Aim of the study: is to evaluate the effect of two different super structure materials which are acrylic and casted metal on implant survival and osseo-integration both by preapical radiography and by measuring implant stability quotient (ISQ) by osstell device at 0,3 and 9 months respectively of immediate loading. Materials and methods: ten completely edentulous medically free male patients divided into two groups one receiving the acrylic resin prosthesis and the other group receiving casted metal restoration immediately loaded on the four inter foraminal implants placed by the use of a computer designed surgical guide according to All-on-4 concept with a bilateral distal cantilever.Results: marginal bone loss was greater in the acrylic resin prosthesis group and the two groups showed greater bone loss on the distal aspect of the posterior implants.Conclusion: cast metal provided better stress distribution and the distal cantilever induced great stress on the distal abutments specially on their distal aspects.