A new questionnaire was used as part of a preliminary dental examination to interview a total of 200 patients concerning the clinical indications and periodontal risk factors. The clinical follow-up examination was conducted by the Periodontal Screening Index (PSI). To include representative periodontitis patients a consecutive sampling was applied. The participants were divided into two groups of non-periodontitis patients (group 1; PSI Code 0,1,2) and periodontitis persons (group 2; PSI Code 3 and 4) for the first PSI classification (Perio 1). The sampling was finished until each group reached a number of hundred patients. To reduce the so-called center effect [25] the patients were all unknown to the examiners. Patients were also required to be at least 18 years to take part in the study. Patients undergoing a periodontal treatment, pregnant and disabled persons were also excluded from the study.