Clinical Cohort Study to Evaluate Survival Rate of Endodontically Treated Premolars Versus Implant Placement:

Introduction: To evaluate the survival and success rate of premolars with a previous root canal treatment which underwent to non-surgical retreatment or to extraction and implant replacement.

Materials and methods: Patients visiting in the Clinical Endodontic Section of the School of Dentistry (University of Bologna) were eligible for the study. Out of these patients, those with previously root canal treated premolars fulfilled the inclusion criteria. Teeth were considered retreatable and restorable (Endo group) or not retreatable and not restorable (Implant group) on the basis of clinical and radiographical examination. Each patient was included in an annual recall programme and final evaluation was performed after 8 years. Clinical parameters were recorded. Differences in baseline characteristics between the two treatment groups were assessed using logistic regression analysis with clustered standard errors. Results were expressed for each variable as odds ratios (ORs) of implant rehabilitation to root canal retreatment with 95% confidence intervals (CIs). Survival and treatment success for the two study groups were estimated using the Kaplan-Meier method. The association of treatment group with time to event was assessed using Cox proportional hazard regression analysis with clustered standard errors to allow for intragroup correlation within teeth belonging to the same patient. Results were expressed as hazard ratios (HRs) of experiencing the study event among implants as compared to root canal retreatments with 95% CIs.