Assessment of the fracture strength of straight and pre-angled (17°) zircon implant abutments supported CADCAM zerconium restoration: An in(vitro study).

Aims :evaluate the effect of abutment angulation on fracture strength of pre-fabricated zircon implant abutment supported CADCAM zircon crown. Material and methods: Ten analog with 3.7514mm were placed into resin blocks divided in to 2 groups: group A (n=5) parallel to long axis and group B (n= 5) fixed at angulation (17) to long axis. Then ten abutments were tightened to 25 N/cm2. Ten full anatomic zircon (CAD/CAM) crowns constructed as upper right central incisor: 5 on each group. After luting all crowns with dual cure resin-based luting, all samples passed to artificial aging using thermocycling machine, 500 cycles at (5 to 55 C2) degree. Then the load was applied by universal testing machine at 30 degree to the long axis until fracture occurred. Results: Statistical analysis showed that the implant abutment angulations significantly (p < 0.05) reduced the fracture resistance of zircon implant abutment. Conclusions: Within the limitation of this in vitro study it may be concluded that: the fracture strength of zircon implant abutment supported CADCAM zircon crown is significantly reduced in respect to the angulation fromstraight to angulated (17) zircon abutment.