Dental implant is a dental treatment that allow oral rehabilitation for partial and fully edentulous patients. Osteointegration is the factor that control success s or failure of dental implant that can be improved by addition of different adjunctive biological materials. Platelets Rich fibrin plays a significant role in tissue regeneration and wound healing. Melatonin is biological hormone that secreted from pineal gland and played an important role in human growth.

Inclusion Criteria:

1. good oral hygiene participants,
2. free of any systemic diseases,
3. Patients' age ranged from 20 to 40 years old.
4. Patients who can complete surgery and the study protocol.
5. Partially edentulous patients in the posterior mandibular region (at least a single-mandibular edentulous area) with periodontal health.

Exclusion Criteria:

1. patients who had parafunctional habits,
2. current and former smokers, pregnant
3. lactating women
4. unmotivated patients
5. patients with psychological problems
6. patients who were not able to follow the treatment protocol -

female as melatonin is sex prevalence