S100A9 and periodontal disorder: Moreover, our results suggest this interaction to possibly play an important role in the progression of periodontal disease due to collagen degradation of Cathepsin K. Calprotectin, a heterodimer of S100A8 and S100A9, has been reported to be released at the inflammation site and induce IL-6 production in human gingival fibroblasts to promote the progression of periodontal disease30.