200 patients took part in the questionnaire and were examined using the PSI. Thereafter the participants were divided into two groups, non-periodontitis persons (group 1; PSI 0-2) and periodontitis persons (group 2; PSI 3-4). The answers were evaluated using a point system ranging from 0 to 8, based on known periodontal risk factors and their assumed degree of influence. Receiver-operating characteristic (ROC) curve analyses were applied to examine the overall discriminatory power, sensitivity and specificity, and corresponding cut-off points of the self-reported periodontal disease scale.