Sixteen patients were selected from the Outpatient Clinic of the Oral and Maxillofacial Surgery Department, Faculty of Dentistry, Mansoura University for replacement of missed single tooth / teeth in posterior atrophic mandible by dental implant.

Patients' grouping:

Patients were divided randomly into two equal uniform groups as follow:

Group I:

Eight implants were placed in patients of missing single tooth / teeth in posterior mandible with subsequent horizontal ridge augmentation by decompression technique.

Group II:

Eight implants were placed in patients of missing single tooth / teeth in posterior mandible with subsequent horizontal ridge augmentation by ridge splitting technique using piezosurgery.

All patients were evaluated clinically and radiographically at regular time interval immediately, 6 and 12 months after surgery.

Inclusion Criteria:

• Patient's cooperation, motivation and good oral hygiene.
• Patient medically free from systemic diseases that absolutely contraindicate implant surgery.
• Moderately atrophic posterior mandible (horizontal alveolar dimension is not more than 4 mm at the crest), with minimum 10 mm vertical height.
• Patients prepared to comply with the follow-up and maintenance programme.
• 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.