Evaluation of Gingival Crevicular Fluid Parathyroid Hormone-Related Protein (PTHrP), RANKL, and OPG Levels in Periodontal Health, Gingivitis, and Periodontitis.

Periodontitis is a chronic inflammatory disease characterized by the destruction of tooth-supporting tissues and alveolar bone loss, primarily driven by an imbalance in bone metabolism. The regulation of bone turnover relies heavily on the balance between RANKL, which promotes osteoclast activation, and OPG, its natural inhibitor. Furthermore, PTHrP acts as a critical autocrine and paracrine regulator in periodontal tissue health and alveolar bone repair. The primary rationale of this research is to investigate the dynamic role of PTHrP in periodontal pathogenesis during both the inflammatory and tissue-destruction phases, evaluating its potential as a biological marker. Following a comprehensive clinical periodontal examination by a single calibrated clinician, specific sampling sites are isolated with cotton rolls and gently air-dried. Supragingival plaque is carefully removed prior to sampling. Gingival crevicular fluid (GCF) is then collected from these designated interproximal sites using sterile filter paper strips, which are inserted into the sulcus until mild resistance is felt and left in place for 30 seconds. Samples contaminated with blood or saliva are immediately excluded. The exact volume of the collected fluid is quantified using an electronic volume meter (Periotron 8010). All valid strips are subsequently transferred to microcentrifuge tubes and preserved at -80°C until laboratory processing. The biochemical quantification of PTHrP, RANKL, and OPG levels is performed via commercially available Enzyme-Linked Immunosorbent Assay (ELISA) kits in accordance with the manufacturer's protocols.