Long-term survival of endodontically treated teeth: A retrospective analysis of predictive factors at a German dental school.

Objectives: The aims were to investigate the survival rate of endodontically treated teeth (ETT) at a German dental school and to identify potential prognostic factors influencing tooth survival.

Methods: Dental records of patients were retrospectively screened for nonsurgical root canal treatment of at least one permanent tooth between 2000 and 2015. Individual-, tooth-, and treatment-related variables were recorded, and survival was defined as the presence of the ETT in the oral cavity until the date of censoring. Survival rates of ETT were assessed by Kaplan-Meier statistics, and mean annual failure rates (mAFRs) after 5- and 10-years were calculated. The effect of the assessed variables on survival was determined by univariable log-rank test and multivariable Cox regression analysis with shared frailty (p < 0.05).

Results: Overall, 3049 teeth from patients with a mean age of 41.53 ± 15.75 years were included. Survival of ETT after 5 and 10 years amounted to 88.0 % and 77.4 % (mAFR: 2.51 % and 2.54 %), respectively. The following variables significantly increased the tooth survival rate: patient age ≤ 60 years (p ≤ 0.035), 2 proximal contacts (p < 0.001), absence of apical periodontitis (p < 0.001), multiple visits (p = 0.033), use of a chelator (p = 0.022), and placement of a new indirect restoration (p < 0.001).

Conclusion: Root canal treatment is effective for maintaining natural teeth. Tooth survival was affected by several individual-, tooth-, and treatment-related variables.

Clinical Significance: This retrospective study confirms the long-term retention of root-filled teeth after nonsurgical (re-)treatment. Several pre-, intra- and postoperative factors significantly reduced survival rates.