Crestal Sinus Lifting Using Densah Burs Versus Lateral Window Technique at Residual Alveolar Ridge Height 3-5 mm With Simultaneous Implant Placement

Inclusion Criteria: * 1\. Patient medically free from systemic, immunologic or debilitating diseases or local conditions that could affect normal bone healing and/or implant placement. 2\. Patient with good oral hygiene. 3. Age from 18 to 55 years. 4. Partially edentulous patients with missed one or more of maxillary posterior teeth with residual alveolar ridge height 3-5 mm and a minimal width of the alveolar ridge 7 mm in the region of the planned implant site. 5\. Patients' edentulous ridges covered with optimal width of keratinized mucosa (\<3 mm) with no signs of inflammation, ulceration of scar tissue. 6\. No history of parafunctional habits. 7. Patients were ready to comply with the follow-up and maintenance program. 8. Sufficient inter arch space for prothesis. Exclusion Criteria: \- 1. Patients with clinical or radiographic evidence of rhinosinusitis or any other pathology in the maxillary sinus. 2\. Smokers. 3. Pregnancy.