Factors Associated with Extraction following Root Canal Filling in Adults

Abstract

Essentially, root fillings are performed to preserve natural teeth. Over time, however, some root-filled teeth will inevitably be extracted. The aim of this historical prospective cohort study in the adult Swedish population was to identify factors associated with extractions within 5 y of registration of a root filling. The cohort consisted of all those whose root fillings had been reported to the tax-funded Swedish Social Insurance Agency (SSIA) in 2009. Demographic data on the individuals registered with a root filling (sex, age, country of birth, disposable income, educational level, and marital status) were received from Statistics Sweden or the SSIA. Dental care setting, tooth type, and any registration of subsequent restorations within 6 mo were received from the SSIA. Multivariable regression analysis was used, and P < 0.05 was considered statistically significant. In total, 216,764 individuals had been registered with at least 1 root filling. Individuals (n = 824) without complete data were excluded from the analyses. After 5 y, 9.3% of the root-filled teeth had been registered as extracted. Logistic regression analysis found significant associations for all variables except country of birth, disposable income, and educational level. The highest odds ratios for extractions were associated with the type of restoration: teeth with no registration of any restoration and teeth with a direct restoration combined with a post were 3 times more likely to undergo extraction than teeth restored with an indirect restoration combined with a post and core. Overall, high odds ratios for extractions were associated with any type of composite restoration, including composite fillings and crowns combined with or without any post. In summary, after root filling in the Swedish adult population, several individual- and tooth-specific variables were associated with extraction. The reasons for the extractions remain to be studied further.