Negotiability of MB2 root canals using rotary or reciprocating systems: a randomized clinical trial.

This randomized clinical trial evaluated the ability to negotiate second mesiobuccal (MB2) root canals in maxillary molars using nickel-titanium (NiTi) instruments in rotary and reciprocating kinematics. A total of 110 patients with MB2 canals were randomly assigned to two groups: EL - Easy Logic2 rotary instruments (n = 57) and X1B - MKLife X1 Blue reciprocating instruments (n = 53). Canals reached to full working length (FWL) were classified as "negotiable". In the X1B group, 96.2% of MB2 canals were negotiable, compared to 86% in the EL group, with no statistically significant difference (p = 0.152). Mean shaping time was shorter in the EL group (12.92 ± 4.36 min) than in the X1B group (14.33 ± 4.72 min), showing a significant difference (p = 0.047). Both systems showed high MB2 negotiability. However, regarding negotiability, both systems did not show statistically significant differences when adjusted Cox regression was used (Hazard ratio: 0.77; 95% confidence interval: 0.51 - 1.14). Rotary instruments showed a slight advantage in shaping time efficiency.