Nominal Size and Taper Analysis of Novel Metallurgy NiTi Files

Abstract

Objective: The aim of this investigation was to assess the nominal tip diameter, taper and true pilot tip length of three nickel-titanium (NiTi) rotary files before and after use. Methods: Three brands of NiTi files of size 25.08 were evaluated: ProTaper Uni-versal (Dentsply Tulsa Specialties, Tulsa, USA), Channels PT (Insight Endo for Henry Schein, Melville, NY) and ProTaper Gold (Dentsply Tulsa Specialties), with ten files from each brand (total n=30). Scanning electron microscope (SEM) images of the files at 50x magnification were acquired before and after the files were used on endodontic training blocks, and the images were analysed by two independent investigators using ImageJ software. The nominal tip diameter (D0), taper and true pilot tip length (measured as the distance from the advertised diameter size of the file to the tip of the file) were recorded for each file and were analysed for statistical differences using repeated measures of analysis of variance (r-ANOVA) and Tukey's post-hoc test (P<0.05). Results:The marginal means of the nominal size showed statistically significant differences between brands of the same size; statistically significant differences were also observed between the advertised sizes and the actual sizes (P<0.001). The mean taper values showed statistically significant differences from the advertised (p<0.001) sizes, except for the ProTaper Gold (P=0.023) group. The changes in the true pilot tip length before and after use were not statistically significant (P>0.05). The pilot tip lengths varied between brands. Conclusion: All nominal tip diameters and most taper sizes of the analysed brands show statistically significant differences from the nominal sizes advertised by the manufacturers. The differences in true pilot tip lengths between brands indicate a current lack of standardization.

Accuracy of the initial diameter of finishing files and gutta-percha cones of the ProTaper Universal® system

“…4 The absence of accuracy was verified from the results of the present study for all groups of finishing files and cones of groups F1, F2, F3 and F4. A similar result was observed by Chesler et al 9 when evaluating the ProTaper F3 files and by Islambasic et al 11 when evaluating ProTaper F2 files. It was also verified that there was a tendency for the files to have lower actual diameters in groups F1, F4 and F5 and for the cones to have actual diameters higher than nominal.…”

“…3 Although the ProTaper Universal ® system is widely used, few studies have evaluated the actual diameters of its files and cones. 4,[9][10][11] In order to measure the files' and cones' D 0 diameters, a profile projector was used as it allows accurate and reliable measurements. 10,13 However, other studies have used methods such as digital imaging obtained by an optical microscope, 14 a measuring microscope, 3,8 a scanning electron microscope 11 and a digital caliper.…”

“…4,[9][10][11] In order to measure the files' and cones' D 0 diameters, a profile projector was used as it allows accurate and reliable measurements. 10,13 However, other studies have used methods such as digital imaging obtained by an optical microscope, 14 a measuring microscope, 3,8 a scanning electron microscope 11 and a digital caliper. 4 Only D 0 was measured because the accuracy and consequent compatibility of files and cones in this regard have a direct influence on the quality of apical sealing.…”

“…Among the studies that evaluated the diameter of ProTaper Universal ® files and cones, 4,9-11 Chesler et al 9 evaluated the F3 files and reported that they had a diameter smaller than the nominal diameter. Islambasic et al 11 verified that the F2 files did not have values similar to nominal. Castilho et al 4 evaluated the D 0 diameters of F2 and F3 cones and verified that all had appropriate values.…”

“…Different studies have been published for the purpose of evaluating the diameters and taper of these systems. 7,[8][9][10][11] According to some studies, the actual diameters of the files and cones differ from the nominal diameters .7,8,10,11 Among the rotary systems available, the ProTaper Universal ® system (Dentsply, Maillefer, Ballaigues, Switzerland) stands out for its widespread use even after the release of the ProTaper Next ® system (Dentsply, Maillefer, Ballaigues, Switzerland), a new version of ProTaper Universal ® . In this system, the nominal values of the initial diameter (D 0 ) and the taper as a percentage are informed.…”