Guided Bone Regeneration is a surgical procedure that uses barrier membranes with or without particulate bone grafts and/or bone substitutes. Osseous regeneration by GBR depends on the migration of pluripotential and osteogenic cells to the bone defects site and exclusion of cells impeding bone formation. To ensure successful GBR , four principles need to be met :exclusion of epithelium and connective tissue, space maintenance, stability of the fibrin clot and primary wound closure.