This study aims to evaluate the effect of Allogenic bone graft mixed with Xenograft in ratio 1:1, on the radiographic and histomorphometric assessment versus Autologous bone graft mixed with Xenograft in ratio 1:1 in maxillary deficient ridges، In guided bone regeneration of deficient edentulous maxillary ridges, will the application of Xenograft mixed with Allograft (1:1) be as effective as Xenograft mixed with Autogenous graft (1:1) in terms of dimensional ridge changes and Quality of newly formed bone? Evaluation of the patient's general condition of the oral cavity, to make sure it complies with the criteria required to be enrolled in the study in terms of oral hygiene and pathological conditions. A full thickness flap will be elevated with two releasing incisions, decortication of the buccal aspect of the ridge, placing of grafting material which will be covered by collagen pericardium membranes, tacks placement at the labial side to fix the membrane in place, horizontal mattress sutures as well as single interrupted and continuous with resorbable sutures for closure. Intervention group: will be filled with mixture of Xenogenic graft and the Allogenic bone graft chips. Control group: will be filled with mixture of Xenogenic graft and Autogenous bone particulate harvested either from the mandibular symphysis or ramus. For both groups, All the subjects will be taking CBCT at pre surgical and 6 months post surgical. outcomes : Bucco-Palatal/Lingual horizontal bone gain, Alveolar ridge height,Percentage of new vital bone formation and Percentage of residual bone graft 6 months post-surgical.