This study was carried out to compare between the effect of two different bar designes in implant supported mandibular overdenture structures using radiographic evaluation. Methodology ten patients were selected from the outpatient clinic of prosthodontics department faculty of oral and dental medicine cariro univerty all patients were completely edentulous with mean age of 45 60 and were free from any systemic diseases which might affect the bone quality or postoperative healing patients were divided into two equal groups each of five patients both groups received two implants in the inter foraminal region of the mandible. Patients of group A received bar joint attachment while those of group B received bar unit attachment Radiographic assessment including bone height and bone density changes around the implant was made using the CBTC at the time of denture insertion 6 and 12 months later. The results of the present study revealed a statistically significant difference between the bar joint attachment and bar unit attachment groups in radiographic evaluation. Within the limitation of the present study it may be concluded that the use joint bar attachment may induce less stresses to the supporting structures of implants than unit bar attachment in two implant retained overdentures. Joint bar attachment may provide less crestal bone resorption around implants than unit bar attachments. 3. There was no significant difference between joint bar and bar unit group regarding bone density.