Inclusion Criteria:  patients >35 years-old. presenting highly atrophic fully edentulous maxilla (residual bone height <5 mm). In need of bilateral sinus floor augmentation aiming full mouth implant-supported rehabilitation. having teeth extraction at least 8 weeks prior to bone augmentation.  Exclusion Criteria:  smokers, illicit drug users and alcohol daily consumers. patients with metabolic and/or systemic diseases leading to impaired healing (e.g. decompensated diabetes, leukocyte or coagulation disorders, immunosuppression). history of radiotherapy in the head or neck region. bisphosphonate-based therapy recipients. intolerant to general/local anesthesia.