Shaping ability and debris extrusion of new rotary nickel-titanium root canal instruments

Bürklein S, Donnermeyer D, Henschel TJ, Schäfer E

Abstract

The aim was to evaluate the canal straightening and the amount of apically extruded debris associated with five rotary nickel-titanium when preparing curved root canals. A total of 100 root canals in extracted human teeth (angles of curvatures 20°-30°; radii 5.9-13.5 mm) were divided into five groups (n = 20/group). The groups were balanced with respect to the angle and the radius of canal curvature. The root canals were prepared using conventional austenite 55-NiTi alloy instruments F360, F6 SkyTaper (both Komet, Lemgo, Germany), and the heat-treated NiTi Jizai, Silk-Complex and Silk-Standard instruments (all Mani, Tochigi, Japan) to an apical size 25. The amount of extruded debris was assessed with a micro balance. Statistical analysis was performed using Kruskal-Wallis test with Bonferroni correction at a significance level of p < 0.05. During canal preparation, neither instrument fractures nor procedural preparation errors were noticed. Regarding canal straightening, the use of Jizai instruments resulted in the significantly lowest straightening (p < 0.05), while no significant differences were obtained between all other groups (p 0.05). Regarding the amount of apically extruded debris, no significant differences between all groups were obtained (p 0.05). Within the limitations of this study, all instruments performed well, and especially the Jizai instruments showed an excellent shaping ability.