibular first molars extracted for periodontal reasons were divided into two groups of root canal preparation with One Shape and K3. CBCT scans were taken before and after instrumentation to assess canal transportation and the centering ratio at 2 (apical third), 5 (middle third) and 8 (coronal third) mm from the apical foramen. Results: Data analysis showed no significant difference in canal transportation between the two groups in the middle (5 mm) and coronal (8 mm) thirds (p>0.05). However, in the apical third (2 mm), canal transportation by K3 was significantly less than that by One Shape (p<0.05). Conclusion: Canal transportation was less in the apical third by use of K3 compared to One Shape. Also, the canal centering ability of One Shape was less than that of K3. However, the two systems were not significantly different in the middle and coronal thirds.