thirty-two implants will be inserted in patients seeking implantation of their lost posterior maxillary teeth (premolar and molars) with limited bone height below the floor of the maxillary sinus, secondary to sinus pneumatization. The patients will be selected from those attending the outpatient clinic of the Oral & Maxillofacial Surgery Department, Faculty of Dentistry, Mansoura University.

Inclusion Criteria:

• Patent ostium of maxillary sinus.
• Patient with missing one or more posterior maxillary teeth.
• Residual bone height of 3-6 mm, measured from the crest of alveolar ridge to the floor of the maxillary sinus at the planned implant site.
• A ridge width at the site of implantation of <5mm.
• Platelets of normal range.
• Good oral hygiene.
• Patients in the age frame between 20 years and 60 years old.
• No gender preface in selection of the patients.
• A minimum crown height space of 8 mm.

Exclusion Criteria:

• Active sinusitis, cyst, tumors or root tips at the planned surgical site.
• Patients with systemic diseases that contra-indicate the surgical procedure such as uncontrolled diabetes mellitus, bleeding disorders, serious osseous disorders, and mental disorders.
• Heavy smoking and alcoholism.
• Parafunctional habits such as bruxism and clenching.
• Signs of acute infection or pus discharge.
• Disturbed occlusion.