Case Definitions of PD: Cohort Definition: the percent of teeth with at least one site meeting the cut points of severe, ≥30% of teeth with CAL ≥4 mm; moderate, 11–29% of teeth with CAL ≥ 4 mm; mild/no, <10% of teeth with CAL ≥4 mm. CDC/AAP Definition (18): severe, ≥2 interproximal sites with CAL ≥6 mm (not on same tooth) and ≥1 interproximal site with PPD ≥5 mm; moderate, ≥2 interproximal sites with CAL ≥4 mm (not on same tooth) or ≥2 interproximal sites with PPD ≥5 mm (not on same tooth); and mild/no PD, neither “severe” nor “moderate”. *(Adapted) EWP/Tonetti Definition (22): severe, the presence of proximal attachment loss of ≥3 mm at ≥2 non-adjacent teeth and the presence of proximal attachment loss of ≥5 mm at ≥30% of teeth present; moderate, the presence of proximal attachment loss of ≥ 3 mm at ≥2 non-adjacent teeth; and mild/no PD, neither “severe” nor “moderate” PD. Note: No subjects met the adapted EWP/Tonetti mild/no definition of PD.