Effect of screw access hole on the fracture load of implant-supported monolithic translucent zirconia crowns after mechanical cycling

This study evaluated the effects of screw hole and preparation techniques on the fracture resistance of implant-supported translucent zirconia crowns after mechanical cycling. Forty crowns were divided into four groups of 10: CNH (cement-retained with no screw access hole) for the control, HBS (hole prepared before dense sintering), HAS (hole manually prepared after sintering), and HRS (hole manually prepared undergo resintered). All crowns survived 360,000 cycles with a peak force of 300 N at 10 Hz. Fracture resistance assessments indicated that the HBS technique exhibited the highest resistance, with CNS demonstrating the lowest. However, statistical analyses (Kruskal–Wallis and Mann–Whitney U tests) revealed no significant differences between them. SEM fractographic analysis indicated that screw hole preparation techniques could influence fracture patterns and failure initiation in zirconia crowns.