Adjunctive 0.8% Hyaluronic Acid Gel in Open-Flap Surgery for Thin Gingival Phenotype in Patients With Periodontitis

The aim of this study is to evaluate the clinical effectiveness of 0.8% hyaluronic acid (HA) gel as an adjunct to open flap debridement (OFD) in periodontitis patients with a thin gingival phenotype. The primary research question is: Does the adjunctive use of 0.8% HA gel reduce gingival recession and improve clinical parameters? To answer this, researchers will compare the adjunctive use of 0.8% HA gel to physiological saline in combination with OFD, assessing their effects on clinical outcomes and gingival recession in patients with a thin gingival phenotype. Participants will: * Receive 0.8% HA gel application during OFD surgery and a second application at 4 weeks postoperatively. * Attend follow-up visits at 1, 3, and 6 months after surgery for clinical assessments and measurements.