Abstract:
The aim of this in vitro study was to investigate the canal centering ability and apical
root canal transportation of pre-curved stainless steel K-files, the ProGlider file and GFiles
after glide path enlargement in curved root canals of extracted human
mandibular molars using micro-CT scanning. The working times for the different glide
path enlargement methods were also recorded.
Ninety untreated curved root canals from extracted molars were randomly divided
into three groups (n = 30). Group 1: manual glide path preparation with size 0.10 Kfile
and enlargement with size 0.15 and 0.20 hand K-files; Group 2: manual glide path
preparation with size 0.10 K-file and enlargement with NiTi rotary G-Files; and Group
3: manual glide path preparation with size 0.10 K-file and enlargement with the NiTi
rotary ProGlider file (ISO tip size 16).
Micro-computed tomography was used to scan the teeth before and after glide
path enlargement. Three-dimensional images were reconstructed from the pre- and
post-instrumentation scans to enable a comparison of the centring ability at three
selected levels: 1 mm from the apical foramen (D1), at the point of maximum root
curvature (Dmc) and 7 mm from the apical foramen (D7). Canal transportation was
assessed at 1 mm from the apical foramen in eight directions (MB, B, DB, D, DL, L, ML,
M). The time it took to enlarge the glide paths for each group was also calculated.
One-way Analysis of Variance was performed to assess if significant differences
existed between the three groups for the variables being compared (p<0.05). A
Bonferroni adjusted p value of 0.016 was used for pairwise comparisons of centring
ability.
K-files displayed statistically significantly higher centering ratios than G-Files at D1. At
all levels the ProGlider file exhibited statistically significantly lower centering ratios
than K-files. At Dmc, the ProGlider file demonstrated statistically significantly lower
centering ratios than G-Files. Ratios were significantly similar between K-files and GFiles
at D7 as well as between G-Files and the ProGlider file at D7 (p<0.016). Apical
canal transportation for K-files was significantly more than G-Files in five directions
and the ProGlider file in six directions (p<0.05). Glide path enlargement time for Kfiles
was significantly slower (74.92 s ± 2.60 s) than G-Files (41.87 s ± 20.19 s) and the ProGlider file (27.95 s ± 8.55 s)(p<0.05). There was no statistically significant difference
between glide path enlargement times of G-Files and the ProGlider file.
Findings suggest that NiTi rotary glide path files are suitable for safe glide path
enlargement because they cause less apical canal transportation than stainless
steel hand K-files. Of the two NiTi rotary glide path file groups, the ProGlider file
showed an overall significantly better centering ability around the entirety of the
original canals, particularly at the point of maximum curvature. Glide path
enlargement with the NiTi rotary glide path file groups was significantly faster than Kfiles
(p<0.05).
