Case definitions of severity of periodontitis

Periodontitis severity was assessed according to the Centers for Disease Control and Prevention and the American Academy of Periodontology (CDC/AAP) case definitions¹⁸. The criteria were as follows: No periodontitis: No evidence of mild, moderate, or severe periodontitis. Mild periodontitis: ≥2 interproximal sites with clinical AL ≥3mm, and ≥2 interproximal sites with PD ≥4mm (not on same tooth) or one site with PD ≥5mm. Moderate periodontitis: ≥2 interproximal sites with clinical AL ≥4mm (not on same tooth), or ≥2 interproximal sites with PD ≥5mm (not on same tooth). Severe periodontitis: ≥2 interproximal sites with clinical AL ≥6mm (not on same tooth) and ≥1 interproximal site with PD ≥5mm. Third molars were excluded from the case definition. The prevalence of periodontitis was calculated as the sum of all types of periodontal disease including mild, moderate, and severe periodontitis.