Intramanufacturer diameter and taper variability of rotary instruments and their corresponding Gutta-percha cones

To simplify endodontic treatment, manufacturers offer systems of nickel-titanium rotary files and matching gutta-percha cones. The aim of this study was to determine whether intramanufacturer file diameters and tapers matched the diameters and tapers of their corresponding cones.

Twenty files and corresponding cones ([ie, size #30, 0.04 [or variable] taper from EndoSequence [Brasseler, Savannah, GA], K3 [SybronEndo, Orange, CA], and ProTaper [Dentsply Tulsa Dental, Tulsa, OK]) were examined using scanning electron microscopy (35×) to establish their actual diameter and taper. Intramanufacturer precision was evaluated using a series of 6 two-sample t tests with a Bonferroni correction (α = 0.05) comparing the mean diameters and tapers of corresponding files and cones. Accuracy was determined by subtracting the nominal diameter (340 μm) or taper (0.04) from the measured diameters and tapers of files and cones. The absolute values of the mean diameter and taper differences were compared using 1-way analysis of variance, α = 0.05, and post hoc Bonferroni correction for pairwise comparison.

All intramanufacturer diameters and tapers were significantly different from each other (P < .001). ProTaper file and K3 cone mean errors (μm) for diameter were closest to the nominal D1 diameter at 11.28 ± 9.56 and 16.33 ± 10.49, respectively. K3 file and EndoSequence cone mean errors of 0.0014 ± 0.0014 and 0.0019 ± 0.0014 most closely approached the nominal taper.

Variability between nickel-titanium rotary file and gutta-percha cone sizes exists within manufacturers' systems.