Assessment of Soft Tissue Thickness Following Utilization of Buccal Pad of Fat Versus Platelet-rich Fibrin for Covering Zygomatic Implants: A Randomized Clinical Trial

Inclusion Criteria: 1. Patients with severely atrophic edentulous upper arch (Cawood class IV, V, VI) that could not be restored by other type of treatment 2. Patients who had at least 8-12 mm vertical bone height in anterior maxilla to allow installation of 2 conventional implants. 3. Lacking posterior maxillary bone support due to significant sinus pneumatization 4. Good systemic health (ASA score I-II) 5. Highly motivated patients Exclusion Criteria: 1. Patient not willing to give his/her informed consent. 2. Patients with systemic disease that did not permit the surgical procedure (including general anesthesia). 3. Patients with uncontrolled diabetes or under bisphosphonate therapy. 4. Heavy smoker. (\> 20 cigarettes daily) 5. Patient with psychiatric problems, severe bruxism or other parafunctional habits. 6. Acute sinusitis. 7. Malignancy or pathology in Maxilla or Zygoma.