Effect of mechanized instrumentation on distal wall thickness of the second mesiobuccal canal

Dentine wall thickness in the mesial roots of molars is critical to prevent root stripping. Understanding the effect of rotatory instruments on the second mesiobuccal canal is crucial to prevent weakening and periodontal communication.

To evaluate the effect of different conservative tapered mechanized instrumentation systems on the distal wall thickness of the second mesiobuccal canal of maxillary first molars in 3D dental replicas.

Fifty radiopaque 3D printed replicas were made of a maxillary first molar with Vertucci classification IV and Schneider curvature (<10°), 23 mm in length. The specimens were divided into 5 groups of 10. In all cases, the second mesiobuccal canal was instrumented to the working length. Group 1 was instrumented with Race Evo (FKG) up to file 30/04, Group 2 with AF F One (Fanta-Dental) up to file 35/04, Group 3 with Slim Shaper (Zarc4Endo) up to file 30/04, and Group 4 with Trunatomy, while the control group was not instrumented. Distal wall thicknesses were measured in the cervical, middle and apical thirds by CBCT before and after instrumentation. Descriptive statistics were calculated, after which analysis of variance and Tukey's test for multiple comparisons were performed (p < 0.05).

Analysis of variance showed a significant effect of instrumented group and thirds (p < 0.001). The multiple comparison test showed that the control and Race Evo groups differed significantly from the other three groups. Within each group, the differences between thirds were statistically significant.

Trunatomy, Slim Shaper and Fanta AF One systems are suitable for shaping second mesiobuccal canals while maintaining critical distal wall thickness.