Curved canals apical transportation and centering ability by using Neoniti A1 with/without pre-flaring with Neoniti C1: a CBCT study

Aim: This study compared curved canal’s apical transportation by using Neoniti A1 with/without Neoniti C1 using cone-beam computed tomography (CBCT). Methods: This experimental in vitro study was conducted to analyze the mesiobuccal canals of extracted mandibular and maxillary molars (n = 62) with 20°–40° curvature. After determining the length of the roots, they were mounted in a custom-made holder and randomly sorted into two groups (n = 31). The roots underwent preoperative CBCT. Root canals in group 1 were only remodeled using the Neoniti A1 file while in group 2, the coronal third of the root canals was first prepared with Neoniti C1, and then the remaining part of the canal was instrumented with Neoniti A1. CBCT images were obtained again, and the preoperative and postoperative CBCT scans were compared using Romexis software to determine canal transportation at 3 mm, 5 mm, and 7 mm from the apex. Data analysis was done using SPSS 18. Results: Canal transportation was lower in the C1 + A1 group compared with the A1 group at all levels, but not significantly (P > 0.05). Canal transportation in both groups was < 0.03 mm at all levels from the apex. In the C1 + A1 group, canal centering was more elevated compared to the A1 group and at 3 mm from the apex, the two groups experienced a significant difference in centering ratio (P = 0.013). Conclusions: The use of Neoniti A1 files alone does not increase canal transportation in curved canals; however, the centering ability was higher in the use of C1 + A1. Therefore, coronal flaring is suggested.