Multiple autoclave cycles affect the surface of rotary nickel-titanium files: an atomic force microscopy study

The purpose of this study was to evaluate the surface of rotary nickel-titanium (Ni-Ti) files after multiple autoclave cycles. Two different types of rotary Ni-Ti (Greater Taper and ProFile) were attached to a glass base. After 1, 5, and 10 autoclave cycles the files were positioned in the atomic force microscope. The analyses were performed on 15 different points. The same files were used as control before any autoclave cycle. The following vertical topographic parameters were measured: arithmetic mean roughness, maximum height, and root mean square. The differences were tested by analysis of variance with Tukey test. All topographic parameters were higher for both Greater Taper and ProFile after 10 cycles compared with the control (P < .05). ProFile also showed higher topographic parameters after 5 cycles compared with the control (P < .05). The results indicated that multiple autoclave cycles increase the depth of surface irregularities located on rotary Ni-Ti files.