DKK1 and periodontitis: These findings are consistent with those reported by Napimoga et al. [36], who studied the roles of SOST, TNF-α, and DKK1 in patients with chronic periodontitis and in healthy individuals; they observed that, in the periodontitis group, the levels of SOST, DKK1, and TNF-α were significantly elevated in gingival tissue, but not in serum.