TNFSF11 and periodontitis: Hierarchical multiple regression elicited a statistically significant association between severity of periodontitis and RANKL/OPG ratio (β = 0.759, t (157) = 12.330, p < .001) controlling for age (β = −0.099, t (157) = −1.634, p = .104), smoking (β = 0.215, t (157) = 3.973, p < .001), and gender (β = −0.019, t (157) = −0.345, p = .730).