MMP9 and periodontitis: Higher abundances of MMP9, S100 proteins (S100-A6/-A8/-A9), Complement C3, profilin-1, Alpha-2-macroglobulin, Haptoglobin, Submaxillary gland androgen-regulated protein, Histatin-1, Fatty acid-binding protein, Thioredoxin, and Albumin were previously linked to periodontitis [6,7,9,25,26,27,28,29,30].