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 assemble is going to be covered by resorbable collagen membrane and fixed by tacks. * Recheck adequate flap advancement by visualizing passive flap approximation, to allow tension free closure. * Double line closure using horizontal mattress placed 5mm away from flap margins followed by interrupted sutures on top to allow contact area which is preferred to point contact and wound edge eversion.