Inclusion Criteria:  Patients with severely atrophic edentulous upper arch (Cawood class IV, V, VI) that could not be restored with other type of treatment. Patients who had at least 8-12 mm vertical bone height in anterior maxilla to allow installation of at least 2 conventional implants.  Exclusion Criteria:  Patients with any systemic disease that might interfere with dental implants placement and/or osseointegration e.g. uncontrolled diabetes, hypertension and osteoporosis, etc. Heavy smoker (> 20 cigarettes daily) and patients with history para-functional habits (e.g. clenching or bruxism, etc.) were also excluded. Intraoral pathological lesion, related to maxilla, maxillary sinus and zygoma.