TNFSF11 and periodontitis: Clinical studies evaluating RANKL, OPG levels in gingival crevicular fluid (GCF) interpreted that high RANKL, and low OPG protein levels participate in the underlying process of periodontal tissue breakdown.22, 23, 24Interaction of RANKL, OPG proteins with bacterial by products, and inflammatory mediators during periodontitis disease triggers and controls the degenerative process of periodontal tissue breakdown.