Cyclic Fatigue Resistance of Three Niti Single-File Systems after Immersion in EDTA

Objective: To evaluate and to compare in vitro the cyclic fatigue resistance of three NiTI single-file systems (One Shape, Reciproc and Wave One) after immersion in 10% EDTA solution over different time periods. Materials and Methods: Cyclic fatigue test of three NiTi single-file systems was performed in a curved stainless steel artificial canal with 60° angle and 5 mm radius of curvature. 45 OneShape, 45 Reciproc R25 and 45 WaveOne Primary were tested after three different immersion protocols: 1 min in 10% EDTA at 37°C, 5 min in 10% EDTA at 37°C, no immersion. The number of cycles to fracture (NCF) was determined by measuring the time to fracture. The data were compared for differences by using 2-way analysis of variance (P=0.05). Results: In general, resistance to cyclic fatigue was not significantly affected by immersion in 10% EDTA. Reciproc R25 showed the highest cyclic fatigue resistance in all groups. Conclusions: 10% EDTA did not decrease/increase the cyclic fatigue resistance of NiTI single-file systems appreciably in vitro. Reciproc R25 was more resistant, but the new rotary OneShape instruments showed good mechanical resistance, similar to WaveOne Primary files developed for reciprocating motion.