The Periodontal Screening Index (PSI in Germany) or Periodontal Screening and Recording (PSR®) [12,13] was registered based on a WHO probe (Morita, Kyoto, Japan). The set of teeth was divided into sextants for the purpose of the investigation. The PSI scores (0 to 4) were recorded: score 0=healthy, score 1=bleeding, score 2=supra-/subgingival calculus, score 3=probing depths from 3.5mm to max. 5.5mm, score 4=probing depths greater than 5.5mm. We noted only the highest findings for each sextant. Persons with findings of code 0 to code 2 were classified as non-periodontitis persons (group 1), whereby codes 3 and 4 were considered a probable periodontitis persons (group 2). Two additional PSI classifications were defined in order to review the robustness of the screening test with respect to the prevalent severity of periodontitis. Classification Perio 2 comprised persons with a PSI code 0,1,2 and once code 3, indicating non-periodontitis, while persons recording two codes 3 or 4 on one occasion were periodontitis persons. In the third classification (Perio 3), only such patients as exhibited at least one code 4 were considered as periodontitis persons, while all others were evaluated as non-periodontitis persons.