The Effect of Accuracy of All on 4 Mandibular Implant Hybrid Prosthesis Fabricated by Two Different Impression Techniques (Digital versus Conventional) on Bone Loss.

Objectives: Comparing the accuracy of all on four implants supported hybrid prosthesis which gained from two different impression techniques (digital versus conventional) in order to show its effect on marginal bone loss. Materials and Methods: 16 completely edentulous patients with age range above 60 years were participated in this study received new upper and lower dentures. Placement of four implants in the inter-foraminal area of the mandible were done according to the concept of “All on four implants” followed by immediate loading with the lower denture. Three months later, the patients were divided in a random manner into two equal groups: Group I: performed a digital intraoral scanning for lower arch, Group II: performed an open tray abutment level impression technique for lower arch then a hyprid prosthesis were fabricated and measure the level of bone loss in 0,3,6,12 months radiographicaly. Results: The results of this study showed statistically insignificant less bone height changes in Group I in comparison to Group II according to the radiographic outcomes. Conclusion: All on 4 mandibular implant hybrid prosthesis fabricated from digital impression prove to be more precise and more reliable than that fabricated from conventional impression and regarding bone height changes the group of digital impression showed less marginal bone loss that enhance prognosis of dental prosthesis and implant survival rate.