Levels of cytokine receptor activator of nuclear factor κB ligand in gingival crevicular fluid in untreated chronic periodontitis patients

Background: Receptor activator of nuclear factor κB ligand (RANK-L) is a cytokine involved in the regulation of osteoclastogenesis in bone remodeling and inflammatory osteolysis. One of the major causes of tooth loss in humans is bone destruction. The aim of our study was to determine the presence of RANK-L in gingival crevicular fluid (GCF) samples from adult patients with untreated chronic periodontitis and in healthy controls. We also identified the RANK-L present in lesions undergoing episodic attachment loss from GCF. Methods: GCF samples were collected from two periodontally affected sites (probing depth ≥5 mm, attachment loss ≥3 mm) in 20 patients (N = 40). After monitoring for 4 months, seven patients showed active periodontal disease, and GCF samples were collected from one active and one inactive site (N = 14 samples). The comparison with healthy controls was carried out by collecting GCF samples from 12 healthy volunteers (N = 24 samples). GCF was collected using a paper strip, and enzyme-linked immunosorbent assay (ELISA) was performed to determine the total amount of RANK-L. Results: RANK-L was found in a higher proportion (85%) of samples from patients than from controls (46%). The total amount of RANK-L was significantly higher in patients (115.53 ± 78.18 picograms [pg]) than in healthy subjects (63.08 ± 55.08 pg) (P = 0.003). Active sites, presumably associated with tissue destruction, had significantly higher levels of RANK-L than their inactive counterparts (125.95 pg versus 91.80 pg, P = 0.007). Conclusion: GCF total amount of RANK-L is significantly increased in periodontal disease, supporting its role in the alveolar bone loss developed in this disease.