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 prostheses gained from two different impressions (digital versus conventional) techniques to show their effect on marginal bone loss.Materials and Methods: 16 completely edentulous patients with age ranges above 60 years were participated in this study received new maxillary and mandibular dentures. Four implants were inserted in the inter-foraminal area of the mandibular jaw according to the "All on four concepts" and the implants were immediately loaded with the lower dentures. After 3 months, the patients were randomly divided into two equal groups: Group I: made a digital intraoral scanning for the lower arch, and Group II: made an open tray abutment level impression technique for the lower arch then a hybrid prosthesis was fabricated, and measured the level of bone loss in 0,3,6,12 months radiographically.Results: The results of the current study showed statistically insignificant bone height change values in Group I in comparison to Group II as per the radiographic outcomes.Conclusion: All 4 mandibular implant hybrid prostheses fabricated from digital impressions proved more precise and reliable than those fabricated from conventional impressions. Regarding bone resorption, the group of digital impressions showed less marginal bone loss enhanced the prognosis of dental prosthesis and implant survival rate.