A comparative analysis of the shaping ability of four different endodontic files: an in vitro study

In this study, the shaping performance of four rotary endodontic files was evaluated and compared using micro-computed tomography (Micro-CT). Four NiTi endodontic file systems (Dentsply ProTaper Gold [PG], EndoArt Action Gold [AG], VDW Reciproc Blue [RB], and EndoArt Expert Blue [EB]) were tested using standardized 3D-printed teeth to investigate the untouched canal surface, canal volume, structure model index (SMI), residual canal wall removal, canal transportation, and centering ability. Data normality was assessed using the Shapiro–Wilk test. Depending on distribution, parametric (ANOVA) or non-parametric (Kruskal–Wallis) tests were applied, with Bonferroni-adjusted post-hoc comparisons. Means with confidence intervals and medians with interquartile ranges were reported. For post-instrumentation surface area, significant differences were observed between PG and both RB and EB, as well as between AG and both RB and EB (p < 0.05). Surface area changed significantly after instrumentation in all groups (p < 0.05). For post-instrumentation canal volume, significant differences were observed between PG and AG, RB, and EB, as well as between AG and RB and EB (p < 0.05). Canal volume changed significantly after instrumentation in all groups (p < 0.05). For post-instrumentation canal wall thickness, significant differences were observed at the apical 3 mm level between PG and AG, PG and RB, and RB and EB, at the middle 5 mm level between PG and RB only, and at the coronal 7 mm level between PG and EB and between AG and EB (p < 0.05). Within the limitations of this in vitro study, all file systems demonstrated generally comparable shaping performance, although differences were observed in specific measured outcomes. The alternative file systems showed similar overall performance to the original systems, with some less favorable findings in canal transportation and centering ability at certain root levels. These findings should be interpreted cautiously and validated under clinical conditions.