Evaluation of operator experience and nickel-titanium retreatment file systems in curved root canals

The aim of this study was to evaluate the influence of operator experience and four different nickel-titanium (NiTi) retreatment systems in curved canals with respect to procedural time, complications, and file distortions during root canal filling removal.

Root canal treatment was performed on 80 acrylic blocks with a 30° curvature. The blocks were assigned to either an endodontist or an endodontic resident (n = 40 each) and further divided into four subgroups (n = 10) according to the retreatment system used: ProTaper Universal Retreatment, ROGIN Retreatment Files, FANTA AF Retreatment Files, and EndoArt Retreatment Gold. Procedural time, complications (perforation, ledge formation, and apical transportation), and file distortions (unwinding, tip deformation, and instrument separation) were recorded.

The median procedural time for the endodontist (120 [95-142]) was significantly shorter than that for the resident (145 [117-162]) (p = 0.007). No statistically significant differences were observed between operators with regard to complications. The ProTaper Universal Retreatment system exhibited the lowest overall complication rates numerically. Additionally, both the FANTA AF Retreatment Files and the ProTaper Universal Retreatment system demonstrated a lower incidence of ledge formation when used by the resident; however, this difference did not reach statistical significance.

The endodontist completed the procedures faster than the endodontic resident. The ProTaper Universal Retreatment system showed the lowest overall number of complications across both operators. The FANTA AF Retreatment Files demonstrated the lowest incidence of ledge formation, whereas EndoArt Retreatment Gold exhibited the highest incidence.