42 patients will be selected from the Outpatient Clinic of the Oral and Maxillofacial Surgery Department, Faculty of Dentistry, Mansoura University for replacement of missed single tooth or multiple teeth in posterior mandible by dental implant in horizontally atrophic ridge.

Inclusion Criteria:

• Patient's cooperation, motivation and good oral hygiene.
• Patient medically free from systemic diseases that absolutely contraindicate implant surgery.
• Moderately atrophic posterior mandibular alveolar ridge width (more than 4 mm), with minimum 10 mm height.
• Free from history of bruxism / parafunctional habits.

Exclusion Criteria:

• Patients with local pathological disease such as cyst, tumor at the planned surgical site.
• Pregnant patients.
• Heavy smoker patients.