Educational case complexity (E‑CAT) and clinical outcomes in undergraduate endodontics: associations with procedural mishaps and postoperative pain

Case allocation in undergraduate dental education must balance student learning with patient safety. The Endodontic Complexity Assessment Tool (E-CAT) provides an objective framework for categorizing non-surgical endodontic cases by difficulty. This study aimed to evaluate the predictive value of E-CAT scores for procedural complications and postoperative pain (PP) in root canal treatments performed by undergraduate dental students. This study was a prospective observational clinical cohort study. A total of 160 patients undergoing primary RCT on mandibular or maxillary molars diagnosed with irreversible pulpitis or pulp necrosis and symptomatic/asymptomatic apical periodontitis were included. Cases were scored using the E-CAT, categorizing complexity as low, moderate, or high. RCT were performed by 5th-year dental students under supervision. Procedural complications were recorded. PP was assessed preoperatively, and at 1-, 3-, 5-, and 7-days post-treatment using a visual analog scale. Data were analyzed statistically using Spearman correlation, Cramér’s V, Chi-square, Kruskal-Wallis, Friedman tests, and Multivariable regression analyses (p < 0.05). A total of 160 patients (50.6% female; mean age: 27.8 ± 10.9 years) were included. Most of the cases (55%) were categorized as moderate complexity (E-CAT score 6–11). Higher E-CAT scores were associated with longer treatment durations (r = 0.21), more treatment sessions (r = 0.24), and increased procedural complications, particularly file separation (Cramér’s V = 0.251) and working length loss (V = 0.216). However, in adjusted count modeling, E-CAT did not independently predict the overall number of complications. Patients with higher E-CAT scores reported significantly greater PP on day 1 (p < 0.001) and required more postoperative analgesics (22.6% low vs. 73.7% high complexity, p < 0.001). PP reporting was slightly higher in complex cases, though without statistical significance (p = 0.067). Anatomical complexity, especially reduced canal visibility (V = 0.262) and apical morphology (V = 0.202), showed the strongest associations with PP. E-CAT scores predicted both technical and patient-reported outcomes in undergraduate root canal treatments. Incorporating E-CAT into undergraduate curricula may improve case allocation, support individualized supervision, and enhance competency-based learning by aligning case complexity with student ability while reducing complications.