Comparative survival analysis of endodontic re-treatment and single-tooth implants: A retrospective cohort study using shared frailty modeling

Purpose: To compare the long-term survival of nonsurgical endodontic re-treatment versus single-tooth implants and to identify independent demographic, systemic, and lifestyle predictors of failure using a statistical model that accounts for patient-level clustering. Materials and Methods: A retrospective cohort study was conducted using electronic health records from a university setting between 2010 and 2016. Two cohorts were defined by Current Dental Terminology (CDT) codes: endodontic re-treatment (n = 1001) and single-tooth implants (n = 1822). The primary outcome was treatment failure (extraction or removal). To address the nonindependence of multiple procedures within the same patient, a shared frailty Cox proportional hazards model was employed to calculate hazard ratios (HRs) adjusted for clustering. Results: The analysis included 2823 procedures. The shared frailty model revealed that single-tooth implants had a significantly lower risk of failure compared to endodontic re-treatment (HR = 0.21; 95% confidence interval [CI]: 0.14–0.33; p < 0.001). Stratified frailty models revealed that tobacco use (HR = 2.76; p < 0.001) and diabetes (HR = 2.37; p = 0.007) were strong predictors of failure, specifically for endodontic re-treatments, alongside thyroid problems and osteoporosis. In the implant cohort, high blood pressure emerged as a significant predictor (HR = 3.96; p = 0.048). Unlike in standard survival models, patient age was not a significant predictor of failure (p = 0.335) after adjusting for patient frailty. Conclusions: When rigorously accounting for intra-patient correlation, single-tooth implants demonstrated a superior survival advantage over endodontic re-treatment in this population. However, the long-term success of both modalities is significantly associated with the patient's systemic health, with specific risk factors varying by modality.