Tooth survival following root canal treatment by general dental practitioners in a Swedish county – a 10‐year follow‐up study of a historical cohort.

Aim: To evaluate the 10‐year survival rate of root filled teeth treated by general dental practitioners (GDPs), and to identify possible prognostic factors. Methodology: In 2006, 3676 individuals had at least one tooth root filled by a GDP within the Norrbotten Public Dental Service, Sweden. Over the next 10 years, 331 individuals died and were excluded. A random sample of 302 of the remaining individuals was included in the study, of whom 280 (n = 280 teeth) were included in the analysis. Dental records were reviewed retrospectively by a calibrated researcher to collect predetermined data regarding individual, pre‐operative, intra‐operative and post‐operative factors. The outcome measure was tooth extraction over time, and cases with no events were censored, regardless of apical status or symptoms, until last known date of tooth survival. In case of missing data, individuals were recalled for a control visit. Kaplan–Meier survival tables and Cox regression models were used for analysis. P < 0.05 was considered statistically significant. Results: The cumulative 10‐year survival was 81.7% (standard error: 2.6%), and the mean incidence of tooth extraction during the 10 years was 1.8% per year. The univariate analysis identified three possible prognostic factors (P < 0.05) that were associated with extraction: molars, two or more emergency inter‐appointment visits during the treatment, and root canal treatments consisting of five or more separate sessions. A multivariate regression analysis revealed no significant relationships for the variables gender, tooth type, number of contacts, any emergency visits during endodontic treatment, number of sessions to complete endodontic treatment, pulp diagnosis, or type of permanent restoration and extraction. Conclusions: The mean incidence of tooth loss over the first 10 years after completion of root canal treatment performed by a GDP was approximately 2% per year. No prognostic factors could be identified. [ABSTRACT FROM AUTHOR]