The goal of this clinical trial is to learn if adding a natural healing material works better to treat receding gums in adults. Receding gums is a condition where the gum tissue pulls back and exposes the tooth root. The main questions it aims to answer are:

• Does the addition of this healing material help cover the exposed root better than the standard surgery?
• Does the material help the gum tissue heal faster and become thicker? Researchers will compare a standard gum surgery alone to the standard gum surgery combined with Advanced Platelet-Rich Fibrin (A-PRF). A-PRF is a healing material made directly from the participant's own blood during the surgery. This comparison will help see if A-PRF improves the final cosmetic look and gum health.

Participants will:

• Have their blood drawn at the start of the surgery to create the A-PRF material.
• Receive the gum surgery with or without the A-PRF material. Visit the clinic for checkups and gum measurements at 1 week, 2 weeks, 4 weeks, 1 month, 3 months, and 6 months after the surgery.

1. Background and Rationale Gingival recession is a prevalent anatomical defect characterized by the apical shift of the gingival margin past the cementoenamel junction (CEJ). The Coronally Advanced Flap (CAF) is a reliable and widely applied technique for achieving esthetic root coverage. To overcome the limitations of autogenous grafts, Advanced Platelet-Rich Fibrin (A-PRF) has been introduced as a biologic adjunct. A-PRF is developed based on the Low-Speed Centrifugation Concept (LSCC), providing a porous 3D fibrin scaffold that continuously releases essential growth factors (such as PDGF, VEGF, and TGF-β) to accelerate soft tissue regeneration. This randomized, controlled, parallel-design clinical study aims to evaluate and compare the clinical efficacy of CAF combined with A-PRF versus CAF alone in treating localized gingival recession defects.

2. Study Design and Sample Size The required sample size was calculated based on reference data from Padma et al. (2013) to achieve 80% power with a significance level of α = 0.05. Accounting for a 20% anticipated dropout rate, the final sample size was set to 11 defects per group, yielding a total of 22 gingival recession defects. Eligible participants must be 18 years or older, present with Cairo RT1 recession defects in the anterior or premolar region, and exhibit a keratinized tissue width ≥ 1 mm, keratinized tissue height ≥ 2 mm, and probing depth ≤ 2 mm. Defects are randomly allocated into the Test Group (CAF + A-PRF membrane) and the Control Group (CAF alone).

3. Clinical and Surgical Procedures

   • A-PRF Preparation: At the initiation of the surgical procedure, 10 ml of venous blood is collected using a 24G butterfly needle into sterile glass tubes. Centrifugation is performed intra-operatively using a PRF Duo Quattro machine at 1500 rpm for 14 minutes following the LSCC protocol. The resulting A-PRF clot is carefully compressed in a PRF box to form a membrane with uniform thickness without damaging the cellular structure.
   • Surgical Protocol: The surgical intervention follows the standardized CAF technique proposed by Martina Stefanini and Giovanni Zucchelli (2021). Following local anesthesia with Lidocaine 2% and mechanical root debridement, the root surface is chemically conditioned with EDTA 24% (PrefGel). In the Test Group, the intra-operatively prepared A-PRF membrane is stabilized over the defect using 6/0 resorbable sutures, whereas no graft is applied in the Control Group. The flap is then coronally advanced and secured tension-free with suspensory and interrupted sutures.

4. Data Collection and Statistical Analysis

   • Clinical Assessments: Wound healing is evaluated using the Early Healing Index (EHI) at 1, 2, and 4 weeks post-surgery. Periodontal parameters-including Recession Depth (RD), Recession Width (RW), Clinical Attachment Level (CAL), Gingival Thickness (GT), and Height of Keratinized Tissue (HKT)-are measured at baseline, 1, 3, and 6 months by a calibrated, independent examiner using a UNC-15 probe and customized acrylic stents. The Mean Root Coverage (MRC), Complete Root Coverage (CRC), and Root Coverage Esthetic Score (RES) will also be calculated.
   • Statistical Analysis: Data is processed using JASP version 0.96. The Shapiro-Wilk test is utilized to check for normal distribution. Intra-group variations over time are analyzed using the Friedman test followed by Conover post-hoc analysis with Bonferroni correction. Inter-group differences are assessed using the Mann-Whitney U test, with statistical significance strictly defined as p < 0.05.

Inclusion Criteria:

• Patients aged 18 years or older.
• Presence of 1 to 2 gingival recession defects requiring treatment, classified as RT1 (Cairo 2011).
• Gingival recession defects located in the anterior or premolar regions of the maxilla or mandible.
• Gingival thickness ≥ 1 mm. Keratinized tissue width ≥ 2 mm. Probing depth ≤ 2 mm.
• Good oral hygiene, demonstrated by a mean Gingival Index (GI) ≤ 1 and a mean full-mouth Plaque Index (PI) ≤ 1.

Exclusion Criteria:

• Patients with systemic diseases affecting wound healing (e.g., diabetes mellitus, coagulation disorders).
• Pregnant or lactating women.
• Patients with a smoking habit.
• Teeth with interproximal bone loss.
• Severely malpositioned teeth.
• Presence of caries or cervical restorations at the experimental site.
• History of previous periodontal surgery at the selected sites.

The raw data will be available upon reasonable request to the corresponding author, provided that the request is aligned with the ethical approval and patient consent forms to ensure participant anonymity and data privacy.

Due to the surgical nature of the intervention and the required venous blood collection for A-PRF preparation, the operating surgeon and the participants cannot be blinded. To minimize observer bias, an independent, calibrated examiner-who is completely unaware of the treatment group assignments-performs all periodontal measurements at baseline and during all follow-up visits.