Analyzing Prognostic Factors of Root Canal Treatment at HSDM AGE Endodontics

Abstract

The objective of this study was to evaluate preoperative, intraoperative, and postoperative factors influencing outcomes of primary root canal treatment (RCT) performed by postgraduate residents at Harvard School of Dental Medicine (HSDM) Advanced Graduate Education (AGE) Endodontics between 2018 and 2024. Patient charts were reviewed from the axiUm electronic dental record system. 367 cases with both treatment and recall codes were identified, and 250 had confirmed recall visits with appropriate periapical radiographs. After excluding cases with less than six months of follow-up, 122 cases were included, comprising 89 retrospective and 33 prospective recalls. Periapical status was assessed using the Periapical Index by two blinded examiners, and cases were classified as success (healed/healing) or failure (non-healed) based on radiographic and clinical criteria. Univariable associations were evaluated using chi-square or Fisher’s exact tests and t-tests, and selected variables were analyzed in a Firth penalized logistic regression model. Time-to-failure was analyzed using Kaplan–Meier and Cox proportional hazards models. The overall success rate was 80.3% (98/122), with a tooth survival rate of 99.2% (121/122). Inter-examiner agreement was high (κ = 0.85). In univariable analyses, satisfactory coronal restoration, apical extent of gutta-percha filling, absence of symptoms at first recall, and higher provider year were associated with success. In the multivariable Firth model, absence of symptoms at recall (OR 0.01; 95% CI 0.001–0.06; p 0.001) and satisfactory coronal restoration (OR 5.11; 95% CI 1.17–30.48; p = 0.029) remained significant predictors, whereas provider year was not independently associated with outcome. The model demonstrated excellent discrimination (AUC = 0.936). In the Cox model, satisfactory coronal restoration was associated with a 75% reduction in hazard of failure (HR 0.25; 95% CI 0.09–0.70; p = 0.01). Within this postgraduate training setting, primary RCT demonstrated favorable outcomes. Coronal restoration quality and symptoms at first recall visit were the strongest predictors of success, highlighting the importance of achieving an adequate coronal seal and closely monitoring symptomatic patients. Longer-term, standardized follow-up is needed to better assess treatment durability and prognostic factors.