Mechanical and Metallurgical Properties of Various Nickel-Titanium Rotary Instruments

Figure 5

SEM images of the fractured instrument surfaces after a cyclic fatigue test: (A, a) ProFile, (B, b) K3, (C, c) One Shape, (D, d) ProTaper NEXT, (E, e) Reciproc, (F, f) WaveOne, (G, g) HyFlex CM, and (H, h) TF. All images at low magnification (A, B, D–H, ×250; C, ×200) show a mixed pattern of brittle fracture (BF) and ductile fracture (DF). The ductile fracture pattern with a dimple area is outlined with a dotted line. A brittle fracture pattern with fatigue striations can be observed more clearly in the higher magnification images (a–c, ×1,000; d, ×2,000; e–h, ×5,000).