forty patients will be selected from the outpatient's clinic of Oral and Maxillofacial Surgery Department, Faculty of Dentistry, Mansoura University for replacement of non-restorable tooth in posterior mandibular area.

Patients' Grouping:

The patients will be randomly divided into two equal uniform groups each consists of 20 patients:

Group A:

20 patients with non-restorable mandibular molar tooth will be treated with an immediately placed dental implant in conjunction with a dentin-derived membrane from the extracted tooth.

Group B:

20 patients with non-restorable mandibular molar tooth will be treated with an immediately placed dental implant in conjunction with extended platelet rich fibrin membrane.

Inclusion Criteria:

• Age above 18 years
• Non-restorable mandibular molar tooth that needs dental extraction & guided bone regeneration for immediate implant placement.
• Acceptable inter-arch space for the future prosthesis.
• Patient medically free from systemic diseases that absolutely contraindicate implant surgery.
• Cooperative patient with high motivation and acceptable oral hygiene.
• Free from history of bruxism / parafunctional habits.

Exclusion Criteria:

• Local and / or systemic conditions that interfere with the procedure.
• Smokers.
• Pregnancy.
• Uncooperative patients.
• Patient had undergone in the past 12 months radiation therapy to the head and neck area.