Efficacy of root canal treatment for chronic apical periodontitis: risk factor analysis and development of a nomogram...

To evaluate the efficacy of root canal treatment in chronic apical periodontitis (CAP) and identify risk factors for poor prognosis and to develop a nomogram for personalized risk assessment.

This retrospective study enrolled 149 CAP patients treated at the 901 Hospital of Joint Logistics Support Force of People Liberation Army from October 2022 to May 2024. Data on demographics, smoking, diabetes, Old Periapical Index (O-PAI), visual analogue scale (VAS), and root canal curvature were collected. Independent risk factors were identified using multivariate logistic regression, followed by nomogram construction. Model performance was assessed using the receiver operating characteristic (ROC) curve, while calibration curves and decision curve analysis (DCA) were used.

Root canal treatment significantly improved O-PAI scores in CAP patients [from 4.00 (3.00, 4.00) pre-treatment to 2.00 (1.00, 2.00)] and significantly reduced VAS pain scores by day 7 post-treatment [(from 2.00 (1.00, 2.00) to 1.00 (1.00, 2.00), P < 0.001]. Multivariate analysis identified smoking (OR = 4.81, P = 0.004), diabetes (OR = 4.30, P = 0.006), higher pre-treatment VAS scores (OR = 2.36, P = 0.002), and greater root canal curvature (OR = 1.27, P < 0.001) as independent risk factors for poor prognosis. The nomogram model achieved an area under the ROC curve (AUC) of 0.85 in the internal validation and 0.78 in the external cohort.

Root canal treatment demonstrates significant efficacy in CAP. Smoking, diabetes, elevated pre-treatment VAS scores, and greater root canal curvature are independent predictors of poor prognosis. The nomogram provides a useful tool for personalized risk assessment and clinical decision-making.