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 3.75×14mm 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 C°±2) 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.