Comparison of Accuracy of Calibration Ring Placement on 4 Different Endodontic Files

The purpose of the current study was to evaluate the accuracy and consistency of the placement of calibration rings on 4 file types: K3 (SybronEndo, Orange, CA), Vortex Blue (Tulsa Dentsply, Tulsa, OK), Kontrol Flex (Brasseler USA, Savannah, GA), and Lexicon (Tulsa Dentsply, Tulsa, OK).

Forty endodontic files, 10 of each type, were measured using a measuring microscope (Model W122; Gaertner Scientific Corp, Skokie, IL). Measurements were made from the file tip to the leading edge of 2 calibration rings and to the handle of each file. Each file measurement was performed 3 times by the same operator to ensure internal validity, and the 3 measurements were used to generate a mean for each file measurement.

Based on a 1-factor analysis of variance and Tukey post hoc test (α = 0.05), K3 files displayed significantly greater accuracy and consistency in calibration ring and handle position. In contrast, Vortex Blue files were the least accurate, whereas both Kontrol Flex and Lexicon files were marked with similar precision.

Calibration rings have been used by some operators to measure files during canal instrumentation. This study showed there was variation in placement of calibration rings and handles. Reliance on calibration rings and file handles as the sole means of measuring endodontic files may lead to inaccuracy in canal instrumentation.