The results from these studies indicated that smokers had more lymphocyte and higher levels of both IFN-γ and IL-13, regardless of periodontal status [82], had higher salivary sCD44 profiles (P < 0.001) with the highest levels recorded in smokers in the periodontitis group [87], and had significantly higher levels of salivary calcium level (P< 0.05) [97]. Here, IFNG is linked to periodontitis.