Histopathologic Validity and Clinical Reliability of Wolters Classification of Pulpitis: An Exploratory Study

AIM: Wolters' classification of pulpitis has been proposed to classify pulpitis into 4 categories (initial, mild, moderate, severe), aiming to guide clinicians to implement the relevant vital endodontic treatment. The main objective of this study was to test the histologic validity and clinical reliability of the Wolters classification. METHODOLOGY: For the validity, before extraction, 52 teeth with pulpitis were examined and classified by one examiner into the appropriate Wolters category. After extraction and histological processing, a blinded pathologist examined the sections and assigned each tooth to a Wolters category. For the reliability, 140 patients with pulpitis were clinically and radiographically examined by two examiners, and pulpal and periapical diagnoses were made independently according to the Wolters and American Association of Endodontists (AAE) classifications. Finally, the diagnoses were unmasked, and the agreement was measured using Cohen's Kappa, weighted Kappa, or intraclass correlation coefficient (ICC). The correspondence between the categories of the Wolters and AAE classifications was examined using the chi-square test and Cramer's V statistics. Statistical significance was set at p < 0.05. RESULTS: The ICC and Kappa analyses indicated poor to fair agreement for the Wolters classification. However, in a re-analysis performed by defining the mild pulpitis category to include a range from no to mild inflammation, the κ coefficients (minimum κ coefficient of 0.4004; p < 0.001) and the ICC value of 0.623 (95% CI: 0.319, 0.791) demonstrated fair to good agreement. Highest sensitivity [0.63 (95% CI: 0.39, 0.82)] and specificity [0.86 (95% CI: 0.69, 0.94)] were found in the severe and mild pulpitis categories, respectively. Regarding the clinical reliability, weighted-Kappa tests (minimum κ coefficient of 0.8118, p < 0.001) and the ICC value of 0.945 (95% CI: 0.923, 0.961) suggested that the interobserver agreement for the Wolters classification was almost perfect to excellent. The Wolters' initial pulpitis category and the moderate and severe pulpitis categories corresponded to the AAE's reversible and irreversible pulpitis categories, respectively. However, the mild pulpitis category was interpreted differently by the examiners. CONCLUSIONS: The Wolters classification demonstrated high clinical reliability; however, its histopathological validity appeared limited. Further research is required to better establish its validity.