Development of a nomogram to predict 5-year tooth loss after root canal treatment in patients with cracked teeth and...

To analyze the influencing factors of tooth retention within 5 years after root canal treatment (RCT) in patients with cracked teeth and chronic irreversible pulpitis, and to construct a nomogram model so as to provide a basis for the selection of clinical treatment regimen for such patients.

This retrospective case analysis included 295 patients (295 affected teeth) with cracked teeth complicated with chronic irreversible pulpitis who were treated from January 2017 to January 2020. Tooth retention within 5 years was taken as outcome event; independent-samples t test and chi-square test were applied for single factor comparison. Lasso was used to screen the variables. Binary logistic regression analysis was utilized to analyze the related factors. The nomogram model was constructed by the 'rms' package of R software. Receiver operating characteristic (ROC) curve was drawn to evaluate the discrimination degree of the model. Hosmer-Lemeshow (H-L) test was performed and the calibration curve was drawn to evaluate the calibration degree of the model. Decision curve analysis was conducted to evaluate the clinical practicability of the model.

Successful and improved teeth were recorded as tooth survival. According to whether the teeth were retained within 5 years, the enrolled patients were categorized into survival group (265 cases) and non-survival group (30 cases), with the 5-year tooth survival rate of 89.9%. Multivariate analysis identified 2-3 RCT visits (Odds Ratio (OR) [95% Confidence Interval (CI)] = 0.15 [0.05, 0.50]), probing depth > 5 mm (OR [95% CI] = 2.99 [1.26, 7.09]), and crown restoration (OR [95% CI] = 0.28 [0.09, 0.83]) as independent predictors of 5-year tooth loss (p < 0.05). The nomogram was constructed based on multivariate results and the area under the ROC curve of the prediction model was 0.73 (0.62,0.84). H-L test revealed p = 0.682, and the calibration curve of the model had a high overlap degree with the ideal curve. The risk threshold ranged from 4 to 68%. The nomogram model line was located at the upper right of the None line and the All line.

Multivariate analysis identified 2-3 RCT visits, probing depth > 5 mm, and crown restoration as independent predictors of 5-year tooth loss, and the nomogram constructed based on the above indicators has good practicability to predict tooth loss in patients. However, the sample size of our study was relatively limited, and the patient population was specific and may not be representative of the general population. Further external validation in a multi-center population is warranted.