External Validation of Periodontal Screening Using Self-Reports in Dental Settings

Background/Objectives: This study aimed to externally validate the screening model for severe PD proposed by Verhulst in a Portuguese population, assessing its discriminative performance and clinical applicability. Methods: A cross-sectional study was conducted with 310 adults recruited from a university dental clinic in Portugal. The participants completed a validated self-reported oral health questionnaire (screening model) and underwent a full-mouth periodontal examination using the CPITN index, with severe PD defined as a score of 4. Model performance was evaluated for discrimination, calibration, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: Of the 310 participants, 51% were diagnosed with severe PD. The Verhulst model showed an area under the curve (AUC) of 0.72 (95% CI: 0.67–0.77), with sensitivity and specificity of 0.709 (95% CI: 0.639–0.779) and 0.724 (95% CI: 0.651–0.796) and PPV and NPV of 0.727 (95% CI: 0.673–0.784) and 0.704 (95% CI: 0.651–0.764), respectively. Calibration was reasonable, with an observed-to-expected ratio of 1.10 (95% CI: 0.939–1.291). Conclusions: The model demonstrated acceptable external validity and could serve as a feasible screening tool for severe PD in Portuguese dental settings. Its integration may enhance early diagnosis and interdisciplinary care. Future studies should consider broader diagnostic criteria to refine accuracy.