Objective: This study was performed to evaluate the effects of a mandibular partial over denture supported by two different implant attachment designs on the supporting peri-implant bone. Materials and methods: Fourteen patients were selected and divided into two groups; each group received one implant supported mandibular partial over denture in the distal extension area retained with ball and socket attachment. Group I: Received implants with conventional platform matching design (the abutment and implant of the same diameter) and Group II: Received implants with platform switched designs (the abutment is smaller in diameter than the implant). Radiographic evaluation was done using direct digital radiography. Bone density and bone loss measurements around implants were measured at denture insertion, 3 months, 6 months and 12 months intervals after partial over denture insertion. Results: Mean percentage change was calculated followed by t-test for comparison between both groups, regarding bone height and density there was a statistically significant difference between the two implant designs for all the follow up periods with platform switched group (Group II) showing less values of bone loss, and better bone quality compared to the platform matching group (Group I). Conclusion: The use of implants with a modified platform (platform switching) improved preservation of the crestal bone