Long-Term Survival of Primary Root Canal Treatment Following Indirect Cuspal Coverage Restoration in Posterior Teeth:...

This study aimed to evaluate the long-term survival of primary root canal treatment in posterior teeth restored with indirect cuspal coverage restorations.

Dental records of patients were retrospectively screened for primary root canal treatments between 1998 and 2019, followed by the placement of an indirect cuspal coverage restoration. Individual-, tooth-, and treatment-related variables were recorded. Surgical retreatment, apicoectomy and extraction were defined as failures. Survival rates of the primary root canal treatment were assessed by Kaplan-Meier statistics, and the mean annual failure rate after 10 years was calculated. The effect of the assessed variables on survival was determined by Log-rank tests and both univariable and multivariable Cox regression analyses (P < .05).

Overall, 607 teeth were included. The 10-year survival of primary root canal treatment was 89.1% (95% confidence interval [CI]: 85.3-93.1, 10-year mean annual failure rate: 1.14%). Three variables were significantly associated with survival in the multivariable model (P < .05): type of indirect restoration (partial crown: hazard ratio [HR] (95% CI) = 2.36 (1.11-5.00) [reference: full-coverage crown]), post placement (yes: HR (95% CI) = 2.77 (1.04-7.40) [reference: no]), and time interval between obturation and restoration placement (>1 year: HR (95% CI) = 2.03 (1.05-3.92) [reference: ≤1 year]).

Primary root canal treatment in teeth restored with cuspal coverage restorations demonstrated a high long-term survival rate. Post placement was associated with reduced survival, whereas improved outcomes were observed in teeth restored with full-coverage crowns and in those receiving indirect restoration within the first year after root canal obturation.