The 2018 Classification of Periodontitis: Challenges from Clinical Perspective.

: The objective of this narrative review was to evaluate the clinical challenges encountered in the application of the 2018 AAP/EFP Classification of Periodontitis. : Electronic and manual searches were conducted to identify studies reporting diagnostic accuracy and inter- and intra-examiner agreement when using the 2018 Classification, both with and without the aid of implementation tools. : Eleven studies were included, encompassing a total of 459 clinical cases. Overall, 852 examiners participated, with 31 gold-standard examiners providing the reference diagnoses. General dentists often exhibited lower diagnostic accuracy and consistency compared to students and periodontal experts. Diagnostic challenges were observed in staging, particularly distinguishing between Stage III/IV and gingivitis/Stage I. Grading reliability was reduced in the absence of longitudinal data and high-level modifying factors. This review also explored difficulties in reporting 'hopeless teeth' and assigning the extent of periodontitis. Education, training, and implementation tools substantially improved diagnostic accuracy and consistency, increasing the agreement with reference diagnosis and strengthening inter- and intra-examiner agreement. : The application of the 2018 Classification showed notable variability in diagnostic accuracy and inter- and intra-examiner agreement. Improving clinician experience and training and incorporating diagnostic aids and emerging AI technologies has the potential to enhance diagnostic accuracy and consistency, which are essential for precisely estimating periodontitis prevalence, interpreting research findings, and determining prognosis and treatment needs.