Evaluating diagnostic accuracy and consistency in applying the 2017 periodontal classification among dental professionals.

BACKGROUND Accurate periodontal disease diagnosis is essential for optimal treatment planning and patient care. However, variability in applying the 2017 Periodontal Classification may affect diagnostic reliability and treatment outcomes. This study investigated diagnostic accuracy and consistency among periodontists, periodontal residents, and dental interns in Saudi Arabia. METHODS Forty-four participants, including 13 periodontists, 14 periodontal residents, and 17 dental interns, independently classified 25 periodontitis cases. Agreement with a gold-standard diagnosis, established by expert periodontists using the 2017 Classification System, was assessed using descriptive statistics. Chi-square tests with Bonferroni-adjusted z-tests were used to compare agreement levels between rater groups. Inter-rater reliability was calculated using Fleiss' kappa, while Cohen's kappa was used to assess intra-rater reliability. RESULTS Periodontists demonstrated the highest agreement with the gold standard (92.0%) for periodontitis diagnosis. Staging agreement was highest among residents (51.7%) and periodontists (49.1%). Grading accuracy was highest for grade C cases across all groups (60.7%). Underestimation was common across rater groups, with interns exhibiting the highest rates in staging (49.6%) and grading (58.3%). The second assessment demonstrated improved diagnostic accuracy across all groups. Inter-rater reliability ranged from fair to moderate across rater groups (κ = 0.22-0.60). Intra-rater reliability was highest among interns, indicating substantial agreement (κ = 0.63-0.75). CONCLUSION Findings highlight considerable variability in the application of the 2017 Periodontal Classification among dental professionals, underscoring the role of clinical experience and training in influencing diagnostic accuracy. Structured calibration and targeted educational strategies are essential to improve diagnostic consistency, minimize misclassification, and support optimal patient care. PLAIN LANGUAGE SUMMARY Understanding gum disease correctly is important for providing patients with the right treatments. This study looked at how accurately different groups of dental professionals - specialists in gum disease (periodontists), dentists in training (residents), and recent dental graduates (interns) - could diagnose cases of periodontitis using a new system called the 2017 Periodontal Classification. A group of expert periodontists created a "gold-standard" diagnosis for comparison. We found that periodontists were the most accurate, while interns had more difficulty correctly identifying disease severity. Across all groups, many participants underestimated how serious the cases were. Participants were better at recognizing advanced disease compared to milder forms. When the participants repeated the diagnosis of the cases later, their accuracy improved, suggesting that practice and training help. Our results show that diagnosing gum disease can vary depending on experience and training. The study highlights the need for ongoing education and practice to make sure that all dental professionals can diagnose gum disease reliably, which is important for making treatment decisions and improving patient care.