Previous studies have reported that the stimulation of TNF-α induces sTNF-R2 shedding from gingival fibroblasts in vitro [15], and that TNF-α, sTNF-R1, and sTNF-R2 in gingival crevicular fluid (GCF) are significantly increased in chronic periodontitis [16]. Here, TNF is linked to periodontitis.