Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology
EndodontologyShaping ability and safety of five different rotary nickel-titanium instruments compared with stainless steel hand instrumentation in simulated curved root canals
Section snippets
Specimens
One hundred fifty transparent resin simulated root canal blocks (Endo-Trainer; Frasaco, Tettnang, Germany) were randomly distributed among 6 groups of 25 canals each. The walls of the simulated canals were colored red. The material for coloration is the manufacturer's secret. Preliminary tests of the present study did not show any influence of sodium hypochlorite and lubricant on the removal of color. The simulated canals had a length of 18 mm, a curvature of 20 degrees determined by the
Unprepared areas
In most of the canals remaining color was observed apically and/or in the outer aspect of the curve (Fig. 1). Specimens with fractured files were not considered for comparison of unprepared areas, preparation time, and loss of working length.
Imaged in both directions canals enlarged with RaCe showed least areas of remaining color compared to all other groups (P < .001), followed by ProTaper. Preparations with ProFile showed the highest means of unprepared canal walls. The ProFile group showed
Discussion
In recent years computerized tomography studies have been performed for analyzing canal shapes after preparation of extracted human root canals with different instruments.25, 26 However, preparation of simulated resin root canals is a widely used and simple technique to evaluate the shaping ability of endodontic instruments, in particular with regard to newly developed instruments.2, 4, 14, 15, 16, 17, 18
In contrast to time-consuming computerized tomography studies using extracted human teeth,
Conclusion
Under the conditions of the present study the design with the alternating cutting edges of RaCe rotary files revealed less unprepared areas and minor loss of working distance compared to the other instruments. Hedström files, ProTaper, and RaCe showed the lowest preparation times. GT Rotary, ProFile, ProTaper, RaCe, and Hedström files seemed to be very safe. Only the FlexMaster group showed file fractures during preparation of resin blocks. Hedström and ProTaper files seemed to have a higher
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