Clinical and Biochemical Effects of Repeated Injectable Platelet‐Rich Fibrin Application in Periodontitis Treatment: A Randomized Controlled Clinical Trial

OBJECTIVES: This study aimed to investigate the clinical and biochemical effects of repeated injectable platelet-rich fibrin (i-PRF) application into periodontal pockets following scaling and root planing (SRP) in patients with periodontitis. METHODS: Twenty patients with Stage III Grade B periodontitis were enrolled in this randomized, controlled, split-mouth study. i-PRF was applied into all periodontal pockets at the test site after SRP and repeated after 2 weeks, whereas the control site received only sterile saline irrigation. Clinical periodontal parameters were recorded at baseline and at 3 months. Gingival crevicular fluid (GCF) samples were collected at baseline, on Day 7 following each i-PRF application, and at 3 months. Levels of Platelet Factor-4 (PF4), Platelet-Derived Growth Factor-BB (PDGF-BB), Transforming Growth Factor-β1 (TGF-β1), and Myeloperoxidase (MPO) were analysed using the enzyme-linked immunosorbent assay (ELISA) method. RESULTS: In periodontal pockets with an initial depth of ≥ 4 mm, no statistically significant differences were observed between the groups in probing depth (PD) or bleeding on probing (BOP) at 3 months (p > 0.05). However, clinical attachment loss (CAL), Plaque Index (PI), and Gingival Index (GI) values were significantly lower in the test sites than the control sites at 3 months (p < 0.01, p < 0.05, and p < 0.05, respectively). TGF-β1 total amounts were higher in the test sites at Week 2 and at Month 3 (p < 0.01). MPO total amounts were higher in the test sites at Week 4 compared to control sites (p < 0.05). CONCLUSIONS: Adjunctive use of i-PRF with SRP may enhance tissue healing and improve periodontal clinical parameters. TRIAL REGISTRATION: ClinicalTrials.gov NCT07029035, 19 June 2025 (retrospectively registered).