patients with Miller class I , II gingival recession will be divided into 2 groups (control, intervention).the control one will receive coronally advanced flap with subepithililal connective tissue graft harvested from the palate while the intervention one will have coronally advanced flap with advanced platelet rich fibrin(A-PRF).as it represent a new generation of platelet concentrate allow for better healing and root coverage results.

Null hypothesis: In patients with Miller class I and II gingival recession, there is no difference in amount of root coverage (mm) following the application of SCTG+A-PRF compared to CAF+SCTG.

• Population (P): Patients with single Miller class I, II gingival recessions.
• Intervention (I): Coronally advanced flap (CAF) plus platelet rich fibrin (A-PRF).
• Comparator (C): Coronally advanced flap (CAF) plus subepithelial connective tissue graft (SCTG).
• Primary Outcome (O): Root coverage (mm).
• Time frame: 9 months.
• Study design: Randomized controlled clinical trial.
• Patients are to be selected from the outpatient clinic of the department of Oral Medicine and Periodontology-Cairo University

Inclusion Criteria:

• Systemically healthy patients 18 years old and older both males and females.
• Good oral hygiene after phase I therapy.
• Miller's class I or II gingival recession.
• Not using antibiotics, steroids, chemotherapy or other medications that may modify results of the surgery and healing.
• Cooperative patients able and accept to come for follow up appointments

Exclusion Criteria:

• Pregnant or lactating females.
• Current Smokers.
• Patients with any systemic disease that may affect the periodontal healing.
• Teeth with endodontic treatment, buccal restoration or caries.
• Patients with poor oral hygiene