The influence of simulated clinical use on the flexibility of rotary ProTaper Universal, K3 and EndoSequence nickel-titanium instruments

作者：Viana A C D; Pereira E S J; Bahia M G A; Buono V T L^*

来源：International Endodontic Journal, 2013, 46(9): 855-862.

DOI：10.1111/iej.12071

• NiTi endodontic instruments
• flexibility
• flexural fatigue
• torsional cyclic loading

Aim To investigate the influence of cyclic flexural and torsional loading on the flexibility of ProTaper Universal, K3 and EndoSequence nickel-titanium instruments, in view of the hypothesis that these types of loading would decrease the flexibility of the selected NiTi rotary files. %26lt;br%26gt;Methodology The instruments evaluated were S2 and F1 ProTaper Universal, sizes 20 and 25, .06 taper K3, and sizes 20 and 25, .06 taper EndoSequence. Flexibility was determined by 45 degrees bending tests according to ISO 3630-1 specification. Values of the bending moment (M-B) obtained with new instruments were considered as the control group (CG). Bending tests were then conducted in instruments previously fatigued to one-fourth and three-fourths of their average fatigue life (fatigue groups, FG1/4 and FG), as well as after cyclic torsional loading (torsional group, TG). Fatigue tests were carried out in a bench device that allowed the files to rotate freely inside an artificial canal with an angle of curvature of 45 degrees and a radius of 5mm. Cyclic torsional loading tests were performed that entailed rotating the instrument from zero angular deflection to 180 degrees and then returning to zero applied torque in 20 cycles. Data were analysed using one-way analysis of variance at a significance level of 5%. %26lt;br%26gt;Results Simulated clinical use by means of flexural fatigue tests did not affect the flexibility of the instruments, except for a significant increase in flexibility observed in a few instruments (P%26lt;0.05). In addition, comparative statistical analyses between the values of M-B measured in new instruments and after cyclic torsional loading showed no significant differences between them (P%26gt;0.05). %26lt;br%26gt;Conclusions The flexibility of rotary ProTaper Universal, K3 and EndoSequence NiTi instruments, measured in bending tests, was not adversely affected by simulated clinical use in curved root canals.

• 出版日期2013-9