Shaping ability and filling quality after root canal preparation of primary teeth using hand files or three different single-file NiTi systems: a micro-CT study.

Aim: This study evaluated the shaping ability and filling quality of three different single-file NiTi systems-XP-Endo Shaper®, Reciproc Blue®, and HyFlex EDM®-in primary molars. Hand K-files were used as a reference for comparison.

Design: Maxillary primary molars (20 teeth and 60 root canals) were scanned using micro-computed tomography and assigned to four groups (15 root canals) of instrumentation: hand K-files, Reciproc Blue® R25, Hyflex EDM®, and XP-Endo Shaper® systems. The specimens were re-scanned after root canal preparation and after filling with zinc oxide-eugenol sealer. The parameters assessed included the percentage of untouched canal walls, canal volume and surface area, dentine removed, dentine thickness, occurrence of perforations, and instrumentation time. The quality of root canal filling was also evaluated. Data were analysed using the Wilcoxon, Kruskal-Wallis, and Mann-Whitney tests for non-normally distributed data, and paired t-tests and ANOVA for normally distributed data (α = 5%).

Results: The hand K-file group consumed more time than the other methods (P < 0.05). Moreover, the hand K-file group showed greater dentine thickness reduction in the mesiobuccal root at 4 mm from the furcation when compared to the Hyflex EDM® and XP-Endo Shaper® groups (P < 0.05). Perforations occurred in 20% of canals in the XP-Endo Shaper® and 6% in the Reciproc Blue® groups. The filling quality was similar across all groups (P > 0.05).

Conclusion: Whilst hand K-files were more time-consuming during root canal preparation, all evaluated systems were effective in shaping primary teeth, however, the XP-Endo Shaper® should be used cautiously due to a higher rate of perforations.