Evgeny Rzhanov (Department of Operative Dentistry and Endodontics, Moscow State University of Medicine and Dentistry, Moscow, Russia)
Tatiana Belyaeva (Department of Operative Dentistry and Endodontics, Moscow State University of Medicine and Dentistry, Moscow, Russia)
To evaluate and compare basic properties of new and old ProTaper F3 instruments by using physico mathematical analysis of its design features.
20 ProTaper F3 instruments (Dentsply Maillefer, Switzerland) were included in this study: 10 of the new design and 10 of the old design. A scanning electron photomicrographs were taken of each instrument Then all instruments were sectioned transversely at 1. 3, 6 and 10 mm from the tip and also examined by SEM. All images were captured digitally and the following design parameters were assessed by a direct measurement technique: helical angle, pitch length, depth of flutes, external and internal diameters, angles of cutting blades. All measurement values were analyzed mathematically to evaluate and compare instrument properties such as: flexibility, self-feeding force component, volume of fluting along the axis, safe depth of cutting per unit step of treatment.
New F3 instrument showed significantly less flexibility than the old F3 instrument at 1 mm and 3 mm from the tip (p<0.05). Where was no statistically significant difference in flexibility between new F3 and the old F3 at the 6 mm from the tip (p>0.05). At the 10 mm from the tip new F3 showed greater flexibility than the old F3 (p<0.05). New F3 has less self-feeding effect than the old F3. New F3 has less volume of fluting (p<0.05) and less safe depth of cutting per unit step of treatment than the old F3 (1,4 mm and 1,6 mm respectively).
New ProTaper F3 differs from the old ProTaper F3 in design that determines its different properties."