Association between case complexity determined using the E-CAT and postoperative pain following single-visit root canal treatment: a prospective clinical study

Abstract This prospective clinical study investigated the association between case difficulty, as determined by the Endodontic Case Difficulty Assessment Tool (E-CAT), and postoperative pain following single-visit root canal treatment. A total of 162 patients requiring endodontic treatment were classified as class 1 (low difficulty; n = 53), class 2 (moderate difficulty; n = 55), or class 3 (high difficulty; n = 54) according to the E-CAT. All procedures were performed by one trained operator using a standardized protocol. The primary endpoint was visual analog scale (VAS) pain intensity on postoperative day 1 (0–24 h); VAS scores on days 3, 5, and 7 and longitudinal pain outcomes were secondary endpoints. Day-1 VAS scores did not differ significantly among the E-CAT classes ( p = 0.083). No significant between-class differences were observed at later time points (all p > 0.05), whereas pain decreased significantly over time within each class ( p < 0.001). In the unadjusted analysis, postoperative pain at any point during the week was more common in class 3 (53.7%) than in class 1 (35.8%) or class 2 (27.3%) ( p = 0.016). A secondary repeated-measures Gaussian generalized estimating equation (GEE) model showed that E-CAT difficulty class was not significantly associated with postoperative VAS pain intensity or its trajectory. Similarly, a secondary repeated-measures logistic GEE model showed that E-CAT difficulty class was not an independent predictor of postoperative pain occurrence after adjustment for time, preoperative VAS score, age, sex, treatment type, and tooth type. Preoperative VAS score remained significantly associated with postoperative pain occurrence. In conclusion, E-CAT case difficulty was not associated with day-1 postoperative VAS pain intensity and did not independently predict secondary longitudinal pain outcomes following single-visit root canal treatment.