Cross-sectional configuration of endodontic files compared with manufacturers' design

The cross-sectional configuration of seven files at coronal and apical levels were compared with diagrams presented by manufacturers. The presence of cutting edges was also examined. Ground-twisted (K-file, K-Reamer, and K-flex) and machined files (Flex-R, Unifile, S-file, and Hedstrom) were included in #10, #25, and #40. Twelve files of each size and brand comprised the samples. Files were embedded in acrylic, which was then cut in cross-section in the apical and coronal parts of the flutes. These were photographed under a microscope. Six clinicians viewed the slides projected onto a screen for comparison with manufacturers' design and evaluation of visible cutting edges. The inconsistencies were primarily in machined files, smaller sizes, and apical sections of the instruments. Data showed that overall the cross-sections and presence of cutting edges compared well with the designs intended by the manufacturers.