Fatigue behavior of zirconia with microgrooved surfaces produced using femtosecond laser

Femtosecond laser is a promising surface treatment tool for zirconia implant. In this study, the fatigue behavior of zirconia specimens with microgrooved surfaces formed by femtosecond laser is reported. One hundred sixty CAD/CAM zirconia bars (20 mmx4 mmx1.4 mm) were evenly divided into four groups with different surface: as sintered; sandblasted with 110 mu m Al2O3; femtosecond laser produced microgrooves having 50 mu m width, 30 mu m depth, and 100 mu m pitch; microgrooves having 30 mu m width, 20 mu m depth, and 60 mu m pitch. The femtosecond laser formed micro/nanostructured microgrooves with precise size on zirconia surfaces. XRD analysis indicated that microgrooved surface showed no obvious tetragonal-to-monoclinic phase transformation. The fatigue strength of sandblasted specimens (728 MPa) was significantly higher than that of as sintered specimens (570 MPa). However, the fatigue strength of specimens with microgrooved surface decreased to about 360-380 MPa. The results suggest femtosecond laser is an effective technique to regulate the surface microtopography of zirconia, while further investigations are needed to improve its fatigue behavior.