the Effect of Hyaluronic Acid on a Prefabricated CAD-CAM Bone Blocks for Ridge Augmentation

10 patients will be included in this study with bilateral atrophic posterior mandible for split mouth research . group I: prefabricated CAD-CAM allogeneic bone block sterilized with gamma rays hydrated using hyaluronic acid group II: prefabricated CAD-CAM allogeneic bone block sterilized with gamma rays hydrated using saline solution under LA mucoperiosteal flap will be elevated to expose the atrophic ridge then the prefabricated CAD-CAM allogenic block either mixed with hyaluronic acid (group I) or saline (group II) will be fixed in its position with titanium miniscrews , The block was coated with a nonporous d-PTFE membrane then closure of flap with nylon second stage: 6 months later exposure of alveolar ridge core biopsy was taken for histological study then insertion of titanium implants. the aim of the study is to investigate the effect of hyaluronic acid on a prefabricated CAD- CAM bone blocks for ridge augmentation radiographically and histologically.