Inclusion Criteria:  Any completely edentulous patient (mandible) with an old satisfactory denture requiring an implant-supported restoration. Patients aged from 40 to 70, able to sign an informed consent will be considered eligible for this trial. Implant sites must allow the placement of four implants. Non- heavy Smokers will be included (smoking up to 10 cigarettes/day) In case of post-extractive sites, they must have been healed for at least 3-month before being treated in the study. Patients with no systemic condition that may interfere with implant placement (e.g., Immunosuppressed or immunocompromised patients, patients under treatment of intravenous amino-bisphosphonates)  Exclusion Criteria:  - Patients with poor oral hygiene and motivation. Pregnancy or nursing. Drug abusers. Psychiatric problems or unrealistic expectations. Patients with infection and or inflammation in the area intended for implant placement. Patients participating in other studies, if the present protocol cannot be properly adhered to. Patients with signs of hyperactive muscles.