Torsional fatigue profiles of ProTaper nickel-titanium rotary instruments.

摘要

The torsional fatigue profiles of the original ProTaper RTM F2, F3 and ProTaperRTM Universal F2, F3, F4, F5 nickel-titanium rotary instruments were determined using a reversible geared motor assembled according a modification of ANSI/ADA Specification No. 28. The motor was programmed to continuously deflect to a set deflection angle (DA) and then return to zero (rest) until instrument fracture occurred. Ten instruments of each size were tested at various DAs. The mean number of cycles to fracture and standard deviation were determined for each DA. All instruments cycled at larger DAs demonstrated fewer cycles to fracture than those cycled at smaller DAs. The ProTaperRTM Universal F2 and F3 instruments had a significant reduction in torsional fatigue at each tested DA compared to the original ProTaperRTM F2 and F3 instruments. Torsional fatigue is only one mode whereby a nickel-titanium rotary instrument may fracture.