Time Required to Retreat Carrier-Based Obturation: Comparison Between Two Techniques at Two Levels of Experience

This study aims to compare two techniques for the removal of Thermafil obturators, evaluating the influence of operator experience in two different typologies of samples. Methods: Sixty single-rooted extracted teeth with round canals and sixty 3D-printed teeth reproducing a maxillary central incisor were obturated with Thermafil obturators. Retreatment was undertaken under a dental operating microscope by an experienced endodontist and a novice operator using either the braiding technique or Reciproc. The removal time was recorded. Results: Considering natural teeth, seven failures were registered, and 60 carriers were removed successfully (90%). Removal time was significantly shorter for the experienced operator than for the novice (Braiding technique: p < 0.001; Reciproc: p = 0.001). No statistically significant difference emerged in the expert operator between braiding and reciprocating techniques (p = 0.403), while a longer carrier removal time emerged in the novice operator using the manual instrumentation (p = 0.019). Considering 3D-printed teeth, eight failures were registered, and 60 carriers were removed successfully (88%). There was no significant difference in removal time between novice and experienced operators. Carrier removal time was significantly lower in the braiding technique for the novice compared to the experienced operator (p = 0.017). This difference was not observed for the reciprocating instrumentation (p = 0.244). Regarding experience, in both operators, removal time was shorter with reciprocating instrumentation than with the braiding technique (p < 0.001). Conclusions: The braiding technique and Reciproc are effective in the retreatment of straight, round-section canals filled with Thermafil. Within the limits of this in vitro study, restoration of the working length can be undertaken quickly and with favourable outcomes. Experience significantly affects the removal time of carrier-based obturations. The removal technique did not influence retrieval time in the experienced operator, while the Reciproc proved to be an effective aid for the novice operator.