Research Article

The Effect of Hydrofluoric Acid Surface Treatment on the Cyclic Fatigue Resistance of K3 NiTi Instruments

Figure 4

Fracture surface of as-received (a) and HF-treated (b) K3 instruments. Both surfaces revealed characteristic patterns of cyclic fatigue fractures with multiple lines (white arrows in (a, b)) and cone and cup appearance (black arrows in (b)). Pore-like structures were also shown (unfilled white arrow in (b)). The multiple lines pointed to by white arrow show the initiation site for the fatigue fracture process.
(a)
(b)