Reconstruction of Deficient Atrophic Ridges Using Guide Bone Regeneration Technique

patients will be informed of the nature of the research work and informed consent will be obtained then randomized in 2 groups. Mixture 1:1 autogenous and xenogenic bone covered with Polytetrafluoroethylene membrane control group and study group p covered with native collagen membrane. * Patients of both groups will be subjected to CBCT (diagnostic for upper arch), diagnostic wax-up and stent fabrication. * Intra operative procedures (for both groups) followed by CBCT will be taken for every patient after 4 months. Both the study and control group will receive: * In Recipient site, using 15C blade on Bard Parker handle incision of full thickness mucoperiosteal flap inorder to obtain, three-line pyramidal flap, reflection using mucoperiosteal elevator molt 9. * The defective site is reevaluated after its primary evaluation on CBCT using UNC (University of North Carolina) periodontal probe and a template is cut using sterile suture pack, prior to donor site preparation. * Flap advancement using periosteal releasing incision inorder to allow later tension free flap closure. * In Donor site, mucoperiosteal flap is done, auto chip maker (ACM) is used for autogenous bone harvesting. * Autogenous particulate bone graft is obtained using auto chip maker bur (ACM), in implant contra 20:1 using surgical motor recommended drilling speed 100 rpm and maximum torque 50 Ncm. as well as, using bone scrapper in push direction. * Xenogenic bone graft particles (De-proteinized bovine bone mineral small granules (0.25-1 mm). is added to the autogenous bone particles to obtain homogenous mixture ratio 1:1. * The gold standard is a mixture of autogenous bone containing viable cells and xenogenic bone which has slower rate of resorption is to be placed in recipient decorticated site and covered by PTFE membrane. * The assemble is to be fixed by titanium bone tacks of diameter 2.5 mm and length 3.5 mm, to avoid micro movements of particulate bone assembly. * In the Study group: The asse