BACKGROUND: Accurate periodontal diagnosis is the cornerstone of effective treatment planning and disease management; however, the clinical application of diagnostic criteria often remains inconsistent. Despite the availability of established international guidelines, dental professionals frequently encounter difficulties in clinical judgment, radiographic assessment and the interpretation of diagnostic parameters. Understanding global patterns of these diagnostic errors across regions and professional groups is crucial for identifying gaps in dental education and improving evidence-based periodontal care worldwide. OBJECTIVES: The aim of the study was to develop a 5-item questionnaire assessing basic periodontal knowledge among dentists, dental students, dental hygienists, and specialists in periodontics worldwide, as well as to understand global patterns and clinical standards. MATERIAL AND METHODS: A total of 3,328 professionals from over 60 countries were invited to participate in the questionnaire between September 1 and October 23, 2025. The invitees received e-mails with a link to access the survey. The questions were developed to assess basic periodontal knowledge, such as diagnostic parameters in periodontology, probing and its significance, evidence-based questions, and radiographic assessment. The data was weighted and statistically analyzed. RESULTS: A total of 543 participants from 46 countries completed the questionnaire (response rate: 16.32%), comprising 266 specialists in periodontics/dental hygienists (S-DHs) and 277 dentists/dental students (D-Ds). Overall, the first group demonstrated superior performance across most questions. The error rates varied markedly across continents. Despite this geographic variation, continents displayed similar internal patterns of errors, as shown by positive intercontinental correlations across most questions. Conversely, question 3 - addressing the balance between clinical judgment and evidence-based guidelines - demonstrated weak or negative correlations with the remaining items, behaving as an independent construct. The observed patterns demonstrated that diagnostic errors cluster within a largely cohesive technical domain, while judgment-based decision-making forms a distinct dimension of performance. CONCLUSIONS: This global analysis revealed substantial differences in periodontal diagnostic performance across continents, countries and professional groups. However, the errors followed a consistent and structured pattern. Specialists and dental hygienists outperformed general dentists and students, especially in the more interpretive questions. The findings suggest that improving periodontal diagnostic accuracy worldwide will require coordinated efforts to strengthen technical calibration and promote consistent use of modern diagnostic guidelines, especially in lower-performing regions.
Fernandes et al. (2026) studied this question.