Introduction: All-on-Four used with anatomical limitations in the atrophied edentulous mandible . All on four requires rigid splinting by metal bar like welding for better distribution of load around implants.
The aim of this study: to evaluate the effect of splinting implants in All-on-four design using welding technique on strain induced from vertical loads on both axial & tilted implants
Materials and methods: lower completely edentulous 3d printed model with all on 4 implants was fabricated .Two printed lower complete dentures were used one in group (A) where provisional all on 4 prosthesis was fabricated by conventional pick up technique engaging four titanium sleeves screwed to the four multi-unit abutments .The second printed lower complete denture was used in group (B) to fabricated splinted welded titanium bar provisional all on 4 prosthesis using same pick up technique as in group (A ).load was applied to the two provisional prosthesis and strains were recorded. Data were collected & statistically analysed to compare both groups by independent t-test, the p-value was considered significant at the level of <0.05.

Results: The two studied groups showed statistically significant where strain induced around all on 4 implants were reduced in group (B) in compared to group(A)
Conclusion: with in the limitation of this study splinting all on four implants in provisional prosthesis reduced stresses and strains around implants in compared to conventional non splinting provisional prosthesis.