Efficacy of Endodontic Files in Root Canal Retreatment: A Systematic Review of In Vitro Studies

The success rate of root canal treatment is high, but it can fail. In these cases, orthograde root canal retreatment is often the treatment of choice, for which numerous biomaterials are available on the market, including endodontic files. This systematic review aimed to study the endodontic files available on the market and establish their efficacy in root canal retreatment. An electronic search of six different databases was performed, and in vitro experimental studies that studied root canal cleaning, debris extrusion, retreatment time, or dentinal damage produced with any of the comparison methods were selected. The quality of the studies was assessed with the QUIN scale. In total, 78 studies were included for the analysis, of which 9 had a high risk of bias, 53 had a moderate risk, and 16 had a low risk. The methods used to evaluate the efficacy of endodontic files in root canal retreatment are heterogeneous. Manual files produce more apical extrusion than rotary files. PTUR files are the most studied endodontic files. It is the file system that leaves the least residual filling material in the canal, takes the least time during retreatment, and removes the greatest amount of dentine. However, no file system achieved the complete removal of the root canal filling material. No consistent pattern emerged across studies when comparing rotary files with continuous and reciprocating rotation in terms of the removal of the filling material, the time required for de-obturation, dentine damage produced, or apical extrusion.